Benzyl Toluene Research Articles

Benzylation and benzoylation of substituted benzenes over solid catalysts containing Ga- and Mg-oxides and/or chlorides derived from Ga–Mg-hydrotalcite by its HCl pre-treatment or calcination

Influence of HCl pre-treatment conditions (temperature: 26 or 110 °C and period: 0.1, 0.5 or 1.0 h) and calcination temperature (300, 600 and 800 °C) of Ga–Mg-hydrotalcite (Mg/Ga=3.0) anionic clay on its catalytic activity in the benzylation (by benzyl chloride) or benzoylation (by benzoyl chloride) of toluene, p-xylene, mesitylene and anisole at 110 °C has been investigated. The hydrotalcite before and after its HCl pre-treatment or calcination is characterized by measuring its surface area and crystalline phases. Its catalytic activity in the benzylation reactions is increased very markedly by the HCl pre-treatment, depending upon the severity of the pre-treatment. It showed no activity in the benzoylation of substituted benzenes (for 3.0 h) but, after its pre-treatment by HCl gas (at 110 °C for 1.0 h), it showed high activity for the benzoylation reactions. Its catalytic activity in the benzylation of toluene is also increased very markedly after its calcination (at 300–800 °C): the higher the calcination temperature, the higher is the catalytic activity. The induction period for the benzylation reactions is drastically reduced after the HCl pre-treatment or calcination of the hydrotalcite. The catalyst activation by the HCl pre-treatment is attributed to the formation of catalytically active mixed GaCl 3 and MgCl 2 species dispersed on MgO and Ga 2O 3. The catalyst activation by the calcination at the lower temperature (300 °C) is attributed mostly to the dehydration of the hydrotalcite, causing an increase in the surface area. However, that at the higher temperatures is attributed to both the dehydration and the decomposition of the hydrotalcite, forming metal oxides (at 600 °C) or a mixture of MgO and MgGa 2O 4 (at 800 °C), with a large increase in the surface area of the catalyst.

Electronic effects of icosahedral carboranes: kinetic evidence for interaction between boron atom and nucleophile in the solvolysis of ( o-carboranyl)benzyl tosylates

Solvolysis of ( o-, m- and p-carboranyl)benzyl toluene- p-sulfonates substituted at the second carbon atom with a phenyl group bearing a range of substituents at the para position has been performed. The rates of hydrolysis of m- and p-carboranyl derivatives measured linearly with increasing electron-releasing character of the substituent group ( ρ=−0.23, ρ=−0.35), which indicates that these carboranes transmit electronic effects, and the substituents affect the stability of the neighboring carbocation. In contrast, the rate of hydrolysis of o-carboranyl derivatives showed a linear decrease with increasing electron-releasing character of the substituent ( ρ=+1.12), which indicates that the interaction between the B(3) atom of the o-carborane cage and the nucleophile controls this particular reaction.

Role of benzyl ether in the inversion of reactivities in Friedel-Crafts benzylation of toluene by benzyl chloride and benzyl alcohol

In the inversion in the reactivities and selectivities of benzyl chloride (BnCl) and benzyl alcohol (BnOH) in a single pot Friedel-Crafts benzylation with toluene, there is not only a preferential adsorption of benzyl alcohol on the solid acid catalyst but also a second preference to the adsorption of benzyl ether (BE) formed in-situ. The order of prefential adsorption is BnOH > BE > BnCl.

Benzylation of toluene and anisole by benzyl alcohol catalysed by niobic acid

The catalytic activities of commercial niobic acid, niobium pentoxide prepared in laboratory and niobic acid treated with phosphoric acid, were evaluated in the benzylation of toluene and anisole with benzyl alcohol, in liquid phase. The best results were achieved with niobic acid treated with phosphoric acid (pretreatment at 423 K), the conversion of benzyl alcohol was 99.2% with anisole and the main product was the benzylation product. The acidity of these solids has been determined by infrared spectrometry using pyridine as a probe molecule. The ratio of Lewis acidity/Brønsted acidity was higher for niobic acid treated with phosphoric acid.

Benzylation of toluene and anisole by benzyl alcohol catalyzed by niobic acid: influence of pretreatment temperature in the catalytic activity of niobic acid

We have studied the influence of the pretreatment temperature (423 K and 573 K) on the catalytic activity of commercial niobic acid for the benzylation of toluene and anisole with benzyl alcohol. The reactions were carried out in liquid phase at reflux temperature of the mixture. Best results were achieved with niobic acid pretreated at 573 K, The conversion of benzyl alcohol was 78.9 to anisole and the main product was the monobenzylation product.

Benzylation of benzene, toluene and anisole with benzyl alcohol catalyzed by cation-exchange resins

The catalytic activity of gel and macroreticular ion-exchange resins (Lewatit and Amberlyst-15) was evaluated for the reaction of benzene with benzyl alcohol and benzyl chloride at 80°C in the liquid phase. With benzyl chloride, the monobenzylation product, diphenylmethane, was obtained in low yield, both with the gel and the macroreticular resins. Better results were obtained with benzyl alcohol as benzylation agent and the most active resin was Amberlyst-15. The benzylation of toluene and anisole with benzyl alcohol, catalyzed by Amberlyst-15, was also evaluated, the conversion of benzyl alcohol being proportional to the concentration of acid sites in the resin. Monobenzylation to benzyl toluene or benzyl anisole is the main reaction and the selectivity was usually found to be higher than 80%, when a toluene/alcohol or anisole/alcohol molar ratio of 10 is used. Secondary reactions to dibenzyl toluenes, dibenzyl anisole and benzyl ether occur to a varying extent, depending on the substrate ratios. In all cases, predominance of ortho/para isomers was observed.

ChemInform Abstract: Benzylation of Toluene by Benzyl Chloride over Protonic Zeolites.

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Benzylation of toluene by benzyl chloride over protonic zeolites

The benzylation of toluene with benzyl chloride was studied at 383 K in the liquid phase on different protonic zeolites: H-ZSM-5, H-BETA and HY. Monobenzylation to benzyltoluenes is the main reaction, usually higher than 90% selectivity when a toluene/benzyl chloride molar ratio of 5 is used. Secondary reactions to dibenzyl- and tribenzyltoluenes occur to various extent depending on the reaction conditions and catalysts. The most active catalysts, and the most selective to monobenzylation, are those possessing mesopores in the 30–200Årange: H-BETA and dealuminated HY (Si/Al = 20). On these zeolites it is proposed that intracrystalline catalysis occurs, shape selectivity then preventing secondary reactions. At variance, on the other zeolites, H-ZSM-5 and nondealuminated HY, the reaction takes place at the external surface of the grain yielding a lower activity and selectivity to monobenzylation.

Liquid phase hydrogenolysis of dibenzyl ether over metals of the VIIIth group

It has been shown that depending on the catalyst and the solvent used, during the conversion of dibenzyl ether to toluene hydrogenolysis of C-O ether bonds, dehydrogenation and hydrogenolysis of benzyl alcohol formed, hydrogenation and decarbonylation of benzaldehyde, and the recombination of benzyl radicals and the benzylation of toluene can take place. The activity of catalysts in hydrogenolysis reactions of dibenzyl ether and benzyl alcohol to produce toluene decreases as follows: Pd/C>Pd>Raney Ni>Rh, whereas the selectivity drops down in the order: Raney Ni>Pd>Pd/C>Rh. The reaction rates depend on the solvent and diminish in the order: ethanol>2-propanol>benzene.

Pyrolysis of benzyl ether under hydrogen starvation conditions

Pyrolysis of dibenzyl ether at 450 °C, without added hydrogen, produces toluene and benzaldehyde as the major low-molecular-weight products. Additionally, carbon monoxide, biphenyl, diphenylmethane, diphenylethane, and benzyl toluenes are formed in significant amounts via secondary reaction pathways. In the absence of added hydrogen, increasing reaction severity (residence time) leads to growth/polymerization reactions ultimately leading to coke. Moderate-pressure molecular hydrogen, as an added reagent, inhibits, to some extent, the polymerization pathway.

Friedel-Crafts reaction in the heterogeneous system: V. Friedel-Crafts benzylation and benzoylation of toluene catalyzed by calcined iron sulfates

The Friedel-Crafts benzylation of toluene with benzyl chloride was carried out at 45 °C over ferrous and ferric sulfates calcined in air at 700, 800, and 900 °C. The benzoylation of toluene with benzoyl chloride was also performed at 110 °C over both iron sulfates heat-treated at 500, 700, 900 °C. The catalysts prepared by calcining both sulfates at 700 °C showed the maximum activity in both reactions. The products were 41% ortho-, 7% meta-, and 52% para-benzyltoluene for the benzylation and 18–22% ortho-, 2–4% meta-, and 74–78% para-methylbenzo-phenone for the benzoylation in all the analyzed runs. The ratio of rate of the benzoylation in toluene and benzene, k T k B , was 7.4 and 6.3 for FeSO 4 and Fe 2(SO 4) 3 calcined at 700 °C, respectively, which are surprisingly small compared with that for AlCl 3 ( k t k b = 110–115 ). From the former values, the positional selectivities of toluene, o f , m f , p f , were obtained as 3–5, 4–9, and 32, respectively. The specific surface areas of calcined sulfates were 49–71 m 2/g, indicating no relationship between them and the catalytic activities. The analysis of Fe and S contents of the catalysts showed that both ferrous and ferric sulfates are mainly remained as sulfate forms at 500 °C of calcination and decomposed to form iron oxides containing 0.15% S at 700 °C. Mössbauer spectra showed that ferrous sulfate calcined in air consists of 73% Fe 2+ and 27% Fe 3+ at 300 °C and 100% Fe 3+ above 500 °C. On the basis of the observed results, the nature of active sites of catalyst was discussed.

Catalytic activity of iron sulfates for friedel-crafts type benzylation of toluene with benzyl chloride

Ferrous and ferric sulfates prepared by calcining their hydrates in air from 200 to 700 °C showed surprisingly high catalytic activity and selectivity for the title reaction. The activities observed at 45 and 53.5 °C showed the higher calcination temperature, the higher catalytic activity, and the shorter induction period. Ferrous sulfate heat treated at 500 °C in vacuo showed the maximum activity. The activation energies over FeSO 4, calcined at 400 and 600 °C were quite small, 2.7 and 5.1 kcal mol −1, respectively. The products were 42% ortho-, 6% meta-, and 51% para-benzyltoluene with an almost negligible amount of polymer in all the analyzed runs. The ratios of rates in toluene and benzene, k T k B , were 6.29 and 6.60 for FeSO 4 and Fe 2(SO 4) 3 calcined at 700 °C, respectively. From these values, the positional reactivities of toluene, o f , m f , and p f were obtained as 9, 1, and 20, respectively. Hammett's constant, ρ, was also estimated to be −4 ~ −5. From these observations, the high catalytic activity and selectivity were tentatively explained by a concept that the catalyst surface deformed by complicated interactions with sulfur remained slightly on the oxide upon the decomposition of sulfate salts, and adsorbed HCl acted catalytically as a push-pull to the reactant.

ChemInform Abstract: FRIEDEL‐CRAFTS BENZYLATION OF TOLUENE WITH BENZYL CHLORIDE CATALYZED BY METAL OXIDES

Metal oxides were found to catalyze significantly the Friedel-Crafts type benzylation of toluene with benzyl chloride with a selectivity similar to that occurring with metal sulfates.

Friedel-Crafts Benzylation of Toluene with Benzyl Chloride Catalyzed by Metal Oxides

Abstract Metal oxides were found to catalyze significantly the Friedel-Crafts type benzylation of toluene with benzyl chloride with a selectivity similar to that occurring with metal sulfates.

THE CHLOROPHOSPHONATION OF TOLUENE AND p-XYLENE

Abstract In the chlorophosphonation of toluene and p-xylene, tolylphenylmethanes (I) and 2,4′,5-trimethyldiphenylmethane (II) were obtained as major products in addition of benzyl- (III) and p-methylbenzylphosphonic dichloride (IV). I and II may be formed by benzylation of toluene or p-xylene with benzyl cation, resulted from electron transfer from benzyl radical to phosphorus trichloride.

Benzylation of benzene and alkylbenzenes at low temperatures

Reactivity of benzene and certain alkylbenzenes (toluene, p-xylene, mesitylene) during benzylation with benzylchloride and some derivatives (α-chloroethylbenzene, benzhydrylchloride, chloromethylmesitylene) has been determined under non-isomerizing conditions, in the temperature range −10° and −120°, in ethyl chloride solution with AlCl 3 as a catalyst. Steric effects are found to play a major role in the reactivity when benzylchloride derivatives are used as benzylating agents. Isomer distribution in the benzylation of toluene has been investigated as a function of the temperature and of the benzylating agent. Experimental data are related to the results obtained in the low temperature polymerisation of benzylchloride and α-chloroethylbenzene.

Aromatic substitution. XXVII. Friedel-Crafts benzylation of toluene and benzene with substituted benzyl chlorides. Substituent effects in the electrophilic substituting agent affecting the nature of the transition state as reflected by substrate and positional selectivity

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAromatic substitution. XXVII. Friedel-Crafts benzylation of toluene and benzene with substituted benzyl chlorides. Substituent effects in the electrophilic substituting agent affecting the nature of the transition state as reflected by substrate and positional selectivityGeorge A. Olah, Masashi Tashiro, and Shiro KobayashiCite this: J. Am. Chem. Soc. 1970, 92, 21, 6369–6371Publication Date (Print):October 1, 1970Publication History Published online1 May 2002Published inissue 1 October 1970https://doi.org/10.1021/ja00724a063RIGHTS & PERMISSIONSArticle Views261Altmetric-Citations29LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (396 KB) Get e-Alerts Get e-Alerts

Studies of Diarylalkanes. VI. The Cleavage of Diphenylmethanes and the Friedel-Crafts Benzylation

Abstract The cleavage reaction of DPM and Me-DPM, and the benzylation of toluene, have been carried out under various conditions. On the basis of the results of this series, the correlations with the cleavage reaction of the DPM and with the Friedel-Crafts benzylation have been inclusively discussed. Furthermore, the mechanism of the isomerization of mono-substituted DPM under the influence of aluminum chloride has been suggested.