Efficient Method for the Preparation of Pure, Water‐Soluble Cellodextrines

Abstract

Summary: An efficient method towards water soluble cellodextrine mixtures is described and detailed information on structure analysis is given. For cellulose degradation in good yield, treatment of cellulose with 85% phosphoric acid for 30 minutes at room temperature and a hydrolysis of 20 hours at 55 8C are suitable. With a work up in tetrahydrofuran (THF), a yield of almost 70% raw product is achievable. After separation of a water insoluble fraction, a yield of 53% of cellodextrines with a degree of polymerization (mean weight average, DP w ) of 7.5 and a polydispersity index of 1.7 is obtained. These cellodextrines are soluble in water, dimethyl sulfoxide (DMSO) and dimethyl acetamide (DMA)/LiCl. Detailed structure analysis by one and two-dimensional NMR, FTIR and mass spectroscopy revealed that the substance consists only of b-1 ! 4 linked glucoses. A partial functionalization was excluded by 13 C NMR-and 31 P decoupled 1 H NMR spectroscopy.

Towards unnatural xylan based polysaccharides: reductive amination as a tool to access highly engineered carbohydrates

“…To remove glucuronic acid residues, the raw material was dissolved in water and sequentially treated with a cation exchange resin IR120 (protonated form), an amberlite IRA 96 anion exchange resin (H-form) and finally freeze dried. Cellodextrins (DP w ¼ 7:4) were obtained after partial hydrolysis of cellulose with H 3 PO 4 and subsequent fractionation according to the procedure described earlier (Liebert et al 2008). All solvents and reagents were obtained from Sigma or Fluka and used without further purification.…”

Tailoring the Degree of Polymerization of Low Molecular Weight Cellulose

“…Previously, cellulose degradation with H 3 PO 4 towards water-soluble cellodextrins has been studied. [15] After hydrolysis at 55 8C, products with a weight-average degree of polymerization (DP w ) of about 15 were isolated. No functionalization with phosphate species was observed.…”

“…This fact can be proved by 31 P-decoupled 1 H NMR spectroscopy. [15] Hydrolysis at temperatures between 25 8C and 55 8C in H 3 PO 4 can yield celluloses with more than 15 repeating units. [16] The reported molecular weights (DP higher than 45) were determined by intrinsic viscosity measurements (copper ethylenediamine complex), a method that is not sensitive enough in the case of low molecular weight celluloses due to its large experimental error at the low relative viscosities of the corresponding solutions.…”

Direct Dissolution of Cellulose: Background, Means and Applications

“…Concentrated mineral acids such as hydrochloric acid, phosphoric acid or mixed acids are utilized as degradation media to prepare cellodextrins, short chained cellulose oligomers [84][85][86][87]. Phosphoric acids, with or without additives such as organic acids as a potent solvent for cellulose was patented already back in 1927 [88].…”