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Reactivity of Brönsted acid ionic liquids as dual solvent and catalyst for Fischer esterifications
Zuojun Wei,Feijin Li,Huabin Xing,Qilong Ren,Shuguang Deng 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3
Several water-stable ionic liquids with different acidity and affinity were synthesized and applied as both solvents and acid catalysts for Fischer esterification of ethanol reacting with four aliphatic carboxylic acids (acetic acid, n-hexanoic acid, lauric acid, and stearic acid). Among the studied ionic liquids, [(n-bu-SO3H) MIM][HSO4] (3-butyl- 1-(butyl-4-sulfonyl) imidazolium sulfate) and [(n-bu-SO3H) MIM][p-TSO] (3-butyl-1-(butyl-4-sulfonyl) imidazolium toluenesulfonate) show higher reactivity for the production of ethyl esters. The catalytic activities of these ionic liquids are strongly dependent on the acidity of their anions and cations, as well as their hydrophilicity and affinity with the reactants. Water refluxing through the condenser may be another important reason for obtaining high conversion of esterification, indicating a water-sequester process is still needed in order to obtain a higher yield of ester in the ionic liquid catalyzed esterification system. Kinetics studies show the conversions of the acids increase with reaction temperature and time, and reach equilibrium within about two hours. The apparent activation energies are 39.1±2.0, 49.7± 2.5, 51.4±2.5 and 59.3±3.0 kJ·mol−1 for the formation of ethyl acetate, ethyl n-hexanoate, ethyl laurate and ethyl stearate, respectively.
Qiwei Yang,Huabin Xing,Kun Yu,Baogen Su,Zongbi Bao,Yiwen Yang,Qilong Ren 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5
Chloride anion-based ionic liquids (ILs) have unique importance among various ILs. Nevertheless, they are usually very viscous, and the study on their mixtures with molecular solvent is important for their practical application. In this work, the viscosities and conductivities of the binary mixtures of 1-butyl-3-methylimidazolium chloride and several protic/aprotic solvents were measured, and the underlying information about intermolecular interaction and microscopic structure was discussed. The result showed that the molecular solvents which have relatively high dielectric constant and hydrogen-bond acidity will be more efficient in promoting the dissociation of chloride anion-based ILs and improving the transport properties of corresponding applications.
Min Li,Minhui Huang,Zhiguo Zhang,Qiwei Yang,Yiwen Yang,Zongbi Bao,Qilong Ren 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.10
L-arabinose and D-galactose could be released during the hydrolysis process of Arabic gum. The development of a crystallization process of L-arabinose is highly dependent on the knowledge of the solubility of both saccharides. In this work, the solubility of L-arabinose and D-galactose in binary mixtures of methanol-water or ethanolwater (mole fraction of water 0.5816) was determined at temperatures between 278.15 and 333.15K by a static equilibrium method. The experimental data correlated well with the modified Apelblat equation, the simplified polynomial empirical equation, NRTL model and UNIQUAC model. Additionally, the thermodynamic properties including the dissolution enthalpy and entropy were obtained from the experimental data. Within the studied temperature range, the dissolution is endothermic and the dissolution process is non-spontaneous.
Liyun Kong,Zhiguo Zhang,Huabin Xing,Qiwei Yang,Baogen Su,Zongbi Bao,Yiwen Yang,Qilong Ren 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.3
Polyethylene glycol (PEG) esters are important, nontoxic and biodegradable non-ionic surfactants. A keyprocedure in producing PEG esters is their separation from unreacted or excess acids. We propose an adsorptionmethod using the weakly basic anion exchange resins for the separation of organic acids and PEG esters for the firsttime. With α-tocopheryl polyethylene glycol succinate (TPGS) and α-tocopheryl succinate (α-TS) as the examples ofPEG ester and organic acid, respectively, single-component equilibrium experiments revealed the great potential of thismethod. Studies on the adsorption equilibrium, thermodynamics and kinetics of α-TS onto a weakly basic anion exchangeresin were also carried out. This research is not only important for the production of TPGS, but also instructivefor the separation of other PEG-esters from the reaction mixtures.