From Tellurium Diiodide

7-Dimethyl-lO-ethylphenotellurazine was prepared from tellurium diiodide and bis[2-lithio-4-methylphenyl]ethylamine .  

Sadekov, G.M. Abakarov, A.D. Garnovskii, V.I. Minkin, Khim. Geterotsikl. Soedin. 1982, 707 engl. 543. 

7-Dimethyl-lO-ethylphenoteIlurazine A 500 ml round bottom flask equipped with a reflux condenser, a dropping funnel, and a stirrer is flushed with argon and then charged with a solution of 15 g (39 mmol) of bis[2-bromo-4-methylphenyl]ethylamine in 150 ml of dry diethyl ether. The flask is cooled in an ice/water bath, 54 ml (78 mmol) of a 1.54 molar solution of butyl lithium in diethyl ether are added, and the solution is stirred for 45 min. 16 g (42 mmol) of tellurium diiodide are added, the mixture is stirred and heated under reflux for 1 h, cooled, and poured into 250 ml of ice/water. The hydrolyzed mixture is filtered, the filter cake is washed with two 50 m/portions of diethyl ether, and the combined ether solutions arc dried with anhydrous calcium chloride. After filtration, the filtrate is evaporated, and the residue is recrystallized from octane yield 8.1 g (55%). 

The reaction of tellurium tetrachloride with bis[2-lithiophenyl]methylamine in THF gave 10-methylphenotellurazine 5,5-dichloride, which was reduced to lO-methylphenotellurazine with hydrazine hydrate.  

10-MethylphenotcIIurazine 5,5-Dichloride Under nitrogen, 3.7 ml (6.3 mmol) of a 1.7 molar butyl lithium solution are added dropwise to a solution of 1.0 g (2.9 mmol) of bis[2-bromophenyl]methylamine in 35 ml of dry tetrahydrofuran at 0°. The mixture is stirred at 0° for 1 h, 0.79 g (2.9 mmol) of tellurium tetrachloride in 10 m/of dry tetrahydrofuran are added dropwise to the solution of bis[2-lithiophenyl]methylamine, and the mixture is stirred for 2 h. The solvent is then evaporated, the residue is dissolved in 250 ml of dichloromethane, and the solution is washed with water, dried, and evaporated. The yellow solid is recrystallized from acetonitrile yield 0.2 g (18%) m.p. 270 . 

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The third known method of synthesis of the heterocycles 82 is exemplified by the preparation of 4,4-diiodo-l-oxa-4-telluracyclohexane 84 on heating bis(2-iodoethyl)ether with powdered tellurium (45JCS11). It has an analogy in the synthesis of dimethyl tellurium diiodide from methyl iodide and elemental tellurium (20JCS86), but is characterized by a rather low yield (10-13%) of product 84 because of partial decomposition of the initial oxide under the reaction conditions. When bis(2-chloroethyl)ether and Nal were used instead of bis(2-iodoethyl)ether and the reaction was... 

The reactivity of the tellurium trihalides decreases from the chlorides to the iodides. The aryl tellurium triiodides do not form diaryl tellurium diiodides and do not react with acetone6. 

Alkyl chlorides and bromides can be used as starting materials when sodium iodide is present in the reaction mixture. Dialkyl tellurium diiodides are isolated from these reaction mixtures. 

Tellurium tetrachloride and tetraaryl tin compounds reacted under similar conditions to give diphenyl tellurium dichloride (75% yield)2,3 and bis[4-methylphenyl tellurium dichloride (86% yield)4. Tellurium tetraiodide and tetraphenyl tin reacted to give diphenyl tellurium diiodide (m.p. 236°) in only 20% yield1. Tetraethyl tin and tellurium tetrahalides produced reaction mixtures from which the diethyl tellurium dihalides could not be isolated1. 

Diphenyl Tellurium Difluoride6 A mixture of 15 ml of dry toluene and 2 g (16 mmol) of silver fluoride is heated to reflux, and 1.3 g (3 mmol) of diphenyl tellurium diiodide are added in portions to the refluxing silver fluoride suspension. Additional diiodide is added after the reddish color of the solution has disappeared. The hot solution is filtered under aspirator vacuum, The filtrate deposits the crystalline product on cooling. The difluoride is filtered off, washed with toluene, and recrystallized from benzene the pure product has m.p. 154°. 

Dimethyl tellurium diiodide and mercury(II) bromide formed a 1 1 complex in absolute ethanol at 20°8. The same compound was obtained from dimethyl tellurium dibromide and mercury(II) iodide. The corresponding mercury(II) chloride adduct is unstable8. 

From Dimethyl Tellurium Diiodide and Dimethyl Tellurium Dicyanide... 

Trimethyl Telluronium Picrate1 Trimethyl telluronium iodide, prepared from 1.6 g of dimethyl tellurium diiodide, potassium sulfite, and methyl iodide, is dissolved in water and a saturated aqueous solution of picric acid is added until precipitation of the telluronium picrate ceases. The solid is filtered off, washed with cold water, and dried in air yield 0.3 g (20% based on dimethyl tellurium diiodide) m.p. 127° (dec.). 

Dipropyl Tellurium Diiodide In a long glass tube are placed 17.45 g (0.1 mol) of 1-iodopropane and 12.0 g (0.1 mol) of powdered tellurium. The tube is closed with a ground-glass stopper, and heated in an oil bath at 85° for 5 days. The hot mixture is then filtered, the black residue is extracted with chloroform, the extract and filtrate are combined, and the solution is evaporated to dryness at 20°. The dark oily residue is recrystallized from hexane yield 6.2 g (26%) m.p. 69°. 

Dibutyl Methyl Telluroniiun Iodide 95 mg (0.19 mmol) of dibutyl tellurium diiodide, 20 ml of methyl iodide, 35 mg (0.22 mmol) of potassium sulfite, 24 mg (0.22 mmol) of sodium carbonate, and 5 ml of water are placed in a conical flask. The mixture is shaken vigorously, kept at 20° for 3 days, filtered, the filtrate is evaporated to dryness, and the residue is recrystallized from water yield 45 mg (62%) m.p. 157°. Similarly prepared were the following telluronium iodides ... 

Diphenyl Tellurium Hydroxide Iodide1 Diphenyl tellurium chloride (or bromide) hydroxide is dissolved in water and a slight excess of potassium iodide dissolved in water is added. The yellow precipitate is filtered off and recrystallizcd from methanol. For dissolution of the product in methanol, the mixture is heated cautiously on a water bath to prevent the hydroxide iodide from disproportionating to the diiodide and the dihydroxide (or oxide). The pure product has m.p. 215°... 

Bis[2-methylphenyl] tellurium hydroxide iodide decomposed to the diiodide and the oxide during attempts at recrystallization from methanol1. 

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