Selenides, precipitation of pure

Samarium (III) nitrate, analysis of anhydrous, 6 41 Selenic acid, crystalline, 3 137 Selenides, precipitation of pure metallic, from solutions of hydrogen selenide, 2 185 Selenium, red and gray, 1 119 Selenium (II) chloride, formation of, by selenium(IV) chloride, 6 127... 

One volume of water at 22.5° dissolves 2.7 volumes of hydrogen selenide. Precipitates of pure metallic selenides can be obtained by allowing salt solutions to drop slowly into saturated aqueous solutions of the gas, an excess of hydrogen selenide being maintained. ... 

Phenyl selenide, CeHg.SeH.1—This selenide may be obtained as follows (1) Selenium tetrachloride is allowed to react with benzene in the presence of aluminium chloride. (2) Magnesium phenyl bromide in ether solution is treated with finely divided selenium and the addition product treated with cold hydrochloric acid. The ether layer is then removed, the extracted solution treated with more ether and the extracts combined, then shaken with one equivalent of sodium hydroxide, calculated on the basis of the total amount of selenium used, and dissolved in water to make a 25 per cent, solution. The ether solution is then dried with calcium chloride, the ether removed and the residue distilled, diphenyl diselenide and diphenyl selenide, B.pt. 303° C., being obtained. The sodium hydroxide solution on acidification with a slight excess of concentrated hydrochloric acid, followed by three more extractions with ether, gives on removal of the solvent almost pure phenyl selenide, B.pt. 182° C. The product melts at 60° C., and is insoluble in water, but dissolves in alcohol mercuric chloride gives a white precipitate.2... 

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