HYDROLYSIS OF SUBSTITUTED ETHYLENE OXIDES IN H2O18 SOLUTIONS
HYDROLYSIS OF SUBSTITUTED ETHYLENE OXIDES IN H2O18 SOLUTIONS
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DOI：
10.1021/ja01593a001
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发表时间：
1956-01-01
影响因子：
15
通讯作者：
PRITCHARD, JG
中科院分区：
文献类型：
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作者：
LONG, FA;PRITCHARD, JG
氧化丙烯和氧化异丁烯已在酸性、碱性和中性条件下在018标记的水中水解。通过对所得二醇进行质谱分析，建立了详细的水解路径。对于环氧丙烷来说，碱催化反应主要发生在伯碳上，对于环氧异丁烷来说，碱催化反应仅发生在伯碳上。相比之下，对于环氧异丁烯，酸催化反应仅发生在支化碳上，对于环氧丙烷则主要如此。结论是碱性反应是Sn2机理，酸催化反应是碳正离子机理。还给出了在25℃、pH范围3至14下环氧异丁烯的水解动力学的数据。众所周知，环氧乙烷在水溶液中的水解存在至少三种动力学上可区分的路径。 2-7 有酸催化水解、碱催化水解和与 pH 无关的“水”反应。本系列的下一篇论文8 91011将表明，在高氯酸溶液中，环氧乙烷和几种取代氧化物的酸催化水解遵循哈米特酸度函数，Ho-In符合类似的水解研究9-11，该结果表明水分子不参与速率决定步骤，并表明该机制涉及碳正离子：
Propylene and isobutylene oxides havebeen hydrolyzed in 018-labeled water under acidic, basic and neutral conditions. The detailed paths of the hydrolysis havebeen established by a mass spectrometric analysis of the resulting glycols. The base-catalyzed reaction occurs predominantly at the primary carbon for propylene oxide and exclusively so for isobutylene oxide. In contrast the acid-catalyzed reaction occurs exclusively at the branched carbon for isobutylene oxide and pre-dominantly so for propylene oxide. It is concluded that the basic reaction goes by an Sn2 mechanism and that the acidcatalyzed reaction involves a carbonium ion mechanism. Data are also givenfor the kinetics of the hydrolysis of isobutylene oxide at 25 in the pH range of from 3 to 14.It is well known that there are at least three kinetically distinguishable paths for the hydrolysis of ethylene oxide in aqueous solution. 2-7 There is an acid-catalyzed hydrolysis, a base-catalyzed hydroly-sis and a pH independent,“water” reaction. It will be shown in the next paper of this series8 91011that in solutions of perchloric acid the acid-catalyzed hydrolysis of ethylene oxide and of several substituted oxides follows the Hammett acidity function, Ho-In accord with similar hydrolysis studies9-11 this result indicates that a water molecule is not involved in the rate-determining step and suggests that the mechanism involves a carbonium ion as