Design, Synthesis And Catalytic Performance Of Novel Heteropoly Acid Functionalized Ionic Liquid

According to the structure design and synthesis method of the functional ionic liquids, and based on N- methylimidazole and organic amine as the organic cation skeleton, then introducted the sulfonic acid group(PS) which is a Br?nsted acidic functional group into the framework. To obtain the Br?nsted acidity from the acidic functional group and counter-charge protons in common by means of varying degrees of substitution of keggin heteropolyacids( H3PW12O40) in the proton; afterwards, introduced the Lewis acid site into the cation by doping various kinds of metal ions(Al3 +, Ce3+, Sm3+, Cs+, Ni2+, Zn2+, Zr4+, Sn2+, etc.) with Lewis acidic in different proportions, therefore, designed and synthesized a series of novel heteropoly acid functionalized like ionic liquids organic- inorganic hybrid catalytic materials with Br?nsted-Lewis double acidity. Analysised the materials’ structures and compositions through using techniques such as infrared spectroscopy(FT-IR), hydrogen nuclear magnetic resonance spectroscopy(1H-NMR) and ICP-AES elemental analysis; thermogravimetric(TG) was used to characterized the thermal stability of the catalysts; the method measuring the solubility in various typical polar and non-polar solvents at different temperatures was used to investigated the performance of catalyst solubility and stability to water and solvent; the acidic characters such as acid type and acid strength of the synthesized heteropoly acid functionalized like ionic liquid organic-inorganic hybrid catalyst materials were determined by using pyridine-infrared method(Py-IR) and n-butylamine potentiometric titration method, furthermore, study the inherent regular pattern between structure and these properties of the synthesized hybrid material.Applied the above synthesized heteropoly acid functionalized like ionic liquids to catalyze three clean model fine organic synthesis reactions in which the by-product is water, such as the esterification, Friedel-Crafts benzylation and Friedel-Crafts acylation reaction of benzene compounds, in order to screen the high efficient green heteropoly acid functionalized like ionic liquid catalysts and further research the optimum reaction process. Among them, Sm0.66[MIMPS]PW12O40 demonstrated the best catalytic performance both in the esterification of acetic acid and benzyl alcohol and Friedel-Crafts benzylation of toluene and benzyl alcohol; Ce0.33[TEAPS]HPW12O40 was the optimum catalyst in the Friedel-Crafts acylation of anisole with benzoic acid. As can be seen, in the selected model reaction, the catalyst with high proportion of Lewis acidity could improve the reaction effect of esterification reaction and Friedel crafts benzylation, and the catalyst with strong Br?nsted acidity could make the Friedel-Crafts acylation have a better catalytic effect.In the esterification of acetic acid and benzyl alcohol, when the molar ratio of acetic acid and benzyl alcohol was 1.2: 1(benzyl alcohol was 0.03 mol), the dosage of the catalyst Sm0.66[MIMPS]PW12O40 which had been screened out as the best catalyst was 0.02 mmol, reacting at reflux temperature for 3 h, the conversion rate of benzyl alcohol reached 96.3%, and the benzyl acetate selectivity was 95.8%. After repeated use three times, the rate of conversion of the reactant was significantly decreased, but the selectivity of main product benzyl acetate had been well maintained. In the Friedel-Crafts benzylation reaction of toluene and benzyl alcohol, under the optimum conditions, the catalytic effect declined after Sm0.66[MIMPS]PW12O40 was reused 3 times.The synthesized heteropoly acid functionalized like ionic liquids catalysts were applied to the Friedel-Crafts acylation reaction of anisole with benzoic acid. The effects of the factors on the catalytic performance of catalyst type, amount of catalyst, reaction temperature and reaction time were studied. Taking Ce0.33[TEAPS]HPW12O40 as a catalyst, under the optimum reaction conditions, the conversion rate of benzoic acid and selectivity of 4-methoxybenzophenone could reach 67.0% and 84.3% respectively. The catalytic effect of Ce0.33[TEAPS]HPW12O40 slowly decreased with the increase of the number of repeated use. But the conversion of benzoic acid and selectivity of 4-methoxybenzophenone was still reached 45.8% and 79.0% after reused to the four times.Experimental results show that the synthesized heteropoly acid functionalized ionic liquids exhibited higher catalytic activity and good water resistance in the esterification reaction and Friedel-Crafts reactions. In addition, the catalysts can realize to be reused. It overcomes the defects of traditional acid catalysts, which provides a promising new idea for high atom economy and green route of acid catalytic reactions.