STRUCTURE AND EFFICIENCY IN INTRAMOLECULAR AND ENZYMIC CATALYSIS - CATALYSIS OF AMIDE HYDROLYSIS BY CARBOXY-GROUP OF SUBSTITUTED MALEAMIC ACIDS
STRUCTURE AND EFFICIENCY IN INTRAMOLECULAR AND ENZYMIC CATALYSIS - CATALYSIS OF AMIDE HYDROLYSIS BY CARBOXY-GROUP OF SUBSTITUTED MALEAMIC ACIDS
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DOI：
10.1039/p29720001206
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发表时间：
1972-01-01
期刊：
影响因子：
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通讯作者：
LANCASTER, PW
中科院分区：
文献类型：
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作者：
KIRBY, AJ;LANCASTER, PW
一系列取代的N-甲基马来酰胺酸的羧基对酰胺水解的分子内催化效率对碳-碳双键上的取代模式非常敏感。单个烷基使水解速率增加一个因子，该因子随其大小而增加。第二个烷基取代基具有不成比例的更大的影响，当两个基团在环中连接在一起时，这种影响急剧降低。一系列的二烷基-N-甲基马来酰胺酸的水解率的范围超过10的10次方，和研究的最具反应性的化合物的羧基的“有效浓度”大于1010 M。这种酰胺，二甲基-N-正丙基马来酰胺酸，在39 °C低于pH 3时转化为更稳定的二甲基马来酸酐，半衰期小于1秒。催化的机制，并负责这种极高的反应性的因素，进行了讨论。
The efficiency of intramolecular catalysis of amide hydrolysis by the carboxy-group of a series of substituted N-methylmaleamic acids is remarkably sensitive to the pattern of substitution on the carbon–carbon double bond. A single alkyl group increases the rate of hydrolysis by a factor which increases with its size. A second alkyl substituent has a disproportionately larger effect, which is sharply reduced when the two groups are joined together in a ring. The rates of hydrolysis of a series of dialkyl-N-methylmaleamic acids range over more than ten powers of ten, and the ‘effective concentration’ of the carboxy-group of the most reactive compound studied is greater than 1010M. This amide, dimethyl-N-n-propylmaleamic acid, is converted into the more stable dimethylmaleic anhydride with a half-life of less than 1s at 39 °C below pH 3. The mechanism of catalysis, and the factors responsible for this extremely high reactivity, are discussed.