| 摘要 |
Ethylenediamine tetraacetic acid is prepared by forming an ethylenediamine formaldehyde adduct, cyanomethylating the adduct with hydrocyanic acid at controlled temperatures to form ethylenediamine diacetonitrile. This is further cyanomethylated under acid conditions with formaldehyde and hydrocyanic acid in slight excess to form the ethylenediamine tetraacetonitrile. The precipitated product, with or without isolation is hydrolyzed to form the tetrasodium salt of the ethylenediamine tetracetic acid in a stock solution for further processing. The process, in semi-batch processing, provides yields above about 98% and in good purity. When combined with ethylenediamine tetraaetic acid production, the process eliminates the need for cyanide waste treatment and greatly simplifies the procedures needed to protect the environment.
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