Ren Jun-Li, Peng Feng, Sun Run-Cang
South China University of Technology, Guangzhou, China.
J Agric Food Chem. 2008 Dec 10;56(23):11209-16. doi: 10.1021/jf802538f.
Wheat straw hemicelluloses were converted to novel bifunctional hemicellulosic derivatives by etherification using acrylamide as reactant and sodium hydroxide as catalyst. The degree of substitution can be monitored by altering the molar ratio of acrylamide to xylose unit in hemicelluloses in the range of 1.0-10.0 and the molar ratio of sodium hydroxide to xylose unit in hemicelluloses in the range of 0.5-1.6, without changing the structure of the hemicelluloses. Comparison of the reaction in different media is discussed in detail. The optimized product with a high DS value of 0.58 was obtained by varying the condition parameters. Novel hemicellulosic derivatives containing carbamoylethyl and carboxyethyl groups could be confirmed by FT-IR, (1)H NMR, and (13)C NMR spectroscopies. The behavior of hemicellulosic derivatives was monitored by means of thermogravimetry (TG) and differential thermal analysis (TGA). It was found that the product with a high DS had a lower thermal stability than the native hemicelluloses.
以丙烯酰胺为反应物、氢氧化钠为催化剂，通过醚化反应将麦秸半纤维素转化为新型双功能半纤维素衍生物。通过改变半纤维素中丙烯酰胺与木糖单元的摩尔比（范围为1.0 - 10.0）以及半纤维素中氢氧化钠与木糖单元的摩尔比（范围为0.5 - 1.6），可以在不改变半纤维素结构的情况下监测取代度。详细讨论了在不同介质中的反应比较。通过改变条件参数，获得了取代度（DS）值高达0.58的优化产物。含有氨甲酰乙基和羧乙基基团的新型半纤维素衍生物可以通过傅里叶变换红外光谱（FT - IR）、核磁共振氢谱（¹H NMR）和核磁共振碳谱（¹³C NMR）进行确认。通过热重分析（TG）和差示热分析（TGA）对半纤维素衍生物的行为进行了监测。结果发现，取代度高的产物热稳定性低于天然半纤维素。
