Process for the manufacture of nitrilotriacetonitrile

Abstract

Abstract 1. IN THE PROCESS FOR THE MANUFACTURE OF NITRILOTRIACETONITRILE BY REACTING AN AMMONIUM SALT OF SULFURIC ACID, PHOSPHORIC ACID OR HYDROCHLORIC ACID WITH AN AQUEOUS FORMALDEHYDE SOLUTION HAVING A STRENGHT OF BETWEEN ABOUT 20 AND 55 WEIGHT PERCENT AND LIQUID HYDROGEN CYANIDE OR AN AQUEOUS SOLUTION THEREOF, HAVIG A STRENGTH OF AT LEAST 40 WEIGHT PERCENT, AT A TEMPERATURE OF BETWEEN ABOUT 50 AND 110*C., WHEREIN (A) A PRELIMINARY REACTOR IS CONTINUOUSLY SUPPLIED WITH A SUBSTANTIALLY SATURATED AQUEOUS SOLUTION OF THE AMMONIUM SALT AND THE AQUEOUS METHANOL-FREE FORMALDEHYDE SOLUTION, WHICH ARE PREHEATED AT A TEMPERATURE OF BETWEEN ABOUT 50 AND 110*C., THE AMMONIUM SALT BEING USED IN A STOICHIOMETRIC EXCESS BETWEEN 5 AND 40 PERCENT OVER THE FORMALDEHYDE; (B) THE SAID AQUEOUS SOLUTION COMPONENTS ARE THOROUGHLY MIXED AND REACTED INSIDE THE SAID PRLIMINARY REACTOR AT A TEMPERATURE OF BETWEEN ABOUT 50 AND 110*C., AND WITHIN A PERIOD OF BETWEEN ABOUT 2 SECONDS AND 4 MINUTES; (C) THE RESULTING REACTION PRODUCT IS DELIVERED TO A SECOND REACTOR SERIES-CONNECTED TO THE SAID PRELIMINARY REACTOR AND THE SAID REACTION PRODUCT IS REACTED IN THE SAID SECOND REACTOR WITH A STOICHIOMETRIC PROPORTION, BASED ON THE AMOUNT OF THE FORMALDEHYDE, OF LIQUID HYDROGEN CYANIDE OR WITH THE AQUEOUS SOLUTION THEREOF, FOR A PERIOD BETWEEN ABOUT 3 AND 10 MINUTES, UNDER A PRESSURE BETWEEN 3 AND 15 ATMOSPHERES GAUGE AND AT A TEMPERATURE BETWEEN ABOUT 90 AND 110*C., WITH THE RESULTANT FORMATION OF NITRILOTRIACETONTRILE AND THE FREE ACID (FORMED IN SITU) OF THE AMMONIUM SALT; (D) THE REACTION MIXTUE RE IS WITHDRAWN FROM THE SAID SECOND REACTOR AND QUENCHED BY COOLING IT DOWN TO A TEMPERATURE BETWEEN ABOUT 20 AND 30*C. WITH PRESSURE RELIEF TO ATMOSPHERIC PRESSURE AND SEPARATED BY FILTERATION OR CENTRIFUGATION INTO FIRSTLY CRYSTLLINE NITRILOTRIACETONITRILE AND SECONDLY AN AQUEOUS ACID MOTHER LIQUOR CONTAINING SUBSTANTIALLY THE SAID EXCESS AMMONIUM SALT AND THE FREE ACID OF THE AMMONIUM SALT, THE IMPROVEMENT WHICH COMPRISES, RECOVERING THE ACID OF THE AMMONIUM SALT AND THE EXCESS PROPORTION OF THE AMMONIUM SALT FROM THE AQUEOUS MOTHER LIQUOR BY INTRODUCING THE MOTHER LIQUOR INTO AN EVAPORATOR, EVAPORATING THEREIN SUBSTANTIALLY BETWEEN 50 AND 75 WEIGHT PERCENT OF THE WATER CONTAINED IN THE MOTHER LIQUOR, TREATING THE RESULTING CONCENTRATED MOTHER LIQUOR WITH AMMONIA SO AS TO ESTABLISH A PHVALUE OF BETWEEN 3 AND 4 THEREIN WITH THE RESULTANT FORMATION OF AN AQUEOUS AMMONIUM SALT SOLUTION CONTAINING THE AMMONIUM SALT IN A CONCENTRATION BETWEEN ABOUT 30 AND 35 WEIGHT PERCENT, SEPARATING OILY BY-PRODUCTS, WHICH MAY BE FOUND TO PRECIPITATE, THEREFROM, AND RECYCLING THE AMMONIUM SALT SOLUTION TO THE PRELIMINARY REACTOR.

Inventors

• 👤 G Lenz
• 👤 K Sennewald
• 👤 R Schuller
• 👤 H Neumaier
• 👤 W Vogt

Bibliographic Details