Nitrosation by alkyl nitrites. Part 6. Thiolate nitrosation
作者:Hanif M. S. Patel、D. Lyn H. Williams
DOI:10.1039/p29900000037
日期:——
differs significantly from the literature value. With simple alkyl nitrites (ethyl, isopentyl, isopropyl and t-butyl) steric effects appear to be the major influences in reactivity, whereas electron-withdrawing substituents in the 2-position greatly increase the rate constants. The reactions of 2,2,2-trichloroethyl nitrite were too fast to measure at all pH values, whereas the reaction of 2,2-dichloroethyl
以下每种硫醇在25°C的水中在6-13的pH范围内与一定范围内的亚硝酸烷基酯反应,在溶液中生成相应的亚硝酸盐:L-半胱氨酸,N-乙酰基-L-半胱氨酸,L-半胱氨酸甲酯,L-半胱氨酸乙酯,谷胱甘肽和巯基乙酸。速率常数的pH依赖性清楚地表明,反应仅通过硫醇根阴离子RS –发生。对于Ñ乙酰基大号-半胱氨酸和巯基乙酸只有一个RS -物种是可能的和定量动力学分析产率p ķ一个RSH电离的值与文献值非常吻合。对于每种剩余的硫醇,可能有两个硫醇根离子(NH 2 RS –和NH 3 RS –),所有亚硝酸烷基酯的测得的速率常数通常跟随从公开的显微图中获得的总硫醇根离子浓度(作为pH的函数)。 p K a值。通过计算机将动力学结果拟合到浓度曲线的另一种方法是产生通常与文献值相吻合的微观p K a值。L-半胱氨酸是一个例外,其中测得的(p K a)D值(对于NH 2 -RSH→NH 2 RS –)与文献值明显