Synthesis of Cumene (Isopropylbenzene) from Diisopropylbenzenes in thepresence of Benzene using Triflic acid as catalyst at room temperature

Abstract

ABSTRACT Cumene (isopropylbenzene) is presently produced from benzene and propylene using either solid phosphoric acid or anhydrous aluminium chloride or zeolite as catalyst. Large amounts of m- and p- diisopropylbenzenes (DIPB) were produced as by-products from the above processes. Therefore, in order to study the activity of trifluoromethane-sulphonic acid (triflic acid) as catalyst to produce higher yield of cumene from DIPB isomers a series of isomerization and transalkylation reactions, of m- and p-isomers in benzene with different molar ratios 1:1:1, 1:3:1 and 1:6:1 of isomer to benzene to catalyst respectively with each isomer using triflic acid as catalyst, were carried out in liquid phase at room temperature and under nitrogen atmospheric pressure. In the case of 1:1:1 molar ratio of m-isomer or p-isomer to benzene to catalyst respectively transalkylation reaction gave a higher yield of cumene (ca. 46 mol%) based on benzene and isomer. It was found that when the molar ratio of isomer to benzene decreases the yield of cumene decreases. In the case of 1:6:1 molar ratio of either m- or p-isomer to benzene to catalyst, yield of cumene decreases from (46 mol%) to about (20 mol%). The conclusion that can be drawn from these series of reactions is that, in all cases the rate of transalkylation of DIPB isomers is faster than the rate of isomerization leading to cumene with a higher yield of (46 mol%). Therefore triflic acid as a catalyst is efficient and effective in producing more yield of cumene from the by-products of isopropylation reactions at room temperature and atmospheric pressure. It is more superior than the other catalysts such as supported phosphoric acid aluminium chloride and zeolite, which are currently used in industries at higher pressures and temperatures.