Oxatellurines

Tellurium tetrachloride condenses with l-acetoxy-3-oxo-5,5-dimethylcyclohex-l-ene in hot glacial acetic acid to produce bis[3-oxo-5,5-dimethylcyclohex-I-eno][1,2-b 2, r-e -l,4-oxatellurin Te, Te-dichloride  

Bis[3-oxo-5,5-dimethylcyclohex-l-eno][l,2-A 2, l -e]-l,4-oxatellurin-10,10-dichloride To a solution of 40 g (0.15 mol) of tellurium tetraehloride in 200 ml of glacial acetic acid are added 55 g (0.3 mol) of l-acetyloxy-3-0X0-5,5-dimethylcyclohexene. The mixture is heated at 100° for 30 min, then cooled to 40°, and filtered. The filtrate is kept at 5° for two days. The precipitate is collected by filtration, washed with diethyl ether, and dried. The dry solid is dissolved in the minimal volume of hot chloroform and the solution is filtered. Carbon tetrachloride is added to the hot filtrate until crystallization begins. The mixture is allowed to cool. The colorless crystals are collected by filtration and dried yield 60% m.p. 228°. 

The dichloride is reduced to the 1,4-oxatellurin by shaking with a mixture of aqueous sodium sulfite solution and chloroform. The compound (92% yield) melted at 184° after recrystallization from a mixture of benzene and ethanoP. 

4-oxatellurin reacted with elemental bromine and iodine in chloroform to give the Te, 7e-dihalides, and with alkyl halides to produce telluronium salts.  

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A more general method of preparation of various 10,10-dichlorophen-oxatellurines comprises intramolecular electrophilic cyclization of 2-phenoxyphenyl tellurium trichlorides, which are readily accessible from the corresponding arylmercury chlorides or aryltrimethylsilanes (83MI2). 

Similarly prepared was dibenzo-1,4-oxatellurin 10,10-diacetate3 (yield 90% m.p. 207°). 

Alkali metal hydrogen sulfites reduced dibenzo-1,4-oxatellurin 10,10-diacelate to dibenzo-1,4-oxatellurin and diphenyl tellurium diacetate to diphenyl tellurium5. Other reducing... 

A number of sulfate-containing derivatives of dibenzo-l,4-oxatellurin were isolated3-5 as products of the reactions between sulfuric acid and the heterocyclic compound or its 10,10-diacetate3. 

A few diorgano tellurium hydroxide (hydrogen) sulfates are reported in the older literature. Diethyl tellurium hydroxide sulfates were claimed to have been produced from the hydroxide chloride and silver sulfate1 and from the dihydroxide and sulfuric acid2. Several ill-defined compounds that could be or could contain hydroxide hydrogen sulfates were obtained when dibenzo-l,4-oxatellurin or its 10,10-diacetate were treated with sulfuric acid3. 

The l,4-oxatellurin-7h.7h-dichlorideand 5,5-dimethyl-1,3-dioxocyclohexanecondensed to form a tellurium ylide1. 

Dibenzo-l,4-oxatellurine 8-Fluoro-2,10,10-trichloro- E12b, 848 (Ar20 + TeCl4)... 

Dibenzo-1,4-oxatellurin 2,8-Dinitro-10,10-dinitrooxy- El2b, 622 (R2Te 4- HNOj)... 

Dibenzo-l,4-oxatellurin 2-Carboxy-10,10-dichlor- E12b, 848 (2-OAr — Ar — TeCl3 A)... 

Dibenzo-l,4-oxatellurin 10,10-Dibrom-2-fluor-8-methyl- E12b, 556 (Bromierung)... 

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