Selenium tetrachloride

Selenium tetrachloride, SeCU m.p. 305"C. Yellowish solid (CI2 plus Se2Cl2). Forms hexachloroselenales containing (SeClo) " in cone. HCI solution. 

Selenium tetrachloride hydrolyzes to form hydrochloric acid, the degree of hydrolysis depending on the acidity of the solution. 

A general route to benzo-2,l,3-selenadiazoles involves the condensation reaction between 1,2-diaminobenzene and selenium tetrachloride. This method has also been used recently for the synthesis of 4,5,6,7-tetrafluoro-2,l,3-benzotelluradiazole (Eq. 2.9) ... 

Selenophenol has been prepared from selenium tetrachloride and benzene in the presence of anhydrous aluminum chloride,6 and by the procedure described,7 which is a development of Taboury s.8... 

Thioamides have been transformed into the corresponding nitriles. Treatment of primary thioamides by tellurium tetrachloride or selenium tetrachloride in combination with triethylamine affords nitriles.66 Treatment of primary amides and thioamides with l-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI) gives nitriles.67 Reactions of thioamides with metal carboxylates in organic solvents enables the selective preparation of nitriles, imides or amides depending on the substitution pattern of the starting material (Scheme 33).68... 

SELENIUM TETRACHLORIDE SELENIUM HEXAFLUORIDE SELENIUM OXYCHLORIDE SELENIUM DIOXIDE SILICON... 

SeCl4 SELENIUM TETRACHLORIDE 62.7934 -5.6601E+03 -2.0127E+01 1.5021E-02 -4.7573E... 

Amidines (161) and tris(trimethylsilyl) amidines (162) react with a mixture of selenium and selenium tetrachloride to give U, 2,3,5-diselenadiazol-l-ylium chlorides (163), some of which are converted into other salts for characterization. These salts are reduced by triphenylantimony to give 1,2,3,5-diselenadiazolyl radicals (164) (Scheme 13). The salts (23) and (43a)-(43d) were thereby prepared and converted into the radicals (21a)-(21e) <89JA9276, 9UA582, 92CC1265, 92IC1802>. The... 

Reaction of the 1,3,2-benzodiselenastannole (166) with selenium tetrachloride gives the triselenole (40) which is converted into the triselenolium hexafluorophosphate (20b) by reaction with nitrosyl hexafluorophosphate <94CC1593>. Benzo[l,2-rf][l,2,3]triselenolium chloride (20c) was obtained by reaction of 1,2-benzene-bis(selenenyl chloride) with selenium <92AG(E)779>. The structure of the trifluoromethanesulfonate (20a) has been established by x-ray crystallography (see Section 4.21.3.1). 

Sulphury chloride, on the other hand, is attacked by selenium at ordinary temperatures, selenium tetrachloride again being formed 1... 

Pyrosulphuryl chloride, Sa05Cla, converts selenium into a colourless crystalline compound, SeS03CI4 or SeCl4.S03, generally known as sulphur-selenium oxytetrachloride2 (p. 82-1), which melts at 165° C. and boils at 185° C., and which can also be obtained by the combination of its constituents, selenium tetrachloride and sulphur trioxide.3... 

Selenium Tetrachloride, SeCl4.—This may be obtained as follows ... 

By various methods from selenium dioxide for example, by the action of hydrogen chloride, thionyl chloride or phosphorus pentachloride. The last-named is perhaps the most convenient chlorinating agent. A mixture of the pentachloride and the dioxide is heated until chemical change causes it to solidify. Phosphorus oxychloride can be distilled off with the aid of a current of carbon dioxide and the residual selenium tetrachloride purified by sublimation.8... 

Selenates, on distillation -with sulphuric acid and sodium chloride, yield a mixture of selenium tetrachloride and chlorine anhydrous selenic acid also gives an excellent yield of selenium tetrachloride on treatment -with acetyl chloride at 0° C.1... 

Selenium tetrachloride is a colourless solid which on heating vaporises without melting. Sublimation in an atmosphere of chlorine is therefore a convenient method of purification. The density of the vapour (which is yellow in colour) indicates that dissociation occurs to a considerable extent above 200° C., although below this temperature the results are in accordance -with the formula SeCI4.3 The products of dissociation are probably the lower chloride and chlorine. There are indications that at higher temperatures (500° C.) the dichloride, ScCL>, is formed. When the tetrachloride is heated in a sealed tube with selenium, the monochloride is produced.3... 

By adding the calculated amount of dry selenium dioxide to selenium tetrachloride suspended in carbon tetrachloride. The oxychloride formed in the cold dissolves in the carbon tetrachloride, from which it may be obtained by distillation. Carbon tetrachloride distils at 76° to 77° C., while the selenium oxychloride distils over at 176-4° C.1... 

When a mixture of selenium dioxide and selenium tetrachloride is heated in a sealed tube, selenium oxychloride is formed 5... 

Selenium oxychloride absorbs all light up to a wave-length of 4050pp. It is miscible with chloroform, carbon disulphide and benzene without chemical change. It is also soluble in carbon tetrachloride, but after a time reaction takes place with formation of selenium tetrachloride and carbonyl chloride.10 At the ordinary temperatures selenium oxychloride is not miscible with the paraffin hydrocarbons,... 

Sulphur Selenium Oxytetrachloride, SeSOsCl4 or SeCl4.SOa. —This can be produced by the direct combination of sulphur trioxide and selenium tetrachloride.3 It has also been obtained by heating selenium tetrachloride with chlorosulphonic acid, sulphuric acid, pyro-sulphurie acid or sulphuryl chloride,... 

Selenium Nitride, Se4N4.—This was first obtained in 1859 by saturating selenium tetrachloride with ammonia in the cold 3... 

Phosphorus Chloroselenide, PSeCl3.—By treating phosphorus pentachloride with selenium tetrachloride, phosphorus chloroselenide has been obtained as a yellow substance which becomes red on heating.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. 

Dichloroselenoacetone, (CHg.CO.CH SeCla.1—Two molecular proportions of pure acetone in a large volume of absolute ether are treated with selenium tetrachloride (1 mol.) in small quantities. The resulting product crystallises in white needles, M.pt. 82° C., which emit a vapour tending to attack the mucous membrane. The compound decomposes on keeping and also on boiling with water, selenium separating. 

Dichloroselenoacetophenone, (C6H5.CO.CH2)2SeCl2,3 occurs when acetophenone (2 mols.) in dry ether reacts with selenium tetrachloride (1 mol.). The product crystallises in white needles, M.pt. 122° C., and is much more stable than the corresponding compound derived from acetone. It can be preserved without undergoing decomposition, but with dilute sodium hydroxide it yields acetophenone and selenious acid, more concentrated alkali causing the separation of selenium. With phenylhydrazine it gives a resinous mass. 

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