Effects of mixed H2O-CH3CN solvents on the rate of hydrazinolysis of N-phenylphthalimide: Spectral and kinetic evidence for the occurrence of N-aminophthalimide on the reaction path

Article abstract of DOI:10.1002/kin.20057

Kinetic study on the cleavage of N-phenylphthalimide (NPhPT) in the presence of 0.05 M NH₂NH₂ and mixed H₂O-CH ₃CN solvents reveals the occurrence of reaction scheme B ← A → C →^-An C₁↑^E → F where A, B, C, C₁, An, E, and F represent NPhPT, 0-CO₂ ^-C₆H₄CONHC₆H₅, 0-CONHNH₂C₆H₄-CONHC₆H₅, N-aminophthalimide, aniline, 0-CO₂^-C₆H ₄CONHNH₂, and 0-CONHNH₂C₆H ₄-CONHNH₂, respectively. But, in the presence of either nonbuffered ≥0.20 M NH₂NH₂ or hydrazine buffer of pH～7.30-8.26 with total buffer concentration ([Buf]_T) of > 0.02 M, further conversion of F to 2,3-dihydrophthalazine-1,4-dione (DHPD) has been detected depending upon the length of the reaction time (t), the values of [Buf]_T, and pH. It has been shown that the rate of conversion of C₁ to F is much faster than that of C to C₁ which is much faster than that of F to DHPD. The reaction step A → C involves general base (GB) catalysis, while step C → C₁ seems to involve specific base-general acid (GA) and GB-GB catalysis.