Propylation, of benzene

Propylation of benzene with propylene, catalyzed by supported phosphoric acid (or related catalysts such as AlCl ), gives cumene [98-82-8] in another important industrial process. Cumene (qv), through the intermediacy of cumene hydroperoxide, is used in the manufacture of phenol (qv). Resorcinol similarly can be made from y -diisopropylbenzene (6). 

Consequently, stronger solid acids were needed to activate the ethylation reaction. The solid acids that were available earlier exhibited only limited acidity, which was sufficient to promote the propylation of benzene with propylene at reasonable temperatures and pressures, but it was not high enough to promote ethylation of benzene with ethylene under similar conditions. 

Further evidence for the need of protons for carboniogenic activity is given by Matsumoto et al. (58), who have shown that NaY, which is inactive for cumene cracking, can be made into an active catalyst by the addition of HCl. This effect of HCl is reversible. In contrast, silica gains no activity on HCl addition, and y-alumina is activated irreversibly by HCl. Similar observations were made by Kolesnikov et al. (51), who found that in the propylation of benzene, a treatment with propyl chloride promotes the activity of NaY and of type X zeolites. 

The zeolites have to be selected according to their pore and cavity dimensions to obtain the desired result. Belhissi et al. [57] studied the propylation of benzene in the Uquid phase over H-ZSM-5, H-Beta (Si/Al = 14), HUSY (Si/Al = 3) and the classical phosphorous inq)regnated kieselguhr catalyst at 150°C, 3 MPa, benzene/propene ratio 7.4 and a ace time of 0.06 min. They observed after one hour on stream, that H-ZSM-5 was hardly active and HY was at that time less active than H-Beta. 

Different alkylation reactions have been investigated with Nafion as a catalyst. An example is the propylation of benzene to cumene. Large rate enhancements were observed on use of Nafion-silica composites, compared with bulk polymeric catalysts such as pure Nafion NR50 and Amberlyst-15. The activity of the composite was ca 6-7 times higher than that of pure Nafion beads on the basis of the total amount of catalyst. If this correlation were made on the basis of the total number of acid sites on Nafion, the activity would be ca 50 times higher. Amberlyst-15 was about twice as active as the Nafion NR50 particles (on the basis of the total amount of catalyst) [7]. 

The methylation of benzene with methyl chloride proceeds to give predominantly dimethylbenzene (xylenes) and tetramethylbenzene, with about 10% hexam-ethylbenzene. In the propylation of benzene with 1-chloropropane, not only does polyalkylation occur, but there is also a considerable degree of isomerization of the n-propyl group to the isopropyl isomer (Scheme 5.2-6). In the butylation, complete isomerization of the butyl side chain occurs to give only sec-butyl benzenes. 

A review on cage and window effects in mainly hydroconversion of alkanes with zeolites [73] shows that bi- and even trinodal distributions of product carbon numbers can be formed. In the erionite (ERI) cage Cs hydrocarbon fragments are selectively trapped, thus undergoing intense secondary cracking. This effect was confirmed in the ketonization of carboxylic acids [74]. Alternatively, in cases of slow diffusion (and counterdiffusion), viz. in the liquid-phase propylation of benzene in mordenite, the possibihty of having pore-mouth catalysis was advanced [75]. Multinodal product distributions from... 

As in ethylbenzene production, alkylation can be performed either in the gas or in the liquid phase. Propylation of benzene in the liquid phase is achieved with sulfuric acid or aluminum chloride as catalyst at 30 to 40 °C, or with hydrogen fluoride at 50 to 70 °C, and propylene pressures up to 7 bar. The propylene used must be largely free from other olefins. A propylene/propane mixture, such as occurs in refinery gases, can be used for the reaction, since propane is not converted and can readily be stripped from the reaction products. 

The second side reaction in aromatic alkylation is skeletal rearrangement (Section 9-3). For example, the attempted propylation of benzene with 1-bromopropane and AICI3 produces (l-methylethyl)benzene. 

The inflammable solvents most frequently used for reaction media, extraction or recrystallisation are diethyl ether, petroleum ether (b.p. 40-60° and higher ranges), carbon disulphide, acetone, methyl and ethyl alcohols, di-Mo-propyl ether, benzene, and toluene. Special precautions must be taken in handling these (and other equivalent) solvents if the danger of Are is to be more or less completely eliminated. It is advisable to have, if possible, a special bench in the laboratory devoted entirely to the recovery or distillation of these solvents no flames are permitted on this bench. 

Medium Boiling Esters. Esterificatioa of ethyl and propyl alcohols, ethylene glycol, and glycerol with various acids, eg, chloro- or bromoacetic, or pymvic, by the use of a third component such as bensene, toluene, hexane, cyclohexane, or carbon tetrachloride to remove the water produced is quite common. Bensene has been used as a co-solvent ia the preparatioa of methyl pymvate from pymvic acid (101). The preparatioa of ethyl lactate is described as an example of the general procedure (102). A mixture of 1 mol 80% lactic acid and 2.3 mol 95% ethyl alcohol is added to a volume of benzene equal to half that of the alcohol (ca 43 mL), and the resulting mixture is refluxed for several hours. When distilled, the overhead condensate separates iato layers. The lower layer is extracted to recover the benzene and alcohol, and the water is discarded. The upper layer is returned to the column for reflux. After all the water is removed from the reaction mixture, the excess of alcohol and benzene is removed by distillation, and the ester is fractionated to isolate the pure ester. 

By operating in this manner 10-(2-methyl-3-chloro-propyl)phenothiazine is obtained. A mixture of 10-(2-methyl-3-chloro-propyl)phenothiazine and 1-[2-(2-hydroxyethoxy)ethyl] piperazine is then heated at 110 -120°C for 20 hours. After cooling, the reaction product is dissolved in 200 cc of benzene and the solution washed several times with water. 

The mixture was then cooled to 20°C and 19 gallons of benzene was added. This was followed by the introduction of 123.5 lb (2.80 Ib-mols) of dry powdered sodium fluoride (95% pure). The mixture was stirred and heated to the refluxing temperature in a period of 1 hour and held at this temperature (95° to 98°C) for 4 hours. The product obtained was cooled and filtered to yield a filter cake which was washed with three 5-gallon portions of benzene. The filtrate and washing were then combined and distilled under reduced pressure. There was obtained 158 lb (74% yield of theory based on PCI3) of diiso-propyl fluorophosphate, 8P 62°C at 9 mm and 46°C at 5 mm. 

The solid residue obtained is recrystallized from a mixture (15 85) of benzene and cyclohexane and there is obtained 3-methoxy-10-[2-methyl-3-(4-hydroxy-1-piperidyl)-propyl]-phenthiazine (5.7 grams) as a white crystalline powder, MP 137°-13B°C. 

Propyl-methyl-carbinyl allyl barbituric acid (also called allyl 1-methyl-butyl barbituric acid) may be prepared as follows 1 mol of propyl-methyl-carbinyl barbituric acid is dissolved in a suitable vessel In a 10 to 35% aqueous solution of 1 mol of potassium hydroxide. To this are added somewhat in excess of 1 mol of allyl bromide, and alcohol equal to about 10% of the total volume of the solution. The vessel Is agitated for 50 to 75 hours. At the end of this time, the solution, which may still exhibit two layers, is concentrated to about one-half its volume to remove the excess allyl bromide and the alcohol. On cooling, an oily layer, which is propyl-methyl-carbinyl allyl barbituric acid, separates out as a sticky viscous mass. It is dried, washed with petroleum ether, and dissolved in the minimum amount of benzene. Any unreacted propyl-methyl-carbinyl barbituric acid, which does not dissolve, is filtered off. The addition of petroleum ether to the clear filtrate causes the propyl-methyl-carbinyl allyl barbituric acid to precipitate as an oily mass. 

Scheme 5.1-49 The alkylation of benzene with methyl chloride or n-propyl chloride in an ionic liquid.

Subsequently, rate coefficients were determined for the zinc chloride-catalysed bromination of benzene, toluene, i-propyl-benzene, r-butylbenzene, xylenes, p-di-f-butylbenzene, mesitylene, 1,2,4-trimethyl-, sym-triethyl-, sym-tri-f-butyl-, 1,2,3,5-and 1,2,4,5-tetramethyl- and pentamethylbenzenes, all at 25.4 °C and in acetic acid, and it was shown that the reaction was inhibited by HBr.ZnCl2 which accumulates during the bromination and was considered to cause the first step of the reaction (formation of ArHBr2) to reverse320. The second-order coefficients for bromination of o-xylene at 25.0 °C were shown to be inversely dependent upon the hydrogen bromide concentration and the reversal of equilibrium (155)... 

The lower reaction rates obtained with this catalyst permitted measurements of the reaction rates of benzene and toluene with a range of alkyl halides including /-propyl and /-butyl bromides, the rate being followed in some cases by the... 

The reaction of benzene with excess (3-chloropropyl)trichlorosilane afforded peralkylated product, hexakis(3-(trichlorosilyl)propyl)benzene. in moderate yield... 

The hydroarylation of olefins is also achieved by using a ruthenium catalyst, TpRu(CO)(NCMe)(Ph) (Tp = hydridotris(pyrazolyl)borate) (Equation (34)).39 The reaction of benzene with ethene is catalyzed by the ruthenium complex to give ethylbenzene (TN = 51, TOF = 3.5 x 10 3mol 1 s-1 at 90 °G for 4h). The ruthenium-catalyzed reaction of benzene with propene gives the hydroarylation products with a 1.6 1.0 ratio of -propyl to isopropylbenzene, with 14 catalytic turnovers after 19 h. 

Styrene is produced by the catalytic vapor phase dehydrogenation of ethylbenzene. Ethylbenzene is made by the Friedel-Crafts condensation of ethylene and benzene. Styrene is also produced by the palladium acetate-catalyzed condensation of ethylene and benzene and by the dehydration of methylphenylcarbinol obtained by the propylation of ethylbenzene. Because of the toxicity of styrene, its concentration in the atmosphere must be severely limited. 

Preparation of l,4-bis-(dimethyl-[3-(methacryloyloxy)propyl]silyl)benzene... 

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