Collect. Czech. Chem. Commun.
1992, 57, 1282-1290
https://doi.org/10.1135/cccc19921282
Kinetics and Mechanism of Cyclization of N-(2-Methoxycarbonylphenyl)-N-methylsulfonamide to 1-Methyl-(1H)-2,1,3-benzothiadiazine-4(3H)-one-2,2-dioxide
Jaromír Kaválek, Vladimír Macháček, Miloš Sedlák and Vojeslav Štěrba
Department of Organic Chemistry, Institute of Chemical Technology, 532 10 Pardubice
Abstract
The cyclization kinetics of N-(2-methoxycarbonylphenyl)-N-methylsulfonamide to 1-methyl-(1H)-2,1,3-benzothiadiazine-4(3H)-one-2,2-dioxide have been studied in glycinamide, morpholine, and butylamine buffers and in solutions of potassium hydroxide. The rate-limiting step consists in splitting off of the proton from the cyclic intermediate formed from the anion of the starting substrate. The value of the Bronsted coefficient β decreases with increasing pKa value of the conjugate acid of buffer. The calculated pKa value of the cyclic intermediate is 9.3.
