β-亚甲基苯乙醇的合成工艺

Synthesis of β-methylene phenethyl alcohol

针对β-亚甲基苯乙醇合成工艺中反应条件较苛刻、操作较复杂、产物难分离纯化和总收率偏低的问题,以苯乙醛为原料,经亚甲基化反应和均相氢转移还原反应两步合成了β-亚甲基苯乙醇.分别考察了两步反应投料比、催化剂的用量和反应温度等条件对产物收率的影响.结果表明,亚甲基化反应在50℃,投料比为n(苯乙醛)∶n(甲醛)∶n(二甲胺盐酸盐)=1∶1.2∶0.2的条件下反应16h最佳,反应液经减压蒸出甲醛、异丙醇和水,中间产物无需进一步纯化,直接用于还原反应;氢转移还原反应于60～65℃下反应12h,投料比n(α-亚甲基苯乙醛)∶n(异丙醇铝)=1∶0.1,反应液用乙酸乙酯和水萃取、纯化,得到β-亚甲基苯乙醇.产物的总收率可达86%,纯度98.5%以上,其结构经核磁共振氢谱确认.该合成工艺反应条件温和、操作简单、产物易于分离和纯化、收率高,具有一定的工业化价值.

To improve the yield of the βmethylene phenethyl alcohol and avoid the disadvantages including harsh conditions, hard to control the reaction process, difficult purification and low yield in the present routes, an approach to synthesize βmethylene phenethyl alcohol was investigated with phenylacetaldehyde as the raw material by methylenation and hydrogen transfer reaction. The effects of molar ratio of material, amount of catalyst and reaction temperature on the yield of the product were discussed, the yield of βmethylene phenethyl alcohol reached 86% with purity of over 98.5% when the methylenation was carried out at 50 ℃ for 16 h and ratio of n（plenylacetaldehyde） ; n（formaldehyde）： n（organic amine salt） = 1 ： 1. 2 ： 0. 2, formaldehyde, isopropanol and water were distilled from the reaction liquid by vacuum evaporation and the intermediate product was directly used without further purification; the hydrogen transfer reaction was carried out at 60-65 ℃ for 12 h with n（intermediate） ：n（aluminum isopropoxide）= 1 ：0. 1, the concentrate was extracted by ethyl acetate and water. The structure of the product was confirmed by 1H NMR. This process has the characteristics of mild reaction conditions, simple operation, easy to be isolated and purified, high total yield, which is feasible for industrialization.