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氨基磺酸催化合成乙酸异戊酯需要注意哪些事项?
来源:http://www.jnjrh.com 日期:2019-08-27 发布人:admin
氨基磺酸作催化剂,环己烷作带水剂,使乙酸与异戊醇反应合成乙酸异戊酯,在醇过量的条件下,可使产率达到97.6%。
Isoamyl acetate was synthesized by the reaction of acetic acid with isoamyl alcohol using sulfamic acid as catalyst and cyclohexane as water carrier. Under the condition of excessive alcohol, the yield could reach 97.6%.
在装有恒压式滴液漏斗、分水器、冷凝管和温度计的三颈瓶中,加入催化剂氨基磺酸、冰醋酸和带水剂环己烷,在滴液漏斗中加入异戊醇。在油浴加热和搅拌下,滴加异戊醇并回流,环己烷循环带水至分水器中,直至水层不再增加,反应时间为2h。蒸去环己烷,将产物和催化剂分离,催化剂氨基磺酸留在三颈瓶底,可重复使用。产物用无水硫酸镁干燥后蒸馏,将134℃以前的馏分作为反应循环物,134-142℃馏分再蒸一次。
Catalyst aminosulfonic acid, glacial acetic acid and water-carrying agent cyclohexane were added to the triple-necked bottle with constant pressure dropping funnel, water separator, condensation tube and thermometer, and isoamyl alcohol was added to the dropping funnel. Under oil bath heating and stirring, isoamyl alcohol was dripped and refluxed. Cyclohexane was circulated to the water separator until the water layer did not increase and the reaction time was 2 hours. Cyclohexane was evaporated and the product was separated from the catalyst. The catalyst aminosulfonic acid remained at the bottom of the three-neck bottle and could be reused. The product was distilled after drying with anhydrous magnesium sulfate, and the fraction before 134 was used as the reaction cycle. The fraction at 134 - 142 was steamed again.
酯化反应通常是比较慢的,除加入氨基磺酸催化剂之外,还需加热才能加速反应的进行。由于反应生成的水分别与异戊醇和乙酸异戊酯生成恒沸混合物,恒沸点在93-95℃左右,需要用环己烷为带水剂,使生成的水不断被除去,从而反应温度升高有利于水的分离和提高产率。
氨基磺酸
Esterification reaction is usually slow. In addition to aminosulfonic acid catalyst, heating is needed to accelerate the reaction. Because the water produced by the reaction is mixed with isoamyl alcohol and isoamyl acetate to form an azeotropic mixture, and the azeotropic point is about 93-95 (?) C, cyclohexane is needed as a water-carrying agent, so that the water generated is continuously removed, thus the higher the reaction temperature, the better the separation of water and the higher the yield of water.
由于酯化反应是可逆反应,加入带水剂可使平衡向生成酯的方向移动,并且可起到控制温度的作用,从而提高产率。传统方法用苯、甲苯为带水剂,考虑到苯和甲苯的毒性对环境有影响,作者采用环己烷为带水剂收到了良好的效果。带水剂用量的多少影响着酯化反应的程度,过少不利于分离水,过多会使反应温度下降,酯的产率降低。
Since the esterification reaction is reversible, adding water-carrying agent can make the equilibrium move towards esterification and control the temperature, thus increasing the yield. In traditional methods, benzene and toluene are used as water carriers. Considering the toxicity of benzene and toluene to the environment, cyclohexane is used as water carriers and good results have been achieved. The amount of water-carrying agent affects the degree of esterification, too little is not conducive to the separation of water, too much will reduce the reaction temperature and the yield of esters.
氨基磺酸可以将羧酸活化成为亲核加成底物,这时醇作为亲核试剂就可进攻底物,稍过量的醇可循环使用以提高收率。
Aminosulfonic acid can activate carboxylic acid into nucleophilic addition substrates. Alcohol as nucleophilic reagent can attack substrates. A little excess of alcohol can be recycled to improve yield.
氨基磺酸可以代替硫酸作酯化反应的催化剂,采用环己烷作带水剂,防止了氨基磺酸高温分解,并能及时移去反应生成的水,提高乙酸异戊酯产率可达97.6%,的产率。
Aminosulfonic acid can be used as catalyst instead of sulfuric acid for esterification and cyclohexane as water-carrying agent to prevent the high-temperature decomposition of sulfamic acid, remove the water generated in the reaction in time, and increase the yield of isoamyl acetate to 97.6%.