Characterisation of regioselectively functionalized 2,3-O-carboxymethyl cellulose by enzymatic and chemical methods
Characterisation of regioselectively functionalized 2,3-O-carboxymethyl cellulose by enzymatic and chemical methods
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通过酶法和化学方法表征区域选择性功能化 2,3-O-羧甲基纤维素
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
J. Puls
中科院分区：
文献类型：
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作者：
U. Heinze;J. Schaller;T. Heinze;S. Horner;B. Saake;J. Puls
采用酶法和化学方法对6-O-(4-单甲氧基)三苯基甲基纤维素制备的2,3-O-羧甲基纤维素(2,3-O-CMC)的分子结构进行了详细测定。 SEC 显示，2,3-O-CMC 的取代度 (DS) 在 0.5-1.2 范围内，显示出窄摩尔质量分布。内切葡聚糖酶处理的结果是，样品发生了强烈的解聚，对于 DS 相对较低的 2,3-O-CMC 来说，这种解聚更为明显。所有降解的样品均可通过制备型 SEC 分成 18 个级分，并在完全水解链降解后通过阴离子交换色谱 (AEC) 分析每个重复单元的比例。结果表明聚合物链内官能团的均匀分布。此外，很明显，与O-3相比，O-2发生了优选的羧甲基化，并且随着反应的进行，已经羧甲基化的单元发生了优选的官能化。具有脉冲电流检测的 AEC 用于分离和分析不同功能化的重复单元以及葡萄糖，必须进行校准。因此，开发了一种使用解聚 2,3-O-CMC 的 13C NMR 光谱测量（反向门控去耦）来确定各个羧甲基化葡萄糖单元的响应因子的方法。
The determination of the molecular structure of 2,3-O-carboxymethyl cellulose (2,3-O-CMC), prepared via 6-O-(4-monomethoxy)triphenylmethyl cellulose, was carried out in detail by means of enzymatic and chemical methods. The 2,3-O-CMCs had degrees of substitution (DS) in the range of 0.5–1.2 showing a narrow molar mass distribution as revealed by SEC. As a result of an endoglucanase treatment, an intensive depolymerization of the samples occurred which was more pronounced for 2,3-O-CMC with comparatively low DS. All degraded samples could be separated into 18 fractions by preparative SEC and the proportion of each individual repeat unit was analysed by anion exchange chromatography (AEC) following complete hydrolytic chain degradation. The results indicated a homogeneous distribution of the functional groups within the polymer chain. Moreover, it became obvious that a preferred carboxymethylation of O-2 compared with O-3 occurred and that a preferred functionalization of already carboxymethylated units occurred as the reaction progressed. AEC with pulsed amperometric detection, which was used to separate and analyse the differently functionalized repeating units as well as glucose, had to be calibrated. Therefore, a method to determine the response factors of the individual carboxymethylated glucose units was developed using 13C NMR spectroscopic measurements (inverse gated decoupling) of depolymerised 2,3-O-CMC.