Phenarsazinic acid

Chloramine-T. On treatment of phenarsazine chloride in cold aqueous alcoholic solution with chloramine-T, phenarsazinic acid is formed (see above). 

Diphenylamine-o-arsinic acid (V), prepared by the condensation of o-bromophenylarsinic acid and aniline, when reduced in alcoholic hydrochloric acid by sulphur dioxide in the presence of iodine, gives lO-chloro-5 10-dihydrophenarsazine, or if boiled with concentrated hydrochloric acid yields the chloride of phenarsazinic acid, which may be reduced to the 10-chloro-compound under suitable conditions. 2-Methyl- and 4-methyldiphenylamine-6 -arsinic acids are also capable of undergoing similar reactions to those just indicated. 

N-Acetylphenarsazinic acid is obtained in theoretical yield by oxidising 10-chloro-5-acetyl-5 10-dihydrophenarsazine. It is insoluble in water, but crystallises from aqueous alcohol in colourless, fiat prisms, M.pt. 244° to 245° C. with decomposition, containing two molecules of water of crystallisation. N-Propionyl- and N-benzoyl-phenarsazinic acids melt at 232° and 250° C., respectively, both decomposing at the melting-iDoint. 

Phenarsazinic acid, or the chloride, is warmed with concentrated nitric acid (density I 4) and the temperature gradually raised to boiling-point. The dinitro-acid has also been obtained by the nitration of the oxide. It separates in bright yellow needles. The sodium salt forms glistening bronze plates from sodium hydroxide solution. This salt is dibasic, but replacement of the hydroxide by sodium carbonate gives a monobasic salt, crystallising in yellow needles. 

The reduction of 3-methyldiphenylamine-6 -arsinic acid by sulphur dioxide in hot alcoholic hydrochloric acitl. solution yields this )roduct, M.pt. 216° to 217° C., obtained as a homogeneous body identical with the reduction product of 3-methyldiphenylamine-C-arsinic acid. The substance also results when arsenious chloride is condensisl with phenyl-m-tolylamine. Oxidation with hydrogen jicroxide or Chloramiue-T gives a product indistinguishable from synthesised 1-methyl- or. 3-metliyl-phenarsazinic acid. The action of concentrated hydrochloric acid on... 

Greschonig et al. used capillary zone electrophoresis to separate phenarsazinic acid 40 and other inorganic and organic compounds in urine <1998FJA218>. 

Bromine. By the action of bromine on phenarsazine chloride in acetic acid solution, a brominated derivative is not obtained. 

Hydrochloric Acid. When phenarsazine chloride is treated with gaseous hydrochloric acid at 160° C. it decomposes, forming arsenic trichloride and diphenylamine as follows ... 

Hydriodic Acid. On treatment with aqueous hydriodic acid on the water-bath, phenarsazine chloride forms diphenylamine as in the previous reaction ... 

Oxidising Agents. Oxidising agents react with phenarsazine chloride, converting the arsenic atom from the trivalent to the pentavalent condition. Hydrogen pearoxide in acetic acid... 

Detection of Phenarsazine Chloride On heating a solution containing phenarsazine chloride with an aqueous solution of hydriodic acid on the water-bath, diphenylamine is formed (see p. 324), which can be distilled off in a current of steam and detected by means of the well-known reaction with nitric acid in sulphuric acid solution. 

Since some of the foregoing diphenylaminearsinic acids are used in the preparation of phenarsazines, dealt with in the following section, the following appear only in that section 4-methyldiphenylamine-6 -arsinic acid (p. 463) 2-methyldiphenylamine-6 -arsinic acid (p. 464) and N-methyldiphenylamine-o-arsinic acid (p. 465). Where compounds appear in botli sections, suitable references hav e been added. 

Phenarsazines containing carboxyl groups are obtainable by the method indicated below. AnthraniUc acid condenses with o-bromo-phenylarsinic acid in boiling nitrobenzene solution in the presence of anhydrous potassium carbonate and a little copper powder, to give 2-carboxydiphenylamine-6 -arsinic add (XXVII) ... 

Phenarsazine oxide crystallises from nitrobenzene or pyridine in colourless plates, which soon become yellow, M.pt. 350° C. It is sparingly soluble in most solvents, and when boiled with alcohols yields ethers, and with phenols, phenyl ethers. Boiling with acetic acid transforms it into 10-acetyl-S lO-dikydrophenarsazine, which occurs in greenish, shimmering plates, M.pt. 228° to 224° C. The corresponding 10-n-butoxy-compound forms pale yellow needles, M.pt. 158° to 160° C., and the lO-hemsyhtxy-denvaiive, colourless needles, M.pt. 178° to 175° C. 

It is sparingly soluble and melts wdth decomposition at 295° to 300° C. When treated with acetic acid, ammonia is evolved and phenarsazine acetate formed, whilst in high-boiling, indifferent solvents, ammonia is split off and phenarsazine formed a sublimate of the latter is also formed if the compound is heated from 200° to 800° C. in high vacuum. 

The nitration of phenarsazine chloride leads to the production of two mononitro-compounds and a dinitro-derivative. The chloride (18 grams) is dissolved in 120 c.c. of boiling acetic acid, the solution 1 Wieland and Bheinlieimer, Joe. eit. 

S-Carboxydiphenylamine-O -arsinic acid is prepared from m-aminobenzoic acid in a similar manner to the 2-carboxy-acid, amyl alcohol replacing nitrobenzene in the condensation mixture. It forms colourless needles, M.pt. 238° to 289° C. lO-Ckloro-5 10-dihydro-phenarsazine-S-earboaylic acid is obtained from it in a similar way to the above, and is a yellow compound, unmelted below 300° C., and very sparingly soluble in organic solvents. 

This acid is obtained by oxidising lO-chloro-l-methyl-5 10-dihydro-phenarsazine in a similar manner to that described for the 3-niethyl isomeride. It crystallises from acetic acid in colourless needles, melting with decomposition at 316° C. The sodium salt crystallises from 20 per cent, sodium hydroxide in fine, colourless needles. The hydrochloride crystallises in fine needles, melting with decomposition and turning emerald-green at 281° to 232° C. 

These two acids have not been distinguished from each other up to the present they are the oxidation products of the two chlorodihydro-phenarsazines (M.pts. 257 to 258 C. and 225 to 226 C.) obtained by the reduction of 3-nitro-4-methyldiphenylamme-6 -arsinic acid. The acids crystallise in minute, yellow needles, unmelted at 297 C. The sodium salts form thin, pale yellow needles, and the barium salts form orange needles. 

Bromination of compounds of the phenarsazine tyj)c (which may Im considered to be derivatives of e-aminophcnylarsimc acid) leads to replacement of the arsenic group by bromine. ... 

Phenarsazine derivatives can be determined spectrophotometrically as the disodium salt of dinitrophenarsazinic acid at 520 nm The sample is dissolved in glacial acetic acid and converted by nitric acid to dinitrophenarsazinic acid. Addition of excess of sodium hydroxide delds a violet disodium salt suitable for photometric evaluation. From 1 to 8 ngjral of phenarsazine can be determined by this method with an error of + 4%. A spectrophotometric method has been described for the determination of 4-hydroxy-3-nitrophenylarsenic acid in animal feeds. ... 

Phenarsazine chloride 1985 traHs-a-Phenylcinnamic acid 8922 Phosphonic acid, (2-chloroethyl)- 4806... 

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