The effect of sodium chloride concentration on the mutarotation and structure of d-xylose in water: Experimental and theoretical investigation.

ABSTRACT

The effect of NaCl concentration on the structure of d-xylose in H2O was studied. It was found that NaCl could prolong the equilibrium time between the two main configurations, α-xylopyranose and ß-xylopyranose. The proportion of α-xylopyranose was slightly increased in NaCl-H2O solution than that in H2O, and the alteration of NaCl on α-xylopyranose and ß-xylopyranose was different. Theoretical calculations demonstrated that NaCl was more favorable to stabilize the structure of α-xylopyranose. Na+ had attraction with O atoms (α O6; ß O6 and O1), with the outflow of electron from C atom to O atom on the C1-O6 bond, which was beneficial to the transformation between chain form and pyran forms. Cl- had interaction with the hydroxyl groups of xylose. The interaction between xylose and NaCl, was also evidenced by the variation of 35Cl and 23Na NMR spectra. The findings could provide guidance for understanding the conformational change and design of xylose conversion ways. It also provided valuable information for making efficient use of hemicellulose.