Crystal and molecular structure of 3-trichloromethyl-4-chloro-5-isopropoxyisothiazole and 4,5-dichloroisothiazole-3-carboxylic acid

X-ray structural data are used to demonstrate that the chlorine in the 5-position of the heterocycle is replaced on reaction of 3-trichloromethyl-4,5-dichloroisothiazole with sodium isopropoxide. The S-N and C-S bond lengths are lengthened in the resulting 3-trichloromethyl-4-chloro-5-isopropoxyisothiazole whereas the C-N and C-C bonds are shortened compared with analogous bonds in 4,5-dichloroisothiazole-3-carboxylic acid. This is explained by conjugation of the carboxylic acid with the heterocycle.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 399–402, March, 1992.