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Structural studies by 1 H and 13 C d.n.m.r.: I —barrier to trans ‐ cis isomerization in aliphatic enamino ketones of the type RCOCHCHNHR 1
Author(s) -
Czerwińska E.,
Kozerski Lech,
Boksa J.
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.1270080704
Subject(s) - isomerization , chemistry , solvent , coalescence (physics) , proton , transition state , computational chemistry , photochemistry , organic chemistry , catalysis , physics , quantum mechanics , astrobiology
D.n.m.r. studies have been performed involving the measurement of rates of trans ‐ cis isomerization of aliphatic enamino ketones of the type RCOCHCHNHR 1 , by means of equilibration experiments and the method of finding the coalescence temperature. Simultaneous observation of the rates of dynamic NH proton exchange and isomerization processes by the latter method has facilitated the assignment of the rate‐determining reaction step in the title compounds studied in aprotic solvents. Thermodynamic parameters are discussed and the dipolar transition state to isomerization in a nonpolar solvent indicated. The dynamic behaviour of all protons undergoing exchange between the possible sites in the molecule are discussed in the light of our own experiments and other recent data.