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Effects of mixed aqueous‐organic solvents on the rate of intramolecular carboxylic group‐catalyzed cleavage of N ‐(4′‐methoxyphenyl)phthalamic acid
Author(s) -
Leng Sim Yoke,
Ariffin Azhar,
Khan M. Niyaz
Publication year - 2004
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20003
Subject(s) - chemistry , phthalic anhydride , phthalic acid , aqueous solution , cleavage (geology) , intramolecular force , reaction rate constant , catalysis , medicinal chemistry , carboxylic acid , kinetics , stereochemistry , organic chemistry , physics , geotechnical engineering , quantum mechanics , fracture (geology) , engineering
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