Phosphinic acids, from phosphine disulfide

Diallylsulfonium salts undergo intramolecular allylic rearrangement with strong bases to yield 1,5-dienes after reductive desulfurization. The straight-chain 1,5-dienes may be obtained by double sulfur extrusion with concomitant allylic rearrangements from diallyl disulfides. The first step is achieved with phosphines or phosphites, the second with benzyne. This procedure is especially suitable for the synthesis of acid sensitive olefins and has been used in oligoisoprene synthesis (G.M. Blackburn, 1969). 

Thionyl chloride Phosphinic acid chlorides from diphosphine disulfides... 

Without additional reagents Thiophosphinic acid bromides from diphosphine disulfides s. 19, 590 Thionyl chloride Phosphinic acid chlorides from diphosphine disulfides s. 19, 591... 

The metal and ammonium salts of dithiophosphinic acids tend to exhibit far greater stability with respect to this thermal decomposition reaction, and consequently these acids are often prepared directly in their salt form for convenience and ease of handling. Alkali-metal dithiophosphinates are accessible from the reaction of diphosphine disulfides with alkali-metal sulfides (Equation 22) or from the reaction of alkali-metal diorganophosphides with two equivalents of elemental sulfur (Equation 23). Alternatively, they can be prepared directly from the parent dithiophosphinic acid on treatment with an alkali-metal hydroxide or alkali-metal organo reagent. Reaction of secondary phosphines with elemental sulfur in dilute ammonia solution gives the dithiophosphinic acid ammonium salts (Equation 24). 

Other sulfur-containing ligands, such as xanthates, disulfides, di- and trithiols, and resorcinarene tetrathiols have been used to stabilize AuNPs. Apart from sulfur containing ligands, other ligands such as phosphine, phosphine oxide, amine and carboxylic acids. 

Potentiometric Methods. - Potassium trithiocarbonate has been used as a reductant (-S-S- reduction cleavage) for the potentiometric (and spectrophoto-metric) determination of the disulfides of dithio-phosphinic acids in DMF-H2O medium at millimolar levels.The protonation equilibria for N,N -diethylami-nomethylenephosphonic acid (88) were elucidated from both potentiometric titration and determination of the pH dependence of the NMR chemical shift (83 ip), and protonation constants for aminoalkanephosphonates RCH(NH2)P(0)(0Et)2 and the acidity constant of di(2-ethylhexyl)thiopho-sphoric acid (111) have also been obtained potentiometrically. 

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). 

Triphenyl phosphine, mercuric chloride, disulfide Subst. carboxylic acid amides from carboxylic acids Redoxidative peptide synthesis... 

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