Chemistry of acetylenic ethers XLII: A simplified method for the preparation of acetylenic thioethers; a number of new reactions of these compounds

Abstract

Abstract Cis ethenylene‐1,2‐ bis ‐thioethers RSCH  CHSR can easily be prepared in liquid ammonia by treating cis or trans 1,2‐dichloroethylene with sodium amide and thiol. From these compounds acetylene thioethers HC ≡ CSR can be obtained by means of sodium amide in liquid ammonia, followed by treatment with one mole of alkyl halide. If two moles of alkyl halide R′X are used, the alkyne thioethers R′C ≡ CSR are formed in satisfactory yield. (Alkylthio)ethynylcarbinols R′R″C(OH)C ≡ CSR are the products of treatment of ethenylene‐1,2‐ bis ‐thioethers with sodium amide and ketones R′R″C = 0 in liquid ammonia. Addition of hydrogen chloride to (ethylthio)ethyne gives 1‐ethylthio‐1‐chloroethylene. Reaction of (ethylthio)ethyne with acetone under the influence of boron fluoride produces a 50% yield of ethanethiol β,β‐dimethylacrylate; similarly 1‐ethylthio‐1‐propyne and acetone form ethanethiol α,β,β‐trimethylacrylate. The Mannich reaction of (ethylthio)ethyne with formaldehyde and diethylamine gives (C 2 H 5 ) 2 NCH 2 C ≡ CSC 2 H 5 in very high yield. Long heating of (ethylthio)ethyne at 90‐100° causes the formation of 2‐(ethylthio)thiophene with much tar.