Synthesis and Characterization of Carboxyethylated Lignosulfonate
Synthesis and Characterization of Carboxyethylated Lignosulfonate
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DOI：
10.1002/cssc.201800994
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发表时间：
2018-09-11
期刊：
影响因子：
8.4
通讯作者：
Fatehi, Pedram
中科院分区：
文献类型：
--
作者：
Bahrpaima, Khatereh;Fatehi, Pedram
Lignosulfonate is a byproduct of the sulfite pulping process and has limited use in industry. The main objective of this study was to investigate the carboxyethylation of lignosulfonate to increase its charge density to broaden its applications. The carboxyethylation of lignosulfonate was optimized under the conditions of 30 wt% NaOH, 2.0 mol mol(-1) 2-chloropropinic acid/lignosulfonate, 90 degrees C, 0.5 h, and 0.03 mol 2-chloropropinic acid, which produced carboxyethylated lignosulfonate with a charge density and molecular weight of -3.51 meq g(-1) and 46493 g mol(-1), respectively. The mechanism of the carboxyethylation reaction using 2-chloropropinic acid by an S(N)1 pathway in an alkaline solution was discussed. Methylation was also used to mask the phenolic hydroxide groups of lignosulfonate to investigate if carboxyethylation occurred on aliphatic hydroxide groups of lignosulfonate. The produced carboxyethylated lignosulfonate was characterized by using FTIR spectroscopy, NMR spectroscopy, gel permeation chromatography, and elemental and functional group analyses. Basic H-1-H-1 2D COSY NMR spectroscopy was used to record the coupled spins of the carboxyethyl group on carboxyethylated lignosulfonate. The information from 1D (HNMR)-H-1 and 2D NMR COSY spectroscopy provided evidence for the existence of a 1-carboxyethyl group on the carboxyethylated lignosulfonate structure.
