Untersuchungen zum Mechanismus der Chlorhydrinierung von Olefinen

Abstract

Studies on the Mechanism of the Chlorohydrination of Olefins We studied the rate‐determining and the product‐determining steps of the chlorohydrination of olefins with Cl2/H2O and HOCl. In competitive kinetic experiments with 3‐ethylpent‐2‐ene and cyclohexene we determined the relative rate constants krel = 1,5 (with Cl2/H2O) and krel = ∞ (with HOCl). This shows that the rate‐determining steps of the chlorohydrination with Cl2/H2O and with HOCl are different. In order to investigate the product‐determining steps we determined the proportion of alkyl‐(2‐chloroethyl)‐ethers 3 and ethylene chlorohydrine 2 in the reaction of ethylene with Cl2 and with HOCl in alcohol/water‐mixtures. The proportion of both the reaction products 3/2 was independent of the chlorinating agent used. Also the proportion of MARKOVNIKOV and anti‐MARKOVNIKOV products in the chlorohydrination of propylene with Cl2/H2O or HOCl was independent of the type of chlorinating agent. In the chlorohydrination of cyclohexene both agents (Cl2/H2O and HOCl) yielded only the trans‐chlorohydrine. From the results obtained it may be concluded that the product‐determining step of chlorohydrination is the same for both the chlorinating agents studied.