关键词: 2-丁酮, 乙偶姻中间体, 间接电氧化, 碘化钾, 甲醇

Abstract:

Acetoin (3-hydroxy-2-butanone) is an important food spice. As a platform compound, it is widely used in medicine, tobacco, cosmetics, chemical material and other industries. In this paper, α-hydroxylated acetal, an intermediate of acetoin, was prepared from 2-butanone by indirect electrooxidation in the plate and frame electrolytic cell, in which graphite plates were used as both an anode and a cathode, while KOH as an electrolyte and KI as a catalyst. Acetoin could be prepared by hydrolysis in acidic aqueous solution from acetoin intermediate. The effects of current density, electrolyte flow rate between the plates, 2-butanone concentration and electrolysis temperature on the yield and efficiency of acetoin intermediate were investigated. Under the optimized conditions, namely, the current density of 40 mA·cm^-2, the flow rate of 6.4 cm·s^-1, the 2-butanone concentration of 1.75 mol·L^-1, the electrolysis temperature of 30 °C, and the passed charge of 1.5 F·mol^-1, the yield and current efficiency of the acetoin intermediate could reach 78.9% and 40.1%, respectively. The cyclic voltammetric tests showed that during electrolysis, iodine ions were oxidized to iodine on the anode, while methanol was reduced to methoxy anion on the cathode. 2-butanone reacted with the electrolytic products, and eventually, the acetoin intermediate was formed.

Key words: 2-butanone, acetoin intermediate, indirect electrooxidation, potassium iodide, methanol