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Kinetic study of a homodienyl‐[1,5]‐hydrogen shift in a vinylzaziridine
Author(s) -
Hussénius Anita,
Somfai Peter,
Tanner David
Publication year - 1996
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/(sici)1099-1395(199609)9:9<623::aid-poc826>3.0.co;2-0
Subject(s) - chemistry , reaction rate constant , solvent , activation energy , atmospheric temperature range , hydrogen , imine , photochemistry , solvent effects , polarity (international relations) , spectroscopy , medicinal chemistry , organic chemistry , catalysis , kinetics , thermodynamics , biochemistry , physics , quantum mechanics , cell
The thermal rearrangement of an N ‐substituted vinylaziridine to the corresponding ( Z )‐allylic imine, i.e. a homodienyl‐[1,5]‐hydrogen shift, was studied at different temperatures in the range 40–90 °C. 1 H NMR spectroscopy was used to follow the reaction. Rate constants and activation parameters were determined in solvents that differ in polarity, namely 1,4‐dimethylbenzene, 1,2‐dichlorobenzene and dimethylformamide (DMF). The activation enthalpies and entropies obtained clearly indicate that the solvent polarity has little influence on the rearrangement, since these values are almost the same in the three solvents used. The low Δ H ≠ values (89, 84 and 91 kJ mol −1 , respectively) are consistent with a concerted mechanism, while the activation entropies are all small and negative, which is also supportive of a cyclic transition state. The rate constant is slightly higher in the most polar of the solvents used, DMF.