The Study On The Synthesis Of Fluorobenzaldehyde

Fluorobenzaldehyde is an intermediate for preparing medicine, pesticide, spice, dyestuff and other fine chemicals. In the synthesis of medicine and pesticide, the introduction of the atom F can improve biological activity and drug effect and reduce the adverse effect. Currently, the application of fluorobenzaldehyde has been continuously extended. In this paper, two methods for the synthesis of p-fluorobenzaldehyde from p-fluorotoluene have been studied.The synthesis of p-fluorobenzaldehyde by chlorination and hydrolysis was studied. The influence of solvent, catalyst and other reaction conditions on experiment result were discussed . The reaction condition in the hydrolysis of mixed chloride products via hexamethylene tetramine was n(4-fluorobenzyl chloride):n (hexamethylene tetramine)=1 :4, m(chloride):m(ethanol)=1: 1.1, the yield was 80.1 % . The yield was 95.2% in the hydrolysis of p-fluorodichloromethylbenzene in ethanol with the reaction condition of V(p-fluorodichloromethylbenzene) :V(ethanol)=1: 5. The reaction condition in the hydrolysis followed with oxidation from p-fluorobenzyl chloride was: n (4-fluorobenzalcohol):n(hydrogen peroxide) =1:1.3, n ( sodium tungstate):n(salicylic acid)=1:1, the yield was 78.4%.The synthesis of p-fluorobenzaldehyde by gas-liquid two phase oxidation was studied. The influence of solvent, catalyst, oxidant, temperature and other reaction conditions on experiment result were discussed. Under the optimum condition of V(p-fluorotoluene): V(glacial acetic acid)=1: 3, n (cobaltous acetate):n (manganese acetate) :n (potassium bromide) =1: 2: 3, reaction temperature 90～95℃, oxygen flow 2.4mL/min, the conversion of p-fluorotoluene was 23.5%;the selectivity to p-fluorobenzaldehyde was 48.5% and the yield was 11.4%.