Prins Condensation Reaction Of Styrene And Formaldehyde Based On Acidic Deep Eutectic Solvent [Im:2PTSA]

Prins condensation reaction is an important carbon-carbon bonding reaction,which has attracted much attention due to its flexibility,variety of products and high economic value.In industry,the Prins reaction of mainly uses inorganic acid catalyst.The production process will produce a large amount of waste acid,which will bring about acid rain,land acidification and other environmental problems.At the same time,inorganic acid will also lead to equipment corrosion.With the promotion and popularization of the concept of "green chemistry",more and more researchers are turning their attention to the development and use of new green acidic catalysts to replace traditional inorganic acids that are not environmentally friendly.The deep eutectic solvent(DES)has been extensively studied because of its simple preparation,low cost,mild conditions,and environmental protection.In this paper,acidic DES was applied for the first time in the Prince condensation reaction of styrene and formaldehyde to synthesize 4-Phenyl-1,3-dioxane(PDO).DES[Im:2PTSA]synthesized by imidazole and p-toluenesulfonic acid was selected as the catalyst for the reaction.The phase separation of the liquid-liquid reaction system was discussed based on the COSMO-RS model,and the formation mechanism of DES and the Prince condensation reaction were studied in detail.The reaction conditions were systematically optimized,and the yield of 4-Phenyl-1,3-dioxane was 91.9%at 100?,the molar ratio of formaldehyde to styrene was 4:1,the dosage of DES was 5 mol%,and the reaction time was 3 hours.The catalytic effect of DES on the reaction is reflected in the Bronsted acid of sulfonic acid group and the nucleophilic effect on carbonyl carbon positive ion in formaldehyde,which together promote the formation of 3-phenylpropanol structure intermediate in the reaction rate control step.The DES used is easier to prepare than ionic liquids,and can greatly shorten the time required for the reaction to reach equilibrium.DES still maintains good catalytic activity after 4 recycling cycles.Finally,the kinetic parameters of the reaction were studied,and the reaction order and reaction activation energy were obtained.