Patent GB-603103-A (GB)
Title: Production of unsaturated organic sulphur compounds
IPC: C07D333/06
Filed: 1945-07-30
Abstract: Thiophenes and unsaturated mercaptans are produced by reacting an unsaturated hydrocarbon which contains at least four carbon atoms and an olefinic linkage between two aliphatic carbon atoms, one of which is directly linked by a single bond to another carbon atom which in turn is directly linked by a double bond to another carbon atom with hydrogen sulphide in the ratio of at least 2 mols. of hydrogen sulphide per mol. of unsaturated hydrocarbon and in the presence of a dehydrogenation catalyst at a temperature of 150-750 DEG  C. Specified hydrocarbons are the conjugated dienes, e.g. butadiene, isoprene, piperylene, 2-methyl- and 3-methyl-pentadiene-1,3; hexadiene-1,3; 3-methyl-hexadiene-1,3; 3-methyl-hexadiene-2,4; 2-phenylbutadiene-1,3; 2,5-diamethyl - hexadiene - 1,3 and 1 - phenyl - 3 - methylbutadiene-1,3; hydrocarbons having one olefinic and one aromatic double bond, e.g. styrene; 1 - phenyl - 1 - propene; 2 - phenyl - 1 - propene; 1 - methyl - 2 - vinyl (3 - vinyl- and 4-vinyl)-benzene; 1,3- (and 1,4)-divinyl benzene; 1 - phenyl - 1 - butene; 2-phenyl - 2 - butene; and 1-ethyl-2-vinyl benzene.  Suitable dehydrogenation catalysts are the oxides, sulphides and other compounds of titanium, vanadium, chromium, manganese, iron, cobalt and nickel or the metals themselves.  The catalyst is preferably employed in conjunction with a promoter, e.g. the highly porous and refractory materials consisting of at least one of the oxides of aluminium, silicon and magnesium, adsorptive alumina and activated bauxite being preferred.  The catalyst is preferably subjected to an elevated temperature, e.g. 300 DEG  C. to 700 DEG  C. in an atmosphere of hydrogen sulphide before use and treatment at a similar temperature in a hydrogen atmosphere prior to the pretreatment with hydrogen sulphide is an advantage.  If the reaction is effected at above 400 DEG  C. and at pressures below 500 pounds per square inch and with a contact time of 2 to 60 seconds the reaction product is mainly thiophenic compounds.  Lower temperatures and pressures of at least 300 pounds per square inch favour the production of unsaturated mercaptans which contain the same number of carbon atoms as the hydrocarbon used.  Mixtures of the unsaturated hydrocarbons may be used and inert gaseous diluents may be added and unreacted hydrocarbons and hydrogen sulphide may be recycled to the reaction zone.  In examples: (1) butadiene-1,3 is reacted with hydrogen sulphide to produce thiophene in separate operations in the presence respectively of the following catalysts: iron oxide supported on activated alumina, Fe2O3 on silica gel, Cr2O3 on adsorptive alumina, Ni on adsorptive alumina, Fe2O3 on magnesium oxide, various molar ratios, temperatures, pressures and contact times being employed; (2) isoprene and hydrogen sulphide yield methylthiophene at 600 DEG  C. and atmospheric pressure, the catalyst being iron oxide on activated alumina; (3) 2-methyl pentadiene-1,3 is reacted with hydrogen sulphide as in (2), the product being dimethyl thiophene (probably 2,4-dimethylthiophene); (4) styrene yields benzo thiophene when reacted with hydrogen sulphide as in (2); (5) butadiene-1,3 mixed with hydrogen sulphide is contacted with the same catalyst as in (2), the temperature not exceeding 400 DEG  C. and the pressure being 500 pounds per square inch, 2-butene-1-thiol being obtained. Specification 464,952 is referred to.  The Specification as open to inspection under Sect. 91 also mentions the following compounds as starting materials: 2-methyl-3-ethylbutadiene-1,3; 2-methyl-3-t-butylbutadiene-1,3; 3-methylenepentadiene - 1,4 and 3 - methylenecyclohexene-1.  This subject-matter does not appear in the Specification as accepted.