Synthesis, control of substitution pattern and phase transitions of 2,3-di-O-methylcellulose
Synthesis, control of substitution pattern and phase transitions of 2,3-di-O-methylcellulose
复制标题
DOI：
10.1016/s0008-6215(00)00024-0
复制
发表时间：
2000-05-19
影响因子：
3.1
通讯作者：
Blume, A
中科院分区：
文献类型：
--
作者：
Kern, H;Choi, S;Blume, A
已发现一种改进的非均相方法，用于在纤维素的主要位置上区域选择性地引入三苯甲基和4-甲氧基三苯甲基。用MeI-NaOH在Me_2SO溶液中将6-O-三苯甲基纤维素完全甲基化。然后完全除去三苯甲基，得到2，3-二-O-甲基纤维素，聚合物没有显著降解。H-1和C-13 NMR光谱和降解分析表明，与常规取代模式的偏差小于5%。在最佳反应条件下，可以得到几乎完全规则的纤维素衍生物。取代模式的微小变化对O-甲基纤维素在水中的相变有很强的影响。DSC首次表明，完全的2，3-二-O-甲基纤维素在高温下不发生相分离。(C)2000爱思唯尔科技有限公司版权所有。
An improved heterogeneous procedure has been found for the regioselective introduction of trityl and 4-methoxytrityl groups at the primary positions of cellulose. The 6-O-tritylcelluloses produced were completely methylated by MeI-NaOH in Me2SO solution. The trityl groups were then completely removed to afford 2,3-di-O-methylcellulose without significant degradation of the polymer. H-1 and C-13 NMR spectroscopy and degradation analysis showed less than 5% deviation from the regular substitution pattern. Under optimum reaction conditions, almost perfectly regular cellulose derivatives could be obtained. Small changes in the substitution pattern had a strong effect on the phase transitions of the O-methylcelluloses in water. It was shown by DSC for the first time that perfect 2,3-di-O-methylcellulose does not undergo phase separation at elevated temperatures. (C) 2000 Elsevier Science Ltd. All rights reserved.