Sodium disulfite

Glycosidic thiol groups can be introduced into glycosyl bromides by successive reactions with thiourea and aqueous sodium disulfite (D. Horton, 1963 M. Cemy, 1961, 1963). Such thiols are excellent nucleophiles in weakly basic media and add to electrophilic double bonds, e.g., of maleic esters, to give Michael adducts in high yields. Several chiral amphiphiles have thus been prepared without any need for chromatography (J.-H. Fuhrhop, 1986 A). 

MRH values calculated for 27 combinations with oxidisable materials are given. Sodium disulfite, Water... 

Sodium disulfite Sodium thiosulfate, both below See Sodium nitroxylate... 

Large-scale addition of solid sodium disulfite to an unstirred and too-concentrated solution of sodium nitrite caused a vigorous exothermic reaction. 

See Potassium iodate Sodium disulfite, Water Sodium nitrite... 

Lithium carbonate, 0533 Lithium dithionite, 4687 Magnesium carbonate hydroxide, 0534 Magnesium nitrate, 4693 Magnesium nitrite, 4692 Magnesium sulfate, 4696 Potassium carbonate, 0531 Potassium nitrite, 4649 Silver hyponitrite, 0031 Sodium acetate, 0779 Sodium carbonate, 0552 Sodium disulfite, 4808 Sodium dithionite, 4807 Sodium hydrogen carbonate, 0390 Sodium hydrogen sulfate, 4446 Sodium metasilicate, 4805 Sodium nitrite, 4720 Sodium sulfate, 4806 Sodium tetraborate, 0185 Sodium thiosulfate, 4804... 

Sodium disulfite, Na2S20g, from Merck Company, Inc. was used. The saturated solution of disulfite should be the lower phase. 

See Potassium thiocyanate, above See Sodium disulfite, below See Sodium nitroxylate See Sodium thiosulfate, below... 

Potassium phosphinate, 4453 Sodium disulfite, 4802 Sodium dithionite, 4801 Sodium hydride, 4438 Sodium hypoborate, 0164 Sodium phosphinate, 4467 Sodium thiosulfate, 4798 Sulfur dioxide, 4831 Tetraphosphorus hexaoxide, 4861 Tin(II) chloride, 4064 Tin(II) fluoride, 4325 Titanium trichloride, 4152 Titanium(II) chloride, 4111 Tungsten dichloride, 4113 Vanadium dichloride, 4112 Vanadium trichloride, 4153 Zinc, 4921... 

When 3-chloro-2-(A -benzoyl-7V-phenylamino)-propyl tellurium trichloride was reduced with aqueous sodium disulfite, bis[3-benzoyloxy-2-phenylaminopropyl] ditellurium (m.p. 106°) was isolated in 90% yield. The benzoyl group had migrated during the reduction and had replaced the chlorine atom3. 

Bis[2-carboxyphenvl] Ditellurium [Sodium disulfite Method]3 10 g (0.03 mol) of 2-carboxyphenyl tellurium bromide are suspended in 100 ml of water and a 10% solution of sodium disulfitc is added dropwiseto the red suspension. The precipitate is collected, dissolved in sodium hydrogen carbonate solution, filtered, and acid is added to the filtrate. The precipitated product is filtered yield 4.1 g (52%) m.p. 216° (dec.). 

The reductions with sodium sulfide proceed when the reactants are heated to 100° without solvents. Sensitive organo tellurium trihalides might be decomposed by some of these reducing agents. /J-Chloroalkyl tellurium trichlorides are converted to olefins upon treatment with sodium sulfide, whereas y-chloroalkyl tellurium trichlorides are reduced to ditellurium products1. 2-Alkoxyalkyl tellurium trichlorides are reduced without difficulty by sodium disulfite to bis[2-alkoxyalkyl] ditellurium compounds2. 

Methoxyphenyl Tellurium Cyanide4 2.45 g (29.2 mmol) of sodium hydrogen carbonate is dissolved in a mixture of 50 ml of water and 3 ml of methanol and 5.0 g (14.2 mmol) of 4-melhoxyphenyl tellurium tribromide is added. The mixture is stirred for 0.5 h, 3.70 g (58.4 mmol) of potassium chloride followed by ll.Og (58.4 mmol) of sodium disulfite are added, the resultant mixture is stirred for 8 min, and 3.70 g (58.4 mmol) of potassium cyanide are added. A white precipitate forms. The reaction mixture is diluted with water, extracted with dichloromethane, the organic phase is dried with anhydrous sodium sulfate, and filtered. The filtrate is diluted with hexane and the resultant solution is concentrated by distilling some of the solvent. The precipitate is filtered yield 3.60 g (93%) m.p. 77°. 

Commonly employed reducing agents are sodium borohydride, sodium sulfide nonahy-drate, potassium sulfide, sodium or potassium hydrogen sulfite (Vol. IX, p. 1068), sodium disulfite, hydrazine hydrate, and thiourea dioxide. Lithium diethylamide1 has been found to reduce diaryl tellurium dichlorides. Methyl magnesium iodide is recommended in the older literature as a reducing agent (Vol. IX, p. 1069). 

Bromobenzntellurophene1 3-Bromobenzotellurophene dichloride is suspended in diethyl ether and an excess of 5% aqueous sodium disulfite solution is added. The mixture is shaken thoroughly until all of the organic material has dissolved. The organic layer is separated, dried with anhydrous calcium chloride, filtered, and the filtrate is evaporated. The oily residue is pure 3-bromobenzotellurophene-, yield 100%. See Table 20 for similary prepared benzotellurophene dichlorides and benzotellurophenes. 

Phenyl-l,3-benzotellurazole 5.0 g (20 mmol) of 2-aminophenyl ethyl tellurium and 5 ml of triethylamine are dissolved in 20 ml of dichloromethane and the solution is cooled in an ice/water bath. 3.5 g (25 mmol) of benzoyl chloride dissolved in 10 m/ of dichloromethane arc added dropwise to the cooled solution of the tellurium compound and the mixture is stirred for 2 h. The crude 2-(N-benzoylamino)-phenyl ethyl tellurium is isolated, placed in 20 ml of phosphoryl chloride, and the mixture is heated under reflux for 3 h. After being cooled in an ice/water bath, the mixture is carefully hydrolyzed with an aqueous base and treated with sodium disulfite. The basic mixture is extracted with dichloromethane, and the extract is dried and concentrated under vacuum. The residue is chromatographed on a column of silica gel with hexane as the mobile phase and the product is recrystallized from hexane yield 0.9 g (15%) m.p. 118-120°. Similarly prepared were ... 

---