- Dr. Gowrisankar received funding from SERC and GSK-EDB to develop catalytic processes for the oxidative depolymerization of lignin into value-added chemicals like vanillin and for sustainable carbon-carbon cross coupling methodologies. - Key research achievements included developing a homogeneous catalytic system to extract 6% vanillin from lignin and synthesizing pharmaceutical compounds like dantrolene and boscalid in gram scales. - The work involves lignin depolymerization, C-H activation, C-C bond formation, and hydrogenation of carbon dioxide to produce useful chemicals. - Products of the work have commercial interest from companies like Solvay and Nestle.

1. Dr. Gowrisankar
Scientist-II
6-7th July 2015

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Dr. Gowrisankar, OC Department
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Objectives:
Development of efficient and environmentally benign catalytic processes for
the oxidative depolymerization of Kraft/Organosolv lignin to value added
chemicals such as vanillin and derivatives preferably under non alkaline
conditions.
Funding Source:
1.3M SGD was received from the Science and Engineering Research Council
(SERC), A*Star, Singapore.

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Dr. Gowrisankar, OC Department
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Chemistry of Lignin
Potential Applications:
Ø Flavors
Ø Fragrances
and
Ø Materials and etc
Chemistry of Lignin
Linkage
Type
Approximate
β-O-4 45-50
α-O-4 6-8
β-5 9-12
5-5 18-25
4-O-5 4-8
β-1 7-10
β-β 3

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Dr. Gowrisankar, OC Department
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State of the Art
Ø Global Consumption ~12000 t.p.a.
Ø Lignin based vanillin is in high demand in certain market sectors (perfume industries
chocolate manufacturers-Price $100-200/Kg).
Ø Eurovanillin (Borregard) 2300 t.p.a (~15%)-from waste sulfite liquor (lignosulfonate).
Ø Modern paper and pulp industries prefer Kraft pulping rather than sulfite pulping and
hence there is only minimal availability of lignosulfonate for vanillin.
Ø Most of the vanillin plants based on sulfite liquor were closed down-also due to disposal issues
of the large amounts of caustic soda wastes (~160 Kg/Kg of vanillin) generated during this
process (J. Chem. Ed. 1997, 74, 1055).
From Petrochemicals
Guaiacol ($15/Kg)
Sensitive to the world oil
market.
From Biomass
waste sulfite liquor
(lignosulfonate) ($0.4/Kg)

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Dr. Gowrisankar, OC Department
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NMR Characterization and Nitrobenzene Oxidation
Lignin Total OMe
mmol/ga
Cϒ(β-O-4)
mmol/ga
Cα, Cβ
mmol/ga
Total Ar
mmol/ga
G/S Ratiob
Kraft Lignin-
Neutral
3.382 0.4292 0.159 6.04 7
Indulin AT-
Kraft
3.108 0.4477 0.179 5.69 7.5
afrom quantitative 13C NMR using trioxane as the internal standard, bfrom quantitative 31P NMR after phosphitylation using cyclohexanol as the
internal standard.
Nitrobenzene Oxidation
Lignin Vanillin
Yield (wt%)
Kraft 9.53
Indulin 9.1
Lignisulfonate 8.37

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Dr. Gowrisankar, OC Department
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Research Achievements
Ø We have developed a homogeneous catalytic system to extract 6 wt% of vanillin from
neutral Kraft lignin in presence of green solvent under neutral conditions.
Ø The selectivity could be switched to vanillic acid by varying the O2 pressure.
Ø The overall yield is about 75% of the expected yield from the Kraft lignin-Neutral.

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Dr. Gowrisankar, OC Department
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Catalytic Oxidative Depolymerization

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Dr. Gowrisankar, OC Department
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Catalytic Oxidative Depolymerization
0
0,5
1
1,5
2
2,5
3
1 wt% Re 2 wt% Re 6 wt% Re
2,15
2,78 2,8
Vanillin
0
0,5
1
1,5
2
2,5
3
3,5
1hr 2hr 5hr
2,15
2,33
3,17Vanillin
0
1
2
3
4
5
6
400 mg/3
wt% Re
200 mg/6
wt% Re
100 mg/12
wt% Re
3,57
4,17
5,93
Vanillin
0
0,5
1
1,5
2
2,5
3
3,5
4
120 160 200
1,61
3,57
2,95
Vanillin
0
1
2
3
4
5
5 bar 10 bar
3,11
4,04
Vanillic acid
Re-Concentration Time effect (hrs)
Amount of lignin/green solvent
Temp effect (OC) Oxygen effect (Bar)

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Dr. Gowrisankar, OC Department
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Depolymerization of Lignin under Flow Conditions
Temp (oC) Residence time (Min) Vanillin
Yield (wt%)
160 30 1.65
220 30 2.5
Reaction Conditions: Pure O2 (1 bar), Lignin Conc: 10g/L

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Dr. Gowrisankar, OC Department
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Output of Our Work
Lignin
+
Catalyst
+
Solvent
Reaction
Vessels
Distillation
Vanillin
+
Other
Aromatics
Solvay
Singapore
Oligomer Nestle
Singapore
Ø SOLVAY is interested in this work.
Ø Nestle is interested in Oligomer for packing purpose.
Ø Patent application is being submitted for this work.

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Dr. Gowrisankar, OC Department
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Objectives:
The development of sustainable carbon-carbon (C-C) cross coupling methodologies based
on carbon-hydrogen (C-H) bond activation.
Funding Source:
1.9M SGD was received from the GSK-EDB-GSM, Singapore.

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Dr. Gowrisankar, OC Department
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C-H Arylation (GSK-EDB Project)
Ø S. Gowrisankar, J. Seayad, Chem. Eur. J. 2014, 20, 12754–12758.
Synthesis of Dantrolene in Gram Scale

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Dr. Gowrisankar, OC Department
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Ø S. Gowrisankar, J. Seayad, Asian J. Org. Chem. 2015, 6, 521–524.
Synthesis of Boscalid in Gram Scale
C-C Bond Formation (GSK-EDB Project)

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Dr. Gowrisankar, OC Department
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Synthesis of Adamantyl-BippyPhos (Ad-BGPhos)
Ø S. Gowrisankar, A. G. Sergeev, P. Anbarasan, A. Spannenberg, H. Neumann, M. Beller, J. Am. Chem. Soc. 2010, 132, 11592.
Ø Ad-BGPhos (Beller-Gowri) also available from Sigma-Aldrich (Cat. No . 740845 Aldrich).

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Dr. Gowrisankar, OC Department
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Synthesis of Adamantyl-BippyPhos (Ad-BGPhos)
15
Ad-BGPhos (Beller-Gowri) also available from Sigma-Aldrich (Cat. No . 740845 Aldrich).
Prof. Buchwald
ü Substituents in 2,4-position prevent oxidation at phosphine
ü Adamantyl group accelerates reductive elimination step
üHeteroarene (bipyrazole) phosphines enhance rate of
oxidative addition
üSolubility of the active species
üConvenient for synthesis
Ø S. Gowrisankar, A. G. Sergeev, P. Anbarasan, A. Spannenberg, H. Neumann, M. Beller, J. Am. Chem. Soc. 2010, 132, 11592.
Ø Ad-BGPhos (Beller-Gowri) also available from Sigma-Aldrich (Cat. No . 740845 Aldrich).

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Dr. Gowrisankar, OC Department
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Palladium Catalyst C-O bond formation
Ø Gowrisankar, S.; Neumann, H.; M. Beller, ChemCatChem 2011, 3, 1439-1441.
Ø S. Gowrisankar, A. G. Sergeev, P. Anbarasan, A. Spannenberg, H. Neumann, M. Beller, J. Am. Chem. Soc. 2010, 132, 11592.
Ø Gowrisankar, S.; Neumann, H.; M. Beller, Chem. Eur. J. 2012, 18, 2498–2502.

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Dr. Gowrisankar, OC Department
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Synthetic Potential of Our Methodology
Synthesis of Butoxycaine

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Dr. Gowrisankar, OC Department
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Synthesis of Phosphomide Ligands
Phosphomide Ligands
ü Phosphomide used as ligand
ü Mostly neglected ligand in phosphine chemistry
ü Electron withdrawing effect (adjacent to a carbonyl group)
ü Oxygen lone pair to delocalise towards the carbon atom
Acid chloride Dialkyl(aryl)phosphine
ØGoerlich, J. R.; Muller, C.; Schmutzler R. Phosphorus, Sulfur Silicon Relat. Elem. 1993, 85, 193–205.
ØBarron, A. R.; Hall, S.W.; Cowley, A. H. J. Chem. Soc. Chem. Commun. 1987, 1753–1754.
ØKunzek, H.; Braun, K.; Nesener, E.; Ruhlmann, K. J. Organomet. Chem. 1973, 49, 149.
ØKostyanovsky, R. G.; Yakshin, V. V.; Zimont, S. L. Tetrahedron 1968, 24, 2995–3000.
ØIssleib, K.; Priebe, E. Chem. Ber. 1952, 85, 239.

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Dr. Gowrisankar, OC Department
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Catalytic Hydrogenation of CO2, Sodium bicarbonate
Ø S. Gowrisankar, C. Federsel, H. Neumann, C. Ziebart, R. Jackstell, A. Spannenberg, M. Beller, ChemSusChem 2013, 6, 85-91.

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Dr. Gowrisankar, OC Department
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Catalytic Hydrogenation of CO2, Sodium bicarbonate
Ø S. Gowrisankar, C. Federsel, H. Neumann, C. Ziebart, R. Jackstell, A. Spannenberg, M. Beller, ChemSusChem 2013, 6, 85-91.
Entry Product T (°C) P H2/CO2 (bar) TON
1 Sodium formate 80 60/0 9128
2 b Methyl formate 100 30/30 4127
3c Phenyl ethanol 80 50/0 498
4 Benzyl alcohol 80 50/0 1650
5 Ethyl cinnamate 80 50/0 1778
Optimisation of the conditions for catalytic hydrogenationa of
bicarbonate, CO2,
b
acetophenone,
c
benzaldehyde and cinnamaldehyde.
Reaction conditions: Ru(me-allyl)2(COD), 20 h, 0.313 µmol catalyst. 2.0 equiv, of Ligand (L12). b0.01435 mol NEt3 used.
cracemic mixture of 50 % of each enantiomer was detected. Potassium tert-butoxide (0.45 mmol) was used as base.

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Dr. Gowrisankar, OC Department
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Ad-BGphos Cy-BellGiphos-1-Nap
Ad-BellGiphos-1-Nap Ad-BellGiphos-Bz
Ø 744816 Aldrich (Ad-BellGiphos-Bz)
Ø 744700 Aldrich (Cy-BellGiphos-1-Nap)
Ø 740845 Aldrich (Ad-BGPhos)
Ø 744913 Aldrich (Ad-BellGiphos-1-Nap)

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Dr. Gowrisankar, OC Department
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Acknowledgement
Prof. Matthias Beller
Director, LIKAT, Germany
Prof. Jae Nyoung Kim
CNU, Korea
Dr. Keith Carpenter
ED, ICES, Singapore
Thank you for your kind attention