An Introduction to Free Radical Chemistry

by Parsons, Andrew F.

• ISBN13: 9780632052929
• ISBN10: 0632052929
• Edition: 1st
• Format: Paperback
• Copyright: 2000-11-30
• Publisher: Wiley-Blackwell

Summary

The past twenty years has seen an explosion of interest in free radicals, as their pivotal role in both chemistry and biology has come to light. This introductory textbook aims to capture this excitement for advanced level undergraduates, with particular emphasis on the importance of radical reactions in organic synthesis. The book provides a gentle, stepwise introduction to the subject, taking the student from the basic principles of radical reactions through to their applications in industry and their role in biological and environmental processes, allowing the relevance of the subject to be grasped more easily.Suitable for advanced level undergraduates and postgraduates in chemistry and biochemistry, the book will also be invaluable for research level scientists requiring an update in the area.

Author Biography

Dr Andrew F. Parsons is a senior lecturer in the Department of Chemistry, University of York, UK.

Table of Contents

Chemical Abbreviations	viii
Preface	ix
Radicals and their Importance	1	(13)
What are radicals?	1	(1)
The discovery and development of radical chemistry	2	(4)
Natural radical reactions	6	(3)
Commercial radical reactions	9	(3)
Summary	12	(2)
Further reading	13	(1)
The Basics	14	(30)
Introduction	14	(1)
Radical detection and observation	15	(10)
Electron spin resonance spectroscopy	16	(8)
Chemically induced dynamic nuclear polarization	24	(1)
The shape of radicals	25	(1)
Radical stability	26	(15)
Thermodynamic stability	26	(10)
Radical lifetime	36	(2)
A frontier molecular orbital approach	38	(3)
Radical reactions: chain vs. non-chain mechanisms	41	(1)
Summary	42	(2)
Further reading	42	(2)
Radical Initiation	44	(17)
Introduction	44	(1)
Thermolysis	44	(2)
Peroxides and diacylperoxides	44	(1)
Azo compounds	45	(1)
Photolysis	46	(7)
Peroxides and diacylperoxides	47	(1)
Azo compounds	48	(1)
Halogens and halides	48	(2)
Nitrites	50	(1)
Organometallics	50	(2)
Carbonyls	52	(1)
Radiolysis and sonolysis	53	(1)
Electron transfer	54	(5)
Reduction	55	(2)
Oxidation	57	(2)
Summary	59	(2)
Further reading	60	(1)
Radical Reactions	61	(35)
Introduction	61	(1)
Propagation reactions	62	(3)
Radical abstraction reactions	62	(1)
Intermolecular (SH2) reactions	63	(1)
Intramolecular (SHi) reactions	64	(1)
Addition reactions	65	(7)
Intermolecular addition to alkenes and alkynes	65	(2)
Intramolecular addition to alkenes and alkynes	67	(1)
Addition to aromatics	68	(2)
Addition to carbonyls	70	(1)
Addition to oxygen	71	(1)
Fragmentation reactions	72	(2)
Alkyl radicals	73	(1)
Alkoxyl radicals	73	(1)
Acyloxyl (or carboxyl), acyl and diazenyl radicals	74	(1)
Rearrangements	74	(1)
Termination reactions	75	(2)
Combination or coupling reactions	75	(1)
Disproportionation	76	(1)
Electron transfer reactions	77	(1)
Reactivity and selectivity	77	(17)
Enthalpy	78	(6)
Entropy	84	(2)
Steric effects	86	(1)
Stereoelectronic effects	87	(3)
Polarity	90	(4)
Redox potential	94	(1)
Summary	94	(2)
Further reading	95	(1)
Radicals in Synthesis	96	(27)
Introduction	96	(1)
Radicals vs. ions	96	(7)
Reaction conditions	96	(1)
Radical concentration	97	(1)
Chemoselectivity	98	(2)
Regioselectivity	100	(1)
Stereoselectivity	101	(1)
Polarity	102	(1)
Chain reactions	103	(12)
Tributyltin hydride	105	(4)
Mercury hydrides	109	(1)
Silicon hydrides	110	(2)
Halogen atom transfer	112	(3)
Non-chain reactions	115	(6)
Samarium(II) iodide---reduction	115	(3)
Cobalt(I) complexes---reduction	118	(1)
Manganese(III) acetate---oxidation	119	(2)
Summary	121	(2)
Further reading	121	(2)
Functional Group Transformations	123	(16)
Introduction	123	(1)
Transformations	123	(15)
Halogenation	123	(3)
Dehalogenation	126	(1)
Oxygenation	127	(3)
Deoxygenation	130	(3)
Decarboxylation	133	(2)
Carbonylation and cyanation	135	(2)
Nitrosation	137	(1)
Summary	138	(1)
Further reading	138	(1)
Intramolecular Cyclization Reactions	139	(21)
Introduction	139	(1)
Ring size	139	(1)
Regioselectivity	140	(6)
Hexenyl radical cyclization	140	(5)
Heptenyl radical cyclization	145	(1)
Stereoselectivity	146	(3)
Hexenyl radical cyclization	146	(2)
Heptenyl radical cyclization	148	(1)
Cyclization reactions leading to rearrangement	149	(1)
Synthetic applications	150	(8)
Summary	158	(2)
Further reading	158	(2)
Intermolecular Reactions	160	(17)
Introduction	160	(1)
Alkene substitution	161	(2)
Stereoselectivity	163	(7)
Cyclic radicals	164	(3)
Acyclic radicals	167	(3)
Synthetic applications	170	(5)
Summary	175	(2)
Further reading	176	(1)
Radical Translocation Reactions	177	(11)
Introduction	177	(1)
Methods for radical translocation	177	(10)
Tin hydride	177	(4)
Photolysis of carbonyls	181	(3)
Photolysis of nitrites	184	(1)
Chlorination	185	(2)
Summary	187	(1)
Further reading	187	(1)
Radical Anions	188	(14)
Introduction	188	(3)
Reactions of radical anions	191	(9)
The pinacol and McMurry reactions	191	(2)
The acyloin condensation	193	(2)
The Birch reduction	195	(3)
Unimolecular radical nucleophilic substitution (SRN1)	198	(1)
Superoxide---a biological radical anion	199	(1)
Summary	200	(2)
Further reading	201	(1)
Radical Cations	202	(10)
Introduction	202	(3)
Reactions of radical cations	205	(6)
Benzylic oxidation	205	(1)
Oxidative phenolic coupling	206	(1)
Substitution of heteroaromatics	207	(2)
The Hoffmann---Loffler---Freytag reaction	209	(1)
The herbicide paraquat	210	(1)
Summary	211	(1)
Further reading	211	(1)
Questions	212	(8)
Outline Answers	220	(9)
Further Reading	229	(1)
Index	230