ω-HYDROXY-1-ALKANESULFONYL CHLORIDES

Abstract

The general synthesis of hydroxyalkanesulfonyl chlorides is illustrated by the preparation of 6-hydroxy-1-butanesulfonyl chloride (2e) and 5-hydroxy-1-pentanesulfonyl chloride (2d) as fairly stable, oily liquids (of ∼95% purity) characterized by ¹Hmr, ¹³Cmr and infrared spectra, and by conversion both to the corresponding sultones (3) and to crystalline acetoxy-piperidides (6); 2d and 2e form apparent polymers, very slowly on standing at room temperature and more rapidly on heating, but on reaction with triethylamine yield the sultones (3d and 3e). A sample consisting mostly (>70%) of 4-hydroxy-1-butanesulfonyl chloride (2c), prepared and characterized similarly, was found to form the sultone (3c) slowly in non-polar solvents, much more readily in polar media (t _½ ∼20 min in water), and very rapidly in the presence of triethylamine. Effective concentrations for the spontaneous cyclization of 4-hydroxy-1-butanesulfonyl chlorides (2c) and the tertiary-amine induced cyclizations of 2d and 2e are estimated at roughly 3 × 10², 0.1, and 0.05 M, respectively. The mechanism of the chlorination reaction and the origins of the different products with different substrates and reaction conditions are discussed.