Research on self-base catalytic hydrolysis of iminodiacetonitrile in near-critical water

Near-critical water is a promising reaction medium for conducting the hydrolysis of nitriles without the addition of any additives. Iminodiacetonitrile (IDAN) was chosen as a heteroatom-containing model compound for the hydrolytic kinetic and mechanism investigations of dinitriles because IDAN is an important raw material for the preparation of iminodiacetic acid (IDA) which is an indispensable intermediate in herbicide manufacturing. Hydrolysis of IDAN in near-critical water, without added catalysts, has been successfully conducted. Hydrolysis kinetics data of the reaction were measured at 10 MPa with temperature and residence time ranges of 200-260°C and 10-60 min, respectively. The effects of temperature, pressure, and initial reactant/water ratio on conversion and yield have been investigated. Final reaction products primarily included iminodiacetic acid (IDA) and ammonia associated with other byproducts; gas formation was negligible. The maximum yield of IDA was 92.3mol% at 210°C, 10 MPa with a conversion almost of 100%. The apparent activation energy and lnA(min^-1) of IDAN hydrolysis were evaluated as (45.77 ± 5.26) kJ/mol and 8.6 ± 0.1 based on the assumption of first-order reaction. Reaction mechanism and network are similar to that of base-catalyzed reactions of nitriles examined in less severe conditions.