Thorough Chemical Modification of Wood-Based Lignocellulosic Materials in Ionic Liquids

Abstract

Homogenous acylation and carbanilation reactions of wood-based lignocellulosic materials have been investigated in ionic liquids. We have found that highly substituted lignocellulosic esters can be obtained under mild conditions (2 h, 70°C) by reacting wood dissolved in ionic liquids with acetyl chloride, benzoyl chloride, and acetic anhydride in the presence of pyridine. In the absence of pyridine, extensive degradation of the wood components was found to occur. Highly substituted carbanilated lignocellulosic material was also obtained in the absence of base in ionic liquid. These chemical modifications were confirmed by infrared spectroscopy, 1 H NMR, and quantitative 31 P NMR of the resulting derivatives. The latter technique permitted the degrees of substitution to be determined, which were found to vary between 81% and 95% for acetylation, benzoylation, and carbanilation, accompanied by similarly high gains in weight percent values. Thermogravimetric measurements showed that the resulting materials exhibit different thermal stabilities from those of the starting wood, while differential scanning calorimetry showed discrete new thermal transitions for these derivatives. Scanning electron microscopy showed the complete absence of fibrous characteristics for these derivatives, but instead, a homogeneous porous, powdery appearance was apparent. A number of our reactions were also carried out in completely recycled ionic liquids, verifying their utility for potential applications beyond the laboratory bench.

Thermal Degradation Analysis on 4-year-old Culms of Cultivated Tropical Bamboo Bambusa Vulgaris

“…Similar observations were made by Xie et al (2007) and Mui et al (2008) during the investigation of the degradation of this wood. The weight losses and the rates of thermal at the different stages of the thermal degradation (de-volatilization and combustion steps) changed with each different fiber and at any particular location on the plant (Jeguirim et al, 2010).…”

Photoresponsive Cellulose Nanocrystals

“…The method described below was developed by the group of Argyropoulos following the principles established in the work described elsewhere [39]. Ionic liquid, 1-allyl-3-methylimidazolium chloride ([Amim]Cl, 950 mg) were added to CNC (50 mg) in a 15 ml sample flasks, vortexed until all solid particles had dispersed and heated at 80°C with magnetic stirring until the solutions were transparent (2 hrs).…”

Characterization of nonderivatized plant cell walls using high‐resolution solution‐state NMR spectroscopy

“…However, for the purposes of dissolving the plant cell wall, dissolution temperatures beyond 50 °C begin to approach the thermal transition points of lignin, thus increasing the probability of degradation. Specific ionic liquids do have the capability of dissolving plant cell wall material, [19][20][21] but the lack of degradative assessments of these systems currently limit their application in structural studies. Two systems that were shown to be effective and nondegradative in dissolving ball-milled plant cell walls have been recently described.…”