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Homogeneous synthesis and characterization of starch acetates in ionic liquid without catalysts

Luo, Zhigang, Zhou, Zidan
Die Stärke = 2012 v.64 no.1 pp. 37-44
Fourier transform infrared spectroscopy, acetates, catalysts, corn starch, crystal structure, ionic liquids, nuclear magnetic resonance spectroscopy, starch, thermal stability
Homogeneous modification of corn starch with acetic anhydride was performed in ionic liquids 1‐butyl‐3‐methylimidazolium chloride (BMIMCl) without catalysts. The results indicated that the pretreatment of starch, which starch was dissolved in BMIMCl at 105°C for 2 h before reaction, provided feasible reaction environment for starch functionalization. Optimum modification conditions for maximum degree of substitute (DS 2.11) were shown as following: acetic anhydride/anhydroglucose units (AGU) molar ratio 5:1, reaction temperature 105°C and reaction time 2 h. The pretence of acetyl groups in starch products was confirmed by FTIR and 1H NMR spectroscopy. SEM and XRD data showed that the crystalline structure of native starch was disrupted and new structure was formed during the dissolution and modification processes. The higher DS due to acetylation had a beneficial effect on the thermal stability of samples.