Chalcogenation of 1,3-Dichlorobut-2-ene with Organic Dichalcogenides in the System Hydrazine Hydrate–Alkali

Abstract

Electron-donor effect of the methyl group in 1,3-dichlorobut-2-ene hampers allylic rearrangement of its primary monochalcogenation products. The use of diphenyl disulfide under harsh conditions (Ph₂S₂–KOH, 1: 10, 75–80°C) makes it possible to obtain a mixture of six bis(phenylsulfanyl)butenes, 1,1-bis(phenylsulfanyl) but-1-ene being the major component. No bis(phenylselanyl) derivatives have been formed on heating up to 80°C. Dipotassium ethane-1,2-dithiolate reacts with 1,3-dichlorobut-2-ene to give a linear product of chlorine substitution at the sp³-carbon atom in two dichlorobutene molecules and a heterocyclic compound, 2-ethylidene-1,4-dithiane (a mixture of E and Z isomers), whose structure is different from the structure of the product obtained from 1,3-dichloropropene under analogous conditions. Mechanisms have been proposed for the formation of the isolated compounds.