Effects of mixed aqueous-organic solvents on the rate of intramolecular carboxylic group-catalyzed cleavage of N-(4′-methoxyphenyl)phthalamic acid

✍ Scribed by Sim Yoke Leng; Azhar Ariffin; M. Niyaz Khan

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 136 KB
• Volume: 36
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.20003

✦ Synopsis

Abstract

Kinetic study on the cleavage of N‐(4′‐methoxyphenyl)phthalamic acid (NMPPAH) in mixed H~2~O‐CH~3~CN and H~2~O‐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 (k~1~) 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 H~2~O‐CH~3~CN solvents at ≥50% v/v CH~3~CN follows an irreversible consecutive reaction path: NMPPAH PA. The values of k~1~ are larger in H~2~O‐CH~3~CN than in H~2~O‐1,4‐dioxan solvents. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 316–325, 2004