Micro- and ultramicrodetermination of the formyl and isonitrile groups in the presence of other acyl groups

Gravimetric and colorimetric micromethods for determination of formyl and isonitrile groups are reported. The gravimetric method is based on a quantitative cleavage of the formyl group and decomposition of formed formic acid to carbon monoxide by means of 60% sulfuric acid. Carbon monoxide is oxidized and the formed carbon dioxide is determined gravimetrically.The colorimetric ultramicromethod is based on the basic hydrolysis of the formyl group. After acidifying the hydrolysate, the quantitatively formed formic acid is distilled under special conditions. The acid is then reduced to formaldehyde. Its quantity is determined spectrophotometrically with chromotropic acid.