Study On Friedel-Crafts Acylation Of Benzene With Phthalic Anhydride Catalyzed By Ionic Liquids

The Friedel-Crafts acylation of benzene with phthalic anhydride is one important way to synthesis anthraquinone.The traditional catalyst is AlCl3, which will cause equipment corrosion and environmental pollution. It has great theoretical and application significance to study the Friedel-Crafts acylation of benzene with phthalic anhydride catalyzed by ILs.Heteropoly acids were used for the acylation of benzene with phthalic anhydride, including HPW, HPMo, HSiW. In this reaction, HPW was a better catalyst and was calcinated under 150℃. The optimum condation as following: reaction temperature 130℃, reaction time 2h, m(PHA):v(benzene)=3:40, m(HPW):m(PHA)=1:5, yield of o-benbzoylbenzoic was 7.6%.We synthesized HPW salts including Al-substituted dodecatungstophosphoric acid, K-substituted dodecatungstophosphoric acid, Cs Cs-substituted dodecatungstophosphoric acid and studied the catalystic activity in the acylation of benzene with phthalic anhydride. Only Cs-substituted dodecatungstophosphoric acid could catalyze the reaction and the yield of o-benbzoylbenzoic was less than 1%.Synthesized non-AlCl3 ILs and AlCl3-IL [Emim]Br-AlCl3, and studied the catalystic activity in the acylation of benzene with phthalic anhydride. Only AlCl3-IL could catalyse the reaction. The optimum condition as following: reaction temperature 30℃, reaction time 3h, n(benzene):n(PHA) = 3:1, m ([Emim]Br-AlCl3): m (PHA) = 7:1, the yield of o-benbzoylbenzoic was 88.4%. Suggested the reaction mechanism of the acylation of benzene with phthalic anhydride.[Emim]Br-AlCl3 was supported over activated carbon by impregnation method and was used in the acylation reaction of benzene with phthalic anhydride.The impregnation time was 16h.The optimum condition as following: reaction temperature 80℃, reaction time 4h, m (PHA): v(benzene) = 1:50, m ([Emim]Br-AlCl3/C): m (PHA) = 10.5:1, the yield of o-benbzoylbenzoic was 17.81%. The [Emim]Br-AlCl3/C could be reused and the yield of o-benbzoylbenzoic decreased to 8.98% in the first reuse of [Emim]Br-AlCl3/C. The catalystic activity of [Emim]Br-AlCl3/C could be recovered by increasing active ingredients and the yield of o-benbzoylbenzoic increased to 12.4%.