Pyrolysis-trimethylsilylation analysis of lignin: preferential formation of cinnamyl alcohol derivatives

Abstract

This paper describes a pyrolysis-trimethylsilylation procedure that is a new pyrolysis-derivatization thermochemolysis procedure of lignin. N, O-Bis(trimethylsilyl)trifluoroacetamide (BSTFA) was used as a trimethylsilylating reagent. A bulk dehydrogenative polymer of coniferyl alcohol (G-DHP) and a Japanese cedar ( Cryptomeria japonica D. Don) wood were pyrolyzed in the presence of BSTFA at 500°C for 4 s. The resultant volatile products were analyzed by gas chromatography/mass spectrometry (GC/MS). The G-DHP and the wood produced large abundances of trimethylsilyl (TMS) derivatized coniferyl alcohol (CA-(TMS) 2), in which both the phenolic and alcoholic hydroxyl groups are derivatized with TMS. CA-(TMS) 2 accounted for about 68% of the TMS derivatized products in the G-DHP pyrolysis, and about 24% of those in the wood pyrolysis. The results indicated that pyrolysis in the presence of trimethylsilylating reagents such as BSTFA is a potentially useful technique for drawing information on the pyrolytic precursors of cinnamyl alcohols (such as cinnamyl alcohol-end groups) from lignin. Pyrolysis-trimethylsilylation occurs in a one-step process and provides the TMS derivatives that are immediately available for the subsequent GC(/MS) analysis. This method is applicable to all lignocellulosic materials.