With Thiourea Dioxide

Thiourea dioxide (aminoiminomethanesulfinic acid) reduced diaryl ditellurium and divinyl ditellurium derivatives in tetrahydrofuran, to which an ammonium salt such as cetyltrimethylammonium chloride, serving as a phase-transfer catalyst, and 50% aqueous sodium hydroxide had been added  

Sodium 3-Trifluoromethylbenzenetellurolate 0.545 g bis[3-trifluoromethylphcnyl] ditcllurium (1 mmol) and 0.108 g thiourea dioxide (1.0 mmol) are dissolved in 7.5 ml tetrahydrofuran. 30 mg of the ammonium salt and 7,5 ml of 50% aqueous solution of sodium hydroxide are added. The mixture is shaken vigorously for 4 h 

These reductions were carried out in the presence of an alkyl halide that reacted with the sodium tellurolate. The expected unsymmetrical diorgano tellurium derivatives were isolated. 

Irgolic Organic Tellurium Compounds with one Te,C Bond 

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Alkyl Aryl Telluriums2 (Reduction with Thiourea Dioxide) To a solution of 1.0 mmol diaryl ditellurium in 7.5 ml tetrahydrofuran are added 0.108 g (1.0 mmol) thiourea dioxide, 30 mg 2HT (phase transfer reagent), and 2.0 mmol of the alkyl bromide. To this mixture are added 7.5 ml of a 50% aqueous solution of sodium hydroxide. The mixture is stirred for several hours at 20°. The organic phase is separated. The aqueous phase is extracted three times with 20 ml ethyl acetate. The organic phase and the ethyl acetate extracts are combined and dried with anhydrous magnesium sulfate. The mixture is filtered and the solvents evaporated from the filtrate. The residue is chromatographed on silica gel with ethyl acetate as mobile phase. 

K Nakagawa, K Minami. Reduction of organic compounds with thiourea dioxide. I. Reduction of ketones to secondary alcohols. Tetrahedron Lett 5 343-346, 1972. 

There has been some interest in the stereochemistry of reactions at C-6 in morphine derivatives. Borohydride reduction of the narcotic antagonist naloxone (101 R = allyl) gave a mixture of alcohols consisting mainly of the 6a-hydroxy-derivative, identical with the principal metabolite in vivo. The 6/3-hydroxy epimer, forming 10% of the mixture, was isolated by liquid chromatography and was also obtained via solvolysis of the 6a-tosyloxy-derivative. Reduction of naloxone and naltrexone (101 R — cyclopropylmethyl) with thiourea dioxide (formamidinesul-phinic acid) in aqueous alkali is reported, on the other hand, to give only the 6j8-hydroxy-derivatives. It has been reported that the major urinary metabolite of naltrexone administered to humans is the 6/3-hydroxy-epimer, while a chicken... 

Reductions of sulfur compds. with thiourea dioxide Phase transfer catalysis Thioethers from sulfonylsulfilimines... 

Sodium telluride and ditelluride are readily generated in situ from Te by reduction with thiourea dioxide, and subsequent treatment with alkyl halide provides the corresponding dialkyl tellurides and ditellurides. E Thiourea dioxide and NaOH in 1 1 water/THF added to Te under N2, the mixture refluxed for 1 h, n-octyl halide and a little cetyltrimethylammonium bromide in THF added, and refluxing continued for 1 h - dioctyl telluride. Y 85%. The method is cheap, simple and does not require very dry conditions. F.e. and sym. ditellurides s. J.T.B. Ferreira et al., Synth. Commun. 19, 239-44 (1989) prepn. of Na2Te from ultra-pure Te-ingots/Na-naphthalenide, or from Te/Na and a little naphthalene, s. K.T. Higa, D.C. Harris, Organometallics 8, 1674-8 (1989). 

Traditionally, these dyes are appHed from a dyebath containing sodium sulfide. However, development in dyeing techniques and manufacture has led to the use of sodium sulfhydrate, sodium polysulfide, sodium dithionite, thiourea dioxide, and glucose as reducing agents. In the reduced state, the dyes have affinity for cellulose (qv) and are subsequendy exhausted on the substrate with common salt or sodium sulfate and fixed by oxidation. 

Thiourea dioxide, or formamidine sulfinic acid, is an oxygenated thiourea derivative synthesized by the oxidation of thiourea with hydrogen peroxide. It has the chemical formula (NH2)NHCS02H and is tautomeric. 

Table 12.28 Analysis of exhaust dyebaths after dyeing of cotton fabric with sulphur dyes using sodium sulphide or thiourea dioxide [213]...

Bjorklund, G. H. et al., Trans. R. Soc. Can., (Sect. Ill), 1950, 44, 28 The solid peroxide produced by action of hydrogen peroxide and nitric acid on thiourea (and possibly a hydrogen peroxidate of thiourea dioxide) decomposed violently on drying in air, with evolution of sufur dioxide and free sulfur. 

The Hurd-Mori reaction,where a tosylhydrazone is converted by thionyl chloride to the corresponding thiadiazole, involves the formation of a 1,2,3-thiadiazole-3,3-dioxide. In one example, this type of compound was isolated and subsequently deoxygenated with thiourea <1991PS175>. There have been no further reports of S-linked sulfoxide or sulfone derivatives of 1,2,3-thiadiazoles since the publication of CHEC-II(1996). 

A difference in reactivity was observed between the phenanthro[9,10-r]- and acenaphtho[l,2-c]-l,2,5-thiadiazole 1,1-dioxides 51 and 53 when treated with thiourea. The acenaphtho derivative 53 gave the expected addition product however, the phenanthro thiadiazole 51 was reduced to the thiadiazoline 1,1-dioxide 52 (Equation 2) <2004JP01091>. The difference in reactivity was attributed to the enhanced resonance stability offered by the phenanthrene group. 

The use of sodium dithionite (Na2S204) and thiourea dioxide (TUDO HN=C(NH2)S(0)0H) has been introduced later as a reducing agent for the preparation of sodium telluride in an aqueous medium, followed by reaction with n-alkyl halides to give dialkyl teUiirides. - ... 

Normally following the Hurd and Mori procedure a tosylhydrazone is converted with thionyl chloride to the corresponding thiadiazole. In one case under these conditions, the dioxide (30) was isolated <91PS(60)175> and subsequently deoxygenated with thiourea (Scheme 7). 

Thiourea dioxide has a stronger reducing effect (-1100 mV) than hydrosulfite. Therefore, with sensitive dyes, a risk of over-reduction exists. In addition, the oxidation products of thiourea dioxide contribute to the nitrogen and sulfur contamination of wastewater. 

Dialkyl Ditellurium (Thiourea Dioxide Method)2 A mixture of 128 mg (1.0 mmol) of elemental tellurium, 4 mg (0.01 mmol) of cetyltrimethylammonium bromide, 0.75 ml tetrahydrofuran, and 0.5 ml dimethyl sulfoxide is heated at 80° for 15 min under an atmosphere of deoxygenated nitrogen. To this mixture is added 100 mg (1.0 mmol) of thiourea dioxide, 112 mg (2.6 mmol) sodium hydroxide, and 0.75 ml water. The resulting mixture is refluxed for 1 h. The purple solution is then cooled to 15°. Alkyl halide (2.0 mmol) is added and the mixture is stirred at 20° for 1 h. After normal work-up, the dark-red oils were passed through a pad of Celite with dichloromethane as the mobile phase. 

Bis[2-methylphenyl] Ditellurium [Thiourea Dioxide Method]4 A mixture of 0.65 g (2.0 mmol) 2-methylphenyl tellurium trichloride and 5 ml of 2 M aqueous sodium hydroxide solution is vigorously stirred at 20° for 15 min. To this mixture are added 0.43 g (4.0 mmol) thiourea dioxide and 5 ml petroleum ether (30-60°). The mixture is stirred at 20° for 15 min. The phases are separated. The organic phase is dried with anhydrous magnesium sulfate, filtered, and the solvent evaporated from the filtrate. The product was isolated in 76% yield. 

Tellurium is reduced by thiourea dioxide in alkaline medium to the telluride dianion that is alkylated with alkyl halides2. 

Bis[6-(tetrahydropyran-2-yl-oxy)-l-hexyl] Tellurium2 (Thiourea Dioxide Method) Under an atmosphere of nitrogen 200 mg (2 mmol) thiourea dioxide, 112 mg (2.6 mmol) sodium hydroxide, 0.75 mt water, 0.75 ml tetrahydrofuran and 128 mg (1 mmol) tellurium are mixed. The mixture is refluxed for 1 h. Then 2 mmol of the alkyl halide and 4 mg cetyltrimethylammonium bromide are added to the pale-pink solution.The mixture is refluxed for 1 h and then worked up in the usual way. The residue is purified by column chromatography on silica gel with petroleum ether as the mobile phase. The product is isolated in 72% yield. Similarly prepared were2 ... 

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