| 摘要 |
Disclosed herein are sulfonated ligno-aminodicarboxylic acid and the salts thereof of the formula <IMAGE> wherein X is an alkali cation, such as sodium, potassium, lithium, and ammonium, and Lignin denotes the polymeric sulfonated lignin material derived from commercial pulping of wood, straw, corn stalks, bagasse and the like. The dicarboxylic acid is made by a three-step process: (1) amination with ammonia and formaldehyde; (2) cyanomethylation with formaldehyde and sodium cyanide; and (3) hydrolysis of nitrile to carboxylic acid. The sulfonated ligno-aminodicarboxylic acid and its salts are useful as metal complexing agents.
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