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_N1 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 ¹H‐¹H 2 D COSY NMR spectroscopy was used to record the coupled spins of the carboxyethyl group on carboxyethylated lignosulfonate. The information from 1 D ¹H NMR and 2 D NMR COSY spectroscopy provided evidence for the existence of a 1‐carboxyethyl group on the carboxyethylated lignosulfonate structure.

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羧乙基木质素磺酸盐的合成与表征

木质素磺酸盐是亚硫酸盐制浆过程的副产物，在工业上用途有限。这项研究的主要目的是研究木质素磺酸盐的羧乙基化以增加其电荷密度，以扩大其应用范围。在30 wt％NaOH，2.0 mol ^-1 -2-氯丙酸/木质素磺酸，90°C，0.5 h和0.03 mol 2-氯丙酸的条件下优化木质素磺酸盐的羧乙基化反应，生成了电荷密度较大的羧乙基化木质素磺酸盐分子量分别为-3.51meq g ^-1和46 493 g mol ^-1。S _N使用2-氯丙酸进行羧乙基化反应的机理讨论了在碱性溶液中的1条途径。甲基化还用于掩蔽木质素磺酸盐的酚羟基氢氧化物，以研究羧乙基化是否发生在木质素磺酸盐的脂肪族氢氧化物上。通过使用FTIR光谱，NMR光谱，凝胶渗透色谱以及元素和官能团分析来表征所产生的羧乙基化木质素磺酸盐。使用碱性¹ H- ¹ H 2 D COZY NMR光谱法记录羧乙基化木质素磺酸盐上羧乙基的偶合自旋。来自1 D ¹ H NMR和2 D NMR COZY光谱的信息提供了在羧乙基化木质素磺酸盐结构上存在1-羧乙基的证据。