کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1197741 | 1492987 | 2007 | 14 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Mechanistic analysis and thermochemical kinetic simulation of the products from pyrolysis of poly(α-methylstyrene), especially the unrecognized role of phenyl shift
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Mechanistic analysis and thermochemical kinetic simulation of the products from pyrolysis of poly(α-methylstyrene), especially the unrecognized role of phenyl shift Mechanistic analysis and thermochemical kinetic simulation of the products from pyrolysis of poly(α-methylstyrene), especially the unrecognized role of phenyl shift](/preview/png/1197741.png)
چکیده انگلیسی
Mechanisms for pyrolysis of poly(α-methylstyrene) must rationalize high selectivity for monomer formation, negligible formation of volatile oligomers, and notably slow decrease in molecular weight compared with the rate of weight loss, i.e., unzipping dominates both back-biting and transfer. Backbone homolysis should form both a tert-benzylic radical Rtb and a prim radical Rp, with formation of the latter potentially supplemented in chain propagation steps emanating from the former. Hence product-forming pathways characteristic of each are expected to compete. Simulations of initial product distributions based on assigned rate constants for chain propagation steps indicate that Rtb is indeed predicted to efficiently unzip with minimal transfer or back-biting. However, Rp is predicted to give comparable amounts of transfer and back-biting with minimal unzipping, behavior inconsistent with experimental data. The proposed escape from this impasse is a previously unrecognized pathway, 1,2-phenyl shift in Rp to form a tert radical. If it undergoes β-scission, the net result is an inter-conversion of Rp to Rtb. Quantitative simulations suggest that this sequence is indeed highly competitive with other reactions of Rp and thus efficiently subverts the otherwise expected propagation of chains emanating from Rp.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Analytical and Applied Pyrolysis - Volume 80, Issue 2, October 2007, Pages 439-452
Journal: Journal of Analytical and Applied Pyrolysis - Volume 80, Issue 2, October 2007, Pages 439-452
نویسندگان
Marvin L. Poutsma,