Rapid phthaloylation and succinylation of hemicelluloses by microwave irradiation

• Published in: e-Polymers 2008-12, Vol.8 (1), p.1231-1241
• Main Authors: Peng, Feng, Ren, Jun-Li, Sun, Xiao-Feng, Xu, Feng, Sun, Run-Cang, Peng, Bai, Sun, Jin-Xia
• Format: Article
• Language: English
• ISSN: 2197-4586; 1618-7229; 1618-7229
• DOI: 10.1515/epoly.2008.8.1.1231

Rapid phthaloylation and succinylation of wheat straw hemicelluloses with phthaloyl dichloride (PdC) and succinyl chloride (SC) in dimethylformamide/ lithium chloride (DMF/LiCl) system using -bromosuccinimide (NBS) as a catalyst was achieved for only 5 minutes at 50 °C by microwave irradiation. The degree of substitution (DS) ranged between 0.43 and 1.47. The effect of the molar ratios of xylose units in hemicelluloses to phthaloyl dichloride or succinyl chloride on the degree of substitution was investigated. It was found that the reactivity of succinyl chloride was higher as compared to Phthaloyl dichloride under similar experimental conditions. C NMR studies revealed that the esterification occurred at the C-3 and C-2 positions in the β-D-xylose units of hemicelluloses, but preferentially at C-3 position. However, it should be noted that microwave irradiation did result in more degradation of the macromolecular hemicelluloses than conventional heating technique as shown by a lower thermal stability of the hemicellulosic derivatives obtained by microwave irradiation than those obtained by conventional heating technique.