Organic Chemistry Lecture 11b
Chapter 11 * Reaction with HBr ?OH of alcohol is protonated. ?OH2+ is good leaving group. 3? and 2? alcohols react with Br- via SN1. 1? alcohols react via SN2. H 3 O + B r - R O H R O H H R B r Chapter 11 Chapter 11 * Reaction with HCl Chloride is a weaker nucleophile than bromide. Add ZnCl2, which bonds strongly with ?OH, to promote the reaction. The chloride product is insoluble. Lucas test: ZnCl2 in concentrated HCl: 1? alcohols react slowly or not at all. 2? alcohols react in 1-5 minutes. 3? alcohols react in less than 1 minute. Chapter 11 Chapter 11 * SN2 Reaction with the Lucas Reagent Primary alcohols react with the Lucas reagent (HCl and ZnCl2) by the SN2 mechanism. Reaction is very slow. The reaction can take from several minutes to several days. Chapter 11 *