Enhanced Spectrophotometry of Sulfonamides with Novel 2‐Acetylbutyrolactone Derivatives

Abstract

2‐Acetylbutyrolactone (ABL) has been characterized as a novel coupling reagent for the spectrophotometric analysis of primary arylamines. 2‐Acetylbutyrolactone is a cyclic β‐keto ester that forms colored α‐oxo‐γ‐butyrolactone arylhydrazones with primary arylamines through the Japp‐Klingemann reaction. The arylhydrazones can be measured spectrophotometrically in alkaline (A532) and acidic solutions (1D349). A similar study on ethyl acetoacetate (EAA), as a coupling carbanion, was carried out. Ethyl acetoacetate is the acyclic β‐keto ester analog of ABL that forms colored azo derivatives with primary arylamines. The azo derivatives can be measured spectrophotometrically in alkaline solution (A416). Four model sulfa drugs namely, sulfadiazine (SD), sulfamethoxazole (SMX), sulfamoxole (SMO), and sulfametrole (SMR), were evaluated throughout the work. The chemistry and the pathway of the reactions of the two β‐keto esters (ABL and EAA) were discussed. Beer's law validation, accuracy, precision, limits of detection, and limits of quantification are presented in the text. The applicability of ABL and EAA was assessed through the analysis of the model drugs in pharmaceutical preparations.