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Synthesis and Characterization of Carboxyethylated Lignosulfonate
Author(s) -
Bahrpaima Khatereh,
Fatehi Pedram
Publication year - 2018
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201800994
Subject(s) - chemistry , hydroxide , nuclear magnetic resonance spectroscopy , sulfite , spectroscopy , fourier transform infrared spectroscopy , gel permeation chromatography , carbon 13 nmr , organic chemistry , nuclear chemistry , chemical engineering , polymer , physics , quantum mechanics , engineering
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 °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 46 493 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 1 H‐ 1 H 2 D COSY NMR spectroscopy was used to record the coupled spins of the carboxyethyl group on carboxyethylated lignosulfonate. The information from 1 D 1 H NMR and 2 D NMR COSY spectroscopy provided evidence for the existence of a 1‐carboxyethyl group on the carboxyethylated lignosulfonate structure.