Year: 1997
Type: article
Abstract: Pyrograms of pyrolysis-gas chromatography (Py-GC) from thirteen species of tropical hardwoods were obtained under pyrolytic conditions with a Curie-point pyrolyzer at 500°Cfor 4 seconds to determine twenty six pyrolysis products and to estimate ratios of syringylunits to guaiacyl units (S/G ratios) of lignin and lignin-like substances. Before thepyrolysis, wood meals were extracted with benzene and successively with 70% acetone/wa-ter to remove tannins and other phenols. The observed S/G ratios were in good agreementwith syringaldehyde/vanillin (S/V) ratios obtained by nitrobenzene oxidation. The extractedkapur wood meals were treated with hot 1% NaOH solution to extract lignin-like sub-stances. On a pyrogram of the 70% acetone/water extractives, guaiacol, 4-vinylguaiacol, syringol, and 4-vinylsyringol were identified as main pyrolysis products. On a pyrogram ofa chloroform-soluble part of the hot 1% NaOH extractives, vanillin and acetoguaiaconewere identified as main peaks, and the characteristic of the pyrogram was quite differentfrom that of lignin. In order to simplify a method for determination of acid-insoluble (Klason) lignin in tropical hardwoods, wood samples extracted with 70% acetone/waterwere hydrolyzed at 121°C, and the acid-insoluble residues were characterized by Py-GC.The conents of acid-insoluble residues, which were given by hydrolysis with 3% or 4%sulfuric acid at 121t for 1 hour, were slightly smaller than the Klason lignin contents. Onpyrograms of the acid-insoluble residues given by hydrolysis with 4% sulfuric acid, ratios of 4-methyl guaiacol (4-methylsyringol) to guaiacol (syringol) were higher than those on pyrograms of the Klason lignins.
Source: JAPAN TAPPI JOURNAL
Authors: Hiroshi Ohi, Yukino Yasuta, Akiko Izumi, Ken-ichi Kuroda
Institution: University of Tsukuba
Language: English
Topic: Lignin and Wood Chemistry
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W4253829590