HYDROLYZES OF 2-FLUORO AND 4-FLUORO N-HETEROCYCLES .2. NUCLEOPHILIC CATALYSIS BY BUFFER BASES IN THE HYDROLYSIS OF 2-FLUORO-1-METHYLPYRIDINIUM IODIDE
HYDROLYZES OF 2-FLUORO AND 4-FLUORO N-HETEROCYCLES .2. NUCLEOPHILIC CATALYSIS BY BUFFER BASES IN THE HYDROLYSIS OF 2-FLUORO-1-METHYLPYRIDINIUM IODIDE
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DOI：
10.1021/jo00232a025
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发表时间：
1987-11-13
影响因子：
3.6
通讯作者：
RUTHERFORD, DR
中科院分区：
文献类型：
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作者：
MUSCIO, OJ;RUTHERFORD, DR
报道了2-氟-1-甲基吡啶碘化物（1）在羧酸盐缓冲液中水解的准一级速率常数。该反应由羧化酶碱催化，布朗斯台德斜率为0.66。用0.04 M未标记乙酸盐在99%18O-标记水中的水解和用90%18O-标记乙酸盐在未标记水中的补充水解表明，产物2中85-95%的氧来源于乙酸盐而不是水。结果是一致的亲核催化的乙酸酯（和推测的其他羧酸盐碱），而不是一般的碱催化。
Pseudo-first-order rate constants are reported for hydrolysis of 2-fluoro-1-methylpyridinium iodide (1) in carboxylate buffers. The reaction is catalyzed by the carboxylase bases, with a Bronsted slope of 0.66. Hydrolyses in 99% lsO-labeled water with 0.04 M unlabeled acetate and complementary hydrolyses in unlabeled water with 90% 180-labeled acetate indicate that 85-95% of the oxygen in product 2 is derived from the acetate rather than from water. The results are consistent with nucleophilic catalysis by acetate (and presumably by the other carboxylate bases) rather than general base catalysis.