Abstract:

Acetylated schizophyllan(Ac·SPG)at milligram level with diferent degree of substitution(DS)was synthesized with dimethyl sulfoxide as the solvent in pyridine·acetic anhydride system.The spectral characters of the samples before and after the acetylation were then analyzed.The infrared spectrum of Ac.SPG reveals tlle C﹦O stretching vibration of ester bond in the range of 1735～1729 em^-1.a weak band of C﹦O stretching at 1251 em and a slight move of C﹦O stretching vibration to high wavenumber with tlle increase in acetic an.hydride content．Th e UV spectrum of Ac·SPG reveals a weak C﹦O absorption in the range of 252～272 nm.The chemical shifts at 2.1 and 5.1 in HNMR spectrum prove that there exists O-acetylation methyl.Moreover,there.suits of GPC for samples before and after the acetylation indicate that the relative molecular mass of Ac-SPG ob-viously decreases,also the polydispersity,as compared with the native SPG.It is a pity that no formula can be es-tablished to calculate the DS of Ac·-SPG according to the infrared an d ultraviolet spec~a due to the nonlinearity be -DS and the corresponding typical absorbanee.

Key words: acetylated schizophyllan, spectroscopic analysis, degree of substitution