Patent GB-578124-A (GB)
Title: Improvements in or relating to manufacture of organic compounds containing sulphur
Filed: 1943-05-26
Abstract: Thiols are prepared by heating ethylenic compounds, which contain carbon-to-carbon multiple bonds as the only unsaturation and which do not contain functional groups reactive under the conditions employed, with hydrogen and hydrogen sulphide in the presence of a heavy metal sulphide catalyst.  As ethylenic compounds there may be employed open chain olefinic hydrocarbons such as the gaseous olefines ethylene, propylene, and butenes and the normally liquid olefines such as the pentenes, hexenes, octenes, cetene and unsaturated polymers. Doubly-unsaturated compounds such as vinyl acetylene, butadiene, divinylacetylene and cyclo-hexadiene; cyclic olefines such as cyclo-hexene, styrene, dihydro-naphthalene, and unsaturated terpenes such as alpha-pinene; and ethylenic compounds containing functional groups that are unreactive under the conditions employed such as the hydroxyl, amino, halogen, thiol, sulphide or ether groups, for example vinyl chloride, allyl alcohol, allylamine, allyl sulphide, ethyl vinyl sulphide, chloroprene and its polymers, are included. With simple ethylenic compounds it is preferred to carry out the process at temperatures of about 150 DEG  to 250 DEG  C.; when the ethylenic compound is not liquid under the reaction conditions, it is preferred to use an inert solvent medium such as a saturated hydrocarbon, for example, petroleum ether and petroleum fractions or benzene, or diethyl ether, dioxane, methanol, ethanol, butanol and chlorinated paraffins.  If the ethylenic compound or product is thermally unstable, reaction temperatures of the order of 50 DEG  to 150 DEG  C. should be used.  With ethylenic compounds having especially reactive unsaturated groups such as conjugated dienes, the lower temperatures are favoured, but with stable compounds, temperatures of 250 DEG  to 350 DEG  C. may be used.  Generally, pressures in the range of 500 to 5000 lbs. per sq. in. are used. Preferably, the ethylenic compound and hydrogen sulphide are employed in equivalent proportions.  Instead of using hydrogen sulphide as such, an equivalent amount of elementary sulphur may be used which, in the presence of the heavy metal sulphide catalysts, is rapidly hydrogenated to hydrogen sulphide (see Group III).  The heavy metal sulphides employed are those comprising the sulphides and polysulphides of metals of Groups VI and VIII of the Periodic Table, particularly cobalt, nickel, iron, molybdenum, tungsten and chromium and their preparations are described (see Group III).  In examples: (1) octene-1, hydrogen sulphide and a cobalt trisulphide catalyst are heated in an autoclave with hydrogen under pressure to yield octanethiol and some octyl sulphide; in the absence of hydrogen or with nitrogen replacing the hydrogen, high yields of octyl sulphide and low yields of thiol result; (2) as in (1) above, the hydrogen sulphide being prepared in situ; (3) a -pinene, sulphur and cobalt trisulphide catalyst are heated with hydrogen under pressure, first, to form hydrogen sulphide and then, at a higher temperature, pinane-thiol and some pinyl sulphide; replacing hydrogen by nitrogen results in a much lower conversion to thiol; (4) allyl alcohol, sulphur and cobalt trisulphide catalyst are heated under hydrogen pressure as in (3) above to yield mercapto-propanol and higher boiling condensation products also containing mercapto groups.