Premium
Kinetic studies of solvent and pressure effects on thermal isomerizations of N ‐phenyl‐ and N ‐methylrhodaminelactams
Author(s) -
Sueishi Yoshimi,
Sugiyama Yukie,
Yamamoto Shunzo,
Nishimura Norio
Publication year - 1993
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610060806
Subject(s) - chemistry , isomerization , heterolysis , solvent , solvent effects , kinetic energy , conformational isomerism , kinetics , thermal , computational chemistry , photochemistry , medicinal chemistry , catalysis , organic chemistry , thermodynamics , molecule , physics , quantum mechanics
Abstract Solvent and pressure effects were examined for the isomerization rates of N ‐phenyl‐ and N ‐methylrhodaminelactams (RL‐Ph and RL‐CH 3 ) from their zwitterionic to the spiro forms. From the pressure dependence of the reaction rate, the activation volumes were estimated to be about 5 cm 3 mol −1 for RL‐Ph and 3–10 cm 3 mol −1 for RL‐CH 3 . It is proposed that there are two rotameric isomers for the coloured zwitterionic forms, and the role of these rotamers in the kinetic effects of solvent and pressure is discussed. The results are consistent with a reaction mechanism involving heterolytic ring closure on activation.