An efficient, cost effective and environmental friendly PEGylated magnetic nanoparticle catalyzed oxida-tive cyanation via CH activation of tertiary amines to corresponding -aminonitriles using hydrogenperoxide as oxidant and sodium cyanide as cyanide source is described. The synthesized nanocatalyst waseasily recovered with the help of external magnet and was successfully reused for several runs withoutany significant loss in catalytic activity.
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenesunitha81
The role of V and Mn incorporated mesoporous molecular sieves was
investigated for the vapor phase oxidation of o-xylene. Mesoporous monometallic
V-MCM-41 (Si/V = 25, 50, 75 and 100), Mn-MCM-41 (Si/Mn = 50) and bimetallic
V-Mn-MCM-41 (Si/(V ? Mn) = 100) molecular sieves were synthesized by
a direct hydrothermal (DHT) process and characterized by various techniques such
as X-ray diffraction, DRUV-Vis spectroscopy, EPR, and transmission electron
microscopy (TEM). From the DRUV-Vis and EPR spectral study, it was found that
most of the V species are present as vanadyl ions (VO2?) in the as-synthesized
catalysts and as highly dispersed V5? ions in tetrahedral coordination in the calcined
catalysts. The activity of the catalysts was measured and compared with each other
for the gas phase oxidation of o-xylene in the presence of atmospheric air as an
oxidant at 573 K. Among the various catalysts, V-MCM-41 with Si/V = 50
exhibited high activity towards production of phthalic anhydride under the experimental
condition. The correlation between the phthalic anhydride selectivity and
the physico-chemical characteristics of the catalyst was found. It is concluded that
V5? species present in the MCM-41 silica matrix are the active sites responsible for
the selective formation of phthalic anhydride during the vapor phase oxidation of
o-xylene.
Visible Light Photocatalytic Degradation of Methylene Blue and Malachite Gree...IJEAB
A facile solid state metathesis synthesis of barium tungstate (BaWO4) followed by ball milling and subsequent preparation of barium tungstate-graphene oxide (BaWO4–GO) nano composite using a colloidal blending process and its application as a visible light photocatalyst for the degradation of Malachite green and Methylene blue dyes. The morphology and composition of barium tungstate (BaWO4) nano composite have been characterized using X-Ray Diffraction (XRD), UV–Visible Diffuse Reflectance Spectra (UV-DRS), Raman Spectra, Field Emission Scanning Electron Microscopy (FESEM) – EDAX and UV Visible Spectroscopy. This composite material is found to be a wide band gap semiconductor with band gap of 4.3 eV. The sample shows poor transmittance in ultraviolet region while it has maximum transmittance in visible-near infrared regions. It shows an increase in range and intensity of light absorption and the reduction of electron–hole pair recombination in BaWO4 with the introducing of GO on to it.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...suresh899
Carbon Supported PtRu nanocatalysts have been prepared by simple impregnation reduction method in which Pt and Ru precursors are reduced by ethanol under reflux conditions for different reaction times. The prepared nanocatalysts were characterized by means of XRD, EDAX, ICP-AAS, FESEM and TEM. XRD analyses showed that all nanocatalysts exhibited f.c.c crystal structure, the structure characteristic for pure Pt, except for that reduced at prolonged reaction time of 4h which showed the presence of characteristic peak for Ru metal. The lattice constant calculations indicate that all catalysts are present in unalloyed phase and the average particle size as determined by TEM was in the range of 3.7 nm. The electrocatalytic activities and stability for the prepared nanocatalysts methanol electro-oxidation reaction (MOR) were studied by cyclic voltammetry. The catalysts prepared at 2h reduction time showed higher electrocatalytic activity in terms of mass specific activity and good stability over potential sweep for 100 cycles for methanol electro-oxidation. The results showed that the prepared nanocatalysts are considered as promising electrode catalyst (anode catalyst) for electro-oxidation of methanol in direct methanol fuel cells.
Selective Oxidation of Limonene over γ-Al2O3 Supported Metal Catalyst with H2O2Dr. Amarjeet Singh
Liquid phase oxidation of limonene by hydrogen
peroxide over the CeO2 and Fe2O3 catalysts supported by γAl2O3 was reported. Etly acetate and acetone were used as
solvent to investigate the effect of the solvent on the
oxidation reaction. The experiments were carried out at 80
°C The conversion of limonene and the selectivities of the
carvone were calculated during the 10h reaction time.
According to experimental results, maximum conversion of
limonene and product selectivity of carvone were obtained
with CeO2-γAl2O3 catalyst as 85% and 41%, respectively
end of the 10 h reaction. The XRD analysis of the CeO2-
γAl2O3 catalyst were performed.
Magnetic Fe3O4@MgAl–LDH composite grafted with cobalt phthalocyanine as an ef...Pawan Kumar
Magnetically separable layered double hydroxide MgAl–LDH@Fe3O4 composite supported cobalt
phthalocyanine catalyst was synthesized and used for the aerobic oxidation of mercaptans to corresponding
disulfides under alkali free conditions. The catalyst exhibited excellent activity for the oxidation of
mercaptans using molecular oxygen as an oxidant which can be effectively recovered by using an external
magnetic field. In addition, the covalent immobilization of cobalt phthalocyanine to MgAl–LDH@Fe3O4
support prevents the leaching of the catalyst and improves its activity and stability
Shift of Reaction Pathway by Added Chloride Ions in the Oxidation of Aromatic...Ratnakaram Venkata Nadh
Role of added chloride ions on the shift of reaction pathway of oxidation of aromatic ketones (acetophenone,
desoxybenzoin) by dichloroisocyanuric acid (DCICA) was studied in aqueous acetic acid—perchloric
acid medium. Participation of enolic and protonated forms of ketones in the rate determining steps is
manifested from zero and first orders with respect to the oxidant in absence and presence of added chloride
ions, respectively. Positive and negative effects of acid and dielectric constant on the reaction rate were
observed. The observations deduce plausible mechanisms involving (i) rate-determining formation of enol
from the conjugate acid of the ketone (SH+) in the absence of added chloride ions and (ii) rapid formation of
molecular chlorine species from HOCl (hydrolytic species of DCICA) in the presence of added chloride ions,
which then interacts with SH+ in a rate-determining step prior to the rapid steps of product formation. The
order of Arrhenius parameters substantiate the proposed plausible mechanisms based on order of reactants
both in presence and absence of added chloride ions.
V mn-mcm-41 catalyst for the vapor phase oxidation of o-xylenesunitha81
The role of V and Mn incorporated mesoporous molecular sieves was
investigated for the vapor phase oxidation of o-xylene. Mesoporous monometallic
V-MCM-41 (Si/V = 25, 50, 75 and 100), Mn-MCM-41 (Si/Mn = 50) and bimetallic
V-Mn-MCM-41 (Si/(V ? Mn) = 100) molecular sieves were synthesized by
a direct hydrothermal (DHT) process and characterized by various techniques such
as X-ray diffraction, DRUV-Vis spectroscopy, EPR, and transmission electron
microscopy (TEM). From the DRUV-Vis and EPR spectral study, it was found that
most of the V species are present as vanadyl ions (VO2?) in the as-synthesized
catalysts and as highly dispersed V5? ions in tetrahedral coordination in the calcined
catalysts. The activity of the catalysts was measured and compared with each other
for the gas phase oxidation of o-xylene in the presence of atmospheric air as an
oxidant at 573 K. Among the various catalysts, V-MCM-41 with Si/V = 50
exhibited high activity towards production of phthalic anhydride under the experimental
condition. The correlation between the phthalic anhydride selectivity and
the physico-chemical characteristics of the catalyst was found. It is concluded that
V5? species present in the MCM-41 silica matrix are the active sites responsible for
the selective formation of phthalic anhydride during the vapor phase oxidation of
o-xylene.
Visible Light Photocatalytic Degradation of Methylene Blue and Malachite Gree...IJEAB
A facile solid state metathesis synthesis of barium tungstate (BaWO4) followed by ball milling and subsequent preparation of barium tungstate-graphene oxide (BaWO4–GO) nano composite using a colloidal blending process and its application as a visible light photocatalyst for the degradation of Malachite green and Methylene blue dyes. The morphology and composition of barium tungstate (BaWO4) nano composite have been characterized using X-Ray Diffraction (XRD), UV–Visible Diffuse Reflectance Spectra (UV-DRS), Raman Spectra, Field Emission Scanning Electron Microscopy (FESEM) – EDAX and UV Visible Spectroscopy. This composite material is found to be a wide band gap semiconductor with band gap of 4.3 eV. The sample shows poor transmittance in ultraviolet region while it has maximum transmittance in visible-near infrared regions. It shows an increase in range and intensity of light absorption and the reduction of electron–hole pair recombination in BaWO4 with the introducing of GO on to it.
Electrooxidation of methanol on carbon supported pt ru nanocatalysts prepared...suresh899
Carbon Supported PtRu nanocatalysts have been prepared by simple impregnation reduction method in which Pt and Ru precursors are reduced by ethanol under reflux conditions for different reaction times. The prepared nanocatalysts were characterized by means of XRD, EDAX, ICP-AAS, FESEM and TEM. XRD analyses showed that all nanocatalysts exhibited f.c.c crystal structure, the structure characteristic for pure Pt, except for that reduced at prolonged reaction time of 4h which showed the presence of characteristic peak for Ru metal. The lattice constant calculations indicate that all catalysts are present in unalloyed phase and the average particle size as determined by TEM was in the range of 3.7 nm. The electrocatalytic activities and stability for the prepared nanocatalysts methanol electro-oxidation reaction (MOR) were studied by cyclic voltammetry. The catalysts prepared at 2h reduction time showed higher electrocatalytic activity in terms of mass specific activity and good stability over potential sweep for 100 cycles for methanol electro-oxidation. The results showed that the prepared nanocatalysts are considered as promising electrode catalyst (anode catalyst) for electro-oxidation of methanol in direct methanol fuel cells.
Selective Oxidation of Limonene over γ-Al2O3 Supported Metal Catalyst with H2O2Dr. Amarjeet Singh
Liquid phase oxidation of limonene by hydrogen
peroxide over the CeO2 and Fe2O3 catalysts supported by γAl2O3 was reported. Etly acetate and acetone were used as
solvent to investigate the effect of the solvent on the
oxidation reaction. The experiments were carried out at 80
°C The conversion of limonene and the selectivities of the
carvone were calculated during the 10h reaction time.
According to experimental results, maximum conversion of
limonene and product selectivity of carvone were obtained
with CeO2-γAl2O3 catalyst as 85% and 41%, respectively
end of the 10 h reaction. The XRD analysis of the CeO2-
γAl2O3 catalyst were performed.
Magnetic Fe3O4@MgAl–LDH composite grafted with cobalt phthalocyanine as an ef...Pawan Kumar
Magnetically separable layered double hydroxide MgAl–LDH@Fe3O4 composite supported cobalt
phthalocyanine catalyst was synthesized and used for the aerobic oxidation of mercaptans to corresponding
disulfides under alkali free conditions. The catalyst exhibited excellent activity for the oxidation of
mercaptans using molecular oxygen as an oxidant which can be effectively recovered by using an external
magnetic field. In addition, the covalent immobilization of cobalt phthalocyanine to MgAl–LDH@Fe3O4
support prevents the leaching of the catalyst and improves its activity and stability
Shift of Reaction Pathway by Added Chloride Ions in the Oxidation of Aromatic...Ratnakaram Venkata Nadh
Role of added chloride ions on the shift of reaction pathway of oxidation of aromatic ketones (acetophenone,
desoxybenzoin) by dichloroisocyanuric acid (DCICA) was studied in aqueous acetic acid—perchloric
acid medium. Participation of enolic and protonated forms of ketones in the rate determining steps is
manifested from zero and first orders with respect to the oxidant in absence and presence of added chloride
ions, respectively. Positive and negative effects of acid and dielectric constant on the reaction rate were
observed. The observations deduce plausible mechanisms involving (i) rate-determining formation of enol
from the conjugate acid of the ketone (SH+) in the absence of added chloride ions and (ii) rapid formation of
molecular chlorine species from HOCl (hydrolytic species of DCICA) in the presence of added chloride ions,
which then interacts with SH+ in a rate-determining step prior to the rapid steps of product formation. The
order of Arrhenius parameters substantiate the proposed plausible mechanisms based on order of reactants
both in presence and absence of added chloride ions.
A ruthenium-carbamato-complex derived from a siloxylated amine and carbon dio...Pawan Kumar
The rutheniumcarbamate complex derived from3-trimethoxysilyl-1-
propyl amine and carbon dioxidewas found to be a novel catalyst for
the oxidative cyanation of aromatic and cyclic tertiary amines to
corresponding a-amino nitriles in high to excellent yields by using
hydrogen peroxide and molecular oxygen as enviro-economic
oxidants. The developed protocol suggested an efficient alternative
for recycling carbon dioxide.
Visible light assisted photocatalytic reduction of CO2 using a graphene oxide...Pawan Kumar
A new heteroleptic ruthenium complex containing 2-thiophenyl benzimidazole ligands was synthesized
using a microwave technique and was immobilized to graphene oxide via covalent attachment. The synthesized
catalyst was used for the photoreduction of carbon dioxide under visible light irradiation without
using a sacrificial agent, which gave 2050 μmol g−1 cat methanol after 24 h of irradiation
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Removal of Coke during Steam Reforming of Ethanol over La-CoOx Catalystinventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
BY AMIT SHAH & SOHAM MULE, F.Y.B. PHARM, KMKCP.
PTC (PHASE TRANSFER CATALYSIS) A SMALL TOPIC IN 2ND SEMESTER OF B.PHARM IN POC - 1 UNDER THE TOPIC SN REACTIONS. PTC FAVOURS SN2 REACTIONS.
PTC IS THE PHASE TRANSFER CATALYSIS HERE TYPES OF PTC ARE DISCUSSED , THEORIES OF CATALYSIS AND MECHANISM OF PTC, ADVANTAGES OF PTC, APPLICATION OF PTC
A ruthenium-carbamato-complex derived from a siloxylated amine and carbon dio...Pawan Kumar
The rutheniumcarbamate complex derived from3-trimethoxysilyl-1-
propyl amine and carbon dioxidewas found to be a novel catalyst for
the oxidative cyanation of aromatic and cyclic tertiary amines to
corresponding a-amino nitriles in high to excellent yields by using
hydrogen peroxide and molecular oxygen as enviro-economic
oxidants. The developed protocol suggested an efficient alternative
for recycling carbon dioxide.
Visible light assisted photocatalytic reduction of CO2 using a graphene oxide...Pawan Kumar
A new heteroleptic ruthenium complex containing 2-thiophenyl benzimidazole ligands was synthesized
using a microwave technique and was immobilized to graphene oxide via covalent attachment. The synthesized
catalyst was used for the photoreduction of carbon dioxide under visible light irradiation without
using a sacrificial agent, which gave 2050 μmol g−1 cat methanol after 24 h of irradiation
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Visible light assisted reduction of nitrobenzenes using Fe(bpy)3+2/rGOnanocom...Pawan Kumar
Visible-light-induced photocatalytic reduction of aromatic nitrobenzenes to the corresponding anilinesat room temperature using reduced graphene oxide (rGO) immobilized iron(II) bipyridine complex asphotocatalyst is described. The rGO-immobilized iron catalyst exhibited superior catalytic activity thanhomogeneous iron(II) bipyridine complex and much higher than metal free rGO photocatalysts. Theheterogeneous photocatalyst was found to be robust and could easily be recovered and reused for severalruns without any significant loss in photocatalytic activity.
Removal of Coke during Steam Reforming of Ethanol over La-CoOx Catalystinventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
BY AMIT SHAH & SOHAM MULE, F.Y.B. PHARM, KMKCP.
PTC (PHASE TRANSFER CATALYSIS) A SMALL TOPIC IN 2ND SEMESTER OF B.PHARM IN POC - 1 UNDER THE TOPIC SN REACTIONS. PTC FAVOURS SN2 REACTIONS.
PTC IS THE PHASE TRANSFER CATALYSIS HERE TYPES OF PTC ARE DISCUSSED , THEORIES OF CATALYSIS AND MECHANISM OF PTC, ADVANTAGES OF PTC, APPLICATION OF PTC
Highly active pd and pd–au nanoparticles supported on functionalized graphene...
Similar to PEGylated magnetic nanoparticles (PEG@Fe3O4) as cost effectivealternative for oxidative cyanation of tertiary amines via C HactivationVineeta
Octahedral rhenium K4[Re6S8(CN)6] and Cu(OH)2cluster modifiedTiO2for the phot...Pawan Kumar
tOctahedral hexacyano rhenium K4[Re6S8(CN)6] cluster complexes were grafted onto photoactive Cu(OH)2cluster modified TiO2{Cu(OH)2/TiO2} support. The rhenium and copper cluster modified TiO2photocata-lyst combines the advantages of heterogeneous catalyst (facile recovery, recycling ability of the catalyst)with the reactivity, selectivity of the soluble molecular catalyst. The synthesized heterogeneous cata-lyst was found to be highly efficient photoredox catalyst for the reduction of CO2under visible lightirradiation. Methanol was found to be the major liquid product with the formation of hydrogen as a byproduct as determined with GC-FID and GC-TCD, respectively. The methanol yield after 24 h irradiationwas found to be 149 mol/0.1 g cat. for Re-cluster@Cu(OH)2/TiO2photocatalyst that is much higher than35 mol/0.1 g cat. for Cu(OH)2/TiO2and 75 mol/0.1 g cat. for equimolar rhenium cluster in the presenceof triethanolamine (TEOA) as a sacrificial donor. The quantum yields (MeOH) of Re-cluster@Cu(OH)2/TiO2and Cu(OH)2/TiO2were found to be 0.018 and 0.004 mol einstein−1, respectively. These values are muchhigher than those reported for other heterogeneous catalysts for six electron transfer reaction
Electro catalytic performance of pt-supported poly (o-phenylenediamine) micro...sunitha81
Poly (o-phenylenediamine) (PoPD) microrods were obtained by interfacial
polymerization using ferric chloride as oxidant and without any template or
functional dopant. Pt/PoPD nanocatalysts were prepared by the reduction of chloroplatinic
acid with sodium borohydride, and the composite catalysts formed were
characterized by X-ray diffraction and electrochemical methods. The nanocomposite
of Pt/PoPD microrods has been explored for their electro-catalytic performance
towards oxidation of methanol. The electro-catalytic activity of Pt/PoPD was
found to be much higher (current density 1.96 mA/cm2 at 0.70 V) in comparison to
Pt/Vulcan electrodes (the current density values of 1.56 mA/cm2 at 0.71 V) which
may be attributed to the microrod morphology of PoPD that facilitate the effective
dispersion of Pt particles and easier access of methanol towards the catalytic sites.
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after 24 h irradiation was 9934 μmol g−1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride 145 μmol g−1cat under identical conditions. The presence of triethylamine was found to be vital for the higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for subsequent six runs without significant loss in photo activity.
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used
for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after
24 h irradiation was 9934 mmol g1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a
sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride
145 mmol g1cat under identical conditions. The presence of triethylamine was found to be vital for the
higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for
subsequent six runs without significant loss in photo activity.
Metal-organic hybrid: Photoreduction of CO2 using graphitic carbon nitride su...Pawan Kumar
A novel heteroleptic iridium complex supported on graphitic carbon nitride was synthesized and used
for photoreduction of carbon dioxide under visible light irradiation. The methanol yield obtained after
24 h irradiation was 9934 mmol g1cat (TON 1241 with respect to Ir) by using triethylamine (TEA) as a
sacrificial donor, which was significantly higher as compared to the semiconductor carbon nitride
145 mmol g1cat under identical conditions. The presence of triethylamine was found to be vital for the
higher methanol yield. After the reaction, the photocatalyst could easily be recovered and reused for
subsequent six runs without significant loss in photo activity.
Nitrogen-doped graphene-supported copper complex: a novel photocatalyst for C...Pawan Kumar
A copper(II) complex grafted to nitrogen-doped graphene (GrN700–CuC) was synthesized and then
demonstrated as an efficient photocatalyst for CO2 reduction into methanol under visible light irradiation
using a DMF/water mixture. The chemical and microstructural features of GrN700–CuC nanosheets were
studied by FTIR, XPS, XRD and HRTEM analyses. Owing to its truly heterogeneous nature, GrN700–CuC
could be easily recovered after the photocatalytic reaction and showed efficient recyclability for
subsequent runs.
Similar to PEGylated magnetic nanoparticles (PEG@Fe3O4) as cost effectivealternative for oxidative cyanation of tertiary amines via C HactivationVineeta (20)
Isolated Iridium Sites on Potassium-Doped Carbon-nitride wrapped Tellurium Na...Pawan Kumar
Many industrial processes such transesterification of fatty acid for biodiesel production, soap manufacturing and biosynthesis of ethanol generate glycerol as a major by-product that can be used to produce commodity chemicals. Photocatalytic transformation of glycerol is an enticing approach that can exclude the need of harsh oxidants and extraneous thermal energy. However, the product yield and selectivity remain poor due to low absorption and unsymmetrical site distribution on the catalyst surface. Herein, tellurium (Te) nanorods/nanosheets (TeNRs/NSs) wrapped potassium-doped carbon nitride (KCN) van der Waal (vdW) heterojunction (TeKCN) is designed to enhance charge separation and visible-NIR absorption. The iridium (Ir) single atom sites decoration on the TeKCN core-shell structure (TeKCNIr) promotes selective oxidation of glycerol to glyceraldehyde with a conversion of 45.6% and selectivity of 61.6% under AM1.5G irradiation. The catalytic selectivity can reach up to 88% under 450 nm monochromatic light. X-ray absorption spectroscopy (XAS) demonstrates the presence of undercoordinated IrN2O2 sites which improved catalytic selectivity for glycol oxidation. Band energies and computational calculations reveal faile charge transfer in the TeKCNIr heterostructure. EPR and scavenger tests discern that superoxide (O2•−) and hydroxyl (•OH) radicals are prime components driving glycerol oxidation.
Isolated Iridium Sites on Potassium-Doped Carbon-nitride wrapped Tellurium Na...Pawan Kumar
Many industrial processes such transesterification of fatty acid for biodiesel production, soap manufacturing and biosynthesis of ethanol generate glycerol as a major by-product that can be used to produce commodity chemicals. Photocatalytic transformation of glycerol is an enticing approach that can exclude the need of harsh oxidants and extraneous thermal energy. However, the product yield and selectivity remain poor due to low absorption and unsymmetrical site distribution on the catalyst surface. Herein, tellurium (Te) nanorods/nanosheets (TeNRs/NSs) wrapped potassium-doped carbon nitride (KCN) van der Waal (vdW) heterojunction (TeKCN) is designed to enhance charge separation and visible-NIR absorption. The iridium (Ir) single atom sites decoration on the TeKCN core-shell structure (TeKCNIr) promotes selective oxidation of glycerol to glyceraldehyde with a conversion of 45.6% and selectivity of 61.6% under AM1.5G irradiation. The catalytic selectivity can reach up to 88% under 450 nm monochromatic light. X-ray absorption spectroscopy (XAS) demonstrates the presence of undercoordinated IrN2O2 sites which improved catalytic selectivity for glycol oxidation. Band energies and computational calculations reveal faile charge transfer in the TeKCNIr heterostructure. EPR and scavenger tests discern that superoxide (O2•−) and hydroxyl (•OH) radicals are prime components driving glycerol oxidation.
Isolated Iridium Sites on Potassium-Doped Carbon-nitride wrapped Tellurium Na...Pawan Kumar
Many industrial processes such transesterification of fatty acid for biodiesel production, soap manufacturing and biosynthesis of ethanol generate glycerol as a major by-product that can be used to produce commodity chemicals. Photocatalytic transformation of glycerol is an enticing approach that can exclude the need of harsh oxidants and extraneous thermal energy. However, the product yield and selectivity remain poor due to low absorption and unsymmetrical site distribution on the catalyst surface. Herein, tellurium (Te) nanorods/nanosheets (TeNRs/NSs) wrapped potassium-doped carbon nitride (KCN) van der Waal (vdW) heterojunction (TeKCN) is designed to enhance charge separation and visible-NIR absorption. The iridium (Ir) single atom sites decoration on the TeKCN core-shell structure (TeKCNIr) promotes selective oxidation of glycerol to glyceraldehyde with a conversion of 45.6% and selectivity of 61.6% under AM1.5G irradiation. The catalytic selectivity can reach up to 88% under 450 nm monochromatic light. X-ray absorption spectroscopy (XAS) demonstrates the presence of undercoordinated IrN2O2 sites which improved catalytic selectivity for glycol oxidation. Band energies and computational calculations reveal faile charge transfer in the TeKCNIr heterostructure. EPR and scavenger tests discern that superoxide (O2•−) and hydroxyl (•OH) radicals are prime components driving glycerol oxidation.
Solar-Driven Cellulose Photorefining into Arabinose over Oxygen-Doped Carbon ...Pawan Kumar
Biomass photorefining is a promising strategy to address the energy crisis and transition toward carbon carbon-neutral society. Here, we demonstrate the feasibility of direct cellulose photorefining into arabinose by a rationally designed oxygen-doped polymeric carbon nitride, which generates favorable oxidative species (e.g., O2–, •OH) for selective oxidative reactions at neutral conditions. In addition, we also illustrate the mechanism of the photocatalytic cellulose to arabinose conversion by density functional theory calculations. The oxygen insertion derived from oxidative radicals at the C1 position of glucose within cellulose leads to oxidative cleavage of β-1,4 glycosidic linkages, resulting in the subsequent gluconic acid formation. The following decarboxylation process of gluconic acid via C1–C2 α-scissions, triggered by surface oxygen-doped active sites, generates arabinose and formic acid, respectively. This work not only offers a mechanistic understanding of cellulose photorefining to arabinose but also sets up an example for illuminating the path toward direct cellulose photorefining into value-added bioproducts under mild conditions.
Solar-Driven Cellulose Photorefining into Arabinose over Oxygen-Doped Carbon ...Pawan Kumar
Biomass photorefining is a promising strategy to address the energy crisis and transition toward carbon carbon-neutral society. Here, we demonstrate the feasibility of direct cellulose photorefining into arabinose by a rationally designed oxygen-doped polymeric carbon nitride, which generates favorable oxidative species (e.g., O2–, •OH) for selective oxidative reactions at neutral conditions. In addition, we also illustrate the mechanism of the photocatalytic cellulose to arabinose conversion by density functional theory calculations. The oxygen insertion derived from oxidative radicals at the C1 position of glucose within cellulose leads to oxidative cleavage of β-1,4 glycosidic linkages, resulting in the subsequent gluconic acid formation. The following decarboxylation process of gluconic acid via C1–C2 α-scissions, triggered by surface oxygen-doped active sites, generates arabinose and formic acid, respectively. This work not only offers a mechanistic understanding of cellulose photorefining to arabinose but also sets up an example for illuminating the path toward direct cellulose photorefining into value-added bioproducts under mild conditions.
Solar-Driven Cellulose Photorefining into Arabinose over Oxygen-Doped Carbon ...Pawan Kumar
Biomass photorefining is a promising strategy to address the energy crisis and transition toward carbon carbon-neutral society. Here, we demonstrate the feasibility of direct cellulose photorefining into arabinose by a rationally designed oxygen-doped polymeric carbon nitride, which generates favorable oxidative species (e.g., O2–, •OH) for selective oxidative reactions at neutral conditions. In addition, we also illustrate the mechanism of the photocatalytic cellulose to arabinose conversion by density functional theory calculations. The oxygen insertion derived from oxidative radicals at the C1 position of glucose within cellulose leads to oxidative cleavage of β-1,4 glycosidic linkages, resulting in the subsequent gluconic acid formation. The following decarboxylation process of gluconic acid via C1–C2 α-scissions, triggered by surface oxygen-doped active sites, generates arabinose and formic acid, respectively. This work not only offers a mechanistic understanding of cellulose photorefining to arabinose but also sets up an example for illuminating the path toward direct cellulose photorefining into value-added bioproducts under mild conditions.
Partial Thermal Condensation Mediated Synthesis of High-Density Nickel Single...Pawan Kumar
Direct selective transformation of greenhouse methane (CH4) to liquid oxygenates (methanol) can substitute energy-intensive two-step (reforming/Fischer–Tropsch) synthesis while creating environmental benefits. The development of inexpensive, selective, and robust catalysts that enable room temperature conversion will decide the future of this technology. Single-atom catalysts (SACs) with isolated active centers embedded in support have displayed significant promises in catalysis to drive challenging reactions. Herein, high-density Ni single atoms are developed and stabilized on carbon nitride (NiCN) via thermal condensation of preorganized Ni-coordinated melem units. The physicochemical characterization of NiCN with various analytical techniques including HAADF-STEM and X-ray absorption fine structure (XAFS) validate the successful formation of Ni single atoms coordinated to the heptazine-constituted CN network. The presence of uniform catalytic sites improved visible absorption and carrier separation in densely populated NiCN SAC resulting in 100% selective photoconversion of (CH4) to methanol using H2O2 as an oxidant. The superior catalytic activity can be attributed to the generation of high oxidation (NiIII═O) sites and selective C─H bond cleavage to generate •CH3 radicals on Ni centers, which can combine with •OH radicals to generate CH3OH.
Partial Thermal Condensation Mediated Synthesis of High-Density Nickel Single...Pawan Kumar
Direct selective transformation of greenhouse methane (CH4) to liquid oxygenates (methanol) can substitute energy-intensive two-step (reforming/Fischer–Tropsch) synthesis while creating environmental benefits. The development of inexpensive, selective, and robust catalysts that enable room temperature conversion will decide the future of this technology. Single-atom catalysts (SACs) with isolated active centers embedded in support have displayed significant promises in catalysis to drive challenging reactions. Herein, high-density Ni single atoms are developed and stabilized on carbon nitride (NiCN) via thermal condensation of preorganized Ni-coordinated melem units. The physicochemical characterization of NiCN with various analytical techniques including HAADF-STEM and X-ray absorption fine structure (XAFS) validate the successful formation of Ni single atoms coordinated to the heptazine-constituted CN network. The presence of uniform catalytic sites improved visible absorption and carrier separation in densely populated NiCN SAC resulting in 100% selective photoconversion of (CH4) to methanol using H2O2 as an oxidant. The superior catalytic activity can be attributed to the generation of high oxidation (NiIII═O) sites and selective C─H bond cleavage to generate •CH3 radicals on Ni centers, which can combine with •OH radicals to generate CH3OH.
Selective Cellobiose Photoreforming for Simultaneous Gluconic Acid and Syngas...Pawan Kumar
Here, we demonstrate the selective cellobiose (building block of cellulose) photoreforming for gluconic acid and syngas co-production in acidic conditions by rationally designing a bifunctional polymeric carbon nitride (CN) with potassium/sulfur co-dopant. This heteroatomic doped CN photocatalyst possesses enhanced visible light absorption, higher charge separation efficiency than pristine CN. Under acidic conditions, cellobiose is not only more efficiently hydrolyzed into glucose but also promotes the syngas and gluconic acid production. Density functional theory (DFT) calculations reveal the favorable generation of •O2− during the photocatalytic reaction, which is essential for gluconic acid production. Consequently, the fine-designed photocatalyst presents excellent cellobiose conversion (>80%) and gluconic acid selectivity (>70%) together with the co-production of syngas (~56 μmol g-1 h-1) under light illumination. The current work demonstrates the feasibility of biomass photoreforming with value-added chemicals and syngas co-production under mild condition.
Selective Cellobiose Photoreforming for Simultaneous Gluconic Acid and Syngas...Pawan Kumar
Here, we demonstrate the selective cellobiose (building block of cellulose) photoreforming for gluconic acid and syngas co-production in acidic conditions by rationally designing a bifunctional polymeric carbon nitride (CN) with potassium/sulfur co-dopant. This heteroatomic doped CN photocatalyst possesses enhanced visible light absorption, higher charge separation efficiency than pristine CN. Under acidic conditions, cellobiose is not only more efficiently hydrolyzed into glucose but also promotes the syngas and gluconic acid production. Density functional theory (DFT) calculations reveal the favorable generation of •O2− during the photocatalytic reaction, which is essential for gluconic acid production. Consequently, the fine-designed photocatalyst presents excellent cellobiose conversion (>80%) and gluconic acid selectivity (>70%) together with the co-production of syngas (~56 μmol g-1 h-1) under light illumination. The current work demonstrates the feasibility of biomass photoreforming with value-added chemicals and syngas co-production under mild condition.
Selective Cellobiose Photoreforming for Simultaneous Gluconic Acid and Syngas...Pawan Kumar
Here, we demonstrate the selective cellobiose (building block of cellulose) photoreforming for gluconic acid and syngas co-production in acidic conditions by rationally designing a bifunctional polymeric carbon nitride (CN) with potassium/sulfur co-dopant. This heteroatomic doped CN photocatalyst possesses enhanced visible light absorption, higher charge separation efficiency than pristine CN. Under acidic conditions, cellobiose is not only more efficiently hydrolyzed into glucose but also promotes the syngas and gluconic acid production. Density functional theory (DFT) calculations reveal the favorable generation of •O2− during the photocatalytic reaction, which is essential for gluconic acid production. Consequently, the fine-designed photocatalyst presents excellent cellobiose conversion (>80%) and gluconic acid selectivity (>70%) together with the co-production of syngas (~56 μmol g-1 h-1) under light illumination. The current work demonstrates the feasibility of biomass photoreforming with value-added chemicals and syngas co-production under mild condition.
Partial Thermal Condensation Mediated Synthesis of High-Density Nickel Single...Pawan Kumar
Direct selective transformation of greenhouse methane (CH4) to liquid oxygenates (methanol) can substitute energy-intensive two-step (reforming/Fischer–Tropsch) synthesis while creating environmental benefits. The development of inexpensive, selective, and robust catalysts that enable room temperature conversion will decide the future of this technology. Single-atom catalysts (SACs) with isolated active centers embedded in support have displayed significant promises in catalysis to drive challenging reactions. Herein, high-density Ni single atoms are developed and stabilized on carbon nitride (NiCN) via thermal condensation of preorganized Ni-coordinated melem units. The physicochemical characterization of NiCN with various analytical techniques including HAADF-STEM and X-ray absorption fine structure (XAFS) validate the successful formation of Ni single atoms coordinated to the heptazine-constituted CN network. The presence of uniform catalytic sites improved visible absorption and carrier separation in densely populated NiCN SAC resulting in 100% selective photoconversion of (CH4) to methanol using H2O2 as an oxidant. The superior catalytic activity can be attributed to the generation of high oxidation (NiIII═O) sites and selective C─H bond cleavage to generate •CH3 radicals on Ni centers, which can combine with •OH radicals to generate CH3OH.
Recent advancements in tuning the electronic structures of transitional metal...Pawan Kumar
The smooth transition from finite non-renewables to renewable energy conversion technologies will require efficient electrocatalysts which can harness intermittent energies to store in the form of chemical bonds. The oxygen evolution reaction (OER) impedes the widespread usage of water electrolyzers to convert H2O into H2 and persists as a bottleneck, including other energy conversion devices with sluggish four H+/e− kinetics. In this context, designing highly active and stable catalysts capable of driving a lower overpotential in the OER to produce continuous hydrogen (H2) is a primary demanded. This chapter discussed the mechanism of the OER in conventional adsorbate oxygen and lattice oxygen participation in transition metal oxides (TMOs). Further, the influences of surface engineering, doping, and defects in the TMOs and understanding the electronic structure to screen electrodes towards the structure–activity relationship are highlighted. Specifically, the adsorption strength of O 2p is understood in detail as its binding ability over the surface of TMOs can be correlated directly to the OER activity. The iterative development of TMOs in terms of understanding electronic structural attributes is essential for the commercial deployment of energy conversion technologies. The comprehensive outlook of this chapter investigates thoroughly how TMOs can be used as significant materials for the OER in the near future.
Hole transport materials (HTMs) have a significant impact on the effectiveness of organic electronic devices; therefore, we present a molecular architecture of pyrazino[2,3-g]quinoxaline (PQ10)-based room-temperature organic liquid crystalline semiconductor (OLCS) as an alternative HTM. The PQ10 compound exhibits three different rectangular columnar (Colr) phases offering an impressive hole mobility of 8.8 × 10−3 cm2V−1s−1 which is found to be dexterous than most of existing polymeric hole transport materials. The charge transport mechanism is governed by the hole polarons hopping through H-aggregates of the PQ10 molecules and the hole mobility remains nearly constant throughout the mesophase range, but it decreases with increasing applied electric field. The current-voltage characteristics of the PQ10 have also been investigated in all three Colr phases and explained via the Poole-Frenkel conduction mechanism. The dielectric spectroscopy has been eventually carried out to understand the nature of dielectric permittivity and conductivity as a function of temperature and a correlation is established between the molecular architecture of the Colr phases and aforementioned physical properties. Solar cell simulation has been additionally performed to demonstrate that the PQ10 material can be a better choice as HTM for organic electronics and photovoltaic applications.
Multifunctional carbon nitride nanoarchitectures for catalysisPawan Kumar
Catalysis is at the heart of modern-day chemical and pharmaceutical industries, and there is an urgent demand to develop metal-free, high surface area, and efficient catalysts in a scalable, reproducible and economic manner. Amongst the ever-expanding two-dimensional materials family, carbon nitride (CN) has emerged as the most researched material for catalytic applications due to its unique molecular structure with tunable visible range band gap, surface defects, basic sites, and nitrogen functionalities. These properties also endow it with anchoring capability with a large number of catalytically active sites and provide opportunities for doping, hybridization, sensitization, etc. To make considerable progress in the use of CN as a highly effective catalyst for various applications, it is critical to have an in-depth understanding of its synthesis, structure and surface sites. The present review provides an overview of the recent advances in synthetic approaches of CN, its physicochemical properties, and band gap engineering, with a focus on its exclusive usage in a variety of catalytic reactions, including hydrogen evolution reactions, overall water splitting, water oxidation, CO2 reduction, nitrogen reduction reactions, pollutant degradation, and organocatalysis. While the structural design and band gap engineering of catalysts are elaborated, the surface chemistry is dealt with in detail to demonstrate efficient catalytic performances. Burning challenges in catalytic design and future outlook are elucidated.
Production of Renewable Fuels by the Photocatalytic Reduction of CO2 using Ma...Pawan Kumar
The photo-reductive performance of natural ilmenite was boosted and the production of renewable fuels from the reduction of CO2 was enhanced by doping the natural mineral with magnesium. The doping was achieved by high energy ball milling in the presence of MgO and Mg(NO3)2. The photo-reduction of CO2 in aqueous solution led to the evolution of H2, CH4, C2H4, and C2H6, and the insertion of Mg in the structure of ilmenite enabled increases of up to 1245% in the fuel production yield, reaching total production of 210.9 µmol h-1 gcat-1. Displacements of the conduction band to more negative potentials were evidenced for the samples doped with magnesium. Indirect effects such as increases in the valence band maximum, and the introduction of intermediate energy levels were also evidenced through the measurement of the crystallite size and the determination of the band structure of the materials. Mott-Schottky analyses of the samples showed the n-type nature of the semiconductor materials and enabled the estimation of the density of charge carriers, which strongly influenced the photocatalytic performance. The strong potential of the application of natural ilmenite in gas phase artificial photosynthesis was proved by the evaluation of CO2 reduction in gas conditions, which allowed the enhancement in the selectivity and significantly increased the production of CH4 as compared to aqueous solution, reaching an important yield of CH4 of 16.1 µmol h-1 gcat-1.
Nanoengineered Au-Carbon Nitride Interfaces Enhance PhotoCatalytic Pure Water...Pawan Kumar
Photocatalytic pure water splitting using solar energy is one of the promising routes to produce sustainable green hydrogen (H2). Tuning the interfacial active site density at catalytic heterojunctions and better light management are imperative to steer the structure-activity correlations to enhance the photo-efficiency of nanocomposite photocatalysts. Herein, we report the decoration of nitrogen defects-rich carbon nitride CN(T) with metallic Au nanostructures of different morphologies and sizes to investigate their influence on the photocatalytic hydrogen evolution reactions (HER). The CN(T)-7-NP nano-heterostructure comprises Au nanoparticles (NPs) of ~7 nm and thiourea-derived defective CN exhibits an excellent H2 production rate of 76.8 µmol g–1 h–1 from pure water under simulated AM 1.5 solar irradiation. In contrast to large-size Au nanorods, the high activity of CN(T)-7-NP was attributed to their strong localized surface plasmon resonance (LSPR) mediated visible absorption and interfacial charge separation. The surface ligands used to control Au nanostructures morphology were found to play a major role in the stabilization of NPs and improve interfacial charge transport between Au NPs and CN(T). First-principles calculations revealed that defects in CN and Au-CN interfacial sites in these nanocomposites facilitate the separation of e-/h+ pairs after light excitation and provide lower energy barrier pathways for H2 production by photocatalytic water splitting.
Nanoengineered Au-Carbon Nitride Interfaces Enhance Photo-Catalytic Pure Wate...Pawan Kumar
Photocatalytic pure water splitting using solar energy is one of the promising routes to produce sustainable green hydrogen (H2). Tuning the interfacial active site density at catalytic heterojunctions and better light management are imperative to steer the structure-activity correlations to enhance the photo-efficiency of nanocomposite photocatalysts. Herein, we report the decoration of nitrogen defects-rich carbon nitride CN(T) with metallic Au nanostructures of different morphologies and sizes to investigate their influence on the photocatalytic hydrogen evolution reactions (HER). The CN(T)-7-NP nano-heterostructure comprises Au nanoparticles (NPs) of ~7 nm and thiourea-derived defective CN exhibits an excellent H2 production rate of 76.8 µmol g–1 h–1 from pure water under simulated AM 1.5 solar irradiation. In contrast to large-size Au nanorods, the high activity of CN(T)-7-NP was attributed to their strong localized surface plasmon resonance (LSPR) mediated visible absorption and interfacial charge separation. The surface ligands used to control Au nanostructures morphology were found to play a major role in the stabilization of NPs and improve interfacial charge transport between Au NPs and CN(T). First-principles calculations revealed that defects in CN and Au-CN interfacial sites in these nanocomposites facilitate the separation of e-/h+ pairs after light excitation and provide lower energy barrier pathways for H2 production by photocatalytic water splitting.
Cooperative Copper Single Atom Catalyst in Two-dimensional Carbon Nitride for...Pawan Kumar
Renewable electricity powered carbon dioxide (CO2) reduction (eCO2R) to high-value fuels like methane (CH4) holds the potential to close the carbon cycle at meaningful scales. However, this kinetically staggered 8-electron multistep reduction still suffers from inadequate catalytic efficiency and current density. Atomic Cu-structures can boost eCO2R-to-CH4 selectivity due to enhanced intermediate binding energies (BEs) resulting from favorably shifted d-band centers. Herein, we exploit two-dimensional carbon nitride (CN) matrices, viz. Na-polyheptazine (PHI) and Li-polytriazine imides (PTI), to host Cu-N2 type single atom sites with high density (∼1.5 at%), via a facile metal ion exchange process. Optimized Cu loading in nanocrystalline Cu-PTI maximizes eCO2R-to-CH4 performance with Faradaic efficiency (FECH4) of ≈68% and a high partial current density of 348 mA cm−2 at a low potential of -0.84 V versus RHE, surpassing the state-of-the-art catalysts. Multi-Cu substituted N-appended nanopores in the CN frameworks yield thermodynamically stable quasi-dual/triple sites with large interatomic distances dictated by the pore dimensions. First-principles calculations elucidate the relative Cu-CN cooperative effects between the two matrices and how the Cu-Cu distance and local environment dictate the adsorbate BEs, density of states, and CO2-to-CH4 energy profile landscape. The 9N pores in Cu-PTI yield cooperative Cu-Cu sites that synergistically enhance the kinetics of the rate-limiting steps in the eCO2R-to-CH4 pathway.
Bioinspired multimetal electrocatalyst for selective methane oxidationPawan Kumar
Selective partial electrooxidation of methane (CH4) to liquid oxygenates has been a long-sought goal. However, the high activation energy of C–H bonds and competing oxygen evolution reaction limit product selectivity and reaction rates. Inspired by iron (IV)-oxo containing metalloenzymes’ functionality to activate the C–H bond, here we report on the design of a copper-iron-nickel catalyst for selective oxidation of CH4 to formate via a peroxide-assisted pathway. Each catalyst serves a specific role which is confirmed via electrochemical, in situ, and theoretical studies. A combination of electrochemical and in situ spectroelectrochemical studies revealed that H2O2 oxidation on nickel led to the formation of active oxygen species which trigger the formation of iron (IV) at low voltages. Density functional theory analysis helped reveal the role of iron (IV)-oxo species in reducing the activation energy barrier for CH4 deprotonation and the critical role of copper to suppress overoxidation. Our multimetal catalyst exhibits a formate faradaic efficiency of 42% at an applied potential of 0.9 V versus a reversible hydrogen electrode.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
ISI 2024: Application Form (Extended), Exam Date (Out), EligibilitySciAstra
The Indian Statistical Institute (ISI) has extended its application deadline for 2024 admissions to April 2. Known for its excellence in statistics and related fields, ISI offers a range of programs from Bachelor's to Junior Research Fellowships. The admission test is scheduled for May 12, 2024. Eligibility varies by program, generally requiring a background in Mathematics and English for undergraduate courses and specific degrees for postgraduate and research positions. Application fees are ₹1500 for male general category applicants and ₹1000 for females. Applications are open to Indian and OCI candidates.
DERIVATION OF MODIFIED BERNOULLI EQUATION WITH VISCOUS EFFECTS AND TERMINAL V...Wasswaderrick3
In this book, we use conservation of energy techniques on a fluid element to derive the Modified Bernoulli equation of flow with viscous or friction effects. We derive the general equation of flow/ velocity and then from this we derive the Pouiselle flow equation, the transition flow equation and the turbulent flow equation. In the situations where there are no viscous effects , the equation reduces to the Bernoulli equation. From experimental results, we are able to include other terms in the Bernoulli equation. We also look at cases where pressure gradients exist. We use the Modified Bernoulli equation to derive equations of flow rate for pipes of different cross sectional areas connected together. We also extend our techniques of energy conservation to a sphere falling in a viscous medium under the effect of gravity. We demonstrate Stokes equation of terminal velocity and turbulent flow equation. We look at a way of calculating the time taken for a body to fall in a viscous medium. We also look at the general equation of terminal velocity.
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
2. 26 V. Panwar et al. / Applied Catalysis A: General 498 (2015) 25–31
Scheme 1. PEGylated magnetic nanoparticles catalyzed oxidative cyanation of ter-
tiary amines.
25% of ammonia), succinic acid (>99%), polyethylene gly-
col (PEG-300) N-(3-dimethylaminopropyl)-N -ethylcarbodiimide
hydrochloride (EDC) and ion exchange resin (Indion 130) was pur-
chased from Aldrich were of analytical grade and used without
further purification. Acetone, methanol was all analytical grade
reagents and stored in cold and dark. Distilled water was used
throughout. Hydrogen peroxide (35%) and ethanol was of analyti-
cal grade and procured from Alfa Aesar. All other chemicals were
of A.R. grade and used without further purification.
2.2. Techniques used
The rough surface morphology of the synthesized catalyst was
determined with the help of scanning electron microscopy (SEM)
by using Jeol Model JSM-6340F. Inner fine structure of sam-
ples was determined with high resolution transmission electron
microscopy using FEI-TecnaiG2 TwinTEM operating at an accel-
eration voltage of 200 kV. The samples for TEM analysis were
made by depositing very dilute aqueous suspension of samples
on carbon coated TEM grid. Phase structure and crystalline state
of material was determined on Bruker D8 Advance diffractome-
ter at 40 kV and 40 mA with Cu K␣ radiation ( = 0.15418 nm).
For XRD, samples were prepared on glass slide by adding well
dispersed catalyst in slot and drying properly. Solid UV–visible
spectra of samples were collected on Perkin Elmer lambda-19
UV–vis–NIR spectrophotometer using a 10 mm quartz cell, using
BaSO4 as reference. The functional groups entities were confirmed
by Fourier transform infrared spectra using Perkin–Elmer spectrum
RX-1 IR spectrophotometer having Potassium bromide window.
Nitrogen adsorption desorption isotherm was used for calculat-
ing surface properties like Brunauer–Emmet–Teller (SBET) surface
area, Barret–Joiner–Halenda (BJH) porosity (rp), pore volume (VP)
of samples at 77 K by using VP; Micromeritics ASAP2010. The ther-
mal degradation pattern of samples for calculating amount of PEG
loading on Fe3O4 nanoparticles was estimated by thermo gravi-
metric analyses (TGA) using a thermal analyzer TA-SDT Q-600. The
TGA analysis was carried out in the temperature range of 40–800 ◦C
under nitrogen flow with heating rate 10 ◦C/min. 1H NMR and 13C
NMR spectra of the cyanation products were recorded at 500 MHz
by using Bruker Avance-II 500 MHz instrument.
2.3. Synthesis of Fe3O4 nanoparticles [42]
The Fe3O4 magnetic nanoparticles were synthesized by co-
precipitation of Fe+2 and Fe+3 solutions under alkaline conditions.
In brief 1.99 g (10 mmol) of FeCl2·4H2O and 3.24 g (12 mmol) of
FeCl3·6H2O were dissolved in 50 mL of distilled water. A separate
solution of NH4OH was made by dissolving 30 mL NH4OH (25%
ammonia) in 50 mL of distilled water. Both the solutions in the
beaker were allowed to stir for about half an hour, to achieve uni-
form mixing. After that NH4OH solution was added drop wise into
the first solution till a pH of 9 is obtained. The obtained solution
was stirred continuously that generates magnetic nanoparticles.
The obtained precipitates were separate with the help of external
magnet and washed with distilled water and ethanol and dried at
120 ◦C overnight then grinded. Finally the black coloured iron oxide
nanoparticles were obtained.
2.4. Succinic acid functionalized Fe3O4 nanoparticles [43]
To getting succinic acid functionalized Fe3O4, succinic acid
(2.4 g) was added to an aqueous solution of Fe3O4 nanoparticles
(150 mL, 0.3 mg) and this reaction mixture was allowed to stir for
24 h under vigorous stirring. The synthesized succinic acid func-
tionalized Fe3O4 nanoparticles were recovered by external magnet
and washed with water continuously to wash away unreacted suc-
cinic acid.
2.5. Synthesis of PEGylated magnetic nanoparticles (PEG@Fe3O4)
EDC (120 mg, 0.6 mmol) and ion exchanger (180 mg, 1.5 mmol)
were added to an aqueous solution of Fe3O4–succinic acid nanopar-
ticles (25 mL, 60 mg) and the mixture was stirred for 30 min at room
temperature. Afterwards, PEG-300 (3.33 mL) was added to the reac-
tion mixture and stirred for 24 h at room temperature. Finally,
Fe3O4–succinic acid–PEG nanoparticles were recovered and puri-
fied as above by means of three steps of magnetic separation,
removal of the supernatant and washing with water to obtain 1.2 g
of Fe3O4–succinic acid–PEG nanoparticles as a black powder.
2.6. General experimental procedure
For the cyanation reaction, tertiary amine (1 mmol), NaCN
(1.2 mmol), MeOH (4 mL), catalyst (0.1 g), and AcOH (1 mL) was
charged in a 25 mL round bottomed flask equipped with a magnetic
stirrer. Aqueous hydrogen peroxide (2.5 mmol, 35 wt%) was added
drop wise over a period of 30 min to the resulting stirred reaction
mixture, and the stirring was continued at room temperature. The
progress of reaction was monitored by TLC. After completion of
the reaction, the catalyst was recovered by an external magnet.
Dichloromethane was added in the obtained solution. The organic
layer was washed with water, dried over anhydrous Na2SO4 and
concentrated under vacuum to give crude product, which was
purified by flash chromatography to afford pure ␣-aminonitrile.
The product of cyanation of tertiary amines to corresponding ␣-
aminonitriles was identified with the help of GC–MS (EI quadrupol
mass analyzer, EM detector) by comparing their spectral data with
authentic samples. The yield and selectivity of product was also
determined with GC–MS.
3. Results and discussion
3.1. Synthesis and characterization of catalyst
The magnetic Fe3O4 nanoparticles were synthesized by using
co-precipitation method by mixing of acidic solution of Fe+2,
Fe+3 and dropping it in a weak alkaline solution as following
the literature procedure [42]. The obtained Fe3O4 nanoparticles
were subsequently functionalized with succinic acid as a linker to
provide active COOH groups for ester bond formation with PEG
[43]. Thus obtained succinic acid modified magnetic nanoparticles
were treated with polyethylene glycol (PEG300) in the pres-
ence of EDC (N-(3-dimethylaminopropyl)-N -ethylcarbodiimide
hydrochloride) and ion exchanger (Indion 130) as shown in
Scheme 2.
The rough surface morphology of magnetic nanoparticles
(Fe3O4) and PEG@Fe3O4 catalyst was determined by scanning elec-
tron microscopy (SEM) as shown in Fig. 1. The SEM image of Fe3O4
confirmed that small sized particles in the range of 50–100 nm
were obtained (Fig. 1a). However, in case of PEGylated nanoparti-
cles some lumps type morphology was observed, which is probably
due to the coating of magnetic nanoparticles with PEG molecules
(Fig. 1b). The EDX pattern of Fe3O4 nanoparticles (Fig. 1c) gave sharp
3. V. Panwar et al. / Applied Catalysis A: General 498 (2015) 25–31 27
Scheme 2. Synthesis of PEGylated magnetic nanoparticles (PEG@Fe3O4).
peaks of iron, which was found to be decreased significantly after
coating with PEG molecules (Fig. 1d).
The fine structure of Fe3O4 nanoparticles and PEG@Fe3O4 was
executed with TEM. TEM image of Fe3O4 showed that most of the
nanoparticles were of spherical in shape and are in 10–25 nm in size
(Fig. 2a). After the coating of PEG the spherical geometry remained
intact, however the surface has become rough which is assumed
due to the coating of magnetic nanoparticles with PEG (Fig. 2b).
The bright spots in SAED pattern clearly indicated that crystalline
nature of Fe3O4 remained intact during the coating step (Fig. 2c).
FT-IR spectra of Fe3O4 (Fig. 3a) showed characteristic peaks at
574 cm−1 and 1384 cm−1 due to Fe O bending and Fe O stretch
vibrations. The peak at 1627 cm−1 was attributed to the bending
vibration of water adsorbed on the surface of Fe3O4. The peak
at 3415 cm−1 was appeared due to the OH present on the sur-
face of Fe3O4 nanoparticles [44,45]. The FT-IR spectra of PEG300
showed its characteristic vibrations at 3405 cm−1 and 1403 cm−1
due to the OH stretching and bending vibration respectively along
with at 2918 cm−1 (C H stretch), 1595 cm−1 ( COO stretch),
1460 cm−1 (C H bending and scissoring), 1342 cm−1 ( OH bend-
ing), 1209 cm−1 (C O stretch), and 1164 cm−1 ( C O C stretch)
and other peaks in fingerprint region (Fig. 3b) [46,47]. The presence
of characteristic peaks of PEG in the FTIR spectra of PEG@Fe3O4
further confirmed the successful formation of PEGylated magnetic
Fe3O4 nanoparticles (Fig. 3c).
XRD diffractogram of Fe3O4 showed the characteristic peaks at
2Â value 30.28◦ (2 2 0), 35.48◦ (3 1 1), 43.36◦ (4 0 0), 54.04◦ (4 2 2),
57.28◦ (5 1 1) and 62.96◦ (4 4 0) that were matched well with JCPDS
card No. 65–3107 (Fig. 4a) [48–50]. The high intensity of peaks con-
firmed the crystalline nature of the magnetic Fe3O4 nanoparticles.
While in PEGylated magnetic (PEG@Fe3O4) nanoparticles the peaks
of Fe3O4 at 35.48◦ (3 1 1), 43.36◦ (4 0 0), 57.28◦ (5 1 1) and 62.96◦
(4 4 0) were observed but the intensity of peaks was significantly
reduced due to coating of amorphous PEG on the surface of Fe3O4
(Fig. 4b).
Nitrogen adsorption desorption isotherm was used for deter-
mining the surface properties. For Fe3O4 the loop of isotherm was
of type (IV) confirms the mesoporous nature of material (Fig. 5a)
[51] BET surface area (SBET), total pore volume (VP) and mean pore
diameter (rp) for Fe3O4 was found to be 53.24 m2 g−1, 0.12 cm3 g−1
and 2.58 nm respectively. For PEG@Fe3O4 the isotherm was type
(IV) and BET surface area (SBET), total pore volume (VP) and
mean pore diameter (rp) for Fe3O4 was found to be 83.93 m2 g−1,
0.3759 cm3 g−1 and 7.98 nm respectively (Fig. 5b). This change in
surface properties was assumed due to coating of PEG on the sur-
face of Fe3O4 nanoparticles the rough surface provides more pore
for the adsorption of nitrogen.
Solid UV–visible absorption spectra of magnetic Fe3O4 nanopar-
ticles gave a broad absorption pattern from 200 to 600 nm, which
is attributed to the d-orbital transitions of Fe3O4 (Fig. 6a) [52]. In
case of PEGyted Fe3O4 nanoparticles, the intensity of absorption
pattern was increased, but there was no specific absorption band
was appeared due to absence of conjugation in PEG (Fig. 6b). The
increased intensity of absorption in PEG@Fe3O4 was assumed due
to mixed transition of composite.
Thermal degradation behaviour of the synthesized Fe3O4
nanoparticles and PEGylated Fe3O4 nanoparticles was elucidated
by TGA (Fig. 7). Because the TG was measured at N2 atmosphere, the
oxidation of Fe3O4 NPs was greatly reduced. The weight loss below
200 ◦C could be attributed to the adsorbed water in the samples
(Fig. 7a) [53]. In PEGylated Fe3O4 nanoparticles a sharp decrease in
weight loss between 200 and 800 ◦C was observed as compared to
neat Fe3O4 NPs. The main weigh loss at 200–350 ◦C and 450–800 ◦C
could be attributed to first decomposition and second decomposi-
tion of organic components, which were presented on the surface
of Fe3O4 NPs (Fig. 7b) [54].
4. 28 V. Panwar et al. / Applied Catalysis A: General 498 (2015) 25–31
Fig. 1. SEM images of (a) Fe3O4 magnetic nanoparticles and (b) PEG@Fe3O4 and EDX pattern of (c) Fe3O4 and (d) PEG@Fe3O4.
Fig. 2. TEM images of (a) Fe3O4, (b) PEG@Fe3O4 and (c) SEAD pattern of PEG@Fe3O4.
3.2. Catalytic activity
The catalytic activity of the synthesized PEGylated magnetic
NPs was tested for the oxidative cyanation of tertiary amines to
␣-aminonitriles using hydrogen peroxide as oxidant and NaCN in
acetic acid as a cyanide donor at room temperature (Scheme 1).
N,N-Dimethylaniline was chosen as the model substrate to opti-
mize the reaction conditions with various oxidants and solvents at
room temperature using NaCN in acetic acid as the cyanide source
(Table 1). No product was obtained when the reaction was car-
ried out without catalyst or using PEG without containing iron NPs
as catalyst under otherwise similar reaction conditions (Table 1,
entries 1 and 2). For the comparison purpose we also performed
the reaction using neat magnetic NPs as catalyst under identical
experimental conditions. The neat magnetic particles were found
to be ineffective and gave only trace yield of the desired reaction
product (Table 1, entry 3). The poor activity of neat MNPs could be
ascribed to the aggregation of MNPs and oxidation of nanoparticles
5. V. Panwar et al. / Applied Catalysis A: General 498 (2015) 25–31 29
Fig. 3. FTIR spectra of (a) Fe3O4, (b) PEG and (c) PEG@Fe3O4.
Fig. 4. XRD diffractogram of (a) Fe3O4 and (b) PEG@Fe3O4.
Fig. 6. UV–vis absorption spectra of (a) Fe3O4 and (b) PEG@Fe3.
Fig. 7. TGA thermogram of (a) Fe3O4 and (b) PEG@Fe3O4.
Fig. 5. BET Ads Des isotherm and pore size distribution of (a) Fe3O4 and (b) PEG@Fe3O4.
6. 30 V. Panwar et al. / Applied Catalysis A: General 498 (2015) 25–31
Table 1
Results of the optimization experimentsa
.
Entry Catalyst Solvent Oxidant Yield (%)b
TOF (h−1
)
1 – MeOH H2O2 – –
2 PEG MeOH H2O2 – –
3 Fe3O4 MeOH H2O2 Trace –
4 Succinic acid@Fe3O4 MeOH H2O2 62.4 12.5
5 PEG@Fe3O4 MeOH H2O2 75c
, 94a
, 94.5d
18.8
6 PEG@Fe3O4 MeOH – – –
7 PEG@Fe3O4 MeOH O2 22 4.4
8 PEG@Fe3O4 MeOH TBHP 48 9.6
9 PEG@Fe3O4 CH2Cl2 H2O2 5 1.0
10 PEG@Fe3O4 Water H2O2 22 4.4
11 PEG@Fe3O4 CH3CN H2O2 34 6.8
12 PEG@Fe3O4 EtOH H2O2 86 17.2
a
Reaction conditions: substarte (1 mmol), catalyst (0.1 g), NaCN (1.2 mmol), AcOH
(1 mL), solvent (4 mL) in the presence of H2O2; reaction time 5 h.
b
Isolated yield.
c
Using 0.05 g of catalyst.
d
Using 0.2 g of catalyst.
under the reaction conditions. Similarly, succinic acid function-
alized magnetic nanoparticles exhibited poor catalytic activity as
compared to the PEGylated magnetic NPs for the oxidative cya-
nation of N,N-dimethylaniline to corresponding ␣-aminonitrile
under otherwise identical reaction conditions (Table 1, entries 4
and 5). The superior catalytic activity of the PEGylated magnetic
nanoparticles was assumed due to their higher chemical stability,
non-aggregation and preventive oxidation due to the presence of
PEG coating. Next, we studied the effect of various oxidants such as
molecular oxygen, hydrogen peroxide and TBHP under described
reaction conditions (Table 1, entries 5 and 7–8). Among the var-
ious oxidants, hydrogen peroxide was found to be best oxidant
for this transformation (Table 1, entry 5). However there was no
reaction occurred in the absence of any oxidant (Table 1, entry
6). The presence of acetic acid was found to be essential and in
its absence no reaction was occurred even after prolonged reac-
tion time (10 h). Among the various solvents such as acetonitrile,
methanol, dichloromethane and water studied (Table 1, entries 5
and 9–12), methanol was found to be best solvent for the present
transformation. Further, we evaluated the effect of catalyst amount
on the conversion of N,N-dimethylaniline in methanol at room
temperature under otherwise identical experimental conditions.
Initially the reaction was found to be increased with increase in
catalyst amount from 0.05 to 0.1 g with respect to 1 mmol of the
substrate, however further increase in catalyst amount from 0.1 to
0.2 g did not affect the reaction to any significant extend (Table 1,
entry 4).
With the optimal conditions for the highly efficient and
selective oxidative cyanation of tertiary amines in hand, the
scope of the reaction was explored for the different substrates
under described reaction conditions. The results of these exper-
iments are summarized in Table 2. As shown in Table 2,
substituted N,N-dimethylanilines with electron-donating and
electron-withdrawing groups were selectively and efficiently con-
verted into the corresponding ␣-aminonitriles in good to excellent
yields (Table 2, entries 2–6). N,N-Dimethyl-o-toluidine offered
a slightly lower yield (78% yield) than N,N-dimethyl-p-toluidine
(89% yield) owing to steric hindrance. In case of N-methyl-N-
ethylaniline, the N-methyl group was oxidized chemoselectively to
give the corresponding N-ethyl-N-phenylaminoacetonitrile in 80%
yield (Table 2, entry 7). The developed catalytic system could also be
applied efficiently for oxidative cyanation of cyclic amines such as
piperidine, and tetrahydroisoquinoline to give the corresponding
␣-aminonitriles in moderate to high yields (Table 2, entries 8–10).
Aliphatic tertiary amines like tert-butyl amine did not produce any
product (Table 2, entry 11). But the tertiary amines having benzyl
Table 2
PEG@Fe3O4 catalyzed oxidative cyanation of tertiary aminesa
.
Entry Reactant Product Time (h) Yield (%)b
TOF (h−1
)
1
N
CH3
CH3
N
CH3
CH2CN 5 94 18.8
2
N
CH3
CH3
N
CH3
CH2CN 4.5 78 17.3
3
N
CH3
CH3
Me N
CH3
CH2CN
Me
4.5 89 19.7
4
N
CH3
CH3
N
CH3
CH2CN 4.5 80 17.7
5
N
CH3
CH3
Br
N
CH3
CH2CN
Br
5.0 72 14.4
6
N
CH3
CH3
Br N
CH3
CH2CN
Br
5.0 81 16.2
7 N
CH3
C2H5 N
CN
C2H5
4.0 86 21.5
8 N
N
NC
5.5 84 15.2
9 N
N
NC
5.5 86 15.6
10 N
Ph
N
Ph
CN
5.0 91 18.2
11 (n-Bu)3N – 32 – –
12
N
CH3
CH3 N
CH2CN
CH3
24 34 1.4
13
N
CH3
CH3 N
CH2CN
CH3
24 47 1.9
a
Reaction conditions: Substrate (1 mmol), PEG@Fe3O4 catalyst (0.1 g), NaCN
(1.2 mmol), AcOH (1 mL), MeOH (4 mL) in the presence of H2O2 at room temperature.
b
Isolated yield.
groups were sluggish in reaction with poor yield (Table 2, entries
12–13).
Furthermore, we checked the recycling of the PEGylated MNPs
by using N,N-dimethylaniline as a model substrate. After comple-
tion of the reaction, the catalyst was easily recovered from reaction
mixture by using an external magnet, washed with methanol and
dried. The recovered catalyst was used for six runs using fresh
substrates and oxidant. The results of recycling experiments are
summarized in Fig. 8. As shown in Fig. 8, the yield of the desired
product in all cases was found to be almost similar which confirmed
that the developed catalyst can be reused efficiently without any
significant loss in activity for several runs.
Although, the mechanism of reaction is not clear at this stage,
the probable mechanistic pathway is shown in the Scheme 3. In
analogy to the mechanism proposed by Murahashi et al. [29] we
7. V. Panwar et al. / Applied Catalysis A: General 498 (2015) 25–31 31
Fig. 8. Results of recycling experiments.
Scheme 3. Possible mechanism of the reaction.
can assume that the reactive oxo-iron (IV) species derived from
iron and H2O2 abstracts hydrogen from the ␣-carbon of the tertiary
amines to give cationic intermediate. The nucleophilic attack of the
HCN, generated in situ by the reaction of NaCN and AcOH yielded
corresponding ␣-aminonitrile as shown in Scheme 3.
4. Conclusion
In summary, we have described a novel, highly efficient and
cost effective PEGylated magnetic nanoparticles as catalyst for the
oxidative cyanation via C H activation of tertiary amines with
hydrogen peroxide in the presence of sodium cyanide in acetic acid
as cyanide source at room temperature to give ␣-aminonitriles in
high to excellent yields. The developed catalyst was easily recov-
ered with the effect of an external magnet and efficiently recycled
for several runs without significant loss of activity.
Acknowledgement
We are thankful to the Director, CSIR-IIP for his kind permis-
sion to publish these results. VP and PK acknowledge the CSIR,
New Delhi, for their Research Fellowships. Analytical department
of institute is kindly acknowledged for the analysis of samples.
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