Phenylarsonic acid preparation

A number of substituted phenylarsonic acids have been prepared by means of the Bart reaction (121). For the preparation of arsinic acids a sodium arylarsonite is used, and mixed diaryl or alkylarylarsinic acids can be prepared ... 

Sodium carbonate is often employed as a buffering agent in the ordinary Bart reaction. In this way phenylarsonic acid has been prepared in yields ranging from 50-60% 7 to as high as 86% 8 as compared with yields of 40-50% by the original process. The yield from benzenediazonium chloride and sodium arsenite is greatly influenced by the concentration of the arsenite, the speed of reaction, and especially by the pH of the solution (which should remain constant). All compounds, like sodium carbonate, which play the role of buffer, tend to increase the yield.9... 

The preparation of phenylarsonic acid, which proceeds in an average yield of 45-55%, must of necessity serve as the basis for comparison of yields from substituted amines. The following discussion deals primarily with reactions taking place in neutral or alkaline solution practically all the yields reported in this discussion are by either the original Bart process or by Schmidt s modification, the few exceptions being noted. 

Alkoxyl Groups. Simple alkoxyl substituted phenylarsonic acids may be synthesized from the corresponding amines without difficulty, o-Methoxyphenylarsonic acid may be prepared in 58% yield, and a nearly quantitative yield of p-ethoxyphenylarsonic acid is obtained from p-phenetidine.14 The favorable influence of a p-alkoxyl group is further illustrated by the preparation of 3-hydroxy-4-methoxyphenylarsonic acid in a 26% yield.89 As previously mentioned, ra-hydroxyphenylar-sonic acid could not be prepared from m-aminophenol o- and m-j3-hy-... 

Carboxyl Groups. Yields of 50-60% of o- and p-carboxyphenylarsonic acids have been reported,42- 43 and the meta isomer has been prepared but no yield was given.14. With negative substituents in the ortho and para positions the reaction is usually improved. 2-Carboxy-4-nitro-phenylarsonic acid has been prepared in a 76% yield.44... 

The phenylarsenous oxide solution is most conveniently prepared from phenyl-dichloroarsine, which is readily available from phenylarsonic acid. Crude phenylarsonic aoid (404 g., 2 moles) is dissolved in concentrated hydrochlorio aoid (700 cc.) and treated with a stream of sulfur dioxide. From time to time a trace of potassium iodide solution is added (0.2-0.5 g. of potassium iodide is usually sufficient to complete the reduction). When the hydrochloric acid solution becomes clear and the addition of more potassium iodide does not form a permanent cloudiness the reaction is complete. Two to three hours is usually required for this reaction. The crude phenyldichloroarsine separates as a heavy oil. The oil is removed, dried with calcium chloride, and fractionally distilled at reduced pressure in a stream of carbon dioxide or nitrogen. The nearly colorless product boiling at 140-143°/40 mm. is collected it weighs 334-400 g. (75-90%), depending on the purity of the original phenylarsonic acid. 

The compounds of type XIX have been prepared by the condensation reaction of phenylarsonic acid or by ester interchange of methyltetra-methoxyarsorane with the corresponding amine (128,204). The crystal... 

The reagent is prepared by dissolving 01 g of p-dimethylaminobenzene-azo-phenylarsonic acid in 5 ml concentrated hydrochloric acid and 100 ml ethanol. 

Sulfo and Sulfamido Groups. It has been shown that sulfanilic acid can be converted into p-sulfophenylarsonic acid (25-45%). By the ordinary Bart reaction p-sulfamidophenylatsonic acid (25%) may be prepared, although a better yield (57%) is obtained by a modified Scheller reaction. Apparently, metanilic acid and naphthionic acid will not yield the correspQnding arsonic acids. Although w-sulfamido-phenylarsonic acid is not available by the usual procedure it can be prepared in a 58% yield by the method of Scheller. ... 

We purified the methanol extract by preparative HPLC (the area from 22 to 35 min. was collected, Figure 1) and lyophilized the extract before dissolving in benzene. To this solution was added excess 3-methylcatechol and the reaction mixture was refluxed for 5 h and worked up to remove the excess 3-methylcatechol. A concentrated sample was subjected to GC-EIMS analysis to provide spectra and scan numbers (retention times) that were identical to the known samples of the 3-methylcatecholates of both methyl- and phenylarsonic acids. 

Haloarsoranes. Halides of the types RAsX R AsX R AsX, and R4AsX are known. The R4AsX compounds are ionic in nature and are discussed under arsonium salts. The tetrahalides are unstable compounds which frequently decompose on standing and are readily hydrolyzed in moist air to form arsonic acids. Aryltetrachloroarsoranes are readily prepared from aryldichloroarsines in an atmosphere of dry chlorine (142). Tetrafluorophenylarsorane [650-44-2], C6H5AsF4, has been prepared from phenylarsonic acid and sulfur tetrafluofide (143) ... 

The Preparation of Compounds XXI, Phenylarsonic acid was prepared by Mr. David Brown by the Bart reaction. ... 

Twenty-seven simple substances containing the phenylarsonic acid group as haptenic group were prepared and used in precipitin tests with antisera made by injecting rabbits with azo-phenylarsonic acid sheep serum. 

Preparation.—The substances R R and R have already been described, and X X and X are described in a paper to be published soon. The substance R X was prepared by diazotizing 1.3 g. (0.0038 mole) of -( -aminophenyl-azo)-phenylarsonic acid, removing excess nitrite with urea, and coupling with 1.35 g. (0.0040 mole) of recrystallized H-acid in acetate buffer. The intermediate red compound was precipitated by addition NHjOH of hydrochloric acid and washed... 

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