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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 26, Number 7
BKCSDE 26(7)
July 20, 2005 

 
Title
Unexpected Rate Retardation in the Formation of Phthalic Anhydride from N-Methylphthalamic Acid in Acidic H2O-CH3CN Medium
Author
Azhar Ariffin, M. Niyaz Khan*
Keywords
Phthalic anhydride, Kinetics, Hydrolysis, O-Cyclization and N-cyclization of N-methylphthalamic acid
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 ~20% 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.
Page
1037 - 1043
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