Phenylarsonic acids

In a 1500 ml. beaker, provided with a mechanical stirrer, place 46-5 g. (46 5 ml.) of aniline, 101 ml. of concentrated hydrochloric acid and 250 ml. of water, and enough finely crushed ice to make a volume of about 

750 ml. stir vigorously and add slowly (during ca. 20 minutes) a solution of 36-5 g. of sodium nitrite in 125 ml. of water. 

Concurrently with the preparation of the phenyldiazonium chloride solution, prepare a cold suspension of sodium arsenite. Place 250 ml. of water in a 3-litre round-bottomed flask equipped with a mechanical stirrer. Heat the water to boiling, add 125 g. of anhydrous sodium carbonate, and, as soon as the carbonate has dissolved, introduce 62-5 g. of pure arsenious oxide and 3 g. of crystallised copper sulphate with stirring. When all the solids have dissolved, cool the solution with stirring under a stream of tap water until the temperature has fallen to 15°. 

---

The phenylarsonic acid should separate from the cold stirred solution within 10-20 minutes. If separation does not occur (due to the addition of too much acid), add a few drops of dilute aqueous sodium hydroxide and again bring the solution very carefully to the desired pH. 

Arsonic acids, like carboxylic and sulphonic acids (pp. 349, 353), usually give crystalline benzylthiouronium salts. Add just sufficient dilute aqueous sodium hydroxide dropwise with shaking to a suspension of 0 5 g. of phenylarsonic acid in 10 ml. of water to give a clear solution. Then add 0 5 g. of benzylthiouronium chloride dissolved in 10 ml. of water. Filter off the precipitated benzylthiouronium salt, wash with water and dry m.p. 114-117° it tends to dissociate on attempted recrystallisation. 

In the example given below, phenylarsonic acid is reduced to dichlorophenyh arsine, Ccll jAsCl. This compound when added to aqueous sodium hydroxide and treated with benzyl chloride gives benzylphenylarsinic acid, which is readily isolated from solution. 

Required Phenylarsonic acid, 15 g. concentrated hydrochloric acid, 30 ml. sulphur dioxide from a cylinder. 

A) Dichloropheny arsine. Add 15 g. of phenylarsonic acid to 30 ml. of concentrated hydrochloric acid in a 150 ml. rounds... 

Phenylarsonic acid may be obtained from the reaction between phenyl-diazonium chloride and sodium arsenite in the presence of a trace of copper sulphate ... 

Arsenic Peroxides. Arsenic peroxides have not been isolated however, elemental arsenic, and a great variety of arsenic compounds, have been found to be effective catalysts ia the epoxidation of olefins by aqueous hydrogen peroxide. Transient peroxoarsenic compounds are beheved to be iavolved ia these systems. Compounds that act as effective epoxidation catalysts iaclude arsenic trioxide, arsenic pentoxide, arsenious acid, arsenic acid, arsenic trichloride, arsenic oxychloride, triphenyl arsiae, phenylarsonic acid, and the arsenates of sodium, ammonium, and bismuth (56). To avoid having to dispose of the toxic residues of these reactions, the arsenic can be immobi1i2ed on a polystyrene resia (57). 

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 ... 

Subtilisin (from Bacillus subtilis) [9014-01-1 ] [EC 3.4.21.62]. Purified by affinity chromatography using 4-(4-aminophenylazo)phenylarsonic acid complex to activated CH-Sepharose 4B. [Chandraskaren and Dhai Anal Biochem 150 141 7955]. 

Various phenylarsonic acids — especially arsanilic acid, sodium arsanilate, and 3-nitro-4-hydroxyphenylarsonic acid—have been used as feed additives for disease control and for improvement of weight gain in swine and poultry for almost 40 years (NAS 1977). The arsenic is present as As+5... 

Phenylarsonic feed additives for disease control and improvement of weight gain in domestic poultry safe dietary levels Maximum levels in diets, in mg/kg feed, are 50-100 for arsanilic acid, 25-188 for 3-nitro-4-hydroxy-phenylarsonic acid (for chickens and turkeys, not recommended for ducks and geese), and 180-370 for others (NAS 1977)... 

---