亜硝酸コバルチナトリウム(ヘキサニトロコバルト(Ⅲ)酸ナトリウム)

外観

黄赤色〜赤褐色, 粉末

溶解性

水に易溶, エタノールに難溶。水に極めて溶けやすく、エタノールに溶けにくい。

化学的特性

SODIUM COBALTINITRITE is deep yellow to brown crystalline powder

使用

SODIUM COBALTINITRITE is used in the detection Potassium.

製造方法

Sodiumhexanitrocobaltate(III) ("sodiumcobaltinitrite") Na3Co(N02)6 is a well-known orange solid which precipitates potassium ions from aqueous solution as K3Co(NO2)6. It is prepared by blowing air through a mixture of cobalt(II) nitrate and sodium nitrite solutions in the presence of acetic acid:
2[Co(H20)6]²⁺ +12NO₂^- +2CH3COOH + 1/2O2 → 2[Co(NO)2)6]^3- +2CH3COO^-+ 13H2O
after filtration of any precipitated potassium or ammonium salts, the sodium salt is precipitated by the addition of ethanol.

純化方法

Dissolve the salt (ca 60g) in H2O (300mL), filter to obtain a clear solution, add 96% EtOH (250mL) with vigorous stirring. Allow the precipitate to settle for 2hours, filter it off, wash it with EtOH (4 x 25mL), twice with Et2O and dry it in air [Glemser in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol II p 1541 1965]. It forms yellow to brown crystals which are very soluble in H2O, are decomposed by acid and form an insoluble K salt. Used for estimating potassium.