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Afscheidsrede prof. dr. R. A

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1 Afscheidsrede prof. dr. R. A
Afscheidsrede prof.dr. R.A. Sheldon hoogleraar Biokatalyse en Organische Chemie December 7, ‘E Factors, Green Chemistry and Catalysis: Records of the Travelling Chemist’ 7 december 2007 R. A. Sheldon, Rec. Trav. Chem. 2007, 1, 1

2 Green Chemistry Green chemistry efficiently utilises (preferably renewable) raw materials, eliminates waste and avoids the use of toxic and/or hazardous solvents and reagents in the manufacture and application of chemical products. Anastas and Warner, Eds, Green Chemistry. Theory & Practice, Oxford U. Press, 1998

3 Sustainability Meeting the needs of the present generation without compromising the needs of future generations to meet their own needs is the goal “What we need is more imagination not more knowledge” Albert Einstein

4 Do politicians understand the issues?
It’s not pollution that is the problem it’s the impurities in our air and water. Dan Quayle

5 Phloroglucinol Synthesis Ca. 40kg of solid waste per kg phloroglucinol
CH3 COOH O2N NO2 O2N NO2 H2N NH2 HO OH K2Cr2O7 Fe/HCl aq.HCl H2SO4 / SO3 - CO2 D T NO2 NO2 NH2 O H TNT phloroglucinol Ca. 40kg of solid waste per kg phloroglucinol HO OH byproducts + Cr2 (SO4)3 + 2KHSO4 + 9FeCl2 + 3NH4Cl + CO2 + 8H2O O H MW = 126 Atom Utilisation = 126/2282 = ca. 5% E Factor = ca. 40 product “ To measure is to know ” Lord Kelvin

6 “Atom for Atom” Syn gas utilisation (1983) 2 CO + 3 H2 HOCH2CH2OH
2 CO + 4 H H2C=CH2 + 2H2O 100% 44% Oxygen utilisation (1990) Oxidant % Active O Byproduct H2O H2O t-BuOOH t-BuOH CH3COOOH CH3COOH NaOCl NaCl KIO KIO3 Atom utilisation (1991) 1. PO : Chlorohydrin process CH3 HC=CH2 + Cl2 + H2O CH3CH(OH)CH2Cl + HCl Ca(OH)2 O CH3HC CH2 + CaCl2 + H2O 25% atom utilisation + H2O CH3HC=CH2 + H2O2 O CH3HC CH2 2. PO : Catalytic Oxidation 76% atom utilisation See Chem. Eng. Progr. 1991, 87(12), 11 See also Trost, Science, 1991, 254, 1471

7 E Factor = kg waste/kg product
E Factors E Factor = kg waste/kg product Tonnage E Factor Bulk Chemicals <1 - 5 Fine chemical Industry >50 Pharmaceutical Industry >10 [i] “Another aspect of process development mentioned by all pharmaceutical process chemists who spoke with C&EN, is the need for determining an E Factor”. A. N. Thayer, C&EN, August 6, 2007, pp R.A.Sheldon, Chem &Ind, 1992, 903 ; 1997, 12

8 I Factor = 4.19 R. A. Sheldon, Green Chem, 2007, 9,

9 The E Factor Is the actual amount of all waste formed in
the process, including solvent losses and waste from energy production (c.f. atom utilisation is a theoretical nr.) E = [raw materials-product]/[product] A good way to quickly show (e.g. to students) the enormity of the waste problem Undergraduate Course : “Green Chemistry & Sustainable Technology”

10 Major Sources of Waste STOICHIOMETRIC ACIDS & BASES
STOICHIOMETRIC OXIDANTS & REDUCTANTS - Na2Cr2O7, KMnO4, MnO2 - LiAlH4, NaBH4, Zn, Fe/HCl SOLVENT LOSSES - Air emissions & aqueous effluent 1

11 The Solution is Catalytic
Substitution of conventional Bronsted & Lewis acids by recyclable,non-corrosive solid acids e.g zeolites Atom efficient catalytic processes: -hydration (H2O) reduction (H2),oxidation (O2 ,H2O2) -carbonylation (CO),hydroformylation (CO/H2) -amination (NH3), reductive amination (NH3 /H2) with olefins and (alkyl)aromatics as raw materials Alternative reaction media / biphasic catalysis Biocatalysis, naturally

12 Research Themes Renewables Cascades Novel Media O2 H2O2 CO H2 H2O
Enzymes Catalysis & Green Chemistry Renewables Cascades Chirotechnology Sheldon, Arends and Hanefeld , Green Chemistry And Catalysis, Wiley, New York, 2007

13 Heterogeneous Catalysis

14 Sheldon and van Doorn, J.Catal. 31, 427, 1973
M + Peroxometal mechanism 1973 Sheldon, Rec.Trav.Chim.Pays-Bas, 92, 253, 1973 Mimoun, Sharpless + R O H T i ( I V ) / S O2 Sheldon and van Doorn, J.Catal. 31, 427, 1973 Shell SMPO process 1973 Metal Catalyzed Epoxidation H2 + O2 H2O2 Pd/Pt (4nm) TS-1 H2O MeOH O Headwaters/Evonik 2006 TS-1 H2O2 + H2O MeOH O Enichem 1985 Ti-beta, Ti-MCM41, Ti-ITQ, etc van Bekkum, Corma Dakka, Sato, LeBars Redox Molecular Sieves (Zeozymes)

15 Green Caprolactam Process : Sumitomo
v a p o u r O H2O2 / NH3 NOH NH p h a s e O T S - 1 H i g h S i MFI A m o x i a t n B e c k m a n r g t C6H10O + H2O2 + NH C6H11NO + 2H2O Atom efficiency = 75% ; E = 0.32 (<0.1) O NOH (NH3OH)2SO4 NH H2SO4 O Atom efficiency =29% ; E = 4.5 Ichihashi and Kitamura,Catal.Today, 73, 23, 2002

16 Redox Molecular Sieves : Philosophers’ Stones or Trojan horses ?
Filtration Test for Heterogeneity: 60 50 40 conversion (%) 30 20 hot 10 cold 30 60 90 120 150 180 Time (min) Lempers (1998) Chen (1995), Elings (1997), Plyuto, Schuchardt Sheldon, Wallau, Arends and Schuchardt, Acc. Chem. Res., 31 (1998)

17 Homogeneous Catalysis

18 Catalysis in Non-conventional Reaction Media
Two challenges : Toxicity and/or hazards of atmospheric and ground water pollution by conventional solvents Separation/recycling of homogeneous catalysts (Biphasic) catalysis in non-conventional media - water - supercritical carbon dioxide (Martyn Poliakoff) - ionic liquids (Ken Seddon) - fluorous biphasic (Istvan Horvath) “The best solvent is no solvent” 5

19 ten Brink, Arends, Sheldon, Science 287 (2000) 1636
Aqueous Biphasic Cataysis 1. Carbonylation 2. Aerobic Oxidation OH COOH Ibuprofen CO Pd / tppts /H+ R2 H + . 5 O2 R1 O H Pd2+/ L air OH O R 2 R R O + H2O Pd2+ L water R 1 NaO3S S O3 N a NaO3S P S O3Na tppts S O3Na N N Papadogianakis, Verspui (2001) Moiseev ten Brink (2001) ten Brink, Arends, Sheldon, Science 287 (2000) 1636

20 Catalysis in Ionic Liquids
Negligible vapour pressure Designer solvents Catalytic hydroformylation, carbonylation, hydrogenation and biocatalysis R2 OH + + + N N + N N OH N OH R R1 R3 R N + R4 OH R Anions : B F4 , P F6 , R C O , H2 P O4 , N O3 , H O C H2 C O2 2 O O O + OH O + OH OH NH2 O O CaLB in [bmim][BF4] and [bmim][PF6] O Madeira Lau (2003) Seddon RCOOOH RCOOH Product recovery? H2O H2O2 Madeira Lau, van Rantwijk, Seddon, Sheldon, Org.Lett. 2, 4189, 2000 Sheldon, Chem. Comm. 2001,

21 In situ product removal with scCO2
scCO2 phase OH OAc OAc lipase IL phase scCO2 as mobile phase in batch or continuous operation Reetz et al,Chem.Comm.,2002, 992 Lozano et al,Chem.Comm.,2002, 692

22 The Miscibility Switch
Reactant Carbon dioxide CO2 + Product IL + Catalyst Reactant CO2 P  P  P  CO2 CO2 IL + Catalyst Product + IL IL Ionic liquid + catalyst Product High pCO2 one phase Low pCO2 two phases Reaction Separation Peters & Witkamp

23 Organocatalysis

24 Organocatalytic Oxidations
Cu(II) / PIPO / O2 PIPO N NH(tert-octyl) (CH2)6 O. 5 No solvent No Br- NaOCl Recyclable Cheap raw material Chimassorb 944 Dijksman (2001) OH H R1 R2 O + “O” + H2O . “O” = NaOCl, m-CPBA, oxone (+ Br -) N van Bekkum et al , Synthesis, 1996, 1153 CH2Cl2 / H2O TEMPO . N O RCH2OH O 2 H l a c s e o x . N RCHO + Laccase : a multicopper oxidase Li (2004), Matijosyte de Vries/Hagen OH H O + . 5 2 TEMPO (5m%) Cu(II) / bipy (5m%) Base / MeCN / H2O Gamez Organocatalytic Oxidations

25 Biocatalysis CPO phytase subtilisin laccase CaLB HNlase
Inventing New Enzymes & Enzymatic Reactions

26 Why Biocatalysis? Mild conditions: ambient temperature &
pressure in water Enzymes are derived from renewable sources and are biodegradable High rates & highly specific : substrate, chemo-, regio-, and enantiospecific Higher quality product Green Chemistry (environmental footprint)

27 > 3000 tpa If you want to find something new
Enzymatic Ammoniolysis BASF Process NH2 Lipase ee > 99% (S) + O NH ee > 99% (R) NaOH glycol-water (2:1), 150oC > 3000 tpa R O O NuH R Nu Ser O Nu = OH, OR, NH2 , RNH, OOH, etc O O NH3/t-BuOH R OEt R NH2 lipase, 40oC Green amide synthesis Enantioselective with amino acid esters Steverink(1995), Hacking (1999) Wegman(2001) If you want to find something new you have to DO something new Edward De Bono

28 Easy-on-easy-off resolution
NHCOCH2Ar H2O NH2 NH2 P h ArCH2COX P h p e n a c y l a s e + P h p H 7 e e > 9 9 % p e n a c y l a s e NH2 p H 1 - 1 1 e e > 9 9 % P h V.Svedas L.van Langen(2001), R.Madeira Lau(2003), H.Ismail(2007) Dynamic Kinetic Resolution - 88 % yield (4 days) - ee product 98 % . NH2 O H N CaLB, 50oC, 96h Nano Pd 10 20 30 40 50 60 70 80 90 100 120 time (h) % yield (amide) Kinetic resolution Dynamic kinetic resolution H.Ismail(2007) Pd –catalyzed racemization of 1-phenethylamine : Murahashi (1983) ; Reetz , DKR (1996).

29 vanadate phytase Linker 65% ee O C P O ArSCH3 + H2O2 S + H2O A r C H3
sp r g N 2 V L y van de Velde Aksu-Kanbak Correia O C P O ArSCH3 + H2O2 S + H2O A r C H3 N N 99% yield >99% ee FeIII N N S C y s van Deurzen (1996) van de Velde (2000) Heme Low stability Se X OH O OOH H2O2 H2O R1 R2 = N 2 , C F 3 ten Brink (2001) Ser O Linker X = N 2 , C F 3 H S e subtilisin van der Toorn Inventing New Enzymes : Chemomimetic Biocatalysis

30 Historically: Adapt Process to fit Catalyst
Available Catalyst Dream Process

31 Future: Adapt Catalyst to fit Ideal Process
EVOLVE Catalyst Adapted Catalyst Nightmare Process Dream Process Compromise process to accommodate catalyst Adapt catalyst to optimum process Directed Evolution BOC HTS (directed evolution lab.) L.Otten

32 DNA Shuffling : Evolution in the Fast Lane
Repeat gene A HTP Screening Genes From Nature Library of Novel Genes DNA ShufflingTM gene B gene C gene D . Novel Genes Stemmer,Nature,370, , 1994; Huisman et al (Codexis) See also Reetz, Advan. Catal. 2006, 1-69.

33 Green Synthesis of Lipitor Intermediate (Codexis)
Presidential Green Chemistry Challenge Award 2006 OEt Cl O NADPH NADP+ OH HHDH NC KRED g l u c o s e n a t GDH q . NaCN , pH 7 (>99.9% ee) > 9 % ee KRED = keto reductase ; GDH = glucose dehydrogenase HHDH = halohydrin dehalogenase (non-natural nucleophile) Nature Biotechnol. 2007, 25, Huisman, Grate, Lalonde et al (Codexis)

34 Improving Performance by Directed Evolution:
test tube to commercial process with gene shuffling 97% ~80% >90% Isolated yield 0.7 g/L 10 g/L <1 g/L Enzyme loading ~1 min. >1 hr Phase separation time 540 g/ 80 g/ >240 g/ Volumetric Productivity 8 hrs 24 hrs <16 hrs Reaction time 180 g/L 80 g/L 160 g/L Substrate loading Final Performance Initial Performance Process Design Parameter 1. KRED + GDH 92% ~60% >90% Isolated yield 1.2 g/L 130 g/L <1.2 g/L Enzyme loading 670 g/ 7 g/ >180 g/ Volumetric Productivity 5 hrs 72 hrs <16 hrs Reaction time 140 g/L 20 g/L 120 g/L Substrate loading Final Performance Initial Performance Process Design Parameter 2. HHDH

35 Disadvantages of Enzymes
Low operational stability & shelf-life Cumbersome recovery & re-use (batch vs continuous operation) Product contamination Solution : Immobilization

36 Cross-Linked Enzyme Aggregates (CLEAs)
X-linker precipitant aggregate CLEA - Enzyme in solution glutaraldehyde or dextran polyaldehyde as X-linker Enables recycling via filtration Higher productivity No need for highly pure enzyme Simple procedure / widely applicable Stability towards denaturation CLEAS active in: scCO2 (M. Poliakoff) ILs (Sheldon) Sorgedrager (2006), Janssen (2006 ) (CLEA Technologies B.V.)

37 Examples of Successful CLEAtion
Hydrolases Pen. acylases (2) Lipases (7) Esterases (3) Proteases (3) Nitrilases (2) Aminoacylase Phytase Galactosidase Oxidoreductases ADH FDH Glucose oxidase Galactose oxidase Laccase Catalase Chloroperoxidase Lyases R- & S- HnLases PDC DERA Nitrile hydratase Cao, Lopez-Serrano, Mateo, Perez, van Langen, Sorgedrager Janssen, Bode, van Pelt, Chmura, Matijosyte, Aksu-Kanbak, Evolution vs Cleationism

38 Catalytic Cascade Processes
97% yield / > 99% ee H 2 N O OH OCH3 , 4 % cat. 5 a t m H2 99% yield / 95% ee amidase Catalyst : Rh(monophos) on TUD-1 Simons (2007) H 2 O lipase PS- I(O2CR)2 PS- I RCOOH RCO2OH Kotlewska

39 Trienzymatic Cascade with a Triple-Decker combi CLEA
OH CONH2 OH O CN H2O Pen G amidase HCN /(S)-HnL NLase OH COOH Conv. 96% / ee >99% Chmura, Stolz

40 Renewables & Green Chemistry :
the Biorefinery Fuels CO2 + H2O photo- Biomass Polymers synthesis Bulk & Fine Chemicals Greener products Emons (1992), Arts(1996), Papadogianakis Metrics for renewables ?

41 Carboxystarch : Safe & Natural Absorbing Polymer (SNAP)
OH H H COOH Laccase CLEA TEMPO/O2 [ H O [ H O O O HO H HO H H OH H OH H O H O ] ] n n starch c a r b o x y s t a r c h Non- toxic & biodegradable Green (bio) catalytic process Green raw materials Boumans (TNO) The plan is nothing, the planning is everything Mao Zedong

42 Enantio- selectivity Environment Think Green E The E Factor Economy
Elegance It’s better to travel one mile than to read a thousand books Confucius

43 So it goes…………

44 Collaboration & Funding
EU IOP Katalyse IOP Koolhydraten Hoechst Celanese

45 successful man there is
behind every successful man there is an astonished woman



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