| 摘要 |
Process for the preparation of 1,1-cyclohexane-diacetic acid (CHDAA) from 1,5-dicarbonitrile-2,4-dioxo-3-azaspiro[5,5]undecane (the imide), by reacting it with sulfuric acid in two steps. The first step at a temperature lower than 100 DEG C and the second step at a reaction temperature from 160 to 190 DEG C. The first step is carried out by dissolving the imide in aqueous sulfuric acid at temperatures from about 65 DEG to about 85 DEG C and then cooling the solution thus obtained to room temperature. The second step is carried out by reacting said solution with aqueous sulfuric acid at temperatures of about 170 DEG C.
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