N-Bromosuccinimide (NBS) – an efficient catalyst for acetylation of wood

Abstract

Abstract Solvent-free acetylation of rubberwood (Hevea brasiliensis Müll.Arg) with acetic anhydride (Ac2O) and by means of N-bromosuccinimide (NBS) as catalyst was carried out in an oil bath at 105°C and 120°C. The effect of catalyst concentration, temperature, and reaction time was studied. The extent of acetylation was measured by determining the weight percent gain (WPG), and the acetylated wood was characterized by FTIR-ATR, CP/MAS 13C NMR, and XRD spectroscopy. The presence of NBS in concentrations between 1.0% and 3.0% elevated the acetylation rate to a great extent. WPG increased from 8.1% without catalyst to 22.1% for 2% NBS concentration after 60 min reaction at 120°C. Similarly, after 60-min reaction time at 105°C, WPG with 3% NBS concentration was 19.0% compared to 7.6% with un-catalyzed reaction under the same reaction conditions. The effect of microwave heating (MWh) on the NBS-catalyzed acetylation was also investigated. A significant level of modification was achieved within a few minutes of MWh. The hydrophobic properties and dimensional stability of the acetylated wood were elevated. NBS was found to be an effective catalyst for wood acetylation.