Found in coal tar, in coal gas, and in technical benzene: V. Meyer, Ber. 16, 1471 (1883); 17, 2642 (1884). Made available in commercial quantities by a process utilizing the dehydrogenation of butane with sulfur as the dehydrogenating agent, followed by cyclization with sulfur to form the thiophene ring: Rasmussen, Ray, Chem. Inds. 60, 593, 620 (1947). Laboratory prepn by heating sodium succinate with phosphorus trisulfide: R. Phillips, Org. Synth. coll. vol. II, 578 (1943). Also prepd by passing ethylene or acetylene into boiling sulfur; or by passing acetylene and hydrogen sulfide over hot bauxite or nickel hydroxide: US 1421743 C.A. 16, 3093 (1922). Review: B. Buchholz in Kirk-Othmer Encyclopedia of Chemical Technology vol. 22 (Wiley-Interscience, New York, 3rd ed., 1983) pp 965-973.