Ionic Liquid-mediated Catalytic Transformation Of Biomass-derived Olefin And Ethyl Lactate

Transformation of biomass and derivatives thereof into valuable chemicals has been paid more attention during the past decade due to the inevitable decline in available fossil resources. Moreover, ionic liquids(ILs) commonly used as environmentally benign media, catalysts or additives, have exhibited their potential in the field of organic synthesis.Anethole is the major constituent of the essential oils usually extracted from star anise, anise seed or sweet fennel. α-Pinene, the main component of turpentine oils, is a particularly valuable and inexpensive renewable resource. Ethyl lactate can be produced by fermentation of different carbohydrates(i.e., glucose and starch) and esterification. Therefore, the use of readily available biomass-derived olefin and ethyl lactate in the synthesis of high value-added fine chemical products is of extraordinary importance. Herein ionic liquid-mediated catalytic transformations of anethole, α-pinene and ethyl lactate were investigated and good results were obtained and the main contents of the thesis are summarized in the following:(1) A series of nano/microscale copper metal-organic frameworks were conveniently prepared via hydrothermal method or precipitation route and characterized by FT-IR, TG and TEM, respectively. The effects of catalyst, additive, solvent type and amount on the oxidation of anetholeto anisaldehyde were investigated systematically. It was found that Cu-BTC-1 obtained from H3 BTC ligands exhibited better performance.Notably, amphiphilic [C12mim]Cl is beneficial to the improved stability and good reusability of nano/microscale Cu-BTC-1. Under the optimum conditions, 74.8%-91.5% conversion of anethole and 93.5%-94.6%selectivity for anisaldehyde can be achieved over Cu-BTC-1 with the aid of ionic liquid [C12mim]Cl. Additionally, nano/microscale Cu-BTC-1exhibited good reusability, as supported by experimental results and TEM analysis.(2) Direct synthesis of sobrerol from α-pinene was studied with hydrogen peroxide catalyzed by VO(acac)2 using ionic liquid as an additive. The effects of ionic liquid, solvent, temperature and reaction time on catalytic performance were investigated. The results showed that the reaction system obtained from [C4mim]Cl/VO(acac)2/H2O2 can act as a good redox-Lewis acid bi-functional catalyst for the transformation ofα-pinene to sobrerol via oxidation, isomerization and hydration. Under the optimal reaction conditions of n(H2O2) : n(α-pinene) : n(VO(acac)2):n(ionic liquid) = 2.5 : 1 : 0.01 : 0.03, reaction temperature 30 oC, using acetone as solvent, conversion of α-pinene can reach up to 91.2% and selectivity of major products sobrerol and verbenone were 52.0% and13.6%, respectively after 6 h reaction.(3) A series of functional amino acid-based ionic liquids,[Bmim][Alanine], [Bmim][Proline] and [Bmim][Cysteine] which can be used for the acetylization of ethyl lactate were synthesized via one-step substitution and characterized by FT-IR and 1HNMR. Using amino acid ionic liquid as the catalyst, ethyl acetolactate was efficiently synthesized by acetylation of ethyl lactate with acetic anhydride. The results showed that the yield of the objective product ethyl acetolactate of 99.4% was attained under the optimum reaction condition as follows: the dosage of the catalyst [Bmim][Alanine] was 5.0 mol% of ethyl lactate amount, n(ethyl lactate) : n(acetic anhydride) = 1 : 1.2, and reaction time 6 h.