Issue 9, 1972

Structure and efficiency in intramolecular and enzymic catalysis. Catalysis of amide hydrolysis by the carboxy-group of substituted maleamic acids

Abstract

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.

Article information

Article type
Paper

J. Chem. Soc., Perkin Trans. 2, 1972, 1206-1214

Structure and efficiency in intramolecular and enzymic catalysis. Catalysis of amide hydrolysis by the carboxy-group of substituted maleamic acids

A. J. Kirby and P. W. Lancaster, J. Chem. Soc., Perkin Trans. 2, 1972, 1206 DOI: 10.1039/P29720001206

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