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13 C n.m.r. spectra of 2‐substituted pyrimidines
Author(s) -
Turner Christopher J.,
Cheeseman Gordon W. H.
Publication year - 1976
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270080707
Subject(s) - electronegativity , chemistry , proton , coupling constant , chemical shift , pyridine , benzene , ion , spectral line , carbon fibers , carbon 13 , pyrimidine , crystallography , computational chemistry , stereochemistry , medicinal chemistry , organic chemistry , materials science , physics , particle physics , quantum mechanics , astronomy , composite number , composite material
13 C n.m.r. chemical shifts and carbon‐proton coupling constants of 2‐substituted pyrimidines are reported. The carbon chemical shifts are correlated with π‐electron densities. Substituents which cause deshielding at the directly bound carbon (e.g. NH 2 , OCH 3 and F) exert a more powerful effect in the benzene series than in the pyridine or pyrimidine series. The carbon‐proton coupling constants do not correlate with the electronegativity of the substituents. Carbon‐proton coupling constants and proton‐proton coupling constants over the same number of bonds do not obey the Karabatsos relationship. The changes in the carbon‐proton coupling constants in 2( 1H )‐pyrimidinone and 2( 1H )‐pyrimidinethione which accompany anion and cation formation are reported.