Collect. Czech. Chem. Commun. 1979, 44, 1790-1798

Study of solvolysis mechanism of some ureas derived from 2-benzoxazolone

Jiří Štohandl and Miroslav Večeřa

Department of Organic Chemistry, Institute of Chemical Technology, 532 10 Pardubice


6-Nitro-, 6-chloro-, 6-bromo- and 6-amino-2-benzoxazolones I have been prepared and aminolyzed with piperidine and butylamine into the respective 2-hydroxy-4-nitro-, 4-chloro-, 4-bromo- and 4-aminophenylureas II, III. pKa values of hydroxyl group of these ureas have been determined. The aminolysis and hydroxylaminolysis mechanism of the mentioned 2-benzoxazolones is discussed on the basis of kinetic data. Reaction of the 6-substituted-2-benzoxazolones with methyl, phenyl and p-toluenesulphonyl isocyanates and N,N-dimethylchloroformamide has been used for preparation of the respective ureas V to VII of the type of 3-alkylcarbamoyl- or arylcarbamoyl-2-benzoxazolone. Hydrolysis mechanism of these ureas possessing a good leaving (3-benzoxazolone) group in alkaline medium and behaviour of anions of ureas VI in alkaline medium are discussed.