کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5157626 | 1500588 | 2017 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Polysaccharide depolymerization from TEMPO-catalysis: Effect of TEMPO concentration
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Polysaccharide TEMPO-oxidation was monitored using automatic continuous online monitoring of polymerization reactions (ACOMP). The products of oxidation, obtained at different pHs (9, 7 and 5) and different concentrations of catalyst TEMPO, were evaluated by Automatic Continuous Mixing (ACM) and Size Exclusion Chromatography (SEC). The degree of oxidation was higher at pH 9 and polysaccharide degradation was observed under different pH conditions, but was much higher without catalyst TEMPO. The rate constant (k) was dependent on reaction pH and TEMPO concentration. The amount of âCOOH per g of polysaccharide, at pH 9, in the presence and absence of TEMPO was different, 0.215 and 0.395 mmol gâ1, respectively. This suggested a secondary and non-selective polysaccharide oxidation occurring at a lower rate in the absence of catalyst. TEMPO protects the polysaccharide from degradation caused by secondary oxidant species, acting as a catalyst and “sacrificial molecule” at higher concentrations.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Carbohydrate Polymers - Volume 170, 15 August 2017, Pages 140-147
Journal: Carbohydrate Polymers - Volume 170, 15 August 2017, Pages 140-147
نویسندگان
Vivian C. Spier, Maria Rita Sierakowski, Wayne F. Reed, Rilton A. de Freitas,