HYDROGEN DISULFIDE.131 PHOSPHINE

Hydrogen selenide Hydrogen telluride Hydrogen polonide Hydrogen disulfide Phosphine... 

As with conformational energy differences, SYBYL and MMFF molecular mechanics show marked differences in performance for rotation/inversion barriers. MMFF provides a good account of singlebond rotation barriers. Except for hydrogen peroxide and hydrogen disulfide, all barriers are well within 1 kcal/mol of their respective experimental values. Inversion barriers are more problematic. While the inversion barrier in ammonia is close to the experimental value, barriers in trimethylamine and in aziridine are much too large, and inversion barriers in phosphine and (presumably) trimethylphosphine are smaller than their respective experimental quantities. Overall,... 

Peroxides are cleaved to 2 mol of alcohols by L1A1H4 or by catalytic hydrogenation. Peroxides can be reduced to ethers with P(OEt)3. ° In a similar reaction, disulfides (RSSR ) can be converted to sulfides (RSR ) by treatment with tris(diethylamino)phosphine, (Et2N)3P. ... 

Cystine, which contains a disulfide bond, is reported to be the most numerous and reactive amino acid present in hair keratin. Disulfide bonds in cystine are reduced by mercaptans and phosphines, and oxidized by perborates, bromates, and bleach. These reactions result in structural rearrangements within keratin which may affect the physiochemical properties of hair, since disulfide bonds in cystine contribute to the stability of hair. For example, hydrogen peroxide bleaching of hair is an oxidative process which occurs readily in an alkaline medium. This results in the formation of perhydroxy anions which have been proposed to react with cystine to form cysteic acid residues. The process of bleaching results in the loss of approximately 15% of the cystine bonds originally present in keratin and may explain the increased permeability of bleached hair to chemicals. - ... 

SAFETY PROFILE Poison by inhalation and ingestion. A corrosive eye, skin, and mucous membrane irritant. Potentially explosive reaction with water evolves hydrogen chloride and phosphine, which then ignites. Explosive reaction with 2,6-dimethylpyridine N-oxide, dimethyl sulfoxide, ferrocene-1,1 -dicarboxylic acid, pyridine N-oxide (above 60°C), sodium -L heat. Violent reaction or ignition with BI3, carbon disulfide, 2,5-dimethyl pyrrole + dimethyl formamide, organic matter, zinc powder. Reacts with water or steam to produce heat and toxic and corrosive fumes. Incompatible with carbon disulfide, N,N-dimethyl-formamide, 2,5-dimethylpyrrole, 2,6-dimethylpyridine N-oxide, dimethylsulfoxide, ferrocene-1,1-dicarboxylic acid, water, zinc. When heated to decomposition it emits highly toxic fumes of Cl" and POx. 

Phosphinic chlorides are obtained by alkylation of white phosphorus in solution in carbon disulfide in the presence of aluminum chloride and hydrogen chloride,181 followed by oxidation.182 Successive action of sodium and an alkyl halide on red phosphorus in liquid ammonia leads to tetraalkyldiphos-phanes R2P4 and trialkylphosphines, or, after addition of sulfur, to their sulfides.183... 

Oxidation of the hydrolysed Grignard mixture with hydrogen peroxide or bromine provides phosphinic acids 383,398,423 however, the methyl and ethyl derivatives are difficult to isolate because of their great solubility in water, and these are better obtained by way of the diphosphane disulfides.409 Thio-phosphinic acids are obtained analogously in good yield by addition of sulfur 424... 

The oily reaction products are weakly acidic. Electrometric titration of the product from 1-decene indicated about one acidic hydrogen for each two phosphorus atoms. Moreover, a barium salt is readily obtained, which is said to be a useful lubricating oil additive. The product appears to contain the tertiary phosphine structure, since treatment with carbon disulfide produces the red color characteristic of tertiary phosphines. The product is readily oxidized by the atmosphere, about three atoms of oxygen being absorbed for each two phosphorus atoms. Oxidation by nitric acid is said to give a crude mbcture of phosphonic and phosphinic acids, but only 7% of the phosphorus is oxidized to phosphoric acid, indicating that the remainder is bonded to carbon. Reactions of these materials with sulfur and with bromine have also been described (33). 

---