- Ruthenium(III) catalyzed oxidation of propane-1,3-diol by potassium periodate was studied in aqueous perchloric acid medium.
- The reaction was found to be first order in oxidant and catalyst concentrations, and inverse fractional order in acid concentration. Substrate inhibition was also observed with increasing substrate concentration.
- Various reaction conditions like temperature, addition of salts, and acetic acid-water solvent composition were varied to determine their effects. Based on the kinetic data, a plausible reaction mechanism was proposed.
Kinetics and feasibility studies of thiol oxidation using magnetically separa...Pawan Kumar
This work describes kinetic studies of the catalytic oxidation of thiols (RSHs) found in kerosene to disulphides
using a magnetically separable iron oxide coated Mg-Al layered double hydroxide supported tetra-sulphonated
cobalt phthalocyanine (CoPcS/LDH@Fe3O4) catalyst in an alkali-free environment. Using 1-octanethiol as a representative
RSH, we investigated the effects of different experimental parameters on RSH oxidation kinetics, including
catalyst concentration, temperature (30–60 °C), and initial thiol concentration ([RSH]0, 100–300 ppm).
The catalyst concentration was varied so that the [RSH]0/[Co]tot molar ratio ranged from 45 to 180. Based on
the results, we propose a mechanistic rate expression to explain the observed oxidation of RSH in the presence
of the CoPcS/LDH@Fe3O4 catalyst. The proposed rate law resembles double substrate Michaelis-Menten kinetics,
however, for commonly encountered industrial conditions, we were able to simplify it to a linear form. This rate
law for RSH oxidation can be used to design industrial reactors for an alkali-free sweetening process.
Kinetics and feasibility studies of thiol oxidation using magnetically separa...Pawan Kumar
This work describes kinetic studies of the catalytic oxidation of thiols (RSHs) found in kerosene to disulphides
using a magnetically separable iron oxide coated Mg-Al layered double hydroxide supported tetra-sulphonated
cobalt phthalocyanine (CoPcS/LDH@Fe3O4) catalyst in an alkali-free environment. Using 1-octanethiol as a representative
RSH, we investigated the effects of different experimental parameters on RSH oxidation kinetics, including
catalyst concentration, temperature (30–60 °C), and initial thiol concentration ([RSH]0, 100–300 ppm).
The catalyst concentration was varied so that the [RSH]0/[Co]tot molar ratio ranged from 45 to 180. Based on
the results, we propose a mechanistic rate expression to explain the observed oxidation of RSH in the presence
of the CoPcS/LDH@Fe3O4 catalyst. The proposed rate law resembles double substrate Michaelis-Menten kinetics,
however, for commonly encountered industrial conditions, we were able to simplify it to a linear form. This rate
law for RSH oxidation can be used to design industrial reactors for an alkali-free sweetening process.
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
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Kinetics and feasibility studies of thiol oxidation using magnetically separa...Pawan Kumar
This work describes kinetic studies of the catalytic oxidation of thiols (RSHs) found in kerosene to disulphides
using a magnetically separable iron oxide coated Mg-Al layered double hydroxide supported tetra-sulphonated
cobalt phthalocyanine (CoPcS/LDH@Fe3O4) catalyst in an alkali-free environment. Using 1-octanethiol as a representative
RSH, we investigated the effects of different experimental parameters on RSH oxidation kinetics, including
catalyst concentration, temperature (30–60 °C), and initial thiol concentration ([RSH]0, 100–300 ppm).
The catalyst concentration was varied so that the [RSH]0/[Co]tot molar ratio ranged from 45 to 180. Based on
the results, we propose a mechanistic rate expression to explain the observed oxidation of RSH in the presence
of the CoPcS/LDH@Fe3O4 catalyst. The proposed rate law resembles double substrateMichaelis-Menten kinetics,
however, for commonly encountered industrial conditions, we were able to simplify it to a linear form. This rate
law for RSH oxidation can be used to design industrial reactors for an alkali-free sweetening process.
Kinetics of Ruthenium(III) Catalyzed and Uncatalyzed Oxidation of Monoethanol...Ratnakaram Venkata Nadh
Kinetics of uncatalyzed and ruthenium(III) catalyzed oxidation of monoethanolamine by N-bromosuccinimide
(NBS) has been studied in an aqueous acetic acid medium in the presence of sodium acetate
and perchloric acid, respectively. In the uncatalyzed oxidation the kinetic orders are: the first order in NBS,
a fractional order in the substrate. The rate of the reaction increased with an increase in the sodium acetate
concentration and decreased with an increase in the perchloric acid concentration. This indicates that free
amine molecules are the reactive species. Addition of halide ions results in a decrease in the kinetic rate,
which is noteworthy. Both in absence and presence of a catalyst, a decrease in the dielectric constant of the
medium decreases the kinetic rate pointing out that these are dipole—dipole reactions. A relatively higher
oxidation state of ruthenium i.e., Ru(V) was found to be the active species in Ru(III) catalyzed reactions. A
suitable mechanism consistent with the observations has been proposed and a rate law has been derived to
explain the kinetic orders.
A micro-review of the Baeyer-Villiger oxidation with recent (2012/2013) references from the literature; last updated on March 1 2013.
The Baeyer-Villiger Oxidation is a popular tool for the synthesis of esters and lactones.
See an animation at: http://www.harinchem.com/named_organic_reactions.html.
Please send feedback or questions through: http://www.harinchem.com/contactpage.aspx
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
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Kinetics and feasibility studies of thiol oxidation using magnetically separa...Pawan Kumar
This work describes kinetic studies of the catalytic oxidation of thiols (RSHs) found in kerosene to disulphides
using a magnetically separable iron oxide coated Mg-Al layered double hydroxide supported tetra-sulphonated
cobalt phthalocyanine (CoPcS/LDH@Fe3O4) catalyst in an alkali-free environment. Using 1-octanethiol as a representative
RSH, we investigated the effects of different experimental parameters on RSH oxidation kinetics, including
catalyst concentration, temperature (30–60 °C), and initial thiol concentration ([RSH]0, 100–300 ppm).
The catalyst concentration was varied so that the [RSH]0/[Co]tot molar ratio ranged from 45 to 180. Based on
the results, we propose a mechanistic rate expression to explain the observed oxidation of RSH in the presence
of the CoPcS/LDH@Fe3O4 catalyst. The proposed rate law resembles double substrateMichaelis-Menten kinetics,
however, for commonly encountered industrial conditions, we were able to simplify it to a linear form. This rate
law for RSH oxidation can be used to design industrial reactors for an alkali-free sweetening process.
Kinetics of Ruthenium(III) Catalyzed and Uncatalyzed Oxidation of Monoethanol...Ratnakaram Venkata Nadh
Kinetics of uncatalyzed and ruthenium(III) catalyzed oxidation of monoethanolamine by N-bromosuccinimide
(NBS) has been studied in an aqueous acetic acid medium in the presence of sodium acetate
and perchloric acid, respectively. In the uncatalyzed oxidation the kinetic orders are: the first order in NBS,
a fractional order in the substrate. The rate of the reaction increased with an increase in the sodium acetate
concentration and decreased with an increase in the perchloric acid concentration. This indicates that free
amine molecules are the reactive species. Addition of halide ions results in a decrease in the kinetic rate,
which is noteworthy. Both in absence and presence of a catalyst, a decrease in the dielectric constant of the
medium decreases the kinetic rate pointing out that these are dipole—dipole reactions. A relatively higher
oxidation state of ruthenium i.e., Ru(V) was found to be the active species in Ru(III) catalyzed reactions. A
suitable mechanism consistent with the observations has been proposed and a rate law has been derived to
explain the kinetic orders.
A micro-review of the Baeyer-Villiger oxidation with recent (2012/2013) references from the literature; last updated on March 1 2013.
The Baeyer-Villiger Oxidation is a popular tool for the synthesis of esters and lactones.
See an animation at: http://www.harinchem.com/named_organic_reactions.html.
Please send feedback or questions through: http://www.harinchem.com/contactpage.aspx
Hindered amine stabilizes
A B3LYP, HF, AM1 and PM2 computational studies of the reaction of hindered amine (HALS) has been perfumed. Four different theories were used to calculate the bond dissociation energy (BDE). In two molecules studied the nitrogen were protonated and not protonated. BDE were calculated when aromatic rings were substituted with NO2 and OCH3. B3LYP was the best theoretical calculation level, The BDE was grater when nitrogen in HALS was protonated. There was no big significant difference in BDE when aromatic ring of hindered amine was substituted with NO2 and OCH3.
Azomethine Metal Chelates as an Efficient Catalyst for Oxidation of Organic C...CrimsonPublishersACSR
Azomethine ligands and their metal chelates are flexible compounds synthesized from the condensation
of an amino compound with carbonyl compounds and extensively used for industrial purposes and also
show a broad range of biological efficiencies including antibacterial, antifungal, antiviral, antimalarial,
antiproliferative, anti-inflammatory, anticancer, anti-HIV, anthelminthic and antipyretic properties.
Azomethine metal chelates show excellent catalytic activity in diversity reactions. Over the past few
years, there have been many reports on their applications in homogeneous and heterogeneous catalysis.
The high thermal and moisture stabilities of many azomethine metal chelates were useful attributes for
their application as catalysts in reactions involving at high temperatures. Recent researches in oxidation
catalysis have focused on how to employ the metal-catalyzed oxidation of organic substrates. This review
concerns with the current developments for the oxidations of organic compounds.
A new Schiff base 4-chlorophenyl)methanimine
(6R,7R)-3-methyl-8-oxo-7-(2-phenylpropanamido)-5-thia-1-
azabicyclo[4.2.0]oct-2-ene-2-carboxylate= (HL)= C23H20
ClN3O4S) has been synthesized from β-lactam antibiotic
(cephalexin mono hydrate(CephH)=(C16H19N3O5S.H2O) and 4-
chlorobenzaldehyde . Figure(1) Metal mixed ligand complexes
of the Schiff base were prepared from chloride salt of
Fe(II),Co(II),Ni(II),Cu(II),Zn(II) and Cd (II), in 50% (v/v)
ethanol –water medium (SacH ) .in aqueous ethanol(1:1)
containing and Saccharin(C7H5NO3S) = sodium hydroxide.
Several physical tools in particular; IR, CHN, 1H NMR, 13C
NMR for ligand and melting point molar conductance, magnetic
moment. and determination the percentage of the metal in the
complexes by flame(AAS). The ligands and there metal
complexes were screened for their antimicrobial activity against
four bacteria (gram + ve) and (gram -ve) {Escherichia coli,
Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus}.
The proposed structure of the complexes using program, Chem
office 3D(2006). The general formula have been given for the
prepared mixed ligand complexes Na2[M(Sac)3(L)], M(II) = Fe
(II), Co(II) , Ni(II), Cu (II), Zn(II) , and Cd(II).
HL= C29H24 ClN3O4S, L= C29H23 ClN3O4S -.
Kinetics and feasibility studies of thiol oxidation using magnetically separa...Pawan Kumar
This work describes kinetic studies of the catalytic oxidation of thiols (RSHs) found in kerosene to disulphides using a magnetically separable iron oxide coated Mg-Al layered double hydroxide supported tetra-sulphonated cobalt phthalocyanine (CoPcS/LDH@Fe3O4) catalyst in an alkali-free environment. Using 1-octanethiol as a representative RSH, we investigated the effects of different experimental parameters on RSH oxidation kinetics, including catalyst concentration, temperature (30–60 °C), and initial thiol concentration ([RSH]0, 100–300 ppm). The catalyst concentration was varied so that the [RSH]0/[Co]tot molar ratio ranged from 45 to 180. Based on the results, we propose a mechanistic rate expression to explain the observed oxidation of RSH in the presence of the CoPcS/LDH@Fe3O4 catalyst. The proposed rate law resembles double substrate Michaelis-Menten kinetics, however, for commonly …
free radicals and antioxidants , effect of free radicals , phases , free radicals in cancer, diabeties and neurodegenerative disease including pathology of each disease.
Similar to Substrate Inhibition in Ruthenium(III) Catalyzed Oxidation of Propane-1,3-diol by Periodate in Acidic Medium: A Kinetic Study (20)
Electrochemical study of anatase TiO2 in aqueous sodium-ion electrolytesRatnakaram Venkata Nadh
In this paper, a basic electro-analytical study on the behavior of anatase TiO2 in aqueous NaOH has been presented using cyclic voltammetry technique (CV). The study has explored the possibility of using TiO2 as anode material for ARSBs in presence of 5 M NaOH aqueous electrolyte. CV profiles show that anatase TiO2 exhibits reversible sodium ion insertion/de-insertion reactions. CV studies of TiO2 anode in aqueous sodium electrolytes at different scan rate shows that the Na+ ion insertion reaction at the electrode is diffusion controlled with a resistive behavior. Proton insertion from aqueous sodium electrolytes into TiO2 cannot be ruled out. To confirm the ion inserted and de-inserted, CV studies are done at different concentration of NaOH and it is found that at lower concentrations of NaOH, proton insertion process competes with Na+ ion insertion process and as the concentration increases, the Na+ ion insertion process becomes the predominant electrode reaction making it suitable anode materials for aqueous sodium batteries in 5 M NaOH.
Validated HPLC Method for Assay and Content Uniformity Testing of Roflumilast...Ratnakaram Venkata Nadh
Roflumilast is a selective enzyme inhibitor of phosphodiesterase-4. This drug is recommended for treatment of patients suffering from
chronic-obstructive-pulmonary-disease with chronic-bronchitis. Roflumilast is not official in pharmacopoeia and the reported methods
are having high chromatographic run times. A short run time HPLC method was developed for assay and content uniformity testing to
determine the roflumilast in blend and tablets. The mobile phase consists of 10 mM sodium dihydrogen phosphate monohydrate buffer
and acetonitrile in the ratio of 45:55 v/v. The HPLC method was developed using accucore-C18 150 × 4.6 mm, 4 μm column with a flow
rate of 1.0 mL min-1, 215 nm wavelength and 10 μL injection volume with run time of 5 min. The method linearity was proved between
5.02-40.17 μg mL-1 and obtained correlation-coefficient value is 1.0000. The mean recovery of roflumilast was 100.6%. The stability
indicating nature was established and performed the validation by considering ICH Q2 (R1) recommendations.
Ruthenium(III) Catalyzed Oxidation of Sugar Alcohols by Dichloroisocyanuric A...Ratnakaram Venkata Nadh
Kinetics of ruthenium(III) catalyzed oxidation of biologically important sugar alcohols (myo-inositol,
D-sorbitol, and D-mannitol) by dichloroisocyanuric acid was carried out in aqueous acetic acid—perchloric
medium. The reactions were found to be first order in case of oxidant and ruthenium(III). Zero order
was observed with the concentrations of sorbitol and mannitol whereas, a positive fractional order was found
in the case of inositol concentration. An inverse fractional order was observed with perchloric acid in oxidation
of three substrates. Arrhenius parameters were calculated and a plausible mechanism was proposed
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 novel reversed-phase liquid chromatographic method for the simultaneous det...Ratnakaram Venkata Nadh
In the present study 12 impurities of bisoprolol fumarate (BISO) and hydrochlorothiazide (HCTZ) were
separated simultaneously in a single HPLC method. Out of these 12 impurities, five are potential
degradants, which are validated as per The International Council for Harmonisation of Technical
Requirements for Pharmaceuticals for Human Use (ICH) guidelines. As the two active drug substances
BISO and HCTZ have different solubilities and polarities, the most critical parameters in resolving the
components from each other are pH, temperature, and solvents. The method is precise (RSD < 1.0%),
accurate, linear (r2 > 0.999), robust, and stability indicating in the range of limit of quantification (LOQ)
to 150%. The HPLC method is then migrated to ultra-performance liquid chromatography (UPLC) to
further reduce the run time and solvent consumption, and increase the sample throughput
The emergence of multidrug-resistant TB (MDR-TB) against first-line drugs and extensively drug resistant TB (XDRTB)
due to misuse of second-line anti tubercular drugs (ATDs) is a further concern. Recommended treatment involves
long term and multiple drug therapy with severe side effects. Due to this concern nanoparticle-based systems
have significant potential for treatment and prevention of tuberculosis (TB) to overcome the need to administer
ATDs at high and frequent doses, would assist in improving patient compliance and circumvent hepatotoxic ity
and/or nephrotoxicity/ocular toxicity/ototoxicity associated with the prevalent first-line chemotherapy.
Nanostructured delivery systems constitute a wide range of systems varying from liposomes, micelles, micro- and
nanoemulsions, to polymeric nanoparticles (PNPs ) and solid lipid nanoparticles (SLNs). Pulmonary administration
of inhaled nanoparticles in the form of dry powder inhalers offer particular advantages for pulmonary administration
of anti tubercular drugs (ATDs). Present review comprehensively about different approaches of nanobased
drug delivery, devises and techniques for pulmonary delivery of nanoparticle encapsulated ATD.
Kinetic, isotherm and thermodynamics investigation on adsorption of divalent ...Ratnakaram Venkata Nadh
Three novel and distinct agricultural waste materials, viz., Casuarinas fruit powder (CFP), sorghum stem powder
(SSP) and banana stem powder (BSP) were used as low cost adsorbents for the removal of toxic copper(II) from
aqueous solutions. Acid treated adsorbents were characterized by SEM, EDX and FTIR. Different factors effecting
adsorption capacity were analyzed and the effi ciency order was BSP>SSP>CFP. Based on the extent of compatibility
to Freundlich/Langmuir/D-R/Temkin adsorption isotherm and different models (pseudo-fi rst and second order,
Boyd, Weber’s and Elovich), chemisorption primarily involved in the case of CFP and SSP, whereas, simultaneous
occurrence of chemisorption and physisorption was proposed in the case of BSP. Based on the observations, it was
proposed that three kinetic stages involve in adsorption process viz., diffusion of sorbate to sorbent, intra particle
diffusion and then establishment of equilibrium. These adsorbents have promising role towards removal of Cu(II)
from industrial wastewater to contribute environmental protection.
Kinetic, thermodynamic and equilibrium studies on removal of hexavalent chrom...Ratnakaram Venkata Nadh
Removal of Cr(VI) by biosorption on two agro waste materials, casuarinas fruit powder (CFP) and sorghum
stem powder (SSP), has been investigated. The prepared adsorbent materials were characterized by SEM, EDX,
FTIR and BET. These biomaterials effectively removed Cr(VI) with a maximum removal of 93.35% and 63.75% using
15 gL−1 and 5 gL−1 of CFP and SSP, respectively, at 60 oC with 20mgL−1 initial Cr(VI) concentration in solution. In both
cases of adsorbents, kinetic data of adsorption fitted well in pseudo-second-order in terms of correlation coefficient
(R2). This helps in proposing the process of adsorption as chemical coordination, which is correlated with the thermodynamic
study results conducted at different values of temperature. Langmuir, Freundlich and D-R models were evaluated
for description of metal sorption isotherms. Values of coefficients of intra-particle diffusion and mass transfer have
also been determined at different values of temperature.
Novel coumarin isoxazoline derivatives: Synthesis and study of antibacterial ...Ratnakaram Venkata Nadh
A highly efficient and mild protocol for the syntheses of ethyl-3-
[7-benzyloxy-4-methyl-2-oxo-2H-8-chromenyl]-5-aryl-4,5-dihydro-4-
isoxazole carboxylates and ethyl-3-[7-benzyloxy-3-chloro-4-methyl-2-
oxo-2H-8-chromenyl]-5-aryl-4,5-dihydro-4-isoxazole carboxylates in
good yields via [3 þ 2] cycloaddition of in situ–generated nitrile
oxides from 7-benzyloxy-4-methyl-coumarin hydroxymoylchlorides
and 7-benzyloxy-3-chloro-4-methyl-coumarin hydroxymoylchlorides
respectively with ethyl-3-aryl prop-2-enoate has been developed.
The new compounds are screened for antibacterial activity.
Ultra performance liquid chromatographic method for simultaneous quantificati...Ratnakaram Venkata Nadh
Plerixafor (PLX) injections are administered to patients with cancers of lymphocytes
(non-Hodgkin’s lymphoma) and plasma cells (multiple myeloma). The main
objective of the current study was to develop a short reverse phase chromatographic
method for the simultaneous quantification of PLX and its impurities, in an injection
formulation, to reduce the time required for these quality tests. Furthermore, the
present work describes the role of nonalkyl branched nonquaternary ion pair reagent
in improving the peak shape and reducing column equilibration time. The separation
of PLX and its related substances is pH dependent (optimum pH = 2.50) and was
achieved on an octadecylsilyl (C18) column. The method was validated for its intended
purpose in accordance with the current regulatory guidelines for validation. The
proposed method can be applied for quality control, release, and stability analyses of
active pharmaceutical ingredient, PLX, as well as finished products, PLX injections
Caralluma lasiantha: A review on it’s vital role in Indian Traditional MedicineRatnakaram Venkata Nadh
Caralluma is a genus used as traditional medicine. Caralluma lasiantha is medicinally important due
to existence of pregnane glycosides, which may possess various biological activities. This article thoroughly
reviewed about the usage of C. lasiantha in traditional medicinal system, phytochemicals present in it, profile
identification studies, anti-hyperglycemic effect, antibacterial, antifungal, cytotoxic and antioxidant activities
Phytochemical Investigation of Caralluma lasiantha: Isolation of Stigmasterol...Ratnakaram Venkata Nadh
Stigmasterol, a phytosteroid was isolated for the first time from C. lasiantha using n-hexane as a solvent. Stigmasterol was characterized on the basis of physical, chemical and spectral data (IR, 1H NMR, 13C NMR, 1HNMR, DEPT-45, 90 & 135, and MS) analysis as well as by comparing them to their literature data. A sequence of steps was adopted like saponification, fractional crystallization and gradient elution column chromatography to isolate stigmasterol because some phytosterols possess identical physical properties which makes it difficult to isolate the constituents.
Phytochemical Screening of Caralluma lasiantha Isolation of C21 Pregnane SteroidRatnakaram Venkata Nadh
Phytochemical screening of Caralluma lasiantha was carried out and one C21 pregnane steroid was isolated from chloroform extract. Based on spectroscopic studies (IR, 1H NMR, 13C NMR and ESI-MS) the isolated compound is 3b,14b-dihydroxy-14b-pregn-5-en-20-one which was earlier isolated from other species.
Supercritical fluid (CO2) chromatography for quantitative determination of se...Ratnakaram Venkata Nadh
In the present study, two cancer therapeutic drugs (docetaxel and bortezomib) were separated from their
potential impurities on a chromatographic platform by utilizing CO2 gas (supercritical state) and quantified.
The chromatographic separations were achieved on two short columns BEH-2EP (100mm 3mm, 1.7 mm)
and CHIRALPAK AD-3 (100 mm 4.6 mm, 3 mm) for docetaxel and bortezomib, respectively. The present
work describes the role of organic modifiers in the separation of polar compounds by supercritical fluid
chromatography. The two new methods were fully validated in accordance with the current ICH
(International Council for Harmonization of technical requirements for pharmaceuticals for human use)
guidelines. The stability indicating power of the methods was demonstrated from the stress studies
conducted on the injection formulations of the two compounds. The methods are precise with % RSD of
0.4, linear with the correlation coefficient of r2 $ 0.999 and accurate in the range of 50–150% of the
target assay concentration. The two methods can be equally employed for the assay determination of
docetaxel and bortezomib APIs as well.
Quality-by-design-based development and validation of a stability-indicating ...Ratnakaram Venkata Nadh
A systematic design-of-experiments was performed by applying quality-by-design concepts to determine
design space for rapid quantification of teriflunomide by the ultraperformance liquid chromatography
(UPLC) method in the presence of degradation products. Response surface and central composite
quadratic were used for statistical evaluation of experimental data using a Design-Expert software. The
response variables such as resolution, retention time, and peak tailing were analyzed statistically for the
screening of suitable chromatographic conditions. During this process, various plots such as perturbation,
contour, 3D, and design space were studied. The method was developed through UPLC BEH C18
2.1 � 100 mm, 1.7-μ column, mobile phase comprised of buffer (5 mM K2HPO4 containing 0.1%
triethylamine, pH 6.8), and acetonitrile (40:60 v/v), the flow rate of 0.5 mL min 1 and UV detection at
250 nm. The method was developed with a short run time of 1 min. Forced degradation studies revealed
that the method was stability-indicating, suitable for both assay and in-vitro dissolution of a drug product.
The method was found to be linear in the range of 28–84 μg mL 1, 2.8–22.7 μg mL 1 with a correlation
coefficient of 0.9999 and 1.000 for assay and dissolution, respectively. The recovery values were found in
the range of 100.1–101.7%. The method was validated according to ICH guidelines.
A convenient new and efficient commercial synthetic route for dasatinib (Spry...Ratnakaram Venkata Nadh
A new and efficient synthetic route for dual-Src/Abl kinase inhibitor
dasatinib (Sprycel®), an anticancer drug, is described. This commercially
viable process yields dasatinib monohydrate free of potential impurities
with consistent yield of 68% in route A and 61% in route B with HPLC
purity >99.80% over four stages.
Utilization of agro-waste for removal of toxic hexavalent chromium: surface i...Ratnakaram Venkata Nadh
Abundantly available agricultural waste materials
(banana bunch, sorghum stem and casuarinas fruit) are
processed with negligible cost and are found to be highly
suitable as biosorbents for chromium(VI) removal from
aqueous environment due to high surface area and functional
groups of adsorbents. The equilibrium data have
been analyzed for the adsorbate–adsorbate/adsorbent
interactions and found to be fitted to the data in the order,
Hill–de Boer C Fowler–Guggenheim % Frumkin[Kiselev.
To determine the characteristic parameters for process
design, mass transfer studies have been carried out using
two-parameter isotherm models (Harkins–Jura, Halsey,
Smith, El-Awady and Flory–Huggins) and three-parameter
isotherm models (Redlich–Peterson and Sips) which are
applied to the experimental data. The fitness of the isotherms
describes that both mono- and multilayer adsorptions
occur in the present studied three biosorbents in
preference to the latter. The mechanism of adsorption has
been studied using diffusion kinetic models (viz. liquid film
diffusion, Dunwald–Wagner intra-particle diffusion model
and moving boundary model) and described the possibility
of diffusion in the order of banana bunch–stem powder[
sorghum stem powder[casuarinas fruit powder in
terms of diffusion coefficients. In essence of all the results,
the selected adsorbents can be used as a potential adsorbent
for the removal of Cr(VI) from aqueous solutions.
Evaluation of in vitro antibacterial activity of Caralluma lasiantha for scie...Ratnakaram Venkata Nadh
Caralluma lasiantha is used as a traditional medicine in India to heal body
heat and inflammations. In order to find out a scientific validation for the Indian
traditional knowledge, antibacterial activity of C. lasiantha extracts was studied
against inflammation causing bacteria (viz., Staphylococcus aureus, Escherichia coli,
Streptococcus Sp., Bacillus subtilis, Enterobacter aerogenes, Klebsiella pneumoniae)
along with other Gram-positive and Gram-negative bacteria. Solvents with different
polarity were used for extraction from dry roots and stems. Minimum inhibitory
concentrations (MIC) were also studied. Differential antibacterial activity was
exhibited by extracts and higher inhibition potential against Gram-positive bacteria
was explained. The observed antibacterial activities were correlated with the chemical
structures of phytochemicals present in C. lasiantha. Anti-inflammation activities
are related to C. lasiantha extracts through their antibacterial activities.
Novel Hybrid Molecules of Isoxazole Chalcone Derivatives: Synthesis and Study...Ratnakaram Venkata Nadh
medicine due to their significant role in the treatment of different health problems.
Methods: We have synthesized new series of isoxazole-chalcone conjugates (14a-m) by the
Claisen-Schmidt condensation of suitable substituted acetophenones with isoxazole aldehydes (12a-d).
In vitro cytotoxic activity of the synthesized compounds was studied against four different selected
human cancer cell lines by using sulforhodamine B (SRB) method.
Results: The adopted scheme resulted in good yields of new series of isoxazole-chalcone
conjugates (14a-m). Potent cytotoxic activity was observed for compounds -14a, 14b, 14e, 14i, 14j
and 14k against prostate DU-145 cancer cell line.
Conclusion: The observed potent cytotoxic activities were due to the presence of 3,4,5-
trimethoxyphenyl group.
Novel Hybrid Molecules of Quinazoline Chalcone Derivatives: Synthesis and Stu...Ratnakaram Venkata Nadh
Abstract: Background: A new series of quinazoline linked chalcone conjugates were synthesized
and evaluated for their in vitro cytotoxicity.
Methods: The quinazoline-chalcone derivatives (13a-r) have been prepared by the Claisen-Schmidt
condensation of various substituted benzaldehydes (12a-r) with substituted l-(4-(3,4-
dihydroquinazolin-4-ylamino)phenyl)ethanone (11a-b) in the presence of aqueous NaOH. Three
potential compounds 13f, 13g and 13h exhibited cytotoxicity against leukemia (GI50 value of
1.07, 0.26 and 0.24 μM), Non-small lung (GI50 values of 2.05,1.32 and 0.23 μM), colon (GI50
values of 0.54, 0.34 and 0.34 μM) and breast (GI50 values of 2.17, 1.84 and 0.22 μM) cell line,
respectively.
Results and Conclusion: Based on these biological results, it is evident that compound 13h has the
potential to be considered for further detailed studies either alone or in combination with existing
therapies as potential anticancer agents.
Salas, V. (2024) "John of St. Thomas (Poinsot) on the Science of Sacred Theol...Studia Poinsotiana
I Introduction
II Subalternation and Theology
III Theology and Dogmatic Declarations
IV The Mixed Principles of Theology
V Virtual Revelation: The Unity of Theology
VI Theology as a Natural Science
VII Theology’s Certitude
VIII Conclusion
Notes
Bibliography
All the contents are fully attributable to the author, Doctor Victor Salas. Should you wish to get this text republished, get in touch with the author or the editorial committee of the Studia Poinsotiana. Insofar as possible, we will be happy to broker your contact.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
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Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
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of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
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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.
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.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
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).
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Exposé invité Journées Nationales du GDR GPL 2024
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Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
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In silico drugs analogue design: novobiocin analogues.pptx
Substrate Inhibition in Ruthenium(III) Catalyzed Oxidation of Propane-1,3-diol by Periodate in Acidic Medium: A Kinetic Study
1. A J CSIAN OURNAL OF HEMISTRYA J CSIAN OURNAL OF HEMISTRY
https://doi.org/10.14233/ajchem.2020.22646
INTRODUCTION
Potassium periodate is a versatile oxidant that can oxidize
a number of organic and inorganic compounds. Periodate is
used both in alkaline and acidic media [1-5]. In acidic medium,
the existing species is H5IO6 and its non-existence was reported
in the pH range of 5 to 9. In aqueous medium with a pH range
of 6.1 to 7.3, the possible species of periodate are IO4
−
, H4IO6
−
and H3IO6
2−
, whereas, the predominant species is H4IO6
−
near
pH = 7.0. In alkaline medium (0.005 to 0.1 M hydroxide concen-
tration), trihydrogen paraperiodate (H3IO6
2−
) and dihydrogen
paraperiodate(H2IO6
3−
)canbetheexpectedpredominantspecies.
Due to participation in the following reaction, the expected
species is H2IO6
3−
in highly alkaline medium.
2 3
3 6 2 6 2H IO OH H IO H O− − −
+ → +
H2I2O10
4−
is another species in alkaline medium. Periodate
existsinitsdimerformI2O9
4−
athigherconcentrationsofperiodate
[6]. Oxidation of pharmaceutically important polyhydric comp-
ounds like polyethylene glycols was studied in alkaline medium
[7,8]. In those PEG oxidations, transfer of one oxygen atom
or two electrons was observed for each periodate, i.e. periodate
was able to act as oxidant in these reactions till its conversion
to iodate. Among the four species of periodate (H2IO6
3−
, H3IO6
2−
,
Substrate Inhibition in Ruthenium(III) Catalyzed Oxidation of
Propane-1,3-diol by Periodate in Acidic Medium: A Kinetic Study
K.V.S. KOTESWARA RAO
1,
, R. VENKATA NADH
2,*,
and K. VENKATA RATNAM
2,
1
Department of Chemistry, G.V.S.M. Government Degree College, Ulavapadu-523292, India
2
Department of Chemistry, GITAM University-Bengaluru Campus, Bengaluru-562163, India
*Corresponding author: E-mail: doctornadh@yahoo.co.in
Received: 22 January 2020; Accepted: 12 March 2020; Published online: 27 June 2020; AJC-19914
Ruthenium(III) catalyzed oxidation of propane-1,3-diol by potassium periodate was studied in aqueous perchloric acid medium. Orders
of reaction with respect to concentrations of oxidant, substrate, acid and catalyst were determined. First order in oxidant and catalyst
concentrations, and inverse fractional order in acid medium were observed. In addition, substrate inhibition (i.e. a decrease in reaction rate
with an increase in substrate concentration) was observed. Effect of addition of salt and solvent was studied. Based on the studies of
temperature variation, Arrhenius parameters were calculated. Plausible mechanism was also proposed based on observed kinetics.
Keywords: Ruthenium(III), Propane-1,3-diol, Oxidation, Acidic medium, Potassium periodate, Kinetics.
Asian Journal of Chemistry; Vol. 32, No. 7 (2020), 1569-1575
This is an open access journal, and articles are distributed under the terms of the Attribution 4.0 International (CC BY 4.0) License. This
license lets others distribute, remix, tweak, and build upon your work, even commercially, as long as they credit the author for the original
creation. You must give appropriate credit, provide a link to the license, and indicate if changes were made.
IO4
−
and H2I2O10
4−
) in alkaline medium, concentrations of the
first two species are considerable, whereas the concentrations
of the other two are trivial in the range of alkali from 0.05 to
0.5 M. Moreover, the predominant species is H2IO6
3−
at higher
concentration of alkali, however at low alkali concentration it
is H3IO6
2−
.
In addition to well-known trivalent, different oxidation
states of ruthenium catalyst were proposed in different reactions.
Ruthenium(IV) was the proposed reactive form of ruthenium
intheoxidationofdiolsbyperoxodiphosphateinacidicmedium.
Alteration of electrons availability at the oxidation site by the
positive inductive effect was used to explain the reactivity order
of ethane-1,2-diol < propane-1,2-diol < butane-1,2-diol. Some
researchers [4,9] reported the quick conversion of trivalent
ruthenium to octavalent by periodate in acidic medium.
Further reported the existence of Ru(VIII) in acidic medium
in the form of H2RuO5 or RuO3(OH)2.The former was assumed
to be active catalytic species in the kinetics of ruthenium(III)
catalyzed oxidation of methyl glycol by periodate in perchloric
acid [4] to form the corresponding monocarboxylic acid as
the product. Participation of more powerful oxidant species
Ru(V) was proposed for the observed catalysis in the oxidation
of alanine [10] and monoethanolamine [11] by N-bromosucci-
2. nimide (NBS) in aqueous acetic acid-perchloric acid medium.
Acceleration of NBS oxidation of monoethanolamine with the
involvement of Ru(V) was substantiated with the presence and
absence of catalysis with Ru(III) and Os(VIII), respectively.
It indicates the absence of complexation in these reactions,
but the formation of Ru(V) [11].
Oxidation of alcohols by various oxidants is well docu-
mented in literature. In the kinetics of oxidation of neopentyl
glycol by diperiodatocuprate(III) [5], protonated form of
H2IO6
3−
coordinates with central copper ion in alkaline medium
to form [Cu(H2IO6)2]3−
, which further reacts with OH−
to give
[Cu(HIO6)]−
. So formed Cu*
(III) was the active species to form
the corresponding aldol as the final product. In the oxidation
of aliphatic alcohols by iodate in acidic medium, reactions
were explained based on the involvement of halic acid (HIO3)
and hypoiodite ion (IO−
). Order of reaction rate in that study
was given as 1-hexanol < isobutyl alcohol < isopropyl alcohol
< 1-butanol <1-propanol. Length of chain and structural features
of the substrates were taken into consideration to explain the
reactivity. Compared to 2º aliphatic alcohols, the oxidation of
1º aliphatic alcohols was faster with an exception to 1-hexanol.
An inverse proportionality in reaction rate was observed with
respect to the chain length. Cadmium(II) was found to be the
effectivecatalystinthoseoxidations,amongthestudiedtransition
metal ions. Aldehydes and ketones were the products in the
oxidation of primary and secondary aliphatic alcohols [12].
In the oxidation of secondary cyclic alcohols by different
inorganic oxidants (potassium bromate, potassium iodate and
potassium periodate) in acidic medium, the corresponding halic
acids (HBrO3, HIO3 and HIO4) were reported as active oxidizing
species [13]. The oxidation products were the corresponding
ketones and same reaction order was reported with all oxidants
as menthol < isoborneol < borneol. Structural features (steric
hindrance and isomeric) were considered to be the responsible
for the observed sequence of secondary alcohols reactivity.
High and low vulnerability of oxidation in borneol and menthol
towards oxidation was explained based on the least and most
hindered α-hydrogen present in them respectively. The H2OBr+
wastheproposedactiveoxidisingspeciestoexplaintheenhanced
reaction rate by the addition of bromide ion in the oxidation
of n-butanol by p-methoxy-n-bromobenzamide in aqueous
acetic acid [14].
Higher rate of ditelluratoargentate(III) oxidation of 2-(2-
ethoxyethoxy)ethanol (EEE) compared to the oxidation of 2-
(2-methoxy ethoxy)ethanol (MEE) in alkaline medium was
described based on the higher electron-donating ability of the
former compared to the latter [15]. The observed experimental
results were explained based on a free radical mechanism.
Similarly, higher rate of oxidation of 2-ethoxyethanol by K2FeO4
in alkaline medium compared to the oxidation of methoxy-
ethanol was based on electron donating ability [16].
Propane-1,3-diol has a spectrum of applications as a mono-
mer in the production of different polymers like polyethers,
polytrimethylene terephthalate, polyurethanes and polyesters
[17,18]. It is also used as protective agent/antifreeze agent and
solvent [19,20]. Oxidation of vicinal diols in presence of ruthe-
nium catalyst was extensively studied and mechanistic pathways
were explored. But, the reaction pattern was not studied compl-
etely in departed hydroxyl groups of diols. Singh et al. [21]
studied the kinetics of oxidation of 1,3-propanediol by alkaline
N-bromoacetamide in presence of Os(VIII). Silver(I) catalyzed
oxidation was studied by Singh et al. [22] using peroxodi-
phosphate as an oxidant in acetate buffers to form 3-hydroxy
propanol.Agrawal et al. [23] carried out the Ru(III) catalyzed
oxidation of diols by ceric sulphate in aqueous sulphuric acid
medium.As the oxidation studies on non-vicinal diols are scanty,
the present study is aimed at understanding the mechanism
involved in ruthenium(III) catalyzed oxidation of propane-1,3-
diol by periodate in aqueous perchloric acidic medium.
EXPERIMENTAL
Allthechemicalsusedinthepresentstudywereofanalytical
grade. Double distilled water was used to prepare the solutions.
Kinetics of Ru(III) catalyzed oxidation of propane-1,3-diol by
periodate in aqueous perchloric acid medium was followed by
iodometry.Thereactiontookplacetilltheconversionofperiodate
toiodate.AseparatetestwasconductedwhereKIO3 didn'toxidize
propane-1,3-diol. However, Singh et al. [24] reported
aquachloro-rhodium(III) catalysis in oxidation of diol (1,2-
propanediol) by potassium iodate in acidic medium.
Generalprocedure:Thecatalystwasmaintainedonoxidant
side before mixing of oxidant and substrate. Both the oxidant
and substrate solutions (maintained along with desired acid
concentration and solvent composition) were kept in thermostat
at the required constant temperature for 1 h. Both of them were
mixed and then drawn at regular intervals of time. The kinetics
experiments were repeated in triplicate and the results were
reproducible within ± 4%.
Detectionmethod:Theformedproductinthepresentstudy
was converted to concerned phenylhydrazone by using acidic
2,4-DNP (2,4-dinitrophenylhydrazine). Then the hydrazone
was characterized by melting point and spectral studies.
RESULTS AND DISCUSSION
In the present study, an attempt is made to study the kinetics
of uncatalyzed and Ru(III) catalyzed oxidation of non-vicinal
diol (propane-1,3-diol) and vicinal diols (glycol, glycerol,
propane-1,2-diol) in aqueous perchloric acid medium. It is
observed that uncatalyzed oxidation of vicinal diols (glycol,
glycerol, propane-1,2-diol) by periodate in aqueous perchloric
acid medium was completed instantaneously. Whereas, the
uncatalyzed oxidation of propane-1,3-diol under similar
conditions was infinitesimally slow and Ru(III) catalyzed
oxidation of non-vicinal diol (propane-1,3-diol) by periodate
is a slow reaction with observable kinetics. The difference in
the reactivity of propane-1,3-diol from vicinal diols can be
understood from the fact that propane-1,3-diol is a simple
acyclic molecule and won't display any sort of steric strain.
Hence, kinetics of Ru(III) catalyzed oxidation of non-vicinal
diol (propane-1,3-diol) by periodate is carried out in the present
study. Effect of variation and hence reaction orders with respect
to various reactants are discussed below.
Variationof[periodate]:Whilekeepingtheconcentrations
of other reactants at constant concentrations, [periodate] was
1570 Koteswara Rao et al. Asian J. Chem.
3. varied in the range 0.00025 to 0.002 M. Constructed the pseudo
first order plots i.e. log(a-x) against time (Fig. 1). Linearity of
plots was observed upto completion of 85% of total reaction.
In addition, it was found that values of pseudo-first-order
constants (k1) were independent of the initial [oxidant] (Table-1).
TABLE-1
RATE CONSTANTS IN Ru(III) CATALYZED
OXIDATION OF 1,3-PROPANE-DIOL BY
POTASSIUM PERIODATE IN AN ACID MEDIUM
General conditions: [KIO4] = 0.0005 M; [Substrate] = 0.025 M;
[Ru(III)] = 2 × 10–7
M; [H+
] = 0.1 M; Temperature = 308 K
Variant Conc. of variant (M) k1 × 104
min–1
0.00025 46.52
0.00050 46.53
0.00100 47.63
[Periodate]
0.00200 49.63
0.01250 52.33
0.02500 46.53
0.05000 28.42
[Substrate]
0.10000 18.02
0.025 65.56
0.050 56.11
0.100 46.53
0.200 25.25
[Acid]
0.500 18.97
0 46.53
KCl (0.1 M) 10.74
KBr (0.1 M) 8.85
KI (0.1 M) No reaction
Salt
KNO3 (0.1 M) 44.88
0 M Infinitesimally slow
0.25 × 10-7
2.94
0.50 × 10-7
7.42
1.0 × 10-7
22.58
2.0 × 10-7
46.53
4.0 × 10-7
82.83
[Catalyst]
8.0 × 10-7
172.49
0 46.53
0.01 51.32
0.025 51.67
[Boric acid]
0.05 53.58
308 46.53
313 54.96
318 64.23
323 96.49
Temperature (K)
333 183.37
0:100 46.53
05:95 26.16
20:80 18.78
40:60 15.34
Acetic acid:water
(v/v)
60:40 14.15
Variation of [substrate]: Substrate inhibition is observed
in the present case i.e. an increase in concentration of propane-
1,3-diol from 0.0125 to 0.1 M has resulted in a decrease of
rate constant from 52.33 × 10-4
to 18.02 × 10-4
min-1
(Table-1).
The plot of log k1 vs. log[propane-1,3-diol] shows a slope of
-0.532 (Fig. 2), which indicates the inverse fractional order in
[substrate]. Literature [25,26] shows that substrate inhibition
0.40
0.39
0.38
0.37
0.36
0.35
0.34
0.33
0.32
4+log(a-x)
0 10 20 30 40
Time (min)
y = -0.00202x + 0.39962
R = 0.99448
2
Fig. 1. Plot of log(a-x) versus time at [KIO4] = 0.0025 M, [1,3-diol] =
0.025 M, [Ru(III)] = 2 × 10–7
M, [H+
] = 0.1 M and Temperature =
308 K
1.8
1.6
1.4
1.2
4+logk1
2.0 2.2 2.4 2.6 2.8 3.0
4 + log [S]
y = -0.5325x + 2.8811
R = 0.9483
2
Fig. 2. Effect of substrate concentration on oxidation of propane-1,3-diol
by KIO4
was reported in the oxidation of different sugar alcohols by
periodate in alkaline medium, which was assigned to the forma-
tion of periodate substrate complex which resists oxidation.
In the present case, an increase in substrate concentration
increases the chances of forming an activated complex between
substrateandthecatalyst.Atthesametime,theincreasednumber
of substrate molecules improves their complexation possibility
withtheoxidant.Andhence,decreasestheavailabilityofoxidant
to attack the substrate-catalyst complex. However, indepen-
dence of substrate concentration was reported in the periodate
oxidation of polyethylene glycols (PEGs) in alkaline medium
[27,28] which can be explained based on the fact that PEGs
possess high hydroxyl values [29].
Variation of [acid] and [catalyst]: A decrease of rate
constant was resulted from 65.56 × 10-4
to 18.97 × 10-4
min-1
by increasing the concentration of perchloric acid concen-
tration from 0.025 to 0.50 M (Table-1). An inverse fractional
order in [H+
] was noticed as the slope is -0.444 in the plot of
logk1 vs. log[perchloric acid] (Fig. 3). Literature survey shows
contrary results regarding acid effect on kinetics of oxidation
of propane-1,3-diol. Inverse order in acid concentration was
reportedbySinghetal.[22,24] inphosphotungsticacidcatalyzed
N-chlorosaccharin oxidation and silver ions catalyzed peroxy-
disulphate oxidation. However, an increase in rate constants
with increase in hydrogen ion concentration was noticed in the
oxidation of terminal hydroxyl compounds by chromium(VI)
Vol. 32, No. 7 (2020) Substrate Inhibition in Ru(III) Catalyzed Oxidation of Propane-1,3-diol by Periodate 1571
4. 2.0
1.8
1.6
1.4
1.2
4+logk1
2.3 2.5 2.7 2.9 3.1 3.3 3.5 3.7
4 + log [H ]
+
y = -0.4447x + 2.9253
R = 0.9476
2
Fig. 3. Effect of acid concentration on oxidation of propane-1,3-diol by
periodate
[30,31]. In addition, present observation is contrary to that of
Bhamare et al. [32], who noticed an increase in rate of reaction
withanincreaseinacidity.Inpercholoricacidmedium,potassium
periodate predominantly exists as potassium metaperiodate
(KIO4) and paraperiodic acid (H5IO6) [33].According to Martin
et al. [33], in acidic medium, periodate exists in the following
equilibria:
H5IO6
K1
H+
+ H4IO6
- (1)
H4IO6
-
K2
2H2O + IO4
- (2)
H4IO6
-
K3
H+
+ H3IO6
-2 (3)
Increase in catalyst concentration has resulted in an increase
inreactionrate.Unitorderdependenceon[Ru(III)]wasobserved
from the slope value of the plot between log k1 and log [Ru(III)]
(Fig. 4). It shows the active involvement of catalyst species in
similar to the studies of Bhamare and Kulkarni [34].
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
4+logk1
0.3 0.8 1.3 1.8 2.3
8 + log [Ru(III)]
y = 1.1674x + 0.0761
R = 0.9874
2
Fig. 4. Effect of concentration of catalyst on oxidation of propane-1,3-
diol by KIO4
Effect of addition of solvent acetic acid: Acetic acid is
a commonly used dipolar aprotic solvent, which possesses lower
dielectric constant compared to water. In order to understand
the influence of dielectric constant on the reaction rate in the
present conditions, different compositions of acetic acid and
water were used. A decrease in reaction rate with an addition
of acetic was observed in this study (Table-1).A negative slope
was observed for the plot between log k1 versus 1/D (Fig. 5).
It indicates the reaction between negative ion and dipole [35].
However, the rate constant value decreased marginally with
an increase in percentage of acetic acid. It specifies the involve-
ment of dipole-dipole reactions too. It indicates that H5IO6 is
also an active oxidant species in addition to H4IO6
−
and IO4
−
.
In the oxidation of propane-1,3-diol and butane-1,4-diol by
N-chlorosaccharin, a decrease in rate constant with an increase
inphosphoricacidwasreportedbySingh etal.[24],whichcorro-
borates with the present trend.
2.8
2.7
2.6
2.5
2.4
2.3
2.2
2.1
2.0
5+logk1
y = -25.419x + 2.7899
R = 0.5987
2
0.010 0.015 0.020 0.025
1/D
Fig. 5. Effect of solvent composition on oxidation of propane-1,3-diol by
KIO4
Temperatureeffect:Anincreaseinfirstorderrateconstants
(k1) was observed with an increase in temperature (Table-1)
and yielded a straight line in the plot of ln k vs. 1/T (Fig. 6). By
using slope of the plot and Eyring equation, various activation
parameters were calculated (Table-2). The transition state is
highly solvated, in view of high positive values for ∆G#
. Further,
a reduction in the degree of freedom of molecule can be
observed in the so formed activated complex, as ∆S#
is negative.
2.4
2.2
2.0
1.8
1.6
4+logk1
y = -2.4964x + 9.7239
R = 0.9638
2
2.95 3.00 3.05 3.10 3.15 3.20 3.25 3.30
1000/T
Fig. 6. Effect of temperature on oxidation of propane-1,3-diol by KIO4
TABLE-2
ARRHENIUS PARAMETERS AT 308 K
∆E≠
(KJ/mol)
∆H≠
(KJ/mol)
−∆S≠
(JK–1
/mol)
log10 PZ
∆G≠
(KJ/mol)
47.79 45.23 177.07 3.99 99.77
1572 Koteswara Rao et al. Asian J. Chem.
5. Effect of boric acid, salts and ionic strength:A marginal
increase in reaction rate was observed with an addition of boric
acid. However, a substantial decrease in reaction rate with an
addition of halide ions is observed. Such an inhibition by
chloride ions was reported by Gupta et al. [30,36] in Cr(VI)
oxidation of diols, which was explained based on the formation
of less reactive CrO3Cl−
. Chloride inhibition was taken as
indirect evidence for the complexation between Cr(VI) and
substrate. Ionic strength variation didn't effect the rate of
reaction. The effect of salts on reaction rate was discussed by
Kulkarni et al. [37] based on their studies about Ru(III) cata-
lyzed oxidative degradation of azidothymidine by Mn(VII).
Stoichiometry and product analysis: The reaction was
allowed to proceed under experimental conditions (i.e.[propane-
1,3-diol] >> [periodate]) for overnight in a thermostatted water
bath in order to determine the reaction stoichiometry. Acidic
solution of 2,4-DNP was added to the reaction mixture and
maintained overnight at refrigerated temperature. Ice cold water
was used to wash the corresponding 2,4-dinitrophenylhyd-
razone, which was separated by centrifugation of the above
refrigerated mixture.The melting point of the air dried product
was found to be 425 K, which is in agreement with the earlier
reported values. IR and NMR spectral data confirmed the form-
ation of phenylhydrazone of 3-hydroxypropanal. Hence, the
corresponding reaction equation is shown below:
4 2 2 2 2 2 3 2IO HOCH CH CH OH HOCH CH CHO IO H O− −
+ → + +
It indicates the attacking of single hydroxy group whereas
the other hydroxyl group of the diol remain intact. It substan-
tiates the above observed stoichiometry of the reaction.
Variation in the product was reported based on either with
or without fission of C-C linkage in diols. Fission of C-C leading
totheformationofacetaldehydeandformaldehydewerereported
in the oxidation of propane-1,3-diol in presence ofAg+
/ peroxy-
disulphate[38] andF−
/acidpermanganate[39].However,instead
of C-C bond cleavage, one of the terminal hydroxyl groups
oxidizes in acid medium to yield hydroxyaldehyde [30,36].
In alkaline medium, 3-hydroxypropanal was reported as the
product in the oxidation of propane-1,3-diol in presence of
different combinations of catalyst/oxidant viz. Os(VIII)/chlor-
amine-T [40], Ru(III)/hexacyanoferrate(III) [41,42]. Same
product was reported in acidic medium in presence of different
catalyst/oxidant combinations viz. Ru(III)/Ce(IV) [23] andAg+
/
peroxodiphosphate [22]. In similar lines, 3-hydroxypropanal,
4-hydroxybutanal and 5-hydroxypentanal were the products
intheoxidationofpropane-1,3-diol, butane-1,4-diolandpentane-
1,5-diol, respectively [24,43].
Reaction mechanism: In aqueous medium, a range of
complexes [Ru(H2O)xCl6-x]x-3
were formed by ruthenium(III)
chloride [44] where x = 0 to 6. Based on structural and electro-
chemical studies, it was confirmed that x value varies from 4
to 6 in acidic medium [45-47]. However, perchlorate ion of
HClO4 has affinity towards ruthenium(III) to form a complex
[44,48]. Based on the spectral study carried out on RuCl3 in
acidic medium by Connick and Fine [49], [Ru(H2O)6]3+
is the
principal species. Literature survey shows that Ru(III) involves
in different mechanisms. In different acidic media (perchloric,
sulphuric, trifluoromethane sulphonic acid, trifluoro acetic acid
and p-toluenesulphonic acid), 0.239V was the redox potential
[45] for [Ru(H2O)6]3+
/[Ru(H2O)6]2+
. Ruthenium(III) is consi-
dered to be a weak oxidant in moderate concentrations of perch-
loric acid as the potential is about 0.1 V. Hence, instead of
trivalent ruthenium, octavalent ruthenium species is considered
to be active species which forms by the oxidation of Ru(III) in
acid medium [45,50]. For some of the substrates, ruthenium
forms a complex with substrate which decomposes to form final
products with recycling of catalyst [51-54]. In other reactions,
Ru(III) is converted to Ru(V) by the oxidant and the activated
catalyst participates in the reaction [55]. As per the previous
investigation, it was reported that at the higher concentration
of H+
or lower values of pH, catalyst Ru(III) is oxidized to its
higher oxidized forms Ru(VI) and Ru(VII) due to the higher
oxidation potential of oxidant. During the oxidation of Ru(III)
to higher oxidized forms by oxidant species [56], Ru(VI) is
found to be unstable species due to its rapid conversion into
hydroxide of ruthenium i.e. Ru(OH)4.
According to Menghani and Bakore et al. [38], propane-
1,3-diol complexes with [Ru(H2O)5OH]2+
to form a complex
in which one hydroxyl group coordinates with the active species.
Singh et al. [41,57] reported theestablishmentofRu(III)-alcohol
complex in alkaline medium, where hydride ion present on the
α-carbon (of alcohol) is abstracted by the catalyst to form
ruthenium ion and carbonium ion. A similar hydride abstrac-
tion from the α-carbon of propane-1,3-diol was proposed in
the Os(VIII) catalyzed oxidation by chloramine-T in alkaline
medium [40]. In such a case, an electron transfer was proposed
to the oxidant from the substrate via the catalyst.
Ionic [58] and free radical [59] pathways were proposed
in the Ru(III) catalyzed oxidations of alcohols. Free radical
mechanism was also adopted in the oxidation of 1,3-propane-
diol in the presence of different catalysts like silver (I) [6]. How-
ever, involvement of ionic pathway is proposed in the present
case taking into consideration of the above solvent effect on
rate of reaction and non-formation of insoluble precipitate in
free radical test by using acrylonitrile [56,60]. In addition,
propane-1,3-diol forms a complex with [Ru(H2O)6]3+
. In rate
determining step, the complex reacts with periodate to form a
geminal diol, which is unstable and hence undergoes loss of
water molecule in a fast step to form the concerned aldehyde
as a final product (Scheme-I).
Rate law:Propane 1,3-diol complexes with ruthenium(III)
catalyst.
1,3-diol + Catalyst
K4
Complex C
In rate determining steps, complex C reacts with different
species of periodate to form intermediate complexes, which
decompose quickly to final products.
C +
k1
IO4
- IP1
P
fast
slow
C + H5IO6 IP2 Pk2
slow
fast
C + H4IO6
- IP3
Pk3
slow
fast
Vol. 32, No. 7 (2020) Substrate Inhibition in Ru(III) Catalyzed Oxidation of Propane-1,3-diol by Periodate 1573
6. H2C
H2C
CH2OH
+ Ru
III CH2 O Ru
IIIH
H2C
CH2OH
OH
IO4
-
H
C
H2C
HOH2C
OHRuIII
+IO3
- + HO
H
C
H2C
HOH2C
OHHO
H2C
H2C
HC
O
OH
+ H2O
Scheme-I: Mechanism of Ru(III) catalyzed oxidation of propane-1,3-diol
by periodate
C + H3IO6
2– IP4 Pk4
slow
fast
From eqn. 1:
1 5 6
4 6
K [H IO ]
[H IO ]
[H ]
−
+
=
From eqn. 2:
1 2 5 6
4 2 4 6
K K [H IO ]
[IO ] K [H IO ]
[H ]
− −
+
= =
From eqn. 3:
2 3 4 6 1 3 5 6
3 6 2
K [H IO ] K K [H IO ]
[H IO ]
[H ] [H ]
−
−
+ +
= =
Total concentration of periodate [IO4
−
]T is given by:
2
4 T 5 6 3 6 4 6 4[IO ] [H IO ] [H IO ] [H IO ] [IO ]− − − −
= + + +
From eqn. 3, it is clear that H3IO6
2–
exists preferably at low
concentrations of acid. As [H+
] >> [IO4
−
], [H3IO6
2−
)] is negli-
gible. Hence, the above equation can be rewritten as:
4 T 5 6 4 6 4[IO ] [H IO ] [H IO ] [IO ]− − −
= + +
1 5 6 1 2 5 6
5 6
K [H IO ] K K [H IO ]
[H IO ]
[H ] [H ]+ +
= + +
{ }5 6
1 1 2
[H IO ]
[H ] K K K
[H ]
+
+
= + +
In percholoric acid medium, potassium periodate predo-
minantly exists in potassium metaperiodate (KIO4) and paraper-
iodic acid (H5IO6) [16]. By rearranging the above equation,
we get:
4 T
5 6
1 1 2
[IO ] [H ]
[H IO ]
[H ] K K K
− +
+
=
+ +
Total concentration of catalyst [Catalyst]T can be written
as:
[Catalyst]T = [Catalyst] + [Complex]
= [Catalyst] + K4 [1,3-diol][Catalyst]
= [Catalyst] {1+ K4 [1,3-diol]}
By rearranging the above equation:
T
4
[Catalyst]
[Catalyst]
1 K [1,3-diol]
=
+
1 4 2 5 6
3 4 6
Rate k [Complex][IO ] k [Complex][H IO ]
k [Complex][H IO ]
−
−
= + +
{ }1 4 2 5 6 3 4 6[Complex] k [IO ] k [H IO ] k [H IO ]− −
= + +
1 2 5 6
4 1
1 5 6
2 5 6 3
K K [H IO ]
K [1,3-diol][Catalyst] k
[H ]
K [H IO ]
k [H IO ] k
[H ]
+
+
= +
+
{ }4 5 6
1 1 2 2 3 1
K [1,3-diol][Catalyst][H IO ]
k K K k [H ] k K
[H ]
+
+
= + +
{ }
4 T
4
4 T
1 1 2 2 3 1
1 1 2
K [1,3-diol] [Catalyst]
[H ] 1 K [1,3-diol]
IO ] [H ]
k K K k [H ] k K
[H ] K K K
+
− +
+
+
=
+
+ +
+ +
1 1 2 2 3 14 T 4 T
4 1 1 2
k K K k [H ] k KK [1,3-diol][Catalyst] [IO ]
1 K [1,3-diol] [H ] K K K
+−
+
+ +
=
+ + +
The above rate law explains the observed first order in
oxidant and ruthenium(III) and inverse fractional order with
the concentrations of acid and substrate.
Conclusion
The observed substrate inhibition in the ruthenium(III)
catalyzed periodate oxidation of propane-1,3-diol was expl-
ained based on the competitive formation of a complex between
propane-1,3-diol and periodate. Based on the inverse acid
dependence and solvent effect, H5IO6, H4IO6
−
and IO4
−
were
the active periodate species. Formation of 3-hydroxy propanal
as the final product indicates the attacking of single hydroxy
group, whereas the other hydroxyl group of substrate remain
intact.
ACKNOWLEDGEMENTS
One of the authors, KVSK is thankful to UGC, New Delhi,
IndiaforfinancialsupportintheformofMinorResearchProject,
F.No.4-4/2015-15(MRP-SEM/UGC-SERO), November 2014.
CONFLICT OF INTEREST
The authors declare that there is no conflict of interests
regarding the publication of this article.
1574 Koteswara Rao et al. Asian J. Chem.
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Vol. 32, No. 7 (2020) Substrate Inhibition in Ru(III) Catalyzed Oxidation of Propane-1,3-diol by Periodate 1575