Disodium telluride

Synthesis by soft chemistry made the first disodium telluride, Na2Te. This product is highly poisonous and oxidable. To make Na2Te we used the two procedures... 

The additions of disodium telluride, dilithium telluride and disodium selenide to chloromethyl alkynyl sulfides and tellurides give a variety of 1,3-dichalcogenoles as shown in Scheme 15 (81RTC10,82TL1531>. The preparation of the 1,3-ditelluroles required the use of dilithium telluride under carefully controlled conditions. 

A suspension of disodium telluride in benzene and trimethylchlorogermane, -stannane, or -plumbane when heated under reflux for 12 h was converted to bis[trimethylgermyl] tellurium or the corresponding tin and lead compounds2. 

Disodium telluride and chlorodi-r-butylphosphane5 or chlorodi-isopropylphosphane4 combined in toluene to produce bis[dialkylphosphano tellurium5. 

Bis[di-t-bntylphosphano] Tellurium5 Disodium telluride is prepared from 5.4 g (22 mmol) of sodium and 16.6 g (13 mmol) of tellurium and suspended in 100 ml of toluene. A solution of 3.7 g(20 mmol) ofchlorodi-t-butylphosphane in 50 ml of toluene is added to the suspension and the mixture is stirred for 12 h. The resultant mixture is filtered and the solid is washed with toluene. The filtrate and washings are combined, the solvent is removed under reduced pressure, and the residue is recrystallized from pentane yield 32 g (80%) m.p. 77°. 

The three-membered P —Te heterocycle is formed as the main product when disodium telluride reacts with /-butyldichlorophosphine or with 1,2-di-/-butyM, 2-dichlorodiphos-phine. The heterocycle readily loses tellurium and it was not possible to isolate the compound2,3. 

The reactions of disodium telluride with equimolar amounts of l-chloro-2-formylethenes yielded sodium 2-formyl-l-ethenetellurolates6. 

Sodium l-f-Butyl-2-formylethenetellurolates1 0.1 mol of disodium telluride is prepared from sodium and tellurium in anhydrous liquid ammonia under nitrogen. The ammonia is evaporated at 20°, the residue is cooled to — 15°, and 100 ml of pure DMF are added. To the well-stirred solution arc added 0.1 mol of the appropriate l-chloro-2-formylethene dissolved in 200 ml of DMF. The mixture is then stirred for 1 h. 

Sodium 2-Methoxybenzenetellurolocarboxylate3 A solution of 0.171 g of 2-melhoxybenzoyl chloride (1 mmol) in 8 ml of tetrahydrofuran is added to 0.174 g of freshly prepared disodium telluride (1 mmol). The mixture is stirred under an atmosphere of nitrogen at 0° for 1 h, then filtered, and the filtrate kept under reduced pressure to remove the solvent. The product remains as a dark-red oil. 

Disodium methaneditellurolate disproportionates in ethanol solution into disodium telluride and telluroformaldehyde1, and disodium 2,2 -biphenylditellurolate into disodium telluride and dibenzotellurophene2. 

Disodium methaneditellurolate disproportionated in ethanol to disodium telluride and polymeric telluroformaldehyde3. 

Disodium 1,2-biphenylditellurolate disproportionated under similar conditions to disodium telluride and dibenzotellurophene4. 

Disodium ditelluride can also be prepared by first reducing tellurium with two moles of sodium borohydride to disodium telluride and then adding an additional mole of tellurium1. 

When aromatic nitro compounds were reduced in dimethylformamide with disodium telluride to aza derivatives, bis[dimethylaminocarbonyl ditellurium was obtained in 5 to 15% yield as a by-product. The formation of this ditellurium compound was attributed to the capture of a telluride anion by a dimethylcarbamoyl radical and subsequent oxidation of the tellurocarbamoyl species5. 

The discovery of efficient methods for the reduction of tellurium in organic media to disodium telluride, which can be alkylated in situ, led to the preparation of many dialkyl telluriums. The greatest progress has been achieved, however, in the preparation of unsymmetrical diorgano telluriums by alkylation or arylation of tellurolates or by modification of the organic groups in diorgano telluriums. 

The limited solubility of long-chain alkyl halides in liquid ammonia makes it advantageous to evaporate the ammonia after the disodium telluride has formed and to dissolve the residue in an appropriate organic solvent. Ethanolic solutions of disodium telluride that had been prepared in liquid ammonia were used for the synthesis of the following heterocyclic tellurium compounds1 ... 

Unsymmetrical dialkyl tellurium derivatives were prepared by mixing an aqueous disodium telluride solution with equimolar amounts of two different alkyl halides. All three possible dialkyl tellurium products are formed. The unsymmetrical dialkyl tellurium is the predominant species. It can be separated from the symmetrical compounds by chromatography1. This one-pot procedure takes less time to complete than the alternative route employing alkyl tellurolates (p. 387) and was used to prepare unsymmetrical dialkyl telluriums containing radioactive tellurium. Sequential addition of two alkyl halides produced only symmetrical dialkyl telluriums. 

Disodium telluride, prepared from tellurium and sodium borohydride, and 2-chloro-3-(2-chloroethyl)quinoline formed 2,3-dihydroquinolo[3,2-d]tellurophene3. 

Disodium telluride, prepared from tellurium pieces, sodium, and naphthalene in tetra-hydrofuran, reacted with allyl bromide to give diallyl telluriuml. 

Diallyl Tellurium (Tellurium-Sodium-Naphthalene Method)1 A tellurium ingot is broken into pieces by shaking in a polyethylene container. A 25-ml Schlenk flask is charged with 6.1 g (48 mmol) tellurium pieces, 2.2 g (96 mmol) sodium, 0.1 g (0.8 mmol) naphthalene, and 20 mi tetrahydrofuran. The mixture is stirred under an argon atmosphere at 25° for 4 days and then filtered. The filter cake is washed with 20 ml fresh tetrahydrofuran and dried under vacuum to give 7.6 g (92%) disodium telluride. Alternatively, 60-mesh tellurium powder and 2 molar equivalents of sodium naphthalide are stirred for 4 h in tetrahydrofuran. Disodium telluride was isolated as a beige-colored solid. 

Disodium telluride can be efficiently prepared from the elements in dimethylformamide at 110° and alkylated without isolation2,3. 

Tellurium mixed with solid sodium hydroxide in dimethylformamide at 60° is reduced to disodium telluride by hydrazine hydrate4. However, neat hydrazine hydrate added to a slurry of tellurium in an aqueous solution of sodium hydroxide (6 M) produced only disodium ditelluride that was reduced to the telluride with sodium dithionite5. Addition of alkyl chlorides or bromides to these disodium telluride solutions gave dialkyl ditelluriums in good yields4,5. 

When organic dihalides with five atoms between the two halogen atoms were reacted with disodium telluride, prepared by the Rongalite method, the corresponding telluranes were formed2-6. 

Dibromobutane and disodium telluride under similar conditions formed tetrahydrotellurophene in 70% yield4. 

Dihydro-l//-2-benzotellurin, prepared from 2-(2 -bromoethyl)benzyl bromide and disodium telluride, has a much greater stability than the telluranes2. 

The following diorgano tellurium derivatives were prepared from disodium telluride, for which the mode of synthesis is not reported, and the appropriate organic bromides in dimethylformamide as the reaction medium3 ... 

For methods to prepare acyl organo tellurium compounds from disodium telluride, carboxylic acid chlorides, and alkyl halides, see p. 500. 

The ditellurium compounds, in which a Te —Te group joins two carbonyl groups, can be considered to be the tellurium analogs of peroxy compounds derived from carbonic acid or benzoic acids (e.g. benzoyl peroxides). Only a few of these compounds are known. During the reduction of aromatic nitro compounds with disodium telluride in dimethylfor-mamide, bis[dimethylaminocarbonyl] ditellurium was formed as a by-product in yields from 5 to 15%. The formation of this compound was attributed to the capture of the dimethylaminocarbonyl radical by the telluride anion and subsequent oxidation of the tellurocarbamoyl species4. 

The reaction of (iodomethyl)iodo-rhodium complexes with disodium telluride also leads to telluroformaldehyde-containing complexes6. 

Disodium telluride and diacetylenes react in methanol to give tellurophenes. With 1,3-butadiyne, tellurophene is obtained. 1 -Organo-l,3-butadiynes yield 2-organotellurophenes. l,4-Diorgano-l,3-butadiynes produce 2,5-diorganotellurophenes. The yields of these reactions generally do not exceed 50%. 

H-, 3-Thiatelluroles were prepared from disodium telluride and (chloromethyl-thio)ethynes2. 

Diorgano-4-oxo-4H-tellurins were formed in 37-67% yield from dilithium or disodium telluride and bis[organoethynyl] ketones2-5. 

The reaction between dialkynyl(organo)phosphine oxides and disodium telluride in dimethylformamide/water produced 2,6-dialky l-4-organo-4-oxo-4//-1,4-telluraphos-phorins2. 

Dimcthyl-4-oxo-4-phenyl-/>v-4//-l,4-teUuraphosphorm This reaction must be performed under a nitrogen atmosphere. 17.4 g (100 mmol) of disodium telluride are prepared from 4.6 g (200 mmol) of sodium and 12.8 g (100 mmol) of tellurium in liquid ammonia. When the reaction between sodium and tellurium is complete, 175 ml of methanol are cautiously added to the sodium telluride suspension in liquid ammonia. The ammonia is allowed to evaporate, and the mixture is then heated on a water bath kept at 40". Methanol is added to bring the volume to 150 ml. 6.1 g (30 mmol) of bis[l-propyn-l-yl](phenyl)phosphine oxide are added, the mixture is stirred for 5 h, 500 ml of ice/water are added, and the resultant mixture is extracted several times with chloroform. The combined extracts are filtered, and the filtrate is washed with water, dried with anhydrous magnesium chloride, and filtered. The solvent is evaporated from the filtrate under aspirator vacuum and the residue is recrystallized several times from toluene yield 7.0 g (71%) m.p. 179-182". Similarly prepared were the following compounds1 ... 

Dialkynyl sulfides combined with disodium telluride in mcthanol/ammonia to form 1,4-thiatellurins7,8. 

Dialkynyl sulfones reacted rapidly with disodium telluride in methanol to produce 3,5-dialkyl-l,4-thiatellurin 1,1-dioxides3. 

Dimcthyl-t, 4-thiatellurin 1,1-Dioxide3 A solution of 5.2 g (30 mmol) of disodium telluride in 100 ml of methanol is prepared. A solution of 3.0 g (20 mmol) of bis[propynyl] sulfone in methanol is added to the disodium telluride solution at 20°. After 10 min, the reaction mixture is poured into 300 ml of ice/water and the organic product is extracted with five portions of chloroform. The combined extracts are washed with saturated aqueous ammonium chloride solution, the organic phase is dried with anhydrous magnesium sulfate, the mixture is filtered, the filtrate is concentrated under vacuum, and the product is recryslallized from diethyl ether/pentane by cooling the solution to —25° yield 3.6 g (65%) m.p. 158°. 

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