Design and teaching practice of pyridine ionic liquid green chemical catalysts: cultivation of innovation ability in the synthesis experiment of ethyl acetate

Addressing the issues of equipment corrosion, waste acid pollution, and difficult-to-control side reactions caused by the use of concentrated H₂SO₄ as a catalyst in the traditional synthesis process of ethyl acetate, this study developed a green catalytic system of N-butylpyridinium bromide ionic liquid and established a "ionic liquid catalysis-inquiry experiment" dual-drive teaching model. Using n-bromobutane as a raw material, N-butylpyridinium bromide ionic liquid was synthesized through the quaternization reaction of pyridine, and its structure was determined using infrared spectroscopy and proton nuclear magnetic resonance technology. By adjusting the reaction temperature, time, and amount of catalyst, the catalytic activity, selectivity, and cyclic stability of this catalytic system were studied. The results showed that when 15 mmol of ionic liquid reacted at 135 ℃ for 90 min, the yield was 52.3%, and the catalyst could be stably recycled 5 times. The optimized catalytic system was superior to the traditional process in terms of product yield, purity, and cyclic usability of the catalyst, and the separation and recovery process of the catalyst was simple, effectively reducing environmental pollution. In teaching, the method of "molecular design-process innovation-teaching reconstruction" was adopted to guide students in designing ionic liquid catalysts to replace concentrated H₂SO₄ and achieve green synthesis of ethyl acetate. By optimizing reaction conditions, mastering multivariable regulation and spectrum analysis methods. Reconstructing inquiry experimental procedures, enhancing experimental design capabilities and green chemistry cognition, and promoting the transformation of traditional experiments to integrated, innovative teaching. This study not only realized the green upgrade of experimental processes, but also integrated scientific research achievements into teaching practice, helping students build systematic scientific research thinking, providing a new path that can be promoted for the reform of chemistry experimental courses.