Preparation of Isobutyl Acrylate and Cyclohexyl Acrylate

Isobutyl acrylate (IBA) and cyclohexyl acrylate (CHA) were synthesized through a modified Reppe process using normal pressure, ester-exchange reaction between methyl acrylate (MA) and iso-butyl alcohol or cyclohexyl alcohol and also through direct esterification of acrylic acid (AA) with alcohols. 1. Modified Reppe process using normal pressure under continuous operation. This reaction is affected by various factors such as molar ratio, acetylene feeding velocity, reaction temperature, circulation velocity, viz, agitating velocity and so on. The best reaction conditions were as follows : a) IBA Acetylene feeding velocity : 200 /hr. Reaction temperature : 40°C Circulation velocity for the reaction mixture : 1, 800 /hr. Reaction composition : IBA/i-BuOH=3040/7060 (wt.) The yield was about 75% and the purity of IBA was 97.597 80%. b) CHA Acetylene feeding velocity : 150 /hr Reaction temperature : 40°C Circulation velocity for the reaction mixture : 1, 500 /hr Reaction composition : CHA/HOH= 5070/5030 (wt.) The yield was about 75% and the purity of CHA was 97.297 60%. 2. Ester-exchange reaction of MA with i-BuOH or HOH. MA/acohol molar ratio of 1.52/1 was employed below 110°C for 5 hrs with stirring. The yield of IBA and CHA was 95 and 85%, respectively. The apparent activation energy for the ester-exrchange reaction between MA and i-BuOH or HOH was 13.3, 16.3 kcal/mol respectively and the reaction was second order in the concentrations of MA and an alcohol. 3. Esterification of AA with i-BuOH or HOH. The esterification of AA in the presence of sulfuric acid was tested. AA/alcohol/organic solvent= 1/1. 2/0.8 (molar ratio) was employed below 110°C for 5 hrs with stirring. The yield of IBA and CHA was 96 and 89%, respectively. The apparent activation energy for the esterification between AA and i-BuOH was found to be 15.9 kcal/mol and the reaction was second order in the concentration of AA.