Synthesis method of intermediate 2-bromine-4-fluorine-5-chlorinated phenol

The invention provides a synthesis method of an intermediate 2-bromine-4-fluorine-5-chlorinated phenol. The synthesis method comprises the following steps: firstly adding a solvent to 3-chlorine-4-fluoropenol, performing stirring, reducing the temperature to minus 10-0 DEG C, then adding bromine, and then performing a heat preservation reaction at minus 5-0 DEG C for 3-10 hours so as to obtain reaction liquid; adding a NaHSO3 aqueous solution to the reaction liquid, performing quenching, performing layering, and taking an organic layer I; then adding a NaCl aqueous solution to the obtained organic layer I, performing layering, and taking an organic layer II; performing decompressed concentration on the organic layer II until a dried state is achieved, then adding petroleum ether as a solvent to obtained substances, performing stirring until a complete dissolving state is achieved, performing low temperature crystallization at minus 2-2 DEG C, and performing filtration so as to obtain filter cakes; finally, dr