METHOD FOR INTERMITTENT PREPARATION OF LOW CONTENT TRANS-TRANS ISOMER-CONTAINING 4,4'-DIAMINODICYCLOHEXYLMETHANE

摘要

The present invention discloses a method for intermittently producing 4,4'-diaminodicyclohexyl methane (H 12 MDA) with a low amount of the trans-trans isomer thereof, which comprises: controlling the reaction process by stopping the reaction when, except for a solvent, the reaction solution comprises MDA of 0-5 wt% and H 6 MAD of 1-20 wt%; and b) separating the reaction solution obtained from step a) by conventional means to obtain H 12 MDA product with desired purity, and allowing the un-reacted material and intermediate product to be recycled to the reactor after being accumulated. The method of the present invention decreases the amount of the trans-trans isomer in H 12 MDA, increases the yield of the reaction, and reduces the production cost. The present invention also provides a post treatment process of the reaction mixture.