tailieunhanh - Ebook A guidebook to mechanism in organic chemistry (6th edition): Part 2

This guidebook is aimed clearly at the needs of the student, with a thorough understanding of, and provision for, the potential conceptual difficulties he or she is likely to encounter. | 8 Nucleophilic addition to c o STRUCTURE AND REACTIVITY p. 205. SIMPLE ADDITION REACTIONS p. 207. Hydration p. 207 Alcohols p. 209 Thiols p. 211 Hydrogen cyanide p. 212 Bisulphite and other anions p. 213 Hydride ions p. 214 Complex metal hydride ions p. 214 Meerwein-Ponndorf reaction p. 215 Cannizzaro reaction p. 216 Electrons p. 217. addition elimination reactions p. 219 Derivatives of NH3 p. 219. CARBON NUCLEOPHILE ADDITIONS p. 221 Grignard etc. reagents p. 221 Acetylide anions p. 223 Carbanions general p. 223 Aldol reactions p. 224 Nitroalkanes p. 226 Perkin reaction p. 227 Knoevenagel and Stobbe reactions p. 228 Claisen ester condensation p. 229 Benzoin condensation p. 231 Benzilic acid rearrangement p. 232 Wittig reaction p. 233. STEREOSELECTIVITY IN CARBONYL ADDITION REACTIONS p. 234. ADDITION eLIMINATION REACTIONS OF CARBOXYLIC DERIVATIVES p. 236 Grignard etc. reagents p. 238 Some other nucleophiles p. 238 Acid-catalysed reactions p. 240. ADDITION TO C N p. 244. Carbonyl compounds exhibit dipole moments z because the oxygen atom of the c o group is more electronegative than the carbon Me Me li 23 D fi 2-8 D As well as the C- -O inductive effect in the Ơ bond joining the two atoms the more readily polarisable 7t electrons are also affected cf. p. 22 so that the carbonyl group is best represented by a hybrid 204 Nucleophilic addition to C O structure 1 e R2C O - R2C o la li ồ ồ . R2C -O R2C -O lafe We would expect the c o linkage by analogy with c c p. 178 to undergo addition reactions but whereas polar attack on the latter is normally initiated only by electrophiles attack on the former because of its bipolar nature could be initiated either by electrophilic attack of X or X on oxygen or by nucleophilic attack of Y or Y1 on carbon radical-induced addition reactions of .