Stibinic acids reduction

The foregoing aimno-acid, obtained by the reduction of 16 grams of potassium 3-nitro-4-hydroxyphenylstibmate, is suspended in 12 c.c. of water and acetyiated by the gradual addition of 9 c.c. of acetic anhydride. A clear solution results and after twenty-four hours several volumes of acetone are added, causing the precipitation of a stibinic acid which may be represented by one of the above formulae. The substance is a white amorphous powder, extremely soluble in water, with an acid reaction, insoluble in acetone, alcohol or glacial acetic acid, and yielding a sodium salt which is readily soluble in water. 

Phenylarsinic acid-stibimc acid is reduced by sodium hyposulphite to a dark brown product. Reduction of 4-hydroxyphciiyl-l-arsmic acid-3-stibinic acid, H0.CeH3(Sb03H2)(As03H2), by stannous chloride and concentrated hydrochloric acid in the presence of a trace of iodine, yields an orange-yellow solid, probably 4 hydroxyphenylstibinea sine. 

All the diarylstibinic acids are solids, and their method of preparation has an influence upon their solubility, eg, the hydrolysis of di-phenylstibinic chloride by ammonium hydroxide yields an acid which is insoluble in ammonium hydroxide or sodium carbonate, but dissolves in sodium hydroxide, whilst solution of the chloride in sodium hydroxide gives a stibinic acid on acidification with acetic acid which dissolves in all the foregoing alkalis. The secondary acids also differ from the primary acids in their action towards hydrochloric acid and ammonium chloride diphenylstibmic acid is insoluble in concentrated hydrochloric acid, and m hot dilute hydrochloric acid its solutions do not give a double salt with ammonium chloride, but pyridine hydrochloride precipitates diphenylstibmic chloride as a double salt. Nitration of the secondary stibinic acids yields nitro-acids containing the nitro-group in the meia-position to the antimony. Reduction of the secondary acids yields stibinoxides. Mercuric chloride converts diphenylstibmic acid in methyl alcohol-hydrogen chloride solution into phenylmercuric chloride and antimony trichloride. 

The aromatic primary and secondary stibines are readily oxidized by air, but they are considerably more stable than their aHphatic counterparts. Diphenylstibine is a powerful reducing agent, reacting with many acids to Hberate hydrogen (79). It has also been used for the selective reduction of aldehydes and ketones to the corresponding alcohols (80). At low temperatures, diphenylstibine undergoes an addition reaction with ketene (81) ... 

Arsine, AsHs, is formed when many As-containing compounds are reduced with nascent hydrogen and its decomposition on a heated glass surface to form a metallic mirror formed the basis of Marsh s test for the element. The low-temperature reduction of AsCls with LiAlH4 in diethyl ether solution gives good yields of the gas as does the dilute acid hydrolysis of many arsenides of electropositive elements (Na, Mg, Zn, etc.). Similar reactions yield stibine, e.g. ... 

Figure 5.20. a Chromatogram of stibine, methylstibine, and dimethylstibine as separated by the OV-3 trap/column with the quartz furnace/AA detector. The stibines were prepared by the NaBH4 reduction of 2 ng Sb each as Sb (III), methylstibonic, and dimethylstibonic acid, b Analysis of a sample of seawater (100 ml) from the open Gulf of Mexico (Station SN4-3-1, 12 March 1981)... 

Reactions of complex hydrides with Sb compounds are effective for stibine syntheses. Metal tetrahydroborate reductions of Sb compounds in both HjO and nonaqueous media occur. Dropwise addition of a basic [Sb(OH) ] -KBH, soln to aqueous acid forms SbHj in 95% yield ... 

Stibine may be prepared by the treatment of metal antimonides with acid, chemical reduction of antimony compounds, and the electrolysis of acid or alkaline solutions using a metallic antimony cathode ... 

In acidic electrolytes containing antimony or arsenic, the evolution of noxious stibine or arsine is possible e.g. during the reduction of As(III) solutions ... 

The reaction between SbPh3 and TiCU in dry benzene initially gives a deep violet solution and ultimately a gummy black solid. It is Ukely that reduction of TiCU has occurred. Although there is a paucity of well-characterized aisine and stibine complexes, a surprisingly large number of patents have dealt with catalyst systems employing these compounds (Table 6) which often contain Lewis acids in addition to Lewis bases. The function of the Lewis acid is often not clearly delineated, but its presence has a pronounced effect on the catalytic activity as does the Lewis base. 

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