催化合成3,3,4-三甲基-4-戊烯-2-酮

Studies on Catalytic Synthesis of 3,3,4-Trimethyl-4-penten-2-one

用无水ZnCl2催化2,3 二甲基 2 丁烯(DMB)与乙酐(即Ac2O)的酰基化反应合成了3,3,4 三甲基 4 戊烯 2 酮TMP).ZnCl2是在室温下对2,3 二甲基 2 丁烯与乙酐酰基化反应的一种有效催化剂.2,3 二甲基 2 丁烯/ZnCl2的适宜摩尔比是1∶0.4.在使用不同处理条件下得到ZnCl2催化剂的情况下,所得酰化产品TMP的产率几乎相同.当n(DMB)/n(Ac2O)分别为1∶1或1∶2时,发现ZnCl2只能部分溶解于液相中,所得酰化产品的产率较低.DMB过量对该酰基化反应产生负面影响.当用ZnCl2作催化剂时,DMB与乙酐的酰化反应仅需在较低的反应温度(通常为室温)下便可实现,并可获得高产率的酰化产品.反应时间对酰化产品TMP产率的影响取决于催化剂的用量,通常情况下,当使用少量催化剂时,较长的反应时间导致TMP产率提高.已知量的乙酸加入到反应体系中导致DMB酰基化反应的速率明显下降.加料顺序的改变对酰基化反应未见明显影响.

3, 3, 4-Trimethyl-4-penten-2-one(TMP) was synthesized by the acylation of 2, 3-dimethyl-2-butene (DMB)with acetic anhydride in the presence of zinc chloride. Zinc chloride is an effective catalyst for the acylation of 2, 3-dimethyl-2-butene by acetic anhydride at room temperature. An appropriate molar ratio of 2,3-dimethyl-2-butene/ZnCl2 is 1:0.4. In the case of using ZnCl2 catalysts obtained under the different treatment conditions, almost the same yields of the acylated product are obtained. When the acetic anhydride/olefin molar ratio is 1:1 or 2:1, ZnCl2 dissolves only partially in the liquid phase, and a low yield of the acylated product is obtained. An excess of olefin produces a negative effect on the reaction. Theacylation of 2,3-dimethyl-2-butene by acetic anhydride using zinc chloride as catalyst needs only a lowreaction temperature (usually at room temperature) to achieve a high yield of the acylated product. The effect of reaction time on the yield of TMP depends upon the amount of the catalyst used, in general, in the case of using small amounts of catalyst longer times lead to a rise in the yield. The addition of a given amount of acetic acid to the reaction system decreases markedly the rate of the acylation reaction. The order of addition of the reagents has no significant effect on the acylation reaction studied in this paper.