Technische Universität Braunschweig, Institute for Food Chemistry, Schleinitzstr. 20, D-38106 Braunschweig, Germany.
Carbohydr Polym. 2013 Jul 1;96(1):246-52. doi: 10.1016/j.carbpol.2013.03.086. Epub 2013 Apr 2.
Two 3-O-ethyl-3-O-propyl celluloses of similar ethyl and propyl content prepared under different conditions were analyzed with respect to their substituent distribution in the glucosyl units and along the polymer chain by ESI-MS analysis of labeled oligosaccharides. Both samples showed similar regioselectivity of substitution and random distribution of ethyl and propyl groups over the 3-O-positions. The distribution of all types of glucosyl residues identified by monomer analysis was also random over the cellulose molecules. Comparison of the substitution pattern in the glucosyl units with the pattern expected for the observed regioselectivity showed relative high 2-O-alkylation in spite of protecting group strategy, but no corresponding 2,3-di-O-substitution. This is probably the result of partial silyl migration under the alkaline alkylation conditions.
两种 3-O-乙基-3-O-丙基纤维素，其乙基和丙基含量相似，是在不同条件下制备的，通过对标记低聚糖的 ESI-MS 分析，研究了其在葡萄糖单元和聚合物链上的取代基分布。两种样品的取代位置选择性和乙基丙基在 3-O-位的随机分布均相似。单体分析确定的所有类型的葡萄糖基残基在纤维素分子上的分布也是随机的。将糖基单元的取代模式与观察到的位置选择性所预期的模式进行比较，尽管采用了保护基团策略，但仍存在相对较高的 2-O-烷基化，而没有相应的 2,3-二-O-取代。这可能是碱性烷基化条件下部分硅烷基迁移的结果。
