Synthesis Of M-Hydroxybenzyl Alcohol

m-Hydroxybenzyl alcohol is an important intermediate for fine chemicals. It is especially used in the manufacture of pharmaceuticals. The properties and applications of m-hydroxybenzyl alcohol were briefly discussed. Its synthetic methods published in the literature were introduced in detail, and the advantage and disadvantage of them were described. A new route to synthesize the target compound starting from m-cresol, which undergoes four steps including acetylation, chloration, esterification, and alcoholysis was proposed.In the experimental sections, the effects of various conditions, e.g., reaction time, temperature, mass ratio, etc., to yields were studied. The suitable reaction conditions and experiment methods were obtained, and the reaction mechanisms were discussed. The final synthesized product was confirmed as m-hydroxybenzyl alcohol by means of melting point, IR, 1H-NMR. Meanwhile its intermediates were analysed by GC.The research demonstrated that the optimum process conditions of synthesizing m-cresyl acetate, which was prepared by acetylation of m-cresol with acetic anhydride using sulfuric acid as catalyst were as follows: n(m-cresol)/n(acetic anhydride)/n(catalyst)=l/l.05/0.001, reaction temperature 70-75℃, reaction time 2.5 h. It was found that the yield of m-cresyl acetate (after purification) can reach 95.0% under the optimum condition.The optimum process conditions of synthesizing of 3-(chloromethyl)phenyl acetate, which was prepared by the reaction of m-cresyl acetate with chlorine using carbon tetrachloride as solvent and azodiisobutyronitrile as catalyst were as follows: n(m-cresyl acetate)/n(solvent)/n(chlorine)/n(catalyst)=l/10-12/l.1-1.2/0.026, reaction temperature 75-78℃, chlorine flux 0.25 g/min. It was found that the yield of 3-(chloromethyl)phenyl acetate (after purification) can reach 42.8% under the optimum condition.The optimum process conditions of synthesizing the final product m-hydroxybenzyl alcohol, which was prepared by esterification of 3-(chloromethyl)phenyl acetate with sodium acetate using acetic acid as solvent, followed by alcoholysis with methyl alcohol using sulfuric acid as catalyst were as follows: n(3-(chloromethyl)phenyl acetate)/n(acetic acid)/n(sodium acetate)/n(methylalcohol)=l:4-5:l.1-1.2:5-6, reaction time of esterification and alcoholysis was 8 h, respectively. The yield of m-hydroxybenzyl alcohol was 32.3% under the optimum condition.Recrystallization from benzene, with w(benzene)/w(unrefined m-hydroxybenzyl alcohol)=0.42, the yield of recrystallization was 16.1%.The innovation of the paper was that a new synthesis process for preparing m-hydroxybenzyl alcohol was proposed. It has abundant raw material, low cost, mild condition, safer, potential for use in large-scale production.