24947-01-1Relevant academic research and scientific papers
Supported phosphotungstic acid catalyst on mesoporous carbon with bimodal pores: A superior catalyst for Friedel-Crafts alkenylation of aromatics with phenylacetylene
Zhao, Zhongkui,Wang, Xianhui
, p. 139 - 146 (2016)
Supported phosphotungstic acid (PTA) catalysts on diverse carriers containing the modified commercially available activated carbon (AC), classical mesoporous carbon via SBA-15 hard template method (CMK-3), and the mesoporous carbon with high surface area and bimodal pores through evaporation-induced tri-constituent co-assembly approach (MC) by using a facile wet impregnation method were employed as solid acid catalysts for Friedel-Crafts alkenylation of p-xylene with phenylacetylene. N2 adsorption–desorption, X-ray diffraction (XRD), and NH3 temperature-programmed desorption (NH3-TPD) characterization techniques were employed to reveal the structure-performance relationship. PTA/MC exhibits much superior catalytic performance to the previously reported PTA/AC, and even to PTA/CMK-3. The PTA/MC catalysts were optimized by varying the PTA loading, and the optimum PTA loading is 35%. The close to 100% of conversion towards phenylacetylene can be achieved in the presence of 2.67% of the 35% PTA/MC solid acid catalyst. It is also found that catalytic properties of the solid acids are strongly depended on acidic properties that affected by the textural properties of supports and PTA loading, as well as the accessibility of active sites affected by specific surface area and pore structure of catalyst. Moreover, the 35?wt.% PTA/MC catalyst has demonstrated outstanding catalytic performance for the Friedel-Crafts alkenylation of diverse aromatics to their corresponding α-arylstyrenes.
Al(OTf)3: An efficient lewis acid additive for domino addition-elimination of Grignard reagents to activated ketones
Pieterse, Tanya,Visser, Melanie,Marais, Charlene,Bezuidenhoudt, Barend C. B.
supporting information, p. 1541 - 1546 (2016/06/14)
It has been demonstrated that aluminium triflate in either stoichiometric or catalytic quantities facilitates the addition-elimination of Grignard reagents to electron-rich ketones, such as methoxy substituted acetophenones, propiophenone and chromanone in a one-pot process, and that it has an enhancing effect on the addition of these reagents to the ketones. It has also been found that the reactions are highly stereoselective towards one regioisomer of the alkene in the case of oxygenated aryl-alkyl substituted substrates, but not when the elimination originates from a double benzylic alcohol intermediate.
Tuning of the textural features and acidic properties of sulfated mesoporous lanthana-zirconia solid acid catalysts for alkenylation of diverse aromatics to their corresponding α-arylstyrenes
Zhao, Zhongkui,Ran, Jinfeng,Guo, Yongle,Miao, Boyuan,Wang, Guiru
, p. 1303 - 1313 (2016/09/07)
The textural features and acidic properties of sulfated mesoporous lanthana-zirconia solid acids (SO42?/meso-La0.1Zr0.9Oδ) were efficiently tuned by modifying the conditions used to prepare the meso-La0.1Zr0.9Oδ composites, such as the molar ratio of the template to La and Zr metal ions (Nt/m), molar ratio of ammonia to La and Zr metal ions (Na/m), hydrothermal temperature (Thydro), and hydrothermal time (thydro). The effect of the textural features and acidic properties on the catalytic performance of solid acid catalysts for alkenylation of p-xylene with phenylacetylene was investigated. Various characterization techniques such as N2 physisorption, X-ray diffraction, NH3 temperature-programmed desorption, and thermogravimetric analysis were employed to reveal the relationship between the nature of catalyst and its catalytic performance. It was found that the catalytic performance significantly depended on the textural features and acidic properties, which were strongly affected by preparation conditions of the meso-La0.1Zr0.9Oδ composite. Appropriate acidic sites and high accessibility were required to obtain satisfactory catalytic reactions for this reaction. It was also found that the average crystallite size of t-ZrO2 affected by the preparation conditions had significant influence on the ultrastrong acidic sites of the catalysts. The optimized SO42?/meso-La0.1Zr0.9Oδ catalyst exhibited much superior catalytic activity and coke-resistant stability. Moreover, the developed SO42?/meso-La0.1Zr0.9Oδ catalyst demonstrated excellent catalytic performance for alkenylation of diverse aromatics with phenylacetylene to their corresponding α-arylstyrenes. Combining the previously established complete regeneration of used catalysts by a facile calcination process with the improved catalytic properties, the developed SO42?/meso-La0.1Zr0.9Oδ solid acid could be a potential catalyst for industrial production of α-arylstyrenes through clean and atom efficient solid-acid-mediated Friedel-Crafts alkenylation of diverse aromatics with phenylacetylene.
Supported phosphotungstic acid catalyst on modified activated carbon for Friedel-Crafts alkenylation of diverse aromatics to their corresponding α-arylstyrenes
Zhao, Zhongkui,Wang, Xianhui
, p. 103 - 110 (2015/08/06)
Abstract The supported phosphotungstic acid catalysts on modified activated carbon (PTA/AC) prepared by a facile wet impregnation method were employed for Friedel-Crafts alkenylation of diverse aromatics with phenylacetylene to synthesize their corresponding α-arylstyrenes. Reaction results demonstrate that the fabricated PTA/AC catalyst with 30 wt.% PTA loading exhibits outstanding catalytic performance. The 100% conversion of phenylacetylene with 95.7% selectivity towards α-(2,5-dimethylphenyl) styrene can be achieved over the developed 30 wt.% PTA/AC catalyst under optimized reaction conditions, and no visible loss in catalytic performance can be observed after it suffers from several times recycling. The various characterization techniques including X-ray diffraction, N2 adsorption-desorption, Fourier transform infrared spectroscopy, and NH3 temperature-programmed desorption were employed to reveal the relationship between the catalysts nature and catalytic properties. Moreover, the results on the scope of aromatics for the Friedel-Crafts alkenylation illustrate that the developed PTA/AC alkenylation catalyst can be efficiently catalyze the diverse aromatics and even for the electron deficient chlorobenzene. The developed PTA/AC catalyst, using the modified low-cost and sustainable AC as support, may be a robust and promising candidate for highly-efficient and clean α-arylstyrenes production through Friedel-Crafts alkenylation of diverse aromatics including electron-donating and electron-withdrawing groups substituted benzene derivatives as well as heterocyclic and polypolycyclic arenes with phenylacetylene.
Aromatic β-silylethenylation reactions via organogallium compounds
Kido, Yoshiyuki,Yoshimura, Satoru,Yamaguchi, Masahiko,Uchimaru, Tadafumi
, p. 1445 - 1458 (2007/10/03)
In the presence of GaCl3, silylethyne reacted electrophilically with aromatic hydrocarbons to give β-silylethenylated arenes. The reaction proceeded via cationic species generated by the interaction of GaCl3 and silylethyne. High reactivity of the intermediate was demonstrated by the rapid reaction rate at -78 °C using close to the equimolar amount of the substrates. ipso-Substitution reaction took place with 1,2,3- trimethoxybenzene. Structures and properties of several organogallium compounds involved in the reactions are discussed.
Electrophilic Alkenylation of Arometics with Phenylacetylene over Zeolite HSZ-360
Sartori, Giovanni,Bigi, Franca,Pastorio, Andrea,Porta, Cecilia,Arienti, Attilio,et al.
, p. 9177 - 9180 (2007/10/02)
Aromatic compounds react with phenylacetylene in the presence of zeolite HSZ-360 affording 1,1-diarylethylenes 3 in good to excellent yields and selectivities.
Substituent-Dependent Electron-Transfer Induced Photooxygenation of 1,1-Diarylethylenes
Gollnick, Klaus,Schnatterer, Albert,Utschick, Gerald
, p. 6049 - 6056 (2007/10/02)
Rates and products of 9,10-dicyanoanthracene-sensitized photooxygenations of 1,1-diarylethylenes (1a-r) in acetonitrile were studied.If at least one of the aryl groups carries an electron-donating substituent at the para (or ortho) position (1a-l), 3,3,6,6-tetraaryl-1,2-dioxanes (2a-l) are generated in high yields (85-100percent).Benzophenones (3) are the only other observable products. 1,1-Diphenylethylene (1n) and its m-methoxy (1m), p-chloro (1o,p), and p-nitro (1q,r) derivatives, however, yield mainly benzophenones (3m-r) (>50percent) (the p-nitro compounds only in the presence of biphenyl). 1,2-Dioxanes (2m-p), cyclobutanes (4n-p), and α-tetralones (5m-o) are obtained as side products.Dioxanes, benzophenones, and α-tetralones are products of electron-transfer induced oxygenations involving triplet ground-state molecular oxygen, 3O2.Singlet molecular oxygen, O2(1Δg), contributes to the benzophenone formation from strongly electron-donor substituted diarylethylenes.An exception is the most powerful electron-donor substituted diarylethylene 1a, with which O2(1Δg) undergoes an electron-transfer reaction affording dioxane 2a.Dioxane formation proceeds via free-radical cations 1.+, which enter into a chain reaction with 1, 3O2, and another molecule of 1 to yield dioxane 2 and a new radical cation 1.+ that maintains the chain reaction.The efficiency of this chain process, however, is found to be several orders of magnitude smaller than expected.To explain this result, a 1,6-biradical .1-1-O2. is proposed to be generated in this chain reaction as the product-determining intermediate that predominantly fragments into 3O2 and two molecules of 1.Cyclization to dioxane 2 and transformation to benzophenone 3 occur at presumably less than 0.1percent from this biradical.The pathways leading to cyclobutanes (4) and α-tetralones (5) are also discussed.
