H H HaPOa catalyst C=c +HO CHOCHOOH 250C H H Ethanol Ethylene c2004 Thomson. Brooks/ole Oxymercuration/羟汞化反应p105 ACH, 1. Hg(OAc)2, H2O/THF CHe 2. NaBH OH 1-Methylcyclopentene 1-Methylcyclopentanol (92%) c2004 Thomson- Brooks/Cole
Oxymercuration(羟汞化反应) p. 105
CH2CH 1. BH THF 1. Hg(OAc), HoO CHCH H H OH 2. H.%, OH 2. NaBH4 COH H H H (a)Syn, non-Markovnikov (b) Markovnikov addition of HO addition of H2O c2004 Thomson-Brooks/Cole
4.5 Addition of x to p98 Alkenes: halogenation Bromine and chlorine add to alkenes to give 1, 2 dihaldes, an industrially important process fo is too reactive and i does not add Cl reacts as Cl+cl br, is similar C—C
4.5 Addition of X2 to Alkenes: Halogenation • Bromine and chlorine add to alkenes to give 1,2- dihaldes, an industrially important process – F2 is too reactive and I2 does not add • Cl2 reacts as Cl+ Cl- , Br2 is similar p.98
Addition of br, to Cyclopentene Addition is exclusively trans H Br Br H B trans. 2-Dibromocyclopentane H H H →Br-B Cyclopentene Br B 2-Dibromocvelopentane (NOT formed)
Addition of Br2 to Cyclopentene • Addition is exclusively trans +
Mechanism of Bromine addition Brt adds to an alkene producing a cyclic ion · Bromonium ion(溴滃离子, bromine shares charge with carbon Gives trans addition product Br B1 = Br
Mechanism of Bromine Addition • Br+ adds to an alkene producing a cyclic ion • Bromonium ion(溴鎓离子), bromine shares charge with carbon • Gives trans addition Product