Arsine oxides protonated

Although ethylmethylphenylphosphine oxide was the first tetrahedral phosphorus compound to be resolved , only negative results were obtained when attempts were made to resolve methyl(a-naphthyl)phenylarsine oxide (142) by protonation and separation of (-i-)-a-bromocamphor-jc-sulphonate salts, or (c>-carboxyphenyl)methylphenyl-arsine oxide (143) or its anhydride 144 after protonation and use of (—)-brucine or (-l-)-morphine . The reversible combination of a tertiary arsine oxide with water was recognized at the outset and it is this property that is responsible for the racemization - ... 

The mechanism involves initial formation of an acetylated or phosphorylated cation, which reacts with a carbanion to form a salt that is strongly acidic because of its substituent electron-withdrawing groups. This salt is hence readily converted into an ylide by loss of a proton, whose removal is assisted by the acetic anhydride or triethylamine (see equation 27). As with method B the arsine oxide method is limited to the preparation of stable ylides, since its success depends upon the acidity of the methylene compound. Almost all examples of this method have utilized triphenylarsine oxide tri-w-butylarsine oxide has been used in triethylamine but gave only intractable products in acetic anhydride In a modification of this method, an ylide has been prepared by reaction of acetoacetanilide with diacetoxytriphenylarsorane, the latter compound having been prepared from triphenylarsine and lead tetra-acetate. ... 

Tris(dimethylamino)arsine (d2o 1.1248 nd 1.4848)3 is a colorless liquid which is readily hydrolyzed to form arsenic (III) oxide and dimethylamine when brought into contact with water. The compound is soluble in ethers and hydrocarbons. The product is at least 99.5% pure (with respect to hydrogen-containing impurities) as evidenced by the single sharp peak at —2.533 p.p.m. (relative to tetramethylsilane) seen in the proton nuclear magnetic resonance spectrum of the neat liquid. 

Some inhibitors are reduced on the surface to yield secondary products that are themselves the active inhibitors. In strong mineral acids, elements from Groups VI and VII tend to become protonated, a necessary prerequisite for many reduction reactions. Such is the case for triphenyl benzyl phosphonium chloride, which forms triphenyl phosphine, and triphenyl arsenic oxide, which undergoes protonation (permitting it to dissolve) and forms triphenyl arsine on the surface. Some sulfonium salts, e.g., tribenzylsulfonium hydrogen sulfate, and dibenzylsulfoxide also can be reduced by iron in HCI. 

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