From hydrogen selenide

The molar ratio of the III compound to the V compound is typically l/lO.t ] To obtain the desired semiconductor properties, dopants are added such as zinc (from diethyl zinc) or magnesium (from bis(cyclopentadienyl) magnesium) for p doping, and silicon (from silane) or selenium (from hydrogen selenide) for n doping. 

Similarly, sulphur can displace selenium, from hydrogen selenide. 

Three types of compounds may be considered to be derived from hydrogen selenide, H2Se, namely RSeH, R2Se and RSeR, where R and R are aliphatic radicals. 

The maximum yield of 2-alkylseIenazole is 25%. In this way. 4-methylselenazole (7) was obtained starting from hydrogen cyanide, hydrogen selenide and chloroacetone. It is the only known selenazole not substituted in the 2-position. The yield relative to chloroacetone is very low (2.5%) (Scheme 2). 

The advantage of this method is that it avoids the use of hydrogen selenide, necessary for the preparation of selenourea from cyanamide (14). Benzoylselenourea is synthesized by the method of Douglass (24) by the action of potassium selenocyanate On benzoyl chloride in acetone solution. 

Selenium heterocycles receive far less mention in the literature than do such homologs as oxazole, thiazole, or imidazole. In fact, preparative methods of selenium heterocycles are much more limited than for the other series, mainly because of manipulatory difficulties arising from the toxicity of selenium (hydrogen selenide is even more toxic) that can produce severe damage to the skin, lungs, kidneys, and eyes. Another source of difficulty is the reactivity of the heterocycle itself, which can easily undergo fission, depending on the reaction medium and the nature of the substituents. 

Other gas-treating processes involving sulfolane are (/) hydrogen selenide removal from gasification of coal, shale, or tar sands (qv) (108) (2) olefin removal from alkanes (109) (J) nitrogen, helium, and argon removal from natural gas (110) (4) atmospheric CO2 removal in nuclear submarines (5) ammonia and H2S removal from waste streams (6) H2S, HCl, N2O, and CO2 removal from various streams (111—120) and (7) H2S and SO2 removal from... 

Trialkyl- and triarylarsine sulfides have been prepared by several different methods. The reaction of sulfur with a tertiary arsine, with or without a solvent, gives the sulfides in almost quantitative yields. Another method involves the reaction of hydrogen sulfide with a tertiary arsine oxide, hydroxyhahde, or dihaloarsorane. X-ray diffraction studies of triphenylarsine sulfide [3937-40-4], C gH AsS, show the arsenic to be tetrahedral the arsenic—sulfur bond is a tme double bond (137). Triphenylarsine sulfide and trimethylarsine sulfide [38859-90-4], C H AsS, form a number of coordination compounds with salts of transition elements (138,139). Both trialkyl- and triarylarsine selenides have been reported. The trialkyl compounds have been prepared by refluxing trialkylarsines with selenium powder (140). The preparation of triphenylarsine selenide [65374-39-2], C gH AsSe, from dichlorotriphenylarsorane and hydrogen selenide has been reported (141), but other workers could not dupHcate this work (140). 

Cautionl Hydrogen selenide is very toxic. This preparation should be carried out in a well-ventilated hood. The operator should wear rubber gloves. The apparatus should be screened from any bright light. 

Diphenyl diselenide has been prepared by disproportionation of phenyl selenocyanate in the presence of potassium hydroxide" or ammonia/ and by air oxidation of benzeneselenol. The preparation of benzeneselenol is described in an earlier volume in this series/ In the present procedure phenylselenomagnesium bromide formed from phenylmagnesium bromide and selenium is oxidized directly to diphenyl diselenide with bromine/ Thus the liberation of the malodorous and toxic hydrogen selenide and benzeneselenol is avoided. Benzeneselenenyl chloride has been prepared by thermal elimination of ethyl chloride from ethyl phenyl selenide di-chloride/ by thermal elimination of chlorine from phenylselenium trichloride," and by chlorinolysis of diphenyl diselenide with either sulfuryl chloride " or chlorine. " ... 

Fig. 2.3 Potential-pH equilibrium diagram for the system selenium-water, at 25 °C (gaseous hydrogen selenide is designated in italic letters) (Reproduced from [3], Copyright NACE International 2010)...

A more general synthesis of selenophene derivatives, starting from diacetylenes and sodium hydrogen selenide, was investigated by Curtis.48 In the synthesis of new tetraphenylporphyrin molecules containing heteroatoms other than nitrogen, Ulman et al.49 used in principle the method of Curtis for the synthesis of the starting material (17). 

Arsenic recoveries from the zinc column in the range 0.1-5pg ml-1 arsenic exceeded 97%. The concentrations at which certain elements interfere are shown in Table 12.16. Various other elements [A1 m, B m, Ca II, Cd II, Co II, Cr VI, Fe III, K I, Li I, Mg II, Mn H, Na I, Ni II, Pb II, S VI, Sn II and Zn II] showed no significant interference at the 500pg level. Only low senium concentrations in extracts can be tolerated. However, few environmental samples contain appreciable amounts of selenium. As selenium is not reduced to hydrogen selenide on the column, selenium will not interfere in the final determination step, but probably suppresses either arsenic reduction or arsine formation. Selenium appears to suppress arsine generation at high arsenic concentrations but causes a slight enhancement at low arsenic concentrations (around O.lpg), which could not be traced to arsenic impurities in the selenium standard used. 

Phenyl hydrogen selenide, generated from diphenyl diselenide and sodium borohydride in ethanol, promotes the /V-bcnzylation of cyclohex-2-enylamine (equation 54)164. 

Hydrogen selenide may be synthesized directly from elements by heating at elevated temperatures. It is prepared by heating hydrogen at 440°C with either selenium metal in a sealed tube or with selenium vapor over pumice stone ... 

Fig. 3.5.6 Absorbance spectra of 190-layer cadmium-10, 12-diynoatc LB films after exposure to (a) hydrogen sulfide, (b) hydrogen selenide, or (c) hydrogen telluride. The spectra have been corrected for background (quartz and film). (From Ref. 31.)...

In aq ale, or from 4-chlono-1,3-dinitrobenzene hydrogen selenide in boiling alcoholic acetic.acid (Refs 1, 2 3)... 

From metallic selenides.—Aluminium selenide is easily decomposed, even by water, with formation of hydrogen selenide 6... 

The Selenides.—Hydrogen selenide exhibits stronger acidic properties than hydrogen sulphide, and many of the heavy metals may be precipitated as selenides from aqueous solutions of their salts under conditions generally analogous to those required for the precipitation of... 

In the wet way selenides are best produced by allowing the solution of the metallic salt to drop slowly into a saturated aqueous solution of hydrogen selenide which is mechanically stirred. In this way the selenide is formed in the presence of excess of hydrogen selenide, no excess of metal ions being at anytime present in the solution.1 The alkali selenides may be obtained by the action of hydrogen selenide on the corresponding carbonates in aqueous solution in an atmosphere of nitrogen,2 followed by crystallisation from solution. 

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