Patent GB-574936-A (GB)
Title: Improvements in or relating to the manufacture of thiols
Filed: 1940-08-12
Abstract: Thiols are prepared by catalytic hydrogenation of an organic compound containing a thio carbonyl group or a sulphhydrate group, or a compound which under the reaction conditions gives rise to a substance having such groups.  In a modification, an organic carbonyl compound is reacted with hydrogen and sulphur or hydrogensulphide or substance yielding the latter in the presence of a sulphactive hydrogenation catalyst.  As sulphactive catalysts, the subsulphides, sulphides or polysulphides of the heavy metals of Groups I, IV, VI, VII and VIII of the Periodic Classification may be employed.  Organic or mineral acids and alkalies, ammonia and amines are stated to improve the yields. The carbonyl compound may first be reacted with hydrogen sulphide and the product then hydrogenated.  By oxidation, the thiols produced yield sulphides and sulphonic acids.  In examples: (1) hydrogen is introduced into an autoclave containing octanone-2, liquid hydrogen sulphide and a cobalt polysulphide catalyst prepared by adding sodium sulphide nonahydrate and sulphur to aqueous cobalt chloride hexahydrate and washing the resulting precipitate with dioxane; octanethiol-2 is obtained; (2) cyclohexanone is hydrogenated in the presence of sulphur and cobalt polysulphide catalyst; (3) isofenchone, mesityl oxide and acetophenone are similarly treated, but acetic acid is also present; (4) benzaldehyde, 2-ethylhexanal, glucose, pentadecanone-8 and heptadecanone-7 are hydrogenated in the presence of sulphur and a catalyst paste made from acetic acid and the cobalt polysulphide prepared as in example (1); (5) pentadecanone-8 is hydrogenated in the presence of hydrogensulphide and a catalyst prepared by treating a methanol suspension of pyrophoric cobalt (prepared by the sodium naphthalene reduction of anhydrous cobalt chloride) with hydrogensulphide, boiling with diluted sulphuric acid and washing the resulting cobalt sulphide; (6) pentadecanone-8 is hydrogenated in the presence of sulphur and a catalyst prepared by treating with hydrogen sulphide a methanol suspension of a sulphuric acid-treated alloy of molybdenum and aluminium; (7) streams of dry hydrogensulphide and hydrogenchloride are passed into a suspension of pentadecanone-8 in alcohol and the product poured into water; the oily upper layer comprises a mixture of pentadecanethione-8 and pentadecanedithiol-8 : 8, which is hydrogenated in the presence of cobalt sulphide paste; (8) a mixture of cyclohexanone, carbonbisulphide and cobalt polysulphide is hydrogenated to give cyclohexanethiol.  Other catalysts specified are sulphides and polysulphides of copper, silver, lead, manganese, iron and nickel, which may be supported on magnesia, alumina or other carrier.  Of the many carbonyl compounds mentioned, the following are typical: acetone, di-isobutylketone, cyclopentanone, camphor, b  - decalone, formaldehyde, heptaldehyde, glyoxal, acetylacetone, acetonylacetone, quinone, furfural, acetyl pyrrol, benzoylacetone-1 : 4-dibenzoylbutane, polymethyl vinylketone and hydroxy, amino, nitro, sulpho and halogen substituted carbonyl compounds, such as aldol, sugars, triacetoneamine, chloracetone and ethoxyacetophenone.  Carbonyl compounds containing ethylenic or acetylenic bonds may be used, e.g. crotonaldehyde, citronal and phorone.  Derivatives of carbonyl compounds which react like carbonyl compounds may be used.  Specified compounds are hemiacetals, e.g. 1-ethoxy-1-hydroxybutane, hemiketals, e.g. 8 - methoxy - 8 - hydroxypentadecane, acetals, ketals, hydrated carbonyl compounds, condensation products of ammonia and carbonyl compounds, e.g. hexamethylenetetramine and acetaldehydeammonia.  The Specification as open to inspection under Sect. 91 comprises also the use of carboxylic acids, their esters and amides levulenic acid, 6-ketohedecane-1 : 11-dioic acid, pyruvic acid and acetoacetic ester. This subject-matter does not appear in the Specification as accepted.