Spectrophotometric and Titrimetric Determination of Carboxylic Acid Anhydrides

Article abstract of DOI:10.1021/ac00276a041

Two redox methods are described for the determination of carboxylic acid anhydrides involving reaction with either an excess of 4-aminophenol or a measured but excessive amount of sulfanilamide and photometric titration of N-acyl-4-aminophenol with 2-iodylbenzoate by measuring the absorbance of orange-red product at 444 nm or the residual amount of sulfanilamide is determined by titration with chloramine-T in the presence of acidified potassium bromide using methyl red as visual indicator.Mixtures of certain anhydrides have also been analyzed by the 2-iodylbenzoate method.The methods are rapid, precise, and accurate.No correlation is needed if carboxylic and mineral acids are also present.Carboxylic acid chlorides also react quantitatively.