Preparation of isoamyl acetate by reaction-distillation using ionic liquid as catalyst

摘要

In this thesis, isoamyl acetate was synthesized by reaction-distillation, using acetic acid and isoamyl alcohol as starting materials, using acid ion-liquid as catalyst and extracting agent. These are some factors were investigated, including different catalysts, ratio between acid and alcohol, amount of Ion-Liquid, and reflux ratio. Technology to prepare iso-pentyl acetate was optimized with single factor experiments. Results showed that acid ion-liquids are good catalysts and extracting agents, which increased the purity and yield of iso-pentyl acetate, as well as diminished the azeotropic point of iso-pentyl acetate and acetic acid. The optimal technological conditions are as following: ratio of acid:alcohol 2:1 (mol), dosage of ion-liquid V = 2 mL, reflux ratio R = 2.5. Under this condition, purity of obtained iso-pentyl acetate is 99%, and the yield is 85%. Isoamyl acetate is a kind of colorless transparent liquid with a pleasant aroma of banana and pear, which is used in perfumery, medicines, paints, printing and dyeing industry. It is a wide range of light industrial production of raw materials, and it is commonly made by acetic acid and isoamyl alcohol esterification which use concentrated sulfuric acid as catalysts in industry. Due to concentrated sulfuric acid corrosion and pollution of the environment and other shortcomings, seeking high performance, green, new catalyst has become one of the important objectives of the modern chemical industry. Ionic liquids are liquid salt at room temperature that are made up of organic-inorganic or organic cations and anions. They have non-volatile, low melting point, wide liquid range, high stability, recyclable, and other unique properties. They are considered to be green solvent in modern organic synthesis and catalyst with good promising [2, 12]. This article attempts to use 1-Octyl methyl imidazole -3-hydrogen sulfate ([OMIm]HSO_4) ionic liquids, used reaction-distillation to prepare isoamyl acetate, reaction and separating from the raw materials are proceeding at the same time, meanwhile isoamyl alcohol of high purity was recieved. This method has the advantages of environment friendly, high purity, catalyst recovery, etc.