2，3-戊二酮的合成研究

Study on the Synthesis of 2,3-Pentanedione

摘要:

乙醛和丙醛经3-乙基-4-甲基- 5-(2-羟乙基) -1，3-噻唑溴盐催化交叉偶联反应生成C5偶姻为主的偶姻混合物，偶姻混合物再经H2O2间接氧化、分离制备了2，3-戊二酮。优化的偶联反应条件是：m（乙醛）：m（丙醛）: m(催化剂)：m(Na2CO3)=110：90:2:1；反应温度120~130℃；压力为1MPa。乙醛和丙醛转化率分别达到94%和95%，C5偶姻产率为48.8%，偶姻总产率为90%。混合偶姻在浓H2SO4存在下，用质量分数30%H2O2/FeSO4·7H2O氧化, m（FeSO4·7H2O）：m（浓H2SO4）：m（H2O）：m（偶姻）：m（30%H2O2）=11：2：4：2：3，2,3-戊二酮相对于偶姻的总质量产率为45.5%，邻二酮产物总产率为84%。经常压分馏，可以分别得到质量分数≥98%的2,3-戊二酮、丁二酮和3,4-己二酮产品。铁离子氧化剂重复使用,邻二酮化合物收率没有明显下降。该合成方法不使用有机溶剂，采用双氧水间接氧化，是一种绿色的合成方法。

Abstract:

The acyloin mixture which mostly consists of C5 acyloin was synthesized from acetaldehyde and propional by cross-condensation under the catalysis of 3-ethyl-5-(2-hydroxyethyl)-4-methyl-1,3-thiazolium bromine.2,3-Pentanedione was prepared through oxiding the mixture indirectly by hydrogenperoxide and separating.The optimized cross-condensation reaction conditions: m（acetaldehyde）：m（propional）: m(catalyst)：m(sodium carbonate)=110：90:2:1；reaction temperature was 120~130℃；the pressure was 1Mpa.the conversions of acetaldehyde and propional were 94% and 95% respectively, The yields of C5 acyloin was 48.8%, the total condensation products amount to 90%.In the presence of concentrated sulfuric acid, acyloin mixture were oxidized by 30%H2O2/ FeSO4·7H2O, m（FeSO4·7H2O）：m（sulfuric acid）：m（water）：m（acyloin）：m（30%H2O2）=11：2：4：2：3, the yield of 2,3-pentanedione relativing to the gross weight of acyloin was 45.5%，the total yields of vic-diketones amount to 84%. 2,3-Pentanedione、butanedione and 3,4-hexanedione can be obtained with purities more than 98% by atmospheric distillation, the iron salt could be reused without obviously decrease of the yields of vic-diketones.The method did not use organic solvent and used H2O2 as oxidant indirectly.It was a green process.