Effective Phosphorylation of 2,2′-Methylene-bis(4,6-di-tert-butyl) Phenol in Continuous Flow Reactors

Nucleating agent intermediate 2,2′-methylene-bis(4,6-di-tert-butylphenol) phosphate chloride was synthesized successfully in a continuous flow by the phosphorylation reaction for the first time. After evaluating several different continuous flow reactors, the continuous Coflore agitated cell reactor (ACR) designed based on the continuous stirred-tank reactor (CSTR) principle was proved capable of overcoming the severe channel clogging caused by the precipitation product triethylamine hydrochloride. This can be attributed to the violent agitation and particle size control by the moving agitators. The yield in continuous flow after optimization reached nearly 98% at 100 °C within the residence time of only 4 min and the optimal equivalents of triethylamine and POCl3 are 2.8 and 1.1, respectively. In contrast to the batch operation, the yield has been increased through continuous operation. This is an effective method for the synthesis of the desired product and exhibits the merits of short residence time, easy operation, and straightforward scale-up.