Iodobenzene dibromide

Diphenyl Tellurium2 A 500-ml, three-necked flask fitted with a dry ice/ethanol cold finger condenser, a nitrogen inlet, and a magnetic stirrer is charged with 250 ml of liquid ammonia. 1.6 g (4 mmol) of diphenyl ditellurium are added followed by 0.2 g (8.7 mmol) of sodium in small pieces which are added over 20 min until the blue color persists. Then, 1.6 g (8 mmol) iodobenzene arc added and the stirred mixture is irradiated with a 250 W UV lamp for 220 min. The reaction is quenched by addition of 10 m/ of distilled water, the ammonia is allowed to evaporate, the residue is treated with 100 ml of water, and the solution is extracted with three 100 ml portions of diethyl ether. The combined extracts are dried with anhydrous sodium sulfate, the solvent is evaporated, and the residue is distilled or converted to diphenyl tellurium dibromide by treatment with bromine yield 2.0 g (90%) b.p. 182"/14torr. 

Phenoxathiin 10,10-dichlorides and dibroinides9, phenoxaselenin dibroinide10, vic-dibromides and diiodides9, and iodobenzene dichloride10 were also used to convert phenoxatellurins to the corresponding 10,10-dihalides. 

Treatment of phenothiatellurin with diphenyldichloromethane, diethyl dibromomalonate, iodobenzene dichloride, phenoxathiin 10,10-dibromide, or phenoxaselenin 10,10-dihalides gave phenothiatellurin 10,10-dihalides2. No reaction was observed with 1,2-dibromoethane2. 

A soln. in lodobenzene dibromide prepared from iodobenzene and bromine in dry hexane added with vigorous stirring below -5° to a soln. of stigmasteryl acetate in the same solvent during 3-4 hrs. at a rate to maintain the soln. pale yellow 5a,6y -dibromostigmastan-3/ -yl acetate. Y 91.5%. M. Fryberg, A. C. Oehlsdilager, and A. M. Unrau, Tetrahedron 27, 1261 (1971). 

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