2-Chloro-thiophene prepn. - by contacting chloride gas with thiophene vapour, useful as a solvent and intermediate

摘要

The process gives high yields (e.g. 60 - 74%) of prod. (I) and only small amts. (e.g. 5%) of polychlorinated by-products. The reaction is pref. carried out by refluxing the thiophene and introducing Cl2 into the vapour phase, so that the (I) formed condenses in the thiophene liq. phase. The Cl2 introduction is pref. stopped when the b.pt. of the liq. phase reaches 105 degrees C. A molar excess of thiophene vapour over Cl2 gas is pref. maintained throughout, and the vapour-phase temp. is pref. kept between the b.pt. of thiophene and 105 degrees C.