丁二烯和醋酸电化学合成山梨酸

正交实验表明 ,在醋酸 醋酐体系中 ,Mn2 + 电解氧化生成Mn3 + 的最佳工艺为 :电解时间 1h ,电解温度 90℃ ,电流密度 5mA/cm2 ,电解液 (2 0 0mL)组成 :5 70gMn(OAc) 2 ·4H2 O +2 0 .0gKOAc+醋酸与醋酸酐的混合物 ,V(HOAc)∶V(Ac2 O) =3∶1,电流效率为 75 %。稳态极化曲线和RDE实验表明 ,在石墨电极上 ,Mn2 + 阳极氧化的电极反应控制步骤为扩散 电荷传递混合控制。通过Mn3 + 氧化有丁二烯存在的醋酸 醋酐体系 ,合成山梨酸的前体乙酰氧基己烯酸 (AA) ,丁二烯的浓度为 0 2 5～ 1.0 0mol/L ,温度控制在 90℃ ,反应 5h ,得到AA。用盐酸可将AA进一步水解生成山梨酸 ,反应温度为 90℃ ,反应 5～ 6h ,产率超过 80 % (对AA而言 )。

Electrochemical Synthesis of Sorbic Acid from Butadiene and Acetic Acid

By orthogonal experiment the optimum conditions of anodic oxidation of Mn 2+ to Mn 3+ on the graphite electrode were determined.Electrolyte solution (200 mL) contained 5.70 g Mn(OAc)\-2·4H\-2O+20.0 g KOAc+(3∶1)HOAc∶Ac\-2O was electrolyzed for 1 hour under 5 mA/cm\+2 and 89-90 ℃.Steady-state polarization curves and RDE results showed that the rate determinating step was charge transfer and diffusion.Acetoxyhexanoic acid(AA),the precusor of sorbic acid,was produced via indirect electro oxidation in acetic acid acetic anhydride with Mn 3+ in the presence of butadiene.Concentration of butadiene was between 0.25～1.00 mol/L,and the reaction was carried out at 90 ℃ for 5 h.AA could be further converted to sorbic acid under the catalysis of HCl.The hydrolysis reaction was carried out at 90 ℃ for 5～6 h and the yield of sorbic acid was up to 80%(vs.AA).