1.A study was made of the effect of the length of the aliphatic chain in 2-thiophenealkanoyl chlorides on the character and yields of the products formed in their cyclization.2.Substantial differences in chemical behavior between 2-thiophenealkanoyl chlorides and their benzene analogs are due to peculiarities in the geometry of the thiophene ring and the marked nonequivalence of the α- andβ-positions of the heterocycl