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Tautomerism and Dimerization of Acetamidothiazole Derivatives − UV/Vis and NMR Spectroscopic Investigation
Author(s) -
Forlani Luciano,
Mezzina Elisabetta,
Boga Carla,
Forconi Marcello
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200107)2001:14<2779::aid-ejoc2779>3.0.co;2-n
Subject(s) - tautomer , chemistry , dichloromethane , carbon tetrachloride , carbon 13 nmr , proton nmr , chemical shift , computational chemistry , nuclear magnetic resonance spectroscopy , stereochemistry , organic chemistry , solvent
Amido ( A )/imido ( B ) tautomerism has been investigated by UV/Vis and NMR spectroscopic methods for a number of 2‐acetamidothiazoles and 2‐acetamidobenzothiazoles, without the use of the physical properties of “fixed parents”. The addition of polar substances to solutions of selected compounds in apolar solvents (carbon tetrachloride, dichloromethane) strongly affects the [ B ]/[ A ] ratios. Data show that the shift of the tautomeric equilibrium A / B towards the B form has two main causes: (i) increase of the polarity of the medium, and (ii) a base effect on the stabilization of the B form. The experimental Δ H and Δ S values indicate (in agreement with 1 H NMR spectroscopic data) that the self‐assembly of 2‐acetamido derivatives is a very important factor in determining the position of the tautomeric equilibrium.