Alkylation, of toluene

The inference of reactive surface formate species formed on zeolite CsOH/ Cs,NaX was further supported by CF MAS NMR spectroscopy (Fig. 27) (235,236). This in situ investigation was performed under CF conditions at a 

Production of cymenes or isopropyl toluene from toluene and propylene is an adaptation of cumene process from benzene and propylene. Through hydroperoxidation of cumene and cleavage of the resultant molecule, phenol and acetone are produced. 

There are a large number of phenol plants operating throughout the world based on alkylation of benzene. The alkylation and oxidation reactions are as follows  

DDM zeolite catalyst. It is claimed that the process is characterized by its low capital cost, superior product yield, high-purity product, corrosion fee environment, low operating cost, etc. 

Oxidation of cumene to cumene hydroperoxide and its cleavage to phenol and acetone were first published by H. Hock and S. Lang in 1944. This was commercialized shortly after World War II by the Distillers Co., Ukand Hercules Powder Co. in the USA. 

UOP is offering the technology for conversion of cumene to phenol and acetone based on UOP/Allied (Now Mobil) phenol process. Similarly, Kellog is offering the technology of Hercules and lately Dow-Mousanto Process. 

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Synthesis ofp-Ethyltoluene. j )i7n7-Ethyltoluene, the feedstock for j )-methylstyrene, is difficult to separate from the products of toluene alkylation with ethane using conventional acidic catalysts. The unique configurational diffusion effect of ZSM-5 permits -dialkylbenzenes to be produced in one step. In the alkylation of toluene with ethene over a chemically modified ZSM-5, -ethyltoluene is obtained at 97% purity (58). 

A modified ZSM-5 catalyst has a unique shape-selective property for producing -ethyltoluene [622-96-8] selectively by the alkylation of toluene [108-88-3] with ethylene (54). j )-Ethyltoluene is an intermediate in the production of poly -methylstyrene) [24936-41-2] (PPMS), which is reported to have... 

Gymene. Methyhsopropylben2ene [25155-15-1] can be produced over a number of different acid catalysts by alkylation of toluene with propylene (63—66). Although the demand for cymene is much lower than for cumene, one commercial plant was started up in 1987 at the Yan Shan Petrochemical Company in the People s RepubHc of China. The operation of this plant is based on SPA technology offered by UOP for cumene. The cymene is an intermediate for the production of y -cresol (3-methylphenol) [108-59-4]. 

The selective alkylation of toluene with methanol to produce -xylene as a predominant isomer can be achieved over shape-selective catalysts (99—101). With a modified ZSM-5 zeoHte catalyst, more than 99% -xylene in xylene isomers can be produced at 550°C. This -xylene concentration exceeds the equiHbrium concentration of 23% (99). The selective synthesis of -xylene using relatively low cost toluene is economically attractive however, this technology was not commercialized as of 1991. 

The same type catalyst modified with boron (41), magnesium (42), or phosphoms (43) to reduce the pore size can be used to alkylate toluene with ethylene to produce predominantly -ethyltoluene. Since -ethyltoluene [622-96-8] has the smallest effective diameter of the ethyltoluene isomers, the selectivity to this isomer is favored because it can most easily escape the ZSM-5 pore stmcture. For the same reason, the alkylation of toluene [108-88-3] to xylene [106 2-3] also is favored over the usual acid catalyzed equiHbrium mixture of isomers when it is carried out over magnesium- or phosphoms-modified ZSM-5 (44). 

Triflates of aluminum, gallium and boron, which are readily available by the reaction of the corresponding chlorides with triflic acid, are effective Fnedel-Crafis catalysis for alkylation and acylation of aromatic compounds [119, 120] Thus alkylation of toluene with various alkyl halides m the presence of these catalysts proceeds rapidly at room temperature 111 methylene chloride or ni-tromethane Favorable properties of the triflates in comparison with the correspond mg fluorides or chlorides are considerably decreased volatility and higher catalytic activity [120]... 

The epoxy toluene oligomer was also obtained by alkylation of toluene with PEC as shown in Scheme (10). 

Relative rates of alkylation of toluene and benzene using a mixture of nitro-sonium hexafluorophosphate, nitromethane (or acetonitrile) and aliphatic amine as the alkylations agent have been determined at 25 °C as follows360 1.5 (ethyl-amine), 2.5 (i-propylamine) and 3.5 (benzylamine) nothing more as yet is known about the kinetics of alkylation with these new alkylating reagents. 

In the alkylation of toluene at various temperatures ranging from —45 C to room temperature, different product distributions (o- m- p-) were observed ranging from... 

The reaction of ethylbenzene with 5 mol of 3 under the same reaction conditions for the alkylation of toluene with 3, gave pentakis 2-(methyldichlorosilyl)ethyl -(25%). tetrakisl2-(methyldichlorosilyl)ethyl]-(9%). tris[2-(methyldichlorosilyl)-... 

As an example of the selective removal of products, Foley et al. [36] anticipated a selective formation of dimethylamine over a catalyst coated with a carbon molecular sieve layer. Nishiyama et al. [37] demonstrated the concept of the selective removal of products. A silica-alumina catalyst coated with a silicalite membrane was used for disproportionation and alkylation of toluene to produce p-xylene. The product fraction of p-xylene in xylene isomers (para-selectivity) for the silicalite-coated catalyst largely exceeded the equilibrium value of about 22%. 

Solid super bases, prepared by successive treatment of y-alumina with alkali metal hydroxide and alkali metal, are highly active catalysts for reactions involving reactive carbanions, and have been commercialised by Sumitomo (Suzukamo et al, 1997). For example, t.vobutylbenzene, the. starting material for ibuprofen (see earlier) is produced by side-chain alkylation of toluene with propylene over a K/KOH/AI2O3 catalyst (Eqn. (14)). 

A number of papers have appeared on the use of layered double hydroxides (e.g. Mg and Al containing oxides). A meixnerite-like catalyst has been reported to give 100% selectivity for diacetone alcohol from acetone at 0 C at close to thermodynamic equilibrium conversion of 23% (Tichit and Fajula, 1999). The side-chain alkylation of toluene with propylene to give isobutyl benzene (for ibuprofen) is a well-known example where Na/K alloy on Na2C03/K2C03 is used as the catalyst. 

Dehydro alkylation of toluene with ethane on zeolites MCM-22 and ZSM-5... 

For the non-oxidative activation of light alkanes, the direct alkylation of toluene with ethane was chosen as an industrially relevant model reaction. The catalytic performance of ZSM-5 zeolites, which are good catalysts for this model reaction, was compared to the one of zeolite MCM-22, which is used in industry for the alkylation of aromatics with alkenes in the liquid phase. The catalytic experiments were carried out in a fixed-bed reactor and in a batch reactor. The results show that the shape-selective properties of zeolite ZSM-5 are more appropriate to favor the dehydroalkylation reaction, whereas on zeolite MCM-22 with its large cavities in the pore system and half-cavities on the external surface the thermodynamically favored side reaction with its large transition state, the disproportionation of toluene, prevails. 

Among the wide variety of organic reactions in which zeolites have been employed as catalysts, may be emphasized the transformations of aromatic hydrocarbons of importance in petrochemistry, and in the synthesis of intermediates for pharmaceutical or fragrance products.5 In particular, Friede 1-Crafts acylation and alkylation over zeolites have been widely used for the synthesis of fine chemicals.6 Insights into the mechanism of aromatic acylation over zeolites have been disclosed.7 The production of ethylbenzene from benzene and ethylene, catalyzed by HZSM-5 zeolite and developed by the Mobil-Badger Company, was the first commercialized industrial process for aromatic alkylation over zeolites.8 Other typical examples of zeolite-mediated Friedel-Crafts reactions are the regioselective formation of p-xylene by alkylation of toluene with methanol over HZSM-5,9 or the regioselective p-acylation of toluene with acetic anhydride over HBEA zeolites.10 In both transformations, the p-isomers are obtained in nearly quantitative yield. 

DETOL [De-alkylation of toluene] A process for making benzene by de-alkylating toluene and other aromatic hydrocarbons. Developed by the Houdiy Process and Chemical Company, and generally similar to its Litol process for the same purpose. The catalyst is chromia/alumina. Licensed by Air Products Chemicals. In 1987,12 plants had been licensed. 

The alkylation of toluene with acetylene in the presence of sulphuric acid is carried out in a batch reactor. 6000 kg of toluene is charged in each batch, together with the required amount of sulphuric acid and the acetylene is fed continuously to the reactor under pressure. Under circumstances of intense agitation, it may be assumed that the liquid is always saturated with acetylene, and that the toluene is consumed in a simple pseudo first-order reaction with a rate constant of 0.0011 s-1. 

Alkylation of toluene and acetylene in the presence of sulfuric acid is accomplished in the four-stage reactor of the sketch. Retention time in each stage is 10 min, temperature is 41 F and pressure is 50 psig. On the assumption that the liquid always is saturated with acetylene, the reaction is first order with respect to toluene. At the conditions shown, the reaction is estimated 95% complete. Find the specific reaction rate. 

It has been found that the disproportionation of toluene over ZSM-5 catalyst can be directed such that p-xylene is the predominant xylene isomer (14-17). This reaction, designated STOP, is one of several in which disubstituted aromatics rich in the para isomer are produced. Others are the alkylation of toluene with methanol to produce p-xylene (15,18) and with ethylene to produce p-ethyltoluene (19,20), as well as the aromatization of olefins (20), paraffins (20) and of methanol... 

The statement in the last paragraph of the paper, that benzene is unlikely to be a chain-breaker, is strange in view of the fact that this author himself discovered the alkylation of toluene (solvent) by the growing cation during cationic polymerisations [15-17, 28], which is a transfer reaction. 

No commercial process is offered at this time for side chain alkylation of toluene with methanol for styrene and ethylbenzene production. In the literature the reaction is typically carried out at toluene to methanol molar ratios from 1.0 7.5 to 5 1 from 350 to 450 °C at atmospheric pressures. In some cases inert gas is introduced to assist vaporizing the liquid feed. In other cases H2 is co-fed to improve activity, selectivity and stability. Exelus recently claimed 80% yields in their ExSyM process at full methanol conversion using a 9 4 toluene methanol feed ratio at 400-425 °C and latm (101 kPa) in a bench-scale operation. This performance appears to be... 

Rigoreau, J., Laforge, S., Gnep, N.S., and Guisnet, M. (2005) Alkylation of toluene with propene over H-MCM-22 zeolite, location of the main and secondary reactions. /. Catal., 236, 45-54. 

Magnoux, Z.D. and Guisnet, M. (1999) Liquid phase alkylation of toluene with 1-heptene over a HFAU zeolite evidence for transalkylation between toluene and non-desorbed products. Appl Catal A, 182, 407-411. 

On selectivity aspects of alkylation of toluene with methanol over zeolites, DGMK tagungsbericht, 9903. Proceedings of DGMK-Confer-ence The Future Role of Aromatics in Refining and Petrochemistry, 1999, pp. 279-286. 

Yashima, T., Ahmad, H., Yamazaki, K Katsuta, M and Hara, N. (1970) Alkylation on synthetic zeolites, 1. alkylation of toluene with methanol. 

Itoh, H., Miyamoto, A., and Murakami, Y. (1980) Mechanism of the side-chain alkylation of toluene with methanol. 

Wieland, W.S., Davis, R.J., and Garces, J.M. (1996) Solid base catalysts for side-chain alkylation of toluene with methanol. Catal Today, 28, 443-450. 

Palomares, A.E., Eder-Mirth, G., Rep, M., and Lercher, J.A. (1998) Alkylation of toluene over basis catalysts-key requirements for side chain alkylation. f Catal, 180, 56-65. 

Borgna, A., Speulveda, J., Magni, S.I., and Apesteguia, A.R. (2004) Active sites in alkylation of toluene with methanol a smdy by selective add-base poisoning. Appl Catal A, 276, 207-215. 

Tsai, T.S., and Wnag, I. (2002) Metal zeolite for trans-alkylation of toluene and heavy aromatics. Catal. Today, Ti, 39-47. 

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