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Study of the self‐association of methylated pyrimidines in aqueous solutions by 1 H NMR chemical shifts
Author(s) -
Aradi Ferenc
Publication year - 1990
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260280310
Subject(s) - chemistry , chemical shift , dimer , aqueous solution , deuterium , molecule , stacking , pyrimidine , computational chemistry , crystallography , stereochemistry , organic chemistry , physics , quantum mechanics
The self‐association of pyrimidine and its methylated derivatives was studied by measuring the concentration‐dependent changes in proton chemical shifts in deuterium oxide at 35°C. The data were analysed by a dimer model with two parameters. The equilibrium constants give an increasing tendency for self‐association within the series pyrimidine (0.091 ° 0.006 l mol −1 ) < 5‐methylpyrimidine (0.165 ° 0.006 l mol −1 ) ≈ 4‐methylpyrimidine (0.183 ± 0.005 l mol −1 ) < 4,6‐dimethylpyrimidine (0.410 ± 0.011 l mol −1 ), and the values of the dimer shifts suggest a stacking‐like arrangement for the associated molecules.