Abstract:
METHOD OF CATALYTICALLY DEHYDROGENATING AN ALKYLATED AROMATIC HYDROCARBON HAVING AT LEAST TWO CARBON ATOMS IN A SIDE-CHAIN TO A VINYLAROMATIC HYDROCARBON BY RAPIDLY PASSING THROUGH A CATALYST ZONE A FEEDSTOCK WHICH HAS BEEN HEATED TO THE REACTION TEMPERATURE AND HAS BEEN OBTAINED BY MIXING A PREHEATED MIXTURE CONTAINING THE ALKYLATED AROMATIC HYDROCARBON AND OPTIONALLY STEAM AND OPTIONALLY THE VINYLAROMATIC HYDROCARBON WITH STEAM HEATED TO A TEMPERATURE ABOVE THE TEMPERATURE OF REACTION. THE PREHEATED MIXTURE HAS A TEMPERATURE OF FROM 400* TO 620* C. AND THE STEAM HEATED TO ABOVE THE REACTION TEMPERATURE HAS A TEMPERATURE OF FROM 820* TO 1,100* C. AND THE RESULTING FEEDSTOCK HAS A BLEND TEMPERATURE OF FROM 550* TO 700* C., THE TIME TAKEN FOR MIXING THE PREHEATED MIXTURE WITH THE HEATED STEAM BEING LESS THAN 0.1 SECOND WHILE THE RESIDENCE TIME OF THE RESULTING FEEDSTOCK BETWEEN THE MIXING POINT AND THE POINT OF ENTRY INTO THE CATALYST ZONE IS LESS THAN 0.2 SECOND. THE PRODUCTS ARE IMPORTANT MONOMERS AND COMONOMERS.
Abstract:
p-Dialkylbenzenes are produced by reaction of alkylbenzenes and olefins in the presence of an AlCl3/HCl catalyst also containing an aromatic hydrocarbon having a carbon-carbon double bond situated in conjugation to a benzene nucleus (which for convenience of definition is assumed to contain 3 conjugated double bonds). Suitable aromatic hydrocarbons include styrene, anthracene, 2 - phenyl - cyclohexene and 1,1,3-trimethyl - 5 - isopropylindene, others also being mentioned. m- and o-dialkylbenzenes and higher alkylated by-products may be transalkylated, e.g. with benzene or an alkylbenzene in the presence of a Friedel-Crafts catalyst. The examples are all directed to the production of p-diisopropylbenzene from cumene and propylene. In Example 6, the aromatic hydrocarbon catalyst component is 1,1,3-trimethyl-5-isopropyl-indene, and the process is carried out continuously in three vessels, in the first of which tri-isopropylbenzene by-product is transalkylated with benzene in the presence of AlCl3/HCl catalyst, a small amount of 1,1,3-trimethyl-5-isopropyl-indene being produced simultaneously, the whole mixture from this vessel then being passed to a second vessel together benzene, m-dialkylbenzene, AlCl3/HCl catalyst and o- and m-dialkylbenzene by-product further transalkylation taking place, and the cumene-propylene alkylation reaction taking place in the presence of the reaction mixture from the second vessel, by-products being separated and recycled to the first, second and third vessel as appropriate.