Polyhalogeno-aromatic compounds. Part XXXIII. Structures of polyhalogenopyridine-2(and 4)-thiols, polyhalogenopyridin-2(and 4)-ols, and their N- and S(or O)-methyl derivatives

Abstract

Comparative u.v. studies of tetrachloropyridine-2-thiol and its N- and S-methyl derivatives in methanol show that the thiol exists predominantly as the thiol tautomer, while tetrachloropyridin-2-ol and 3,5-dichloro-2,4-difluoropyridin-6-ol exist predominantly in the enol form in methanol. U.v. data are given also for a number of polyhalogeno-pyridine-4-thiols and -pyridin-4-ols and their S- or O-methyl derivatives. Chemical shift values for the methyl protons in N- and S(or O)-methyl derivatives of polyhalogeno-pyridinethiols or -pyridinols allow them to be distinguished. Mass spectroscopic data are reported.