کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5418309 | 1506987 | 2006 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Theoretical study of the elimination kinetics of several 2-substituted ethyl N,N-dimethylcarbamates in the gas phase, [(CH3)2NCOOCH2CH2Z, Z=CH2Cl, Câ¡CH, Câ¡N]
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The theoretical studies of the gas-phase elimination of 2-substituted ethyl N,N-dimethylcarbamates (Z=CH2Cl, Câ¡CH, Câ¡N) were performed using ab initio MP2/6-31G and MP2/6-31G(d) levels of theory. The gas phase elimination reaction of these carbamates yields N,N-dimethylcarbamic acid and the corresponding substituted olefin in a rate-determining step. The intermediate N,N-dimethylcarbamic acid is unstable and rapidly decomposes through a four-membered cyclic transition state to dimethylamine and CO2 gas. The results of these calculations suggest a mechanism to be concerted, asynchronous, and a six-membered cyclic transition state structure. Plotting the relative theoretical rate coefficients against Taft's Ï* values gave an approximate straight line (Ï*=0.4057, r=0.9894 at 360 °C). The correlation between experimental log krel vs. theoretical log krel. for these 2-substituted ethyl N,N-dimethylcarbamates gave an approximate straight line (r=0.9715 at 360 °C), suggesting the same type of mechanism.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure: THEOCHEM - Volume 770, Issues 1â3, 29 September 2006, Pages 131-137
Journal: Journal of Molecular Structure: THEOCHEM - Volume 770, Issues 1â3, 29 September 2006, Pages 131-137
نویسندگان
Mirna M. Heredia R., M. Loroño, Tania Córdova, Gabriel Chuchani,