The reaction of phenyl acetate with hydroxylamine to form acetohydroxamic acid is catalyzed by nickel (11). Kinetic studies revealed that of the two steps in this process (the first being formation of 0-acetylhydroxylamine and the second its conversion to acetohydroxamic acid), it is the second step that is catalyzed by nickel (11). Formation of a five-membered chelate ring between nickel (11) and 0-acetylhydroxylamine was postulated to account for the catalysis. This hypothesis suggested that acid hydrazides, which are structurally similar to 0-acylhydroxylamines, should also undergo hydroxylaminolysis catalyzed by nickel (11). This predicted catalysis was observed with four acid hydrazides. A spectrophotometric method for acid hydrazides was developed based upon their nickel (11)-catalyzed conversion to hydroxamic acids, followed by treatment with ferric ion to give the colored ferric hydroxamate complex. Isonicotinic acid hydrazide can be determined in the 10-'-10-2 M concentration range in aqueous solutions without interference from isonicotinic acid.
Keyphrases 0 Acid hydrazides-nickel (11)-catalyzed hydroxamic acid formation, ferric hydroxamate colorimetric analysis 0 Nickel (11)-catalyzed hydroxylaminolysis-in spectrophotometric analysis of acid hydrazides 0 Ferric hydroxamate complex formationin spectrophotometric analysis of acid hydrazides I J Colorimetryanalysis, acid hydrazides