Ammonia → Iminodisuccinic acid

Participants

Reaction Steps

In another particular embodiment, an Ma melt and aqueous sodium hydroxide solution are metered simultaneously and continuously in a molar ratio of MA:NaOH:H2O=2:1.5-3.5:6-20 into a maleic acid salt solution or pumpable suspension, which has been initially introduced and is of like composition, at temperatures of 75-125° C. This solution or suspension is pumped, with residence times of 0.1-5 h, into a second mixer, into which liquid ammonia or a concentrated aqueous ammonia solution is added continuously. the molar ratio of MA:ammonia here is 2:1.5-3.5. This solution is reacted at temperatures of 90-145° C. and residence times of 0.3-25 h in a continuous reactor. Ammonia and water are distilled off from the reaction mixture in a continuous distillation column at temperatures of 70-140° C. and residence times of 0.1-25 h, with continuous addition of water and aqueous sodium hydroxide solution corresponding to 0.5-2.5 mol of NaOH per 2 mol of MA originally employed. After the addition of water, solutions with solids contents of 5-60% by weight are obtained, and are subjected to a clarifying filtration, if appropriate. The product solutions have yields of >73% of iminodisuccinic acid, <3% of maleic acid, <10% of fumaric acid, <5% of malic acid and <15% of the particular theoretical yields of aspartic acid.

Provenance & Evidence