New Trends in GREEN CHEMISTRY

New Trends in GREEN CHEMISTRY

V. K. Ahluwalia Visiting Professor

Dr. B. R. Ambedkar Centre for Biomedical Research University of Delhi. Delhi - J 10007. India

M.Kidwai Coordinator

International Chapter of Green Chemistry in India Department of Chemistry. University of Delhi.

Delhi - llO 007. India

~ . . , Kluwer Academic Publishers

BOSTON DORDRECHT LONDON

Anamaya Publishers NEW DELHI

A C/.P. catalogue record for the book is available from the Library of Congress

ISBN 978-94-015-7102-9 ISBN 978-1-4020-3175-5 (eBook) DOI 10.1007/978-1-4020-3175-5

Copublished by Kluwer Academic Publishers, P.O. Box 17,3300 AA Dordrecht, The Netherlands with Anamaya Publishers, New Delhi, India

Sold and distributed in all the countries, except India, by Kluwer Academic Publishers, 101 Philip Drive, Norwell, MA 02061, U.S.A. and in Europe by Kluwer Academic Publishers, P.O. Box 322, 3300 AH Dordrecht, The Netherlands

In India by Anamaya Publishers F-230, Lado Sarai, New Delhi - 110 030, India

All rights reserved. Copyright © 2004. Anamaya Publishers, New Delhi, India Softcover reprint of the hardcover 1 st edition 2004 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without the written permission from the copyright owner.

To

Professor Sukhdev, FNA

on his 80th birthday

Foreword

Organic chemistry has played a vital role in the development of diverse molecules which are used in medicines, agrochemicals and polymers. Most ofthe chemicals are produced on an industrial scale. The industrial houses adopt a synthesis for a particular molecule which should be cost-effective. No attention is paid to avoid the release of harmful chemicals in the atmosphere, land and sea. During the past decade special emphasis has been made towards green synthesis which circumvents the above problems. Prof. V. K. Ahluwalia and Dr. M. Kidwai have made a sincere effort in this direction.

This book discusses the basic principles of green chemistry incorporating the use of green reagents, green catalysts, phase transfer catalysis, green synthesis using microwaves, ultrasound and biocatalysis in detail. Special emphasis is given to liquid phase reactions and organic synthesis in the solid phase.

I must congratulate both the authors for their pioneering efforts to write this book. Careful selection of various topics in the book will serve the rightful purpose for the chemistry community and the industrial houses at all levels.

PROF. JAVED IQBAL, PhD, FNA

Distinguished Research Scientist & Head Discovery Research

Dr. Reddy's Laboratories Ltd. Miyapur, Hyderabad - 500 050, India

Preface

Organic chemistry dealS' with the synthesis of molecules having diverse uses in medicines, agio chemicals and biomolecules. The industries producing such chemicals are basically concerned with the type of reaction involved, the percentage yield etc. so that synthesis becomes cost effective. Special attention is given to ensure that there is no environmental pollution. All these form the basis of Green Chemistry-the pressing need of all nations. This book discusses designing green synthesis, basic principles of green chemistry with its role in day-to-day life, environmental pollution, green reagents and catalysts, phase transfer catalysis in green synthesis, microwave induced green synthesis, ultrasound assisted green synthesis, biocatalysts in organic synthesis, aqueous phase reactions, organic synthesis in the solid state, versatile ionic liquids as green solvents and finally some examples of synthesis involving basic principles of green chemistry.

We are grateful to Dr. Dennis Hjersen, Director, Green Chemistry Institute, USA; Professor Sukhdev, FNA, INSA Professor, New Delhi; Professor Nityanand, FNA, Former Director, CDR! Lucknow; Prof. Harjeet Singh, FNA, Professor Emeritus, Guru Nank Dev University, Amritsar; Prof. Mihir K. Chaudhury, FNA, Head, Department of Chemistry, Indian Institute of Technology, Guwahati; Prof. S. Chandrasekharan, FNA, Head, Department of Chemistry, Indian Institute of Science (Bangalore); Professor Javed Iqbal, FNA, Distinguished Research Scientist and Head, Discovery Research, Dr. Reddy's Laboratories Ltd., Hyderabad, for their valuable discussions.

V. K. AHLUWALIA

M. KJDWAI

Foreword Preface

1. Introduction

Contents

2. Designing a Green Synthesis 2.1 Choice of Starting Materials 2 2.2 Choice of Reagents 2 2.3 Choice of Catalysts 2 2.4 Choice of Solvents 3

3. Basic Principles of Green Chemistry 3.1 Prevention of Waste/By-Products 5 3.2 Maximum Incorporation of the Reactants (Starting

Materials and Reagents) into the Final Product 6 3.2.1 Rearrangement Reactions 6 3.2.2 Addition Reactions 7 3.2.3 Substitution Reactions 7 3.2.4 Elimination Reactions 8

3.3 Prevention or Minimization of Hazardous Products 8 3.4 Designing Safer Chemicals 9 3.5 Energy Requirements for Synthesis 9 3.6 Selection of Appropriate Solvent 9 3.7 Selection of Starting Materials 10 3.8 Use of Protecting Groups 10 3.9 Use of Catalyst 11 3.10 Products Designed Should be Biodegradable 12 3.11 Designing of Manufacturing Plants l3 3.12 Strengthening of Analytical Techniques 14

4. Green Chemistry in Day-to-Day Life 4.1 Dry Cleaning of Clothes 15 4.2 Versatile Bleaching Agent 15

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2

5

15

xii Contents

5. Environmental Pollution 17

6. Green Reagent 21 6.1 Dimethylcarbonate 21 6.2 Polymer Supported Reagents 22

6.2.1 Polymer SupportedPeracids 22 6.2.2 Polymer Supported Chromic Acid 22 6.2.3 Polymeric Thioanisolyl Resin 22 6.2.4 Poly-N-Bromosuccinimide (PNBS) 22 6.2.5 Polymeric Organotin Dihydride Reagent as a Reducing Agent 24 6.2.6 Polystyrene Carbodiimide 24 6.2.7 Polystyrene Anhydride 24 6.2.8 Sulfonazide Polymer 24 6.2.9 Polystyrene Wittig Reagent 25 6.2.10 Polymeric Phenylthiomethyl Lithium Reagent 25 6.2.11 Polymer Supported Peptide Coupling Agent 26

7. Green Catalysts 27 7.1 Acid Catalysts 27 7.2 Oxidation Catalysts 29 7.3 Basic Catalysts 30 7.4 Polymer Supported Catalysts 31

7.4.1 Polystyrene-aluminium Chloride 32 7.4.2 Polymeric Super Acid Catalysts 32 7.4.3 Polystyrene-metalloporphyrins 32 7.4.4 Polymer Supported Photosensitizers 33 7.4.5 Polymer Supported Phase Transfer Catalysts 33 7.4.6 Miscellaneous Illustrations 34

Ti02 Photocatalyst in Green Chemistry 34 Solid Support Reagents 34 Synthesis of Bromo organics: Development of

Newer and Ecofriendly Sromination Protocols and Brominating Agents 35

Synthesis ofPyridinium Fluorochromate (PFC) 35 Synthesis of Isooctane 36

8. Phase Transfer Catalysis in Green Synthesis 8.1 Introduction 39 '8.2 Applications ofPTC in Organic Synthesis 41

8.2.1Nitriles from Alkyl or Acyl Halides 41 8.2.2 Alkyl FluQrides from Alkyl Halides 42 8.2.3 Generation ofDihalocarbenes 42 8.2.4 Generation ofVinylidene Carbenes 44 8.2.5 Elimination Reactions 44

39

Contents xiii

8.2.6 C-Alkylations 45 C-Alkylation of Activated Nitriles 45 C-Alkylation of Activated Ketones 46 C-Alkylation of Aldehydes 46

8.2.7 N-Alkylations 46 N-Alkylation of Aziridines 46 N-Alkylation of P--Lactams 46

8.2.8 S-Alkylation 47 8.2.9 Darzen's Reaction 47 8.2.10 Williamson's Ether Synthesis 48 8.2.11 The Wittig Reaction 48 8.2.12 Sulphur Ylides 48 8.2.13 Heterocyclic Compounds 49

3-Alkyl Coumarins 49 Flavones 49 3-Aryl-2H-l,4-Benzoxazines 50

8.3 Oxidation Using Hydrogen Peroxide Under PTC Condition 50 8.4 Crown Ethers 51

8.4.1 Esterification 51 8.4.2 Saponification 51 8.4.3 Anhydride Fonnation 52 8.4.4 PotassiumPennanganate Oxidation 52 8.4.5 Aromatic Substitution Reaction 53 8.4.6 Elimination Reaction 54 8.4.7 Displacement Reaction 54 8.4.8 Generation of Car bene 54 8.4.9 SuperoxideAnionReaction 55 8.4.10 Alkylation 56

9. Microwave Induced Green Synthesis 9.1 Introduction S9 9.2 Applications 60

9.2.1 Microwave Assisted Reactions in Water 61 Hofinann Elimination 61 Hydrolysis 61 Oxidation of Toluene 62 Oxidation of Alcohols 62 Hydrolysis of Methyl benzoate to Benzoic Acid (Saponification) 63

9.2.2 Microwave Assisted Reactions in Organic Solvents 64 Esterification: Reaction of Carboxylic Acid and Alcohol 64 Esterification: Reaction of Carboxylic Acids and

Benzyl Ethers Using LnBr) (Ln = La, Nd, Sm, Dy, Er) 64 Fries Rearrangement 64 Orthoester Claisen Rearrangement 65 Diels Alder Reaction 65 Synthesis of Chalcones 65 Decarboxylation 66

59

xiv Contents

9.2.3 Microwave Solvent Free Reactions (Solid State Reactions) 66 Deacetylation 67 Deprotection 67 Saponification of Esters 68 Alkylation of Reactive Methylene Compounds 68 Condensation of Active Methylene Compounds with Aldehydes 68 Synthesis of Nitriles from Aldehydes 68 Synthesis of Anhydrides from Dicarboxylic Acid 69 Reductions 70 Synthesis of Heterocyclic Compounds 71

9.3 Conclusion 71

10. Ultrasound Assisted Green Synthesis 10.1 Introduction 73 10.2 Applications of Ultrasound 74

10.2.1 Esterification 74 10.2.2 Saponification 74 10.2.3 Hydrolysis 74 10.2.4 Substitution Reactions 75 10.2.5 Addition Reactions 76 10.2.6 Alkylations 77 10.2.7 Oxidation 78 10.2.8 Reduction 78 10.2.9 Hydroboration 80 10.2.10 Coupling Reactions 81 10.2.11 Fridel-Crafts Reaction 82 10.2.12 Diels-Alder Reaction 82 10.2.13 Sinunons-SmithReaction 82 10.2.14 BouveaultReaction 83 10.2.15 CannizaroReaction 84 10.2.16 Strecker Synthesis 84 10.2.17 Reformatsky Reaction 84 10.2.18 Conversion of Ketones into Tertiary Alcohols 85 10.2.19 SynthesisofChromenes 86

10.3 Conclusion 86

73

11. Biocatalysts in Organic Synthesis 88 11.1 Introduction 88 11.2 Biochemical (Microbial) Oxidations 90 11.3 Biochemical (Microbial) Reductions 99 11.4 Enzymes Catalysed Hydrolytic Processes 102

11.4.1 Enantioselective Hydrolysis of Meso Diesters 102 11.4.2 Hydrolysis ofN-acylarnino Acids 103 11.4.3 Miscellaneous Applications of Enzymes 104

Contents xv

12. Aqueous Phase Reactions 108 12.1 Introduction 108 12.2 Diels-Alder Reaction 109 12.3 Claisen Rearrangement 113 12.4 Wittig-Homer Reaction 116 12.5 Michael Reaction 117 12.6 Aldol Condensation 120 12.7 Knoevenagel Reaction 123 12.8 Pinacol Coupling 125 12.9 Benzoin Condensation 126 12.10 Claisen-Schmidt Condensation 127 12.11 Heck Reaction 129 12.12 Strecker Synthesis 131 12.13 Wurtz Reaction 132 12.14 Oxidations 132

12.14.1 Expoxidation 133 12.14.2 Dihydroxylation 136

Syn-Dihydroxylation 136 Anti Dihyrdoxylation 138

12.14.3 Miscellaneous Oxidations in Aqueous Medium 13 9 Alkenes 139 Alkynes 140 Oxidation of Aromatic Side Chains and Aromatic Ring System 140 Oxidation of Aldehydes and Ketones 140 Oxidation of Amines into Nitro Compounds 143 Oxidation of Nitro Compounds into Carbonyl Compounds 144 Oxidation ofNitriles 144 Oxidation of Sulphides 145 Oxidation with Hypochlorite 147 Oxidation with Ferricyanide 147

12.15 Reductions 148 12.15.1 Introduction 148 12.15.2 Reduction of Carbon-Carbon Double Bonds 148 12.15.3 Reduction of Carbon-Carbon Triple Bonds 150 12.15.4 Reduction of Carbonyl Compounds 152 12.15.5 Reduction of Aromatic Rings 155 12.15.6 Miscellaneous Reductions 156

12.16 Polymerisation Reactions 158 12.16.1 Polymers 158

Recycling of Polymers 158 Conversion of PET Materials into Monomers 158 To Make Polymers which are Biodegradable 159 Manufacture of Poly carbonates 159 Emulsion Polymerisation 160

12.17 Photochemical Reactions 162

xvi Contents

12.18 Electrochemical Synthesis 169 12.18.1 Introduction 169 12.18.2 Synthesis of Adiponitrile 170 12.18.3 Synthesis ofSebacic Acid 171 12.18.4 Miscellaneous Electrochemical Reactions 171

12.19 Miscellaneous Reactions in Aqueous Phase 172 12.19.1 Isomerisation of Alkenes 172 12.19.2 Carbonylation 173 12.19.3 HydroformylationofOlefms 176 12.19.4 Homologation ofl,3-dihydroxyacetone 177 12.19.5 Weiss-Cook Reaction 178 12.19.6 Mannich Type Reactions 178 12.19.7 Conversion of o-nitrochalcones into

Quinolines and Indoles 179 12.19.8 Synthesis ofOctadienols 179

13. Organic Synthesis in Solid State 189 13.1 Introduction 189 13.2 Solid Phase Organic Synthesis Without Using Any Solvent 189

13.2.1 Halogenation 189 13.2.2 Hydrohalogenation (addition ofHBr) 191 13 .2.3 Michael Addition 191 13.2.4 Dehydration of Alcohols to Alkenes 194 13.2.5 Aldol Condensation 195 13.2.6 Dieckmann Condensation 196 13.2.7 Grignard Reaction 196 13.2.8 Reformatsky Reaction 197 13.2.9 Wittig Reaction 197 13.2.10 Aromatic Substitution Reactions 198

Nuclear Bromination 198 Nitration 199 Synthesis of Amines 200

13.2.11 Pinacol-Pinacolone Rearrangement 200 13.2.12 Benzil-Benzilic Acid Rearrangement 201 13 .2.13 Beckmann Rearrangement 201 13.2.14 Meyer-Schuster Rearrangement 202 13.2.15 ChapmannRearrangement 202 13.2.16 Miscellaneous Reactions 203

Coupling Reactions 203 Solid Phase Synthesis ofOxazolidines 208 Synthesis of Azomethines 209 Synthesis ofHomoalIylic Alcohols 209 Synthesis of Cyclopropane Derivatives 209 Synthesis of Oxirazines 2 I 0 Synthesis of Aziridines 2 I 0 Synthesis of Disulphides 21 I

Contents xvii

Synthesis of Thiocarbonylimidazolide Derivatives 212 Synthesis of Secondary and Tertiary Halides 212 Formation of Ethers from Alcohols 212 Synthesis of High Molecular Weight Polypeptides 213

13.3 Solid Supported Organic Synthesis 213 13.3.1 Introduction 213 13.3.2 Synthesis of Aziridines 214 13.3.3 Synthesisof~-lactams 215 13.3.4 Synthesis ofPyrrole 217 13.3.5 Synthesis ofFurans 217 13.3.6 Synthesis ofPyrazoles 217 13.3.7 Synthesis oflmidazoles 218 13.3.8 Synthesis ofAzoles 219 13.3.9 Synthesis ofPyridines 222 13.3.10 Synthesis of Chromenes and Flavones 222 13.3.11 Synthesis of Quinoline 223 13.3.12 Synthesis of Pyrimidines 224 13.3.13 Synthesis ofOxadiazines 225 13.3.14 Synthesis ofThiadiazepines 227 13.3.15 Miscellaneous Reactions 227

14. Versatile Ionic Liquids as Green Solvents 232 14.1 Green Solvents 232 14.2 Reactions in Acidic Ionic Liquids 233 14.3 Reactions in Neutral Ionic Liquids 235

14.3.1 Hydrogenations 235 14.3.2 Diel's-Alder Reaction 235 14.3.3 Heck Reaction 236 14.3.4 O-AlkylationandN-alkylation 236 14.3.5 Methylene Insertion Reactions 237 14.3.6 Miscellaneous Applications 238

Synthesis of Pharmaceutical Compounds 238

15. Synthesis Involving Basic Principles of Green Chemistry: Some Examples 240 15.1 Introduction 240 15.2 Synthesis of Styrene 240 15.3 Synthesis of Adipic Acid, Catechol and

3-dehydroshikimic Acid (a potential replacement for BHT) 241 15.4 Synthesis of Methyl Methacrylate 243 15.5 Synthesis of Urethane 245 15.6 An Environmentally Benign Synthesis of Aromatic Amines 245 15.7 Selective Alkylation of Active Methylene Group 247 15.8 Free Radical Bromination 247 15.9 Acetaldehyde 248

xviii Contents

15.10 Furfural from Biomass 249 15.11 Synthesis of (S)-metolachlor, an Optically Active Herbicide 249 15.12 Synthesis of Ibuprofen 250 15.13 Synthesis ofParacetamol 251 15.14 Green Synthesis of 3-phenyl Catechol 252 15.15 Synthesis of Epoxystyrene 253 15.16 Synthesis of Citral 253 15.17 Synthesis of Nicotinic Acid 254 15.18 Use of Molting Accelerators to Replace More

Toxic and Harmful Insecticides 254 15.19 An Environmentally Safe Marine Antifoulant 255

Suggested Readings Index

259 261

New Trends in GREEN CHEMISTRY