Para Methoxyacetophenone was synthesized by acylation of anisole with acetic anhydride using heteropolyacid as catalyst.
Pretreatment of catalyst and preparation of supported heteropolyacid:
The heteropoly acid is dried to a certain temperature in a controllable oven, and dried at a constant temperature for 1.5 h. The loaded H3 [PW12O40] was prepared by the excess impregnation method. A certain amount of carrier was mixed and stirred with the aqueous solution of H3 [PW12O40] respectively, kept in a water bath at a constant temperature for 14 hours, then evaporated to dryness in a water bath, and then placed in a controllable oven and dried at 150 °C for 2 hours to obtain the load. H3[PW12O40].
Friedel-Crafts acylation of anisole with acetic anhydride:
In the reaction flask, add the catalyst, anisole and acetic anhydride, install a reflux condenser, and stir with a magnetic stirrer. Through a water bath or an oil bath, a certain reaction temperature is controlled, and the reaction is kept constant for a certain period of time and then cooled. Chloroform was added to precipitate the heteropolyacid, and the catalyst was filtered off. Add water to the filtrate to hydrolyze the unreacted acetic anhydride, stand for stratification, wash the organic layer to near neutrality with sodium hydroxide solution, dry the organic layer obtained after the separation with anhydrous magnesium sulfate, distill at atmospheric pressure first, and recover chloroform , anisole and other light fractions, and then collect under reduced pressure the fractions at 152～154 ℃ under the pressure of 3.5Kpa, which is the reaction product Para Methoxyacetophenone.
The optimal reaction conditions are: the catalyst needs to be pretreated, the temperature is 150 ℃, the molar ratio of anisole to acetic anhydride is 1:1.5, the optimal mass ratio of anisole to catalyst is 11, and the reaction time is 4h 9%。 , the reaction temperature of 100 ° C, the product yield reached 52.9%. Under the optimal conditions, the catalytic effects of different heteropolyacids and supported heteropolyacids on the acylation of p-anisole with acetic anhydride were investigated. As the strongest acid among heteropolyacids, phosphotungstic acid has the best catalytic activity.