New Substituted Hydroxamic Acid Derivatives as Spectrophotometric Reagents for Niobium (V)

Department of Chemistry, University of Calicut, Caliout Manuscript received 7 July 1970; accepted 10 August 1970 Methyl and halogen substituted derivatives of N-acetylsalicyloyl-N-phenylhydroxylamine (ASPHA.) and N-p-nitrobenaoyl-N-phenylhydroxylamine are synthesised and used for the spectro­photometric determination of niobium (V). These reagents form deep yellow complexes with niobium (V) and thiocyanate in strong hydrochloric acid media which can be extracted into carbon tetrachloride or cnloroform. The complexes absorb strongly around 400 nm and the sensitivities are about 0.005 µg. Nb per mt. A large excess of associated ions including Ta(V) are tolerated