Fluoroalkene chemistry: Part 2. Reactions of thiols with some toxic 1,2-dichlorinated polyfluorocycloalkenes

1,2-Dichlorotetrafluorocyclobutene, 1,2-dichlorohexafluorocyclopentene and 1,2-dichlorooctafluorocyclohexene were treated with an equimolar amount of benzenethiol, 2-methoxybenzenethiol, 3-methoxybenzenethiol and 4-methoxybenzenethiol in acetonitrile with potassium carbonate. Each combination of fluoroalkene and thiol gave a mixture of mono and bis vinyl substitution products whose proportions depended on the ring size of the fluorocycloalkene and the size and electronic characteristics of the thiol. Treatment of 1,2-dichlorotetrafluorocyclobutene with one or two molar equivalents of N-acetylcysteine isopropyl ester in acetonitrile with potassium carbonate produced the mono and bis vinyl substitution products accordingly. The results support the contention that the high inhalation toxicity of the fluorocycloalkenes is due to reaction with two molar equivalents of biological thiols in the lung.