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Reaction of phthaloylasparic anhydride with o ‐phenylenediamine in solution and spectral analysis of the reaction products
Author(s) -
Yang ChinPing
Publication year - 1982
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570190414
Subject(s) - chemistry , acetic anhydride , tetrahydrofuran , methanol , solvent , chloroform , ring (chemistry) , condensation reaction , polymer chemistry , acetic acid , xylene , reaction mechanism , o phenylenediamine , organic chemistry , medicinal chemistry , catalysis , benzene
The ring‐opening addition reaction of phthaloylasparic anhydride (I) with o ‐phenylenediamine (II) in a solution is affected by the polarity of the solvent used. At the molar ratio of 1:1, I and II undergo a β‐oriented ring‐opening reaction in polar solvents, such as DMF, DMAC, and DMSO; while in weaker polar solvents, such as dioxane and tetrahydrofuran, α‐orientation predominates. By heating in a solvent mixture of DMF and xylene, the ring‐opening products undergo condensation, and are converted into two isomers. One is methanol soluble 3‐phthalimido‐3‐(2)benzimidazolylpropanoic acid (V) resulting from the α‐oriented ring‐opening reaction, the other is the sparingly soluble (in DMF) 2‐phthalimido‐3‐(2)benzimidazolylpropanoic acid (VI) resulting from the β‐oriented ring‐opening reaction. The soluble V can be precipitated as cotton‐like crystals from methanol and chloroform. When treated with acetic anhydride, V and VI are converted to other isomers, namely 3‐phthalimidobenzimidazopyrrolone (VII) and 2‐phthalimidobenzimidazopyrrolone (VIII). The isomers were identified by spectral analysis.