| 摘要 |
FIELD: chemistry. ^ SUBSTANCE: invention relates to a method of extracting methylglycine nitrile-N,N-diacetonitrile from an aqueous mixture obtained by reacting aminodiacetonitrile with a strong acid and acetaldehyde or alanine nitrile with a strong acid and formaldehyde, where the aqueous mixture is used in form of an emulsion containing from 3 to 50 wt % methylglycine nitrile-N,N-diacetonitrile and the process is carried out in a crystalliser. The method involves (a) cooling the water emulsion from temperature higher than solidification point to temperature lower than solidification point at average rate of not more than 5 K/h until all the amount of emulsified methylglycine nitrile-N,N-diacetonitrile solidifies; (b) further cooling the obtained aqueous suspension and, if necessary, its concentration at low pressure, where the rate of cooling is higher than that at step (a). ^ EFFECT: method enables to obtain larger methylglycine nitrile-N,N-diacetonitrile crystals which can be easily separated, thereby considerably cutting on expenses for cleaning the crystalliser. ^ 7 cl, 3 dwg, 3 ex |
