Method of preparing alkyl phosphate compound based on micro-reaction system

A method of preparing an alkyl phosphate compound based on a micro-reaction system, the micro-reaction system comprising a feed pump, a first micro-mixer, a second micro-mixer, a first micro-channel reactor, a second micro-channel reactor and a back-pressure device;

• the first micro-mixer, the second micro-mixer, the first micro-channel reactor, the second micro-channel reactor and the back-pressure device being sequentially connected;
• and the method comprising:
• (1) simultaneously feeding a solution of an alkylamine compound of formula (I) in a first solvent and a solution of an acid-binding agent in a second solvent to a first micro-mixer for mixing followed by pre-reaction in the first micro-channel reactor to obtain a pre-reaction solution;
• (2) simultaneously feeding the pre-reaction solution and a solution of a phosphate of formula (II) or a phosphite of formula (III) in a third solvent to the second micro-mixer for mixing to obtain a first reaction mixture;
• (3) feeding the first reaction mixture to the second micro-channel reactor to carry out a condensation reaction under a back pressure condition set by the back pressure device to obtain a second reaction mixture;
• (4) collecting the second reaction mixture by a storage tank for concentration to obtain an alkyl phosphate ester compound of formula (IV) or formula (V);
• wherein R1 is selected from the group consisting of hydrogen, a C1-C12 alkyl, —COOH, —CH2COOH, and a C2-C12 alkylcarboxylic acid;
• R2 is selected from the group consisting of hydrogen, a C1-C12 alkyl, and a C3-C6 cycloalkyl;
• R3 is selected from the group consisting of hydrogen, —OCH3, —OCH2CH3, a C2-C12 alkoxy, trifluoromethyl, trifluoromethoxy, and 2-oxocyclopentylidenemethylidene;
• R4 is selected from the group consisting of hydrogen, carbonyl, a C1-C12 alkyl, and a C3-C6 cycloalkyl;
• R5 and R6 are each selected from the group consisting of hydrogen, a C1-C12 alkyl, a C3-C6 cycloalkyl, and a C2-C12 alkoxy;
• and R7 and R8 are each selected from the group consisting of hydrogen, —OCH3, —OCH2CH3, a C2-C12 alkoxy, trifluoromethyl, trifluoromethoxy, and 2-oxocyclopentylidene.