Synthesis of sulfur compounds by the aid of vinyl ethers and acetylene

Abstract

1. Methods have been developed for the synthesis from vinyl ethers and thiols of two series of sulfides: monothioacetals (1-alkoxy-1-(alkylthio)ethanes) and diethers of 2-mercapioethanol(1-alkoxy-2-(alkylthio)ethanes). 2. It has been shown that the noncatalyzed addition of thiols to vinyl ethers in accord with Markovnikov's rule is a very slow reaction. The introduction of a catalyst, such as traces of sulfur dioxide, accelerates this reaction and leads to the quantitative synthesis of monothioacetals 3. Addition of thiols in the direction contrary to that given by Markovnikov's rule is readily effected in a sealed evacuated ampoule. The reaction is greatly accelerated by rise of temperature, and is evidently catalyzed by traces of dissolved oxygen. 4. In presence of air, addition of thiols to vinyl ethers gives mixtures of “abnormal” and “normal” products, the former predominating. The composition of the mixture depends on the mixture of the vinyl ether and of the thiol taken. 5. The products of the oxidation by air of vinyul ethers and thiols do not accelerate abnormal addition, but, on the contrary, slow it down, which is in conflict with certain consequences of Kharash's peroxide theory.