フェニルアルソン酸

解説benzenearsonic acid．C6H7AsO3(202.04)．フェニルアルソン酸, 塩化ベンゼンジアゾニウムと三塩化ヒ素とから得られるテトラクロロ(フェニル)アルソランを加水分解すると合成される．無色の柱状晶．分解点158 ℃．pKa1 3.47，pKa2 8.48(水)．水，エタノールに可溶，エーテルに不溶．亜鉛アマルガムと酸により還元されてフェニルアルシンになる．チタン，ジルコニウムなどの金属イオンと錯体を形成するので，分析用試薬として用いられる．森北出版「化学辞典（第2版）

用途Zr, Sn, Th, Nb, Ta, Biの分析試薬、有機合成原料。

使用Arsonic acids (arsonic acid, phenylarsonic acid, p-hydroxyphenylarsonic acid, arsanilic acid) react with the tetravalent metals of group IV of the periodic system to give water-insoluble complexes of composition MA2 . The composition of the precipitates is not exactly stoichiometric, and hence the precipitates are not suitable for direct gravimetric analysis. Instead, the precipitates are transformed by ignition to the corresponding metal oxides and weighed as such. The main advantage of the application of these reagents is the possibility offered of the selective determination of zirconium(IV), hafnium(IV) and titanium(IV) in the presence of many other metals, such as zinc, manganese, nickel, cobalt, aluminium, copper, calcium, magnesium and chromium. In practice they are utilized most frequently for the determination of zirconium. In strong mineral acidic media phenylarsonic acid forms water-insoluble precipitates with zirconium and hafnium only. In highly concentrated acetic acid solution the thorium phenylarsonate complex is also precipitated, which makes possible the separation of thorium from rare earth metals. The procedure gives satisfactory results in the presence of alkaline earth metals, iron, aluminium, manganese, cobalt, nickel, copper, zinc and bismuth.

一般的な説明Colorless solid. Used as an analytical reagent for tin.

純化方法Crystallise it from H2O (3mL/g) between 90o and 0o. Alternatively dissolve 600g of the acid in 500mL of boiling H2O, add 20g of Norite, filter hot, cool, filter off the crystals and dry them. On heating at ~154-160o it is converted to the anhydride. [Bullard & Dickery Org Synth Coll Vol II 494 1943, for the 4-nitro derivative see Ruddy & Starkey Org Synth Coll Vol III 665 1955, Beilstein 16 H 868, 16 I 448, 16 II 457, 16 III 1057, 16 IV 1183.]