کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5265602 | 1385289 | 2012 | 4 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Non-steady state intermediates: a re-examination of the kinetics of hydrolysis of N-methylisobutylidene and N-isopropylethylidene under acidic conditions
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Direct measurement by stopped flow and UV-vis spectroscopy of the decay of two protonated imines, N-methylisobutylidene and N-isopropylethylidene, below a pH 3 resulted in a biphasic kinetic profile involving a rapid decay of the iminium ion to a carbinolamine intermediate. Previously published hydrolysis studies on N-methylisobutylidene did not report observation of non-first order kinetics. Spectroscopic evidence of the carbinolamine intermediate of N-methylisobutylidene was observed by 1H NMR. The rate constants for the pH independent step, k1, were similar for both compounds, 0.94 sâ1 for N-methylisobutylidene versus 0.87 sâ1 for N-isopropylethylidene. Following k1, the rate constants, kâ1 and k±Ka(OH) differed by a factor of approximately 3 with the carbinolamine intermediate of N-isopropylethylidene being more stable over the carbinolamine of N-methylisobutylidene. An in-depth examination of the rate constants is presented.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Tetrahedron Letters - Volume 53, Issue 46, 14 November 2012, Pages 6250-6253
Journal: Tetrahedron Letters - Volume 53, Issue 46, 14 November 2012, Pages 6250-6253
نویسندگان
Daniel P. Predecki,