Hydrogen selenides reactions with

Thus a second method was envisaged, the reaction of a nitrile, hydrogen selenide, and an a-halogenated ketone in the presence of a condensation catalyst, which can be POCl, or POCI3 with a Lewis acid such as PCI3 or anhydrous ZnCl. The use of fresh AICI3 leads to the formation of tarry side-products. 

The first involves the reaction of aziridine with an aldehyde or a ketone and the treatment of the resulting carbinol with hydrogen selenide (Scheme 69) (Methode I). 

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). 

The comparatively ready accessibility of selenocarboxamides has encouraged the use of this procedure for the synthesis of selenazoles (1889LA(250)294). Reaction of the a-chloro-carbonyl compound (73) with the selenocarboxamide (74) provided a ready synthesis of a variety of substituted selenazoles (75). Useful variations of this general procedure are described in detail in Chapter 4.20, and particularly attractive is the reaction of hydrogen selenide with a mixture of a nitrile and the a-halogenoketone to afford the selenazole (48YZ191, 79S66). 

Thermolysis of the aziridine (446) in the presence of diphenylketene gave a mixture of the pyrrolidone (447 minor product) and the oxazolidine (448 major product). In this instance the preferential addition to the C=0 bond is explained in terms of steric effects (72CC199). Similar addition to diphenylacetaldehyde takes place with the same orientation and the oxazolidine (448a) was obtained. When the reaction of the aziridine with the aldehyde was carried out in the presence of hydrogen selenide a selenazolidine was obtained (72BSB295). 

By this process, 4-methylselenazole (2 R = CH3, R = R" = H) could be obtained by the reaction of hydrocyanic acid and hydrogen selenide with chloroacetone. This is the solitary selenazole unsubstituted in the 2-position that is known. The yield, however, was only 2.5% calculated on the chloroacetone used. 

ZnSe is deposited by the reaction of hydrogen selenide with zinc vapor transported in argon, at a deposition temperature of700-750°C and at a pressure <100 Torr 1 0... 

Trigonal, metallic selenium has been investigated as photoelectrode for solar energy conversion, due to its semiconducting properties. The photoelectrochemistry of the element has been studied in some detail by Gissler [35], A photodecomposition reaction of Se into hydrogen selenide was observed in acidic solutions. Only redox couples with a relatively anodic standard potential could prevent dissolution of Se crystal. 

Primary selenoamides are prepared by reaction of nitriles with appropriate selenating reagent, such as phosphorus (V) selenide (P2Se5), hydrogen selenide (H2Se), Al2Se3, NaSeH, trw(trimethylsilyl)monoselenophosphate or potassium selenobenzoate (Scheme 81).248 252... 

This pyridoxal-phosphate-dependent enzyme [EC 4.4.1.16], also known as selenocysteine reductase, catalyzes the reaction of L-selenocysteine with a reduced acceptor to produce hydrogen selenide, L-alanine, and the acceptor. The enzyme can use dithiothreitol or 2-mercaptoethanol as the reducing agent. Cysteine, serine, or chloroalanine are not alternative substrates for this enzyme. 

The selenides may also be obtained by direct combination of the elements, either by passing selenium vapour over the heated metal in a vacuum or by heating the metal with selenium in a crucible, the reaction being started by means of a magnesium fuse.3 In the case of potassium the reaction is explosive. The compounds may also be obtained by the action of hydrogen selenide on the heated metal,4 on the heated metallic chloride or its vapour, preferably in the presence of nitrogen,5 or by reduction with hydrogen or carbon of an oxysalt such as a selenite.6 Selenides have also been prepared by electrolytic methods.7... 

Under the action of zinc and hydrochloric acid the compound suffers reduction to hydrogen sulphide and hydrogen selenide. Chlorine reacts with it to form thiocarbonyl tetrachloride and selenium tetrachloride bromine acts analogously, except that under certain conditions the compound C 2S2SeBr6 may be formed.6 With ammonia the products of reaction are ill-defined. 

The introduction of selenium in the (4 +1) sense was achieved by the use of aqueous sodium hydrogen selenide in several instances where the appropriate di(halomethyl) precursors were readily available. Thus, the dichlorides (254c) and (287) and the dibromides (288) and (289) were converted to the five-membered cyclic selenides (290), (291), (292) and (293) by reaction with aqueous sodium hydrogen selenide high dilution conditions were used to minimize the formation of the dimeric diselenides (294)-(297) (Scheme 99) (77H(6)1349, 77CC163). 

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