Lithium hydrosulphide

W. Biltz and E. Wilke-Dorfurt prepared rubidium hydrosulphide, RbSH, by the method used by J. J. Berzelius for lithium hydrosulphide they also prepared ceesium hydrosulpnide, CsSH. Both salts crystallized in about a week from the aq. soln., in vacuo over calcium chloride, in white lustrous very deliquescent needle-like crystals of the anhydrous salts. 

Among alkylating affinity labels, 8-[(4-bromo-2, 3-dioxobutyl)thio] ADP and -ATP (199 n = 2 or 3), formed by successive treatments of the corresponding 8-bromoadenosine phosphates with lithium hydrosulphide and 1, 4-dibromo-butanedione, have been used to label pyruvate kinase from rabbit muscle.355... 

Lithium monosulphide, Li2S.—The monosulphide can be prepared by direct synthesis or by reduction of the sulphate with charcoal. The yellow, product is amorphous, but heating in the electric furnace transforms it into transparent cubes 8 of specific gravity 1 63 to 1 7. Evaporation of its aqueous solution yields hygroscopic crystals of the hydrosulphide, LiSH ... 

The monosulphide and polysulphides are formed by burning the metals in sulphur vapour, by the action of sulphur on the metals dissolved in liquid ammonia, and by the action of the molten metals on sulphur dissolved in toluene. Hydrates or alcoholates and, in some cases, the anhydrous compounds may be prepared by dissolving sulphur in hot solutions of the hydrosulphides or monosulphides. Potassium, rubidium and caesium give all the sulphides where = 1, 2, 3, 4, 5, or 6 sodium only up to the pentasulphide, and lithium only those for which x = 1, 2 and 4 (Pearson and Robinson, 1931). All the metals form two polysulphides of relatively outstanding stability one is invariably the disulphide, and the other tetrasulphide in the case of lithium or sodium, and pentasulphide in the case of potassium, rubidium or caesium. The amount of water of crystallisation and the solubility decrease with increase in atomic number of the metal, the gradation being most marked between sodium and potassium. 

Only the most electropositive metals, the alkali metals and alkaline-earths, form hydrosulphides. LiSH is particularly unstable, being very sensitive to hydrolysis and oxidation, and decomposes at temperatures above about 50°C. It may be prepared in a pure state by the action of HjS on lithium n-pentyl oxide in ether solution. Its structure is of the zinc-blende type and similar to that of UNH2, but there is considerable distortion of the tetrahedral coordination groups ... 

Cyclic Disulphides and Cyclic Diselenides.—Formation. No fundamentally new methods of synthesis of this class of compounds have been reported in the past two years. For l,2>dithiolan the oxidation of l,3>dithiols remains a favoured method, the use of iodine in the presence of triethylamine leading smoothly to 1,2-dithiolans without attendant polymerization. cis- and tra/ -l,2-Dithiolan-3,5-dicarboxylic acids were prepared from a diastereo-isomeric mixture of dimethyl 2,4-dibromoglutarates by sequential treatment with potassium thioacetate and potassium hydroxide in the presence of iodine,and jyn-2,3-dithiabicyclo[3,2,l]octan-8-ol was formed from 2,6-dibromocyclohexanone by successive treatment with potassium thiocyanate, lithium aluminium hydride, and iodine. The stereoselective formation of the less thermodynamically stable alcohol in this case was attributed partly to the formation of chelates with sulphur-aluminium bonds. 2,2-Dimethyl-l,3-dibromopropane was converted into 4,4-dimethyl-l,2-diselenolan on treatment with potassium selenocyanate at 175 °C, but at 140 °C the product was 3,3-dimethylselenetan. Reductive debenzylation of 2-alkylamino-l,3-bis(benzylthio)propanes with lithium in liquid ammonia and oxidation of the resultant dithiols with air afforded 4-dialkylamino-l,2-dithiolans, whilst treatment of a-bromomethyl-chalcone with sodium hydrosulphide gave, as minor product, trans-3 phenyl-4-benzoyl-l,2-dithiolan. Among the many products of thermal decomposition of /ra/ -2,4-diphenylthietan was l,4,5,7-tetraphenyl-2,3-dithiabicyclo [2,2,2]octane. ... 

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