%0 Journal Article
%T Ring-Chain Tautomerism of the Condensation Products of 2-Mercaptobenzohydrazide with Aliphatic and Aromatic Aldehydes: Influence of Electronic and Steric Factors
%A Andrei Yu Ershov
%A Igor V. Lagoda
%A Marina Yu Vasileva
%A Stanislav I. Yakimovich
%A Boris V. Chernitsa
%A Lyudmila Yu Kuleshova
%A Lyudmila V. Pavlova
%A Aleksandr V. Yakimansky
%J Open Access Library Journal
%V 4
%N 5
%P 1-10
%@ 2333-9721
%D 2017
%I Open Access Library
%R 10.4236/oalib.1103584
%X
It has been shown by 1H
and 13C NMR spectroscopy that 2-mercaptobenzoyl-hydrazones of aliphatic
and aromatic aldehydes exist in solution as tautomeric mixtures of linear and
cyclic benzo-1,3,4-thiadiazepine forms. The linear hydrazone form is
represented by (E,E')-and (E,Z')-conformational
isomers, differing in the disposition relative to the amide C¨CN bond. Growing bulk
of the alkyl substituent at the C=N bond of the aliphatic aldehydes derivatives
decreases the fraction of the cyclic tautomer; therewith the logarithms of the
constants of the chain-ring tautomeric equilibrium correlate with the ES steric constants of the
alkyl substituents. In the series of the aromatic aldehydes 2-mercaptobenzoylhydrazones
the linear tautomer prevails, and the logarithms of the tautomeric equilibrium
constants KT correlate
with the ¦Ò-constants
of the substituents in the aromatic nucleus.
%K Hammett and Taft Equations
%K Ring-Chain Tautomerism 2-Mercaptobenzoylhydrazones
%K Benzo-1
%K 3
%K 4-Thiadiazepines
%U http://www.oalib.com/paper/5285188