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13 C‐NMR Spectra of 2‐ and 3‐Phthalimido‐3(2)‐Benzimidazolylpropanoic Acid and 2‐ and 3‐Phthalimidobenzimidazopyrrolone, Reaction Products of Phthaloylaspartic Anhydride with Ortho‐Phenylenediamine
Author(s) -
Yang ChinPing
Publication year - 1986
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.198600021
Subject(s) - chemistry , methylene , benzimidazole , chemical shift , carbon fibers , nmr spectra database , carbon 13 nmr , medicinal chemistry , carbon 13 , organic chemistry , stereochemistry , spectral line , materials science , physics , quantum mechanics , astronomy , composite number , composite material
Two pairs of isomers of 3‐ and 2‐phthalimido‐3(2)benzimidazolylpropanoic acid (V and VI) and 2‐ and 3‐phthalimidobenzimidazopyrrolone (VII and VIII) were produced from the reaction of phthaloylaspartic anhydride ( I ) with o ‐phenylenediamine (II). The 13 C‐NMR spectra of V and VI both showed 11 carbon signals indicating that the structures of their benzimidazole groups were symmetric. Isomers V and VI were easily distinguished from each other by the chemical‐shift‐differences (Δδ) of the methylene carbon and the methine carbon. Compounds VII and VIII displayed 14 carbon signals and no longer showed the symmetric structure of the benzimidazole moity, The chemical‐shift‐differences (Δδ) between methylene carbon and methine carbon in pyrrolones of VII and VIII can also be used to distinguish VII from VIII. The Δδ of compound VII is less than that of compound VIII.