Kinetics of the hydrolysis of cyclic N-substituted sulfamides: 4-amino-2-cyclohexyl- and 4-amino-2-phenethyl-2,3-dihydro-3-oxo-1,2,5-thiadiazole 1,1-dioxides

✍ Scribed by M. F. Rozas; E. L. Svartman; M. V. Mirífico; E. J. Vasini

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 150 KB
• Volume: 11
• Category: Article
• ISSN: 0894-3230
• DOI: 10.1002/(sici)1099-1395(199807)11:7<489::aid-poc29>3.0.co;2-g

✦ Synopsis

The hydrolysis reactions of 4-amino-2-phenethyl-and 4-amino-2-cyclohexyl-2,3-dihydro-3-oxo-1,2,5thiadiazole 1,1-dioxide (Ia and Ib) were investigated in the range 24-73 °C in buffered aqueous solutions. The observed rate constants (k obs ) are independent of pH in the range ca 1-4 pH, but increase with increase in pH above ca 4. A linear log k obs vs pH profile with unit slope is observed from pH ca 4 up to the highest experimental pH (ca 10). The products are the corresponding new compounds: 2-amino-2-[(N-substituted-sulfamoyl)imino]acetic acid salts. The C=N bond of these compounds hydrolyses further, in a slow reaction, to the sulfamide and oxalic acid derivatives. The substrates decompose to the final products without accumulation of the acetic acid derivatives under these experimental conditions. A mechanism is proposed. Rate constants and activation parameters are given for the first reaction step. Owing to steric effects, the reaction rate is higher for the N-phenethyl-substituted derivative than for the 2-cyclohexyl-substituted derivative.