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13 C NMR study of the enol forms of β‐diketones
Author(s) -
Shapet'ko N. N.,
Berestova S. S.,
Lukovkin G. M.,
Bogachev Yu. S.
Publication year - 1975
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.1270070507
Subject(s) - tautomer , enol , chemical shift , chemistry , ring (chemistry) , redistribution (election) , hydrogen , carbon fibers , chelation , carbon 13 nmr , keto–enol tautomerism , computational chemistry , medicinal chemistry , stereochemistry , organic chemistry , catalysis , materials science , politics , political science , composite number , law , composite material
Carbon‐13 NMR spectra of a series of β‐diketones in the enol form with various β‐substituents have been studied. An additive influence of the β‐substituents on the chemical shifts of the carbon atoms in the hydrogen bonded chelate ring has been found. It is shown that the α‐ and β‐carbon chemical shifts can be calculated by means of a set of increments for arbitrary combinations of the X and Y substituents. Analysis of the experimental data enables the conclusions to be drawn that enol–enolic tautomerism with different populations of the forms (A) and (B) is absent in β‐diketones and that the carbon chemical shift changes are caused by electron density redistribution in the hydrogen bonded chelate ring (C).