Study On Synthesis Of 2,4,6-trimethylbenzaldehyde

2,4,6-trimethyl benzaldehyde (mesitaldehyde) is a novel final chemical intermediate. As the shortage of industrialize manufacturing technology, high purity mesitaldehyde is scarce in the market. So, the research for the synthesis of mesitaldehyde is essential. In domestic and overseas, there are many synthetical methods, including incomplete oxidation, bromination and hydrolyzation, Grignard reaction, using zinc cyanide, chloromethylation and hydrolyzation, reducing benzoic acid, oxidating benzyl alcohol, formylation and so on. In these methods, the product are complicated, the yield is low and the cost is high. We adopt means of formylation to synthesize mesitaldehyde, using mesitylene CO and HCl as the materials, 1,2-Chloroethane as the solvent, Lewise acid as the catalyst. This technology has some merits such as low cost of material, low requirement for reaction condition, little environmental pollution.Compared with technics and equipment of different synthetic routes for 2,4,6-trimethyl benzaldehyde Low temperature formylation process was adopted, under special reactor and mild reaction conditions, the product was prepared by formylate reaction of mesitylene with CO and HCl, using Lewise acid as the catalyst, 1,2-Chloroethane as the solvent. We make out single factor experiment and optimal trial to optimization catalysis system and technics of the reaction,, The influence factors on purity of final product were investigated in detail, sush as catalyst, reaction time and temperature, The synthetic route and reaction mechanism of 2,4,6-trimethylbenzaldehyde were also introduced in this paper. After a series of stable experiment, the optimal conditions of synthesis were: mesitylene /AlCl₃/Cu₂Cl₂/1,2-CH₂ClCH₂Cl=l : 2.0: 0.21 : 2.0, reaction time: 18 hours, temperature: 25 to 30℃, the single-pass-conversion can reach 80% 90%, and the yield reached 59%. Various element were separated by rectification, the content of the aimed product reached 98.5% by the area normalization method. The product was determinated by NMR, IR and GC-MS, during the course of reaction, GC was used to quantitative determination. This method of formylation has some merits, including abundant raw materials, mild reaction conditions, much less of the content of isomer. At the same time, solvent and unreaction materials were recycled conveniently, After refined, purity of final product were quite high, selectivity and yield of formylation were obvious improved.