Preparation of 8-hydroxyquinoline thermosensitive ionic liquid and method for catalyzing long-chain fatty acid ethyl esterification

Abstract

The invention discloses a preparation method of a temperature sensitive ionic liquid, and a method for catalyzing long-chain fatty acid esterification by using the ionic liquid. A general formula (I) shown in the specification represents the structure of the temperature sensitive ionic liquid, the ionic liquid is formed by a 8-hydroxyquinoline cation and anions comprising a tetrafluoroborate radical, a methane sulfonate radical, a bisulfate ion and a dihydrogen phosphate radical, and the solubility of ionic liquid in ethanol is temperature sensitive. The introduction of a hydroxy group to 8-position of aquinoline ring greatly increases the acidity and improves the esterification reaction yield. The ionic liquid can be mixed with ethanol to form one phase at a high temperature, and the ionic liquid and a product rapidly separate to different phases at room temperature or a low temperature, so the whole reaction system ensures high catalytic efficiency of a homogeneous reaction and makes separation and recovery simple, avoids the limitations of limited two-phase catalytic efficiency and the disadvantage of difficult ion liquid recovery of homogeneous catalysis, and accords with the principle of green chemistry. The esterification yield of the esterification reaction of the long-chain fatty acid under the catalysis of the ionic liquid reaches 90.6-95.5%.

Description

technical field [0001] The invention relates to a preparation method of a temperature-sensitive ionic liquid of 8-hydroxyquinoline cation and its application in long-chain fatty acid ethyl ester reaction, and belongs to the technical field of combining green chemistry and organic chemistry catalytic reaction methods. Background technique [0002] Esters are a class of excellent organic solvents, fine chemicals and pharmaceutical intermediates, etc., and have a wide range of applications. In order to speed up the esterification reaction rate, various types of acid-base catalysts are added. Traditionally, inorganic liquid acid and alkali catalysts are used, and its main disadvantage is that it is difficult to recycle. In recent decades, relatively new solid acid-base catalysts have been adopted to solve the problem of recycling. However, the above-mentioned catalysts have limitations in practice due to their traditional preparation methods and narrow application range, showi...

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Problems solved by technology

However, the above-mentioned catalysts have limitations in practice due to their traditional preparation methods and narrow application range, showing many shortcomings: for example: too high acidity, unstable performance, complicated preparation process, high cost, etc. (Deng Youquan. Ionic Liquids—Properties, Preparation and Applications. Beijing: Sinopec Press, 2006)

It can be mixed into one phase at high temperature in the ethanol system, and at room temperature or low temperature, the ionic liquid and the product rapidly transform into a solid-liquid phase, so that the entire reaction system not only ensures high catalytic efficiency during homogeneous reactions, but also enables Separation and recovery are more convenient, which solves the problem of low temperature sensitivity of quinoline-based ionic liquids in ethanol systems, inability to efficiently catalyze ethyl esterification and easy recovery

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