Unexpected rate retardation in the formation of phthalic anhydride from N-Methylphthalamic Acid in acidic H2O-CH3CN medium
Document Type
Article
Publication Date
1-1-2005
Abstract
Kinetic study on the cleavage of N-methylphthalamic acid (NMPA) in mixed acidic aqueous-acetonitrile solvent reveals the formation of both phthalic anhydride (PAn) (through O-cyclization) and N-methylphthalimide (NMPT) (through N-cyclization). The formation of NMPT varies from similar to 20% to similar to 3% with the increase in the content of acetonitrile from 2 to 70% v/v. Pseudo first-order rate constants for the formation of PAn are more than 4-fold larger than those for the formation of NMPT at 2% v/v CH3CN in mixed aqueous solvents. Pseudo first-order rate constants for alkaline hydrolysis of NMPT reveal a nonlinear decrease with increase in the content of CH3CN in mixed aqueous solvents.
Keywords
phthalic anhydride, kinetics, hydrolysis, o-cyclization and n-cyclization of n-methylphthalamic acid, intramolecular catalysis, amide hydrolysis, alkaline-hydrolysis, aqueous cleavage, imide formation, mechanism, kinetics, cyclization, hydroxyphthalimide, participation
Divisions
CHEMISTRY
Publication Title
Bulletin of the Korean Chemical Society
Volume
26
Issue
7
Additional Information
Department of Chemistry, Faculty of Science Building, University of Malaya, 50603 Kuala Lumpur, MALAYSIA