Oxygen → Iminodiacetic acid

Participants

Reaction Conditions

Reaction Steps

183 g. of 97% sodium hydroxide; 300 g. of demineralized water; 163.2 g. of 98% diethanolamine; 64 g. of Copper-Raney with a humidity level of 30%, which really means using 44.8 g. of net-weight catalyst in the test, and finally 40 further g. of demineralized water, to break down all the previous reagents, are all stirred into a stainless steel autoclave reactor (AISI 316) with a 1 liter capacity, and in the above-mentioned order. Then, and while still stirring, the heating process is started until 170° C. is reached and the pressure inside the reactor is 18 Kg/cm2. At this stage, the reactor is brought into contact with a shot of oxygen previously set at 18 Kg/cm2 so as to have the same pressure and making sure that the pressure is kept constant during the course of the process, the oxygen consumed being continually replaced. The suspension is continuously stirred for 3.5 hours. When this time has elapsed, the reaction is concluded, and it is cooled to 90° C. and filtered with suction with Buchner and Kitasato, regaining the humidity weight of 71.0 g. of the copper catalyst, this being kept for successive reuse after regeneration. The reaction solution, once analyzed by chromotography, provides a 95% yield of free iminodiacetic acid in the form of disodium salt, and this can be easily isolated and purified either by crystalization at 85° C. at pH 22, or electrochemically using one of the electrodialysis processes mentioned before. The purification yield is quantitative (100%) using the isolation procedure and purification by electrodialysis.

Provenance & Evidence