From Aluminum Telluride

Heating aluminum telluride and excess 1,4-dibromobutane at 125° produced 4-bromobutyl tetramethylene telluronium bromide and butane-1,4-diyI bis[tetramethylene telluronium] 

Tetramethylene Telluronium Bromides 30 g (69 mmol) of aluminum telluride and 67 g (310 mmol) of 1,4-dibromobutane are placed in a 250 m/, round-bottom flask fitted with a reflux condenser and a stirrer. The stirred mixture is heated at 125° when the reaction becomes too vigorous the flask is cooled. When the reaction has subsided the mixture is heated for 2 h, then cooled to 20°. The semi-solid mass is extracted in sequence with carbon tetrachloride, acetone, ethanol, and water. The acetone and ethanol extracts are combined, evaporated, and the residue is recrystallized from ethanol to give white crystals of 4-bromobutyl tetramethylene telluronium bromide. 

The aqueous extract is concentrated to give the monohydrate of tetramethylene bis[tetramethylene telluronium] dibromide yields not reported for the two products. 

Similar reactions between aluminum telluride and 1,5-dihalopentanes produced 5-halopentyl pentamethylene telluronium halides and pentane-1,5-diyl bis[pentamethylene telluronium] dihalides.  

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Hydrogen tclluride, H,Te. Mol. wt. 129.62. unstable gas. The reagent can be generated in situ from aluminum telluride, Al2Te3 (Alfa), and water. 

Hydrogen telluride, generated in situ from aluminum telluride in aqueous tetrahydrofuran containing sulfuric acid, reacted with aliphatic aldehydes to produce dialkyl ditellurium compounds in yields of aproximately 50%. Strong acids are required to obtain acceptable yields of ditellurium compounds. Weak acids (acetic acid, chloroacetic acid) reduce the yields to approximately 10%. In a basic medium (triethylamine), no ditellurium derivative was formed the major product was the alcohol. 

Hydrogen telluride, prepared from aluminum telluride and 2 molar hydrochloric acid, added to the double bond in vinyl cyanide and formed bis[2-cyanoethyl tellurium1. 

There are several recent methods for the reduction of azobenzene to hydrazobenzene in near-quantitative yield. Samarium(II) iodide reduces azobenzene to hydrazobenzene rapidly at room temperature. Hydrogen telluride, generated in situ from aluminum telluride and water, reduces both azobenzene and azoxybenzene to hydrazobenzene a mixture of phenyllithium and tellurium powder has been used to reduce azobenzene. A complex of the coenzyme dihydrolipoamide and iron(II) is also effective for the reduction of azo- and azoxy-benzene to hydrazobenzene the reduction probably involves coordination of the azobenzene to iron(II) as shown in structure (1). Electrochemical reduction has been used to prepare a number of hydrazobenzenes from the corresponding azobenzenes. In the presence of an acylating agent a diacylhydrazine (e.g. the pyridazinedione derivative 2) can be isolated from the electrochemical reduction of azobenzene. 

Tellurols, derivatives of dihydrogen telluride, have received little attention. Only methane-, ethane-, propane-, and butane tellur ol have been isolated from reactions of aluminum telluride with alcohols at 300° or from additions of alkyl bromides to a solution of dihydrogen telluride in absolute ethanol containing sodium ethoxide (s. Vol. IX, 970). No arenetellurol has yet been isolated. 

Tr ideu ter ome thane tellurol was similarly prepared the yields vary greatly from preparation to preparation)1. Methane-, ethane-, propane-, and hutanetellurol1 2 were obtained from reactions of aluminum telluride and alkanols under a hydrogen atmosphere at temperatures between 240° and 350°. 

Bis[3-phenyl-l-rf-propyl] Ditelluriumh A suspension of 266 mg (2.0 mmol) 3-phenylpropanal and 1.75 g (4.0 mmol) aluminum telluride in 10 m/tetrahydrofuran is cooled to — 78°. A solution of 0.21 ml (4.0 mmol) of concentrated (98%) sulfuric acid in 1.75 ml (96 mmol) deuterium oxide is added to the chilled suspension. The mixture is warmed to 20° and then heated to the reflux temperature with continuous stirring over a 30 min period. The mixture is then refluxed for 1.5 h. After cooling to 20°, the black precipitate is removed by filtration. The filtrate is washed with aqueous sodium hydrogen carbonate solution and dried with calcium sulfate. The mixture is filtered, the solvent removed from the filtrate, and the residue chromatographed with hexane/benzene (1 1) as the mobile phase. The product was obtained as a dark-red oil in 70% yield. 

The first step was achieved by three alternative procedures (i) the action of aluminum telluride on 1,4-dihalobutane at temperatures ranging from 125° to 175° this method is very tedious and the yield is poor (ii) the reaction between amorphous tellurium and 1,4-diiodobutane at 130°-140°, which gives a good yield (iii) the reaction between sodium telluride made in situ and 1,4-dibromobutane this is the most reliable method. The subsequent reduction of 1,1-dihalotetrahydrotellurophene (22) has been carried out using sulfur dioxide. By a similar procedure 3,3 -bistetrahydrotellurophene (24) has been prepared. 8,69... 

The catalyst was prepared from a nickel-aluminum (50 50) alloy using the procedure given by Mozingo. The catalyst is used in large excess. Reduced amounts of catalyst resulted in decreased yields, and the product is contaminated with detectable (gas chromatography) amounts of bis(4-methoxyphenyl) telluride. 

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