Abstract: | Kinetic study on the cleavage of N‐(4′‐methoxyphenyl)phthalamic acid (NMPPAH) in mixed H2O‐CH3CN and H2O‐1,4‐dioxan solvents containing 0.05 M HCl reveals the formation of phthalic anhydride (PAn)/phthalic acid (PA) as the sole or major product. Pseudo first‐order rate constants (k1) for the conversion of NMPPAH to PAn decrease nonlinearly from 60.4 × 10?5 to 2.64 × 10?5 s?1 with the increase in the contents of 1,4‐dioxan from 10 to 80% v/v in mixed aqueous solvents. The rate of cleavage of NMPPAH in mixed H2O‐CH3CN solvents at ≥50% v/v CH3CN follows an irreversible consecutive reaction path: NMPPAH PA. The values of k1 are larger in H2O‐CH3CN than in H2O‐1,4‐dioxan solvents. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 316–325, 2004 |