Synthesis Of 3-tert-Butyl-2,5-dihydroxybenzaldehyde

3-tert-Butyl-2,5-dihydroxybenzaldehyde was one of the important materials to synthe-size chiral Salen complexes. Chiral Salen Complexes, an asymmetric catalyst, is widely used in asymmetric epoxides reactions, cyclopropanation, strecker reaction, hydrolytic kinetic resolution of racemic terminal epoxides and other areas.A process route to synthesize 3-tert-Butyl-2,5-dihydroxybenzaldehyde has been designed in this article.2-tert-Butylhydroquinone was got by the reaction of hydroquinone and tert-butyl alcohol,85% phosphoric acid was used as a catalyst and xylene was used as solvent. The product was purified by recrystallization in the mixture of water/methanol solution to get purity of 95.8%. The reactive time, amount of tert-butyl alcohol, catalyst, solvent and other conditions on the reaction were discussed. The best reaction conditions were optimized. 3-tert-Butyl-2,5-dihydroxybenzaldehyde was synthesized by protection of 4-hydroxy group of 2-tert-butylhydroquinone with benzyl chloride, formylation with paraformaldehyde and cleavage the protecting group. Protection of 4-hydroxy group by benzyl chloride was carried by potassium carbonate as an acid binding agent, and potassium iodide as an initiator. Formylation by paraformaldehyde was processed by stannic chloride and triethylamine catalysis. Cleavage of the benzyl group was worked in acetic acid/hydrochloric acid. The total yield of above three steps was 46.6%. The intermediates and target compound was determined by 1HNMR. The total yield of 3-tert-butyl-2,5-dihydroxybenzaldehyde was 31.1% when the reaction was enlarged 20 times.