Kono Hiroyuki
Division of Applied Chemistry and Biochemistry, National Institute of Technology, Tomakomai College, Nishikioka 443, Tomakomai, Hokkaido, 059 1275, Japan.
Carbohydr Res. 2017 Jun 5;445:51-60. doi: 10.1016/j.carres.2017.04.004. Epub 2017 Apr 6.
Three samples of ethyl cellulose (EC) with different degrees of substitution (DS)-0.51, 1.41, and 2.28-were prepared by a slurry method using ethyl bromide as the etherification reagent. H-C HSQC and HSQC-TOCSY NMR spectral analysis allowed for complete assignment of the H and C chemical shifts, respectively, of eight anhydroglucose units (AGUs) comprising EC chains-un-, 2-mono-, 3-mono-, 6-mono-, 2,3-di-, 2,6-di-, 3,6-di-, and 2,3,6-tri-substituted AGUs. In addition, the lineshape of the quantitative C NMR spectra of the three EC samples provided change in the mole fractions of these AGUs against DS, making it possible to estimate the reaction mechanism for the production of EC, elucidating reactivities of the hydroxyl groups at the 2, 3, and 6 positions of cellulose and interactions between the substituent groups within the same AGU and vicinal AGUs.
采用溴乙烷作为醚化试剂，通过淤浆法制备了三种不同取代度（DS）的乙基纤维素（EC）样品，其取代度分别为0.51、1.41和2.28。氢碳异核单量子相干（H-C HSQC）和异核单量子相干-全相关谱（HSQC-TOCSY）核磁共振光谱分析分别对构成EC链的八个脱水葡萄糖单元（AGU）——未取代、2-单取代、3-单取代、6-单取代、2,3-二取代、2,6-二取代、3,6-二取代和2,3,6-三取代AGU——的氢和碳化学位移进行了完全归属。此外，这三种EC样品的定量碳核磁共振光谱的线形提供了这些AGU的摩尔分数随取代度的变化情况，从而有可能估算出EC生产的反应机理，阐明纤维素2、3和6位羟基的反应活性以及同一AGU内和相邻AGU内取代基之间的相互作用。
