Toluene alkylation product distribution

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... 

Product distribution data (Table V) obtained in the hydrocracking of coal, coal oil, anthracene and phenanthrene over a physically mixed NIS-H-zeolon catalyst indicated similarities and differences between the products of coal and coal oil on the one hand and anthracene and phenanthrene on the other hand. There were differences in the conversions which varied in the order coal> anthracene>phenanthrene coal oil. The yield of alkylbenzenes also varied in the order anthracene >phenanthrene>coal oil >coal under the conditions used. The alkylbenzenes and C -C hydrocarbon products from anthracene were similar to the products of phenanthrene. The most predominant component of alkylbenzenes was toluene and xylenes were produced in very small quantities. Methane was the most and butanes the least predominant components of the gaseous product. The products of coal and coal oil were also found to be similar. The most predominant components of alkylbenzenes and gaseous product were benzene and propane respectively. The data also indicated distinct differences between products of coal origin and pure aromatic hydrocarbons. The alkyl-benzene products of coal and coal oil contained more benzene and xylenes and less toluene, ethylbenzene and higher benzenes when compared to the products from anthracene and phenanthrene. The gaseous products of coal and coal oil contained more propane and butanes and less methane and ethane when compared to the products of anthracene and phenanthrene. The differences in the hydrocracked products were obviously due to the differences in the nature of reactants. Coal and coal oil contain hydroaromatic, naphthenic, heterocyclic and aliphatic structures, in addition to polynuclear aromatic structures. Hydrocracking under severe conditions yielded more BTX as shown in Table VI. The yields of BTX obtained from coal, coal oil, anthracene and phenanthrene were respectively 18.5, 25.5, 36.0, and 32.5 percent. Benzene was the most... 

Boon et al. investigated the reactions of benzene and toluene in room-temperature ionic liquids based on [EMIM]Q-AlCl3 mixtures [33] ([EMIM] = 1-ethyl-3 -methylimidazolium). The reactions of various alkyl chlorides with benzene in the ionic liquid [EMIM]Q-AlCl3 (X = 0.60 or 0.67) was carried out and the product distribution is given in Table 5.2-1 and Scheme 5.2-6. 

Cymene or isopropyltoluene is produced via alkylation of toluene with propylene. Cymene is an important intermediate in the production of cresol, and it is also used as an industrial solvent. Again, for both environmental and economic reasons, the use of zeolitic materials for this conversion has been studied. For example, Flockhart et al. have used zeolite Y to effect this reaction (7). They observed that the state of the zeolite, including its degree of ion-exchange and the temperature at which it was calcined, strongly affected the distribution of cymene isomers obtained. In order to enhance the selectivity to para-cymene, the direct precursor to para-cresol, various studies have focused on the use of surface modified zeolites, for example, ZSM-5 materials, including those produced by chemical vapor deposition (CVD) of silicate esters. These species serve to reduce surface acidity and change limit diffusion within the crystal. 

Recently, we investigated the associative alkylation reaction of toluene with methanol catalyzed by an acidic Mordenite (see Figures 13 and 14) by means of periodic ab initio calculations." We observed that for this reaction some transition selectivity occurred, and induced sufficiently large differences in activation energies to explain the small changes in the para/meta/ortho distribution experimentally observed on large pore zeolites. Thepara isomer is the more valuable product as it is an important intermediate for terphthalic acid, an important polymer monomer." The steric constraints obtained for the transition state structures could be estimated from local intermediates for which the orientations of the toluene molecule were similar as the ones observed for the transition states (see Figure 14). 

Isopropylation of toluene by isopropyl halo- and alkyl-sulfonates (equation 54) has been performed by Olah et al. A variety of cattdysts, such as AlCb, AlCb-MeNOa and Nafion-H were employed, and the isomer distribution (o, m, p) in the product was determined. Sartori et al have recently reported an unusual Friedel-Crafts alkylation of lithium phenolates with ethyl pyruvate in the presence of AlCb to afford a-(2-hydroxyphenyl)ethyl lactates (22), which are the precursors of 3-methyl-2,3-dihydrobenzo-furan-3-ols (23 Scheme 6). 

Alkylation seems characteristic of the support acidity. Over NigHY2>7, the alkylaromatics distribution reveals 62 % toluene and 38 % Cg when dimethyldisulfide is used as a sulfiding agent, and shifts to 22 % C7-78 % C8 when diethyldisulfide is injected in place of DMDS. Therefore the alkylation reaction is mainly due to the presence of an alkyldisulfide. The initial formation of toluene is immediately followed by disproportionation, yielding xylenes. But product analysis also reveals that with the (benzene + DMDS) mixture, more methane is produced with HY2-7 catalyst where alkylation goes on, than over HY45 where no benzene conversion occurs. Thus, some of the methane may arise from a deep degradation of benzene, and such a reaction may also be considered as a minor source of alkylaromatics. 

Interestingly these complexes showed high activity without addition of alkyl aluminum compounds in the ionic liquid while they are almost inactive in toluene. These results are interpretable in terms of catalyst stabilization by the imidazolium-based ionic liquid. Reductive elimination of imidazolium is also possible as in toluene as in the ionic liquid but in the ionic liquid, a rapid reoxidation via addition of the solvent imidazolium cation seems possible and may prevent the formation of Ni deposits associated with catalyst deactivation. The carbene complex with R = n-Bu showed the highest activity with a dimer yield of 70.2% (TOF = 7020 h ). The preferred product of the nickel-catalyzed reaction is methylpentene. Additional phosphine ligand had no significant influence on the distribution of the products in this case. 

Unlike the isomerization of l-chloro[l- C]butane with aluminium trichloride, which proceeds without major participation of protonated cyclo-propanes, the isotopic scrambling from the reaction of [l- C]-l-propyl-mercuric perchlorate in trifluoroacetic acid does require intermediate protonated cyclopropanes. The isolated 1-propyl trifluoroacetate (565) was shown by degradation to have the label distributed as shown in Scheme 76. The greater scrambling from C-1 to C-3 than from C-1 to C-2 requires an edge-rather than a comer-protonated ion. Full details have appeared of the liquid-phase thermolyses of cycloalkyl and cycloalkylmethyl chloroformates which take place via carbonium ions. Protonated cyclopropanes are believed to be intermediates for 5-10% of the products. The alkylation of benzene and toluene by cyclopropane with acidic catalysts also involves initial formation of a protonated cyclopropane. ... 

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