Thiophene may be prepared from hydrocarbons and hydrogen sulfide over a variety of catalysts including chromia or molybdena on alumina, bauxite or silica. Production of thiophene is greatest from the normal C4 hydrocarbons especially the olef ins.
When using hydrocarbons containing more than 4 carbon atoms in a straight chain not only thiophene but also allryl thiopheiies are formed. The reaction is mildly endothermic and can easily be carried out in a fixed bed system. Preferred catalysts can be regenerated with air. Because of the highly exothermic nature of the regeneration, a fluidized catalyst system is advantageous in permitting more rapid regeneration of the catalyst at a given maximum temperature.
I1 est possible de faire la synthèse du thiophène A partir d'hydrocarbures et d'hydrogène sulfuré, eri présence de catalyseurs variés, tels que les oxydes de chrome ou de molybdène déposé sur alumine, la bauxite ou la silice.
Le meilleur rendement est obtenu à partir des hydrocarbures normaux en C4, particulièrement des oléfines. Si l'on utilise des hydrocarbures à chaîne droite d'un nombre de carbone supérieur à 4, on n'obkieni pas seulement du thiophène mais aussi des alkyl thiophènes.
La réaction est légèrement endothermique et peut être facilement conduite sur catalyseur en lit fixe.
Les catalyseurs généralement préférés peuvent être régénérés par l'air. La nature très exothermique de cette réaction rend un système de catalyse fluide avantageux, car il permet une régénération plus rapide du catalyseur à une température maxima àonnée. * The Texas Company, Beacon, N.Y., U.S.A. ** The Ethyl Corporation, Baton Rouge, La., U.S.A. *** Baylor University, Waco, Texas, U.S.A.
Proceedings 3rd W.P.C., Section V
A number of methods of preparing thiophene have been summarized by Steinkopf in a book published in 1941 (7)". These methods appear to suffer from one or more of the following defects:
Yields are low
Starting materials are scarce or expensive
Operating procedures are not adaptable to large scale manufacture.
Since that time, methods which appear somewhat more suitable for large scale manufacture have been published. These methods involve the reaction oi hydrocarbons with sulfur (6) or with sulfur dioxide (2). The present paper describes a method involving the use of hydrogen sulfide and hydrocarbons. The preparation of thiophenes from dienes and hydrogen sulfide is referred to by Steinkapf (7) and has been investigated more recently by Moore and Greensfelder (9, 10).
In the previous paper describing the catalytic preparation of thiophene from hydrocarbons and sulfur dioxide it was reported that production of thiophene was greatest for the normal C4 hydrocarbons especially the olef ins
