ISSN:
0030-4921
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
At room temperature and below, the proton NMR spectrum of N-(trideuteriomethyl)-2-cyanoaziridine consists of two superimposed ABC patterns assignable to two N-invertomers; a single time-averaged ABC pattern is observed at 158.9°C. The static parameters extracted from the spectra in the temperature range from -40.3 to 23.2°C and from the high-temperature spectrum permit the calculation of the thermodynamic quantities ΔH0 = -475±20 cal mol-1 (-1.987 ± 0.084 kJ mol-1) and ΔS0 = 0.43±0.08 cal mol-1 K-1 (1.80±0.33 J mol-1 K-1) for the cis ⇌ trans equilibrium. Bandshape analysis of the spectra broadened by non-mutual three-spin exchange in the temperature range from 39.4-137.8°C yields the activation parameters ΔHtc≠ = 17.52±0.18 kcal mol-1 (73.30±0.75 kJ mol-1), ΔStc≠ = -2.08±0.50 cal mol-1 K-1 (-8.70±2.09 J mol-1 K-1) and ΔGtc≠ (300 K) = 18.14±0.03 kcal mol-1 (75.90±0.13 kJ mol-1) for the trans → cis isomerization. An attempt is made to rationalize the observed entropy data in terms of the principles of statistical thermodynamics.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1270110404
Permalink