香料王朝酮中间体4,4-二甲基-2-环己烯-1-酮的制备方法研究

Study on the Preparation Method of 4,4-Dimethyl-2-cyclohexen-1-one

王朝酮是一种类似于格蓬香同时具有菠萝的青香及风信子香气的香料,4,4-二甲基-2-环己烯-1-酮是合成王朝酮的重要中间体。目前合成此中间体多以有剧毒的甲基乙烯基酮作为原料,违背了绿色化学的原则。本实验对此路线进行了优化,以二乙胺盐酸盐、多聚甲醛、丙酮为起始原料,替代了有剧毒的甲基乙烯基酮,经曼尼希反应合成4-二乙氨基-2-丁酮,再与异丁醛进行迈克尔加成成功制备目标产物,并且优化了反应条件(反应温度、反应物投料比和反应时间)。结果表明:当4-二乙氨基-2-丁酮和异丁醛的投料比为1∶1.2、反应时间为8h、反应温度为80℃时,4,4-二甲基-2-环己烯-1-酮的产率可达83%。

Dynascone is a kind of spice that is similar to Gapeng and has the fragrance of pineapple and hyacinth. 4,4-Dimethyl-2-cyclohexen-1-one is an important intermediate for the synthesis of dynascone. At present, most of the synthesis methods of this intermediate use highly toxic methyl vinyl ketone as a raw material, which violates the principles of green chemistry. In this experiment, this route was optimized. Using diethylamine hydrochloride, paraformaldehyde, and acetone as starting materials, instead of the highly toxic methyl vinyl ketone, 4-diethylamino-2-butanone was synthesized by Mannich reaction, and then the target product was successfully prepared by Michael addition with isobutyraldehyde. The route is simple and environmentally friendly. In addition, the reaction conditions(reaction temperature, reactant feed ratio and reaction time) were optimized. The results showed that the feed ratio of 4-diethylamino-2-butanone and isobutyraldehyde was 1∶1.2, the reaction time was 8 h, and the reaction temperature was 80 ℃, the yield of 4,4-dimethyl-2-cyclohexen-1-one reached 83%.