کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5419409 | 1506988 | 2006 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Theoretical study of the gas phase unimolecular elimination kinetics of 2-substituted electron-withdrawing groups of ethyl N,N-dimethylcarbamates
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The gas-phase elimination of ethyl N,N-dimethylcarbamates substituted with electron-withdrawing groups at the 2-position of the ethyl were studied by using the Møller-Plesset MP2/6-31G method. Calculations suggest a concerted non-synchronous six-membered cyclic transition state type of mechanism of the above-mentioned carbamates. These substrates undergo thermal elimination to produce the N,N-dimethylcarbamic acid and the corresponding substituted olefin in the rate-determining step. The unstable intermediate, N,N-dimethylcarbamic acid rapidly decomposes through a four-membered cyclic transition state to dimethylamine and CO2 gas. The logarithm of relative theoretical rate coefficients when plotted against original Taft's Ï* values gave an approximate straight line (Ï*=â0.137±0.023, r=0.9610 at 360 °C). In addition to this fact, plotting experimental log krel. against the theoretical log krel. for 2-substituted ethyl N,N-dimethylcarbamates an approximate straight line (r=0.9578 at 360 °C) is obtained, which means similar mechanism.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure: THEOCHEM - Volume 769, Issues 1â3, 14 September 2006, Pages 193-199
Journal: Journal of Molecular Structure: THEOCHEM - Volume 769, Issues 1â3, 14 September 2006, Pages 193-199
نویسندگان
Argenis J. Ruiz C, Marcos Loroño, Tania Córdova, Gabriel Chuchani,