The Study On The Synthetic Process And Reaction Kinetics Of Isobutyl Benzene

Isobutyl benzene is the main intermediate which is used to synthesize ibuprofen with the characteristics of anti-inflammatory, antipyretic and analgesic. The main production method of isobutyl benzene is side-chain alkylation reaction of toluene and propylene at home and abroad. The production technology of isobutyl benzene is "YiGuoZhu synthetic" in our country, which has the disadvantages of the yield of isobutyl benzene is low and the selectivity is poor, side reaction are more, and production cost is higher, etc.The production technology of "step by step synthesis" had been used in this paper, according to the study on the reaction mechanism of synthesis of isobutyl benzene by the side-chain alkylation reaction of toluene and propylene. The catalytic system using potassium-sodium alloy as catalyst and potassium carbonate as the carrier was proposed with overall consideration of all factors such as the activity and economical efficiency of catalyst, by studying the effect of different catalyst systems on the yield of isobutyl benzene.Some influencing factor on the yield of isobutyl benzene such as reaction temperature, time, the dosage of catalyst, the speed of agitator, the mole ratio of reactants and so on were studied in the stainless steel autoclave reactor. The conversion rate of toluene could reach67.8%, the yield of isobutyl benzene was55.1%, and the selectivity of toluene was81.3%under the suitable reaction conditions of the molar ratio of propylene and toluene was0.85:1, the dosage of catalyst was2.5%of the mass of toluene, the dosage of potassium carbonate was8.0%of the mass of toluene, the dosage of dispersant A was0.5%of the mass of toluene, the benzylation reaction temperature was200℃, the benzylation reaction time was1.5h, the alkylation reaction temperature was210℃, the alkylation reaction time was6.0h, and the stirring speed was800r/min. The kinetics of side-chain alkylation of toluene and propylene to produce isobutyl benzene was studied in this paper. By pre-experiments, the following conclusions were obtained:(1) The effect of internal diffusion could be neglected when the mesh number of potassium carbonate was greater than150mesh.(2) The influence of external diffusion could be eliminated when the stirring speed was higher than800r/min. The dynamics equation was established under those conditions:...