微晶纤维素的羧甲基化反应

纤维素通过特殊的化学物理手段处理后，得到的微晶纤维素在有机溶剂中能很好地分散开，且所需要的有机溶剂的量较少。对其反应条件的探索表明，用微晶纤维素来进行羧甲基化反应，碱化和醚化时间较短，且一氯醋酸的利用率较高；用异丙醇作溶剂比乙醇作溶剂反应效果好。产物用1H－NMR研究表明，取代基在2位、3位和6位上的分布较均匀。

Carboxy methylation of microcrystalline cellulose

In order to increase the use ratio of chloroacetic and improve its the distribution of substituted group, MCC is used to be carboxylmethylated. MCC exists in form of white powder after being processed chemically and physicrtlly. So at low ratio of solvent to cellulose being 1: 3~5 mass ratio, it can dispersed and swell quickly in organic solvent. The conditions of reaction (time of alkalization and etherification) were investigated and two kinds of solvent (ethyl alcohol and iso-propanol) were compared. The result demonstrated that tAne of alkalization and etherification was relatively shorter than those of literature. The use ratio of chloroacetic acid is higher. The reactivity is better in iso-propanol than in ethyl a1cohol. It was showed by 1H-NMR that the distribution of substituted groups at different positions on the anhydroglucoce is C2>C6>C3, which indicate that the reactivity order is C2>C6>C3, but distribution between dmerent positions has smaller difference than that of literature has.