Study On The Preparation Of 2-Methyleneglutaronitrile (MGN) By Dimerization Of Acrylonitrile In Ionic Liquid

Imidazolium ionic liquids were selected as reaction medium in the process of the preparation of 2-methyleneglutaronitrile (MGN), dimerized by acrylonitrile, in this paper. Process conditions of the preparation of MGN in ionic liquids (A and D) were investigated and optimized then.A and D were originated from the quaterisation reaction. The effects of different reaction temperature, reaction time and feed composition on the reaction mentioned above were studied to ensure a better operation conditions:80℃,24h and reagent molar ratio 1.2 for A and reaction yield 93.8%; 50℃,8h and reagent molar ratio 1.2 for B and reaction yield 92.8%. Melting points, densities and water contents were determinated by melting point method, hydrometer method, and Kart-fischer method respectively. The purity of ionic liquid was determinated by electrometrictitration of silver nitrate. Accordingly, the kinetics characteristic of quaterisation of A was obtained. Kinetic can be described as:ν=dc/dt=-κc2. The reaction rate at 80℃,85℃and 90℃is 0.06975 mol-1·dm-3·h-1,0.08265 mol-1·dm-3·h-1 and 0.10103 mol-1·dm-3·h-1 respectively. And then activation energy (Ea) and exponential factor (A) were obtained:Ea=3.95×104 J·mol-1, A=exp(lnko)= 4.78×104 L·mol-1·h-1C and D were produced by two-steps double decomposition of A and B. Solubility, hygroscopicity and density were determinated by solubilitymethod, hydrometermethod, and Karl-fischer method respectively.The effects of reaction temperature, reaction time, catalyst and ionic liquid amount on the yield of dimerization reaction were investigated by orthogonal experiment and single factor experiments to ensure a better operation conditions:55℃,24h, catalyst 1.2g, A 4.0g and reaction yield 55.4%; 50℃,24h, catalyst 2.0g, D 5.0g and reaction yield 90.7%.The experiment results of the recycle and cycle use of ionic liquid indicated that the yield of acrylonitrile dimerization reaction changed little during four times of recycle use for both ionic liquids. Therefore, it’s convenient to recycle ionic liquid for cycle use at least four times.