Holding Ashley J, Mäkelä Valtteri, Tolonen Lasse, Sixta Herbert, Kilpeläinen Ilkka, King Alistair W T
Laboratory of Organic Chemistry, Department of Chemistry, University of Helsinki, A.I. Virtasen aukio 1 (Chemicum), PL 55, 00014 University of, Helsinki, Finland.
Department of Forest Products Technology, School of Chemical Technology, Aalto University, P.O. Box 11000, 00076, Aalto, Finland.
ChemSusChem. 2016 Apr 21;9(8):880-92. doi: 10.1002/cssc.201501511. Epub 2016 Mar 24.
High-molecular-weight celluloses (which even include bacterial cellulose) can be dissolved fully in methyltrioctylphosphonium acetate/[D6 ]DMSO solutions to allow the measurement of resonance-overlap-free 1 D and 2 D NMR spectra. This is achieved by a simple and non-destructive dissolution method, without solvent suppression, pre-treatment or deuteration of the ionic component. We studied a range of cellulose samples by using various NMR experiments to make an a priori assignment of the cellulose resonances. Chain-end resonances are also visible in the (1) H NMR spectrum. This allows the rough determination of the degree of polymerisation (DP) of a sample for low-DP celluloses by the integration of non-reducing chain ends C1 versus polymeric cellobiose C1. Low-DP celluloses show a good agreement with the gel-permeation chromatography (GPC) values, but high-DP pulps show more deviation. For high-purity pulps (pre-hydrolysis kraft and sulfite), residual xyloses and mannoses can also be identified from the (1) H-(13) C heteronuclear single-quantum coherence (HSQC) spectra. Resonances are thus assigned for the common polymeric polysaccharides found in chemical pulps.
高分子量纤维素（甚至包括细菌纤维素）可完全溶解于乙酸甲基三辛基鏻/[D6]DMSO溶液中，从而能够测量无共振重叠的一维和二维核磁共振谱。这是通过一种简单且无损的溶解方法实现的，无需对离子成分进行溶剂抑制、预处理或氘代。我们通过各种核磁共振实验研究了一系列纤维素样品，以便对纤维素共振进行先验归属。链端共振在氢核磁共振谱中也可见。这使得通过对非还原链端C1与聚合纤维二糖C1进行积分，能够粗略测定低聚合度纤维素样品的聚合度（DP）。低聚合度纤维素与凝胶渗透色谱（GPC）值吻合良好，但高聚合度纸浆的偏差较大。对于高纯度纸浆（预水解硫酸盐浆和亚硫酸盐浆），还可从氢-碳异核单量子相干（HSQC）谱中鉴定出残留的木糖和甘露糖。因此，为化学纸浆中常见的聚合多糖确定了共振峰。
