ISOTOPE RATE EFFECTS IN THE ENOLIZATION OF OXALACETIC ACID
ISOTOPE RATE EFFECTS IN THE ENOLIZATION OF OXALACETIC ACID
复制标题
草乙酸烯化反应中同位素速率的影响
DOI：
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发表时间：
1962
期刊：
影响因子：
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通讯作者：
G. Kosicki
中科院分区：
文献类型：
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作者：
G. Kosicki
在pH（pD）为5.5 ~ 7.5的范围内，乙酸乙酯在H/sub 2/O和D/sub 2/O中的酸催化烯醇化反应产生了恒定的同位素速率效应k/sub H/sub 2/O/ /k/sub D /sub 2/O = 2.4。在pH（pD）为7.0 ~ 8.0的范围内，在H/sub 2/O和D/sub 2/O中碱催化下，乙酸的烯醇化反应产生的恒定同位素速率效应k/sub H/sub 2/O/k/sub D/sub 2/O为4.5。使用在255 μ m处的醚中的烯醇形式的吸收和在pH 0.5的含水体系中的酮形式的吸收，计算出在pH 8.0下的二乙酸的烯醇形式的百分比为15.3%。分光光度法测量的同位素速率效应参与烯醇化的乙酸提供了直接的证据，在酸和碱催化的反应，没有后续的反应的速率决定步骤。
Acid-catalyzed enolization of oxalacetic ncid in H/sub 2/O and D/sub 2/O gives rise to a constant isotope rate effect k/sub H/sub 2/O/ /k/sub D /sub 2/O of 2.4 over the pH (pD) range of 5 5 to 7.5. Base-catalyzed enolization of oxalacetic acid in H/sub 2/O and D/sub 2/O gives rise to a constant isotope rate effect k/sub H/sub 2/O/k/sub D/sub 2/O of 4.5 over th e pH (pD) range of 7.0 to 8.0. The percentage of enol form of oxalacetic acid was calculated to be 15.3% at pH 8.0, using the absorption of the enol form in ether at 255 m mu and the absorption of the keto form at pH 0.5 in an aqueous system. The spectrophotometric measurement of the isotope rate effect involved in the enolization of oxalacetic acid gives direct evidence for the rate-determining step in both the acid- and the base-catalyzed reactions without subsequent reactions.