Structural studies by 1H and 13C d.n.m.r.: I—barrier to trans-cis isomerization in aliphatic enamino ketones of the type RCOCHCHNHR1

✍ Scribed by E. Czerwińska; Lech Kozerski; J. Boksa

• Publisher: John Wiley and Sons
• Year: 1976
• Tongue: English
• Weight: 557 KB
• Volume: 8
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270080704

✦ Synopsis

Abstract

D.n.m.r. studies have been performed involving the measurement of rates of trans‐cis isomerization of aliphatic enamino ketones of the type RCOCHCHNHR~1~, by means of equilibration experiments and the method of finding the coalescence temperature. Simultaneous observation of the rates of dynamic NH 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.