620-14-4Relevant articles and documents
Alkylation of toluene with ethanol to para-ethyltoluene over MFI zeolites: Comparative study and kinetic modeling
Ogunbadejo, Babatunde A.,Osman, Mogahid S.,Arudra, Palani,Aitani, Abdullah M.,Al-Khattaf, Sulaiman S.
, p. 109 - 117 (2015)
The production of para-ethyltoluene (p-ET) from the alkylation of toluene with ethanol was investigated over three MFI zeolites with varying SiO2/Al2O3 ratio (80, 280, and 2000). The ethylation reaction was conducted in a batch fluidized-bed reactor at a temperature range of 300-400 °C, reaction times of 5-20 s and molar feed ratio of toluene to ethanol at 1:1. Toluene conversion increased with temperature over all the MFI zeolites except for MFI-80, which showed a maximum conversion of 29% at 300°C. The product distribution exhibited ethyltoluenes as major product with a maximum yield of 26% over MFI-80. At 400°C, constant toluene conversion of 14% and 100% ethanol conversion, para-selectivity to p-ET was 100% over MFI-2000 compared with 27% and 48% over MFI-80 and MFI-280, respectively. The high para-selectivity over MFI-2000 is attributed to the combined effects of higher SiO2/Al2O3 ratio, very weak acid sites and larger crystal size (longer diffusion length). The experimental data were analyzed for each MFI zeolite and suitable reaction mechanism for toluene ethylation was proposed based on the Langmuir-Hinshelwood model. The activation energy for the formation of p-ET over MFI-280 and MFI-2000 is 30 kJ/mol and 65 kJ/mol, while the heat of adsorption of ethanol is 19 kJ/mol and 29 kJ/mol, respectively.
Effect of phosphorus content on physicochemical and catalytic properties of H-ultrasil in the reaction of toluene ethylation
Aliev,Akhmedov,Mamedov,Gakhramanov
, p. 512 - 514 (2009)
Physicochemical properties of H-ultrasil modified with phosphorus and effect of the modification on the toluene alkylation with ethanol were studied.
Ligand-enabled and magnesium-activated hydrogenation with earth-abundant cobalt catalysts
Han, Bo,Jiao, Hongmei,Ma, Haojie,Wang, Jijiang,Zhang, Miaomiao,Zhang, Yuqi
, p. 39934 - 39939 (2021/12/31)
Replacing expensive noble metals like Pt, Pd, Ir, Ru, and Rh with inexpensive earth-abundant metals like cobalt (Co) is attracting wider research interest in catalysis. Cobalt catalysts are now undergoing a renaissance in hydrogenation reactions. Herein, we describe a hydrogenation method for polycyclic aromatic hydrocarbons (PAHs) and olefins with a magnesium-activated earth-abundant Co catalyst. When diketimine was used as a ligand, simple and inexpensive metal salts of CoBr2in combination with magnesium showed high catalytic activity in the site-selective hydrogenation of challenging PAHs under mild conditions. Co-catalyzed hydrogenation enabled the reduction of two side aromatics of PAHs. A wide range of PAHs can be hydrogenated in a site-selective manner, which provides a cost-effective, clean, and selective strategy to prepare partially reduced polycyclic hydrocarbon motifs that are otherwise difficult to prepare by common methods. The use of well-defined diketimine-ligated Co complexes as precatalysts for selective hydrogenation of PAHs and olefins is also demonstrated.
Chemoselective Hydrogenation of Olefins Using a Nanostructured Nickel Catalyst
Klarner, Mara,Bieger, Sandra,Drechsler, Markus,Kempe, Rhett
supporting information, p. 2157 - 2161 (2021/05/21)
The selective hydrogenation of functionalized olefins is of great importance in the chemical and pharmaceutical industry. Here, we report on a nanostructured nickel catalyst that enables the selective hydrogenation of purely aliphatic and functionalized olefins under mild conditions. The earth-abundant metal catalyst allows the selective hydrogenation of sterically protected olefins and further tolerates functional groups such as carbonyls, esters, ethers and nitriles. The characterization of our catalyst revealed the formation of surface oxidized metallic nickel nanoparticles stabilized by a N-doped carbon layer on the active carbon support.
Controlling the Lewis Acidity and Polymerizing Effectively Prevent Frustrated Lewis Pairs from Deactivation in the Hydrogenation of Terminal Alkynes
Geng, Jiao,Hu, Xingbang,Liu, Qiang,Wu, Youting,Yang, Liu,Yao, Chenfei
, p. 3685 - 3690 (2021/05/31)
Two strategies were reported to prevent the deactivation of Frustrated Lewis pairs (FLPs) in the hydrogenation of terminal alkynes: reducing the Lewis acidity and polymerizing the Lewis acid. A polymeric Lewis acid (P-BPh3) with high stability was designed and synthesized. Excellent conversion (up to 99%) and selectivity can be achieved in the hydrogenation of terminal alkynes catalyzed by P-BPh3. This catalytic system works quite well for different substrates. In addition, the P-BPh3 can be easily recycled.
Effect of solvent in the hydrogenation of acetophenone catalyzed by Pd/S-DVB
Bereta, Tomasz,Mieczyńska, Ewa,Ronka, Sylwia,Tylus, W?odzimierz,Trzeciak, Anna M.
, p. 5023 - 5028 (2021/03/26)
A solvent effect was found in the hydrogenation of acetophenone catalyzed by a new Pd/S-DVB catalyst, immobilized on a styrene (S)/divinylbenzene (DVB) copolymer containing phosphinic groups. The porous structure of the catalyst was characterized by a specific surface area of 94.7 m2g?1. The presence of Pd(ii) and Pd(0) in Pd/S-DVB was evidenced by XPS and TEM. Pd/S-DVB catalyzes the hydrogenation of acetophenone (APh) to 1-phenylethanol (PhE) and ethylbenzene (EtB). The highest conversion of APh was obtained in methanol (MeOH) and in 2-propanol (2-PrOH), while in water it was lower. The conversion of APh correlates well with the hydrogen-bond-acceptance (HBA) capacity of the solvent. However, in all binary mixtures of alcohol and water the APh conversion and the yield of products significantly decreased. The observed inhibiting effect can be explained by the microheterogeneity of these mixtures and the blocking of the catalyst surface restricting access of the substrates to the Pd centers.
Highly selective hydrogenation of aromatic ketones to alcohols in water: effect of PdO and ZrO2
Alsalahi, W.,Trzeciak, A. M.,Tylus, W.
, p. 10386 - 10393 (2021/08/09)
Pd/ZrO2and PdO/ZrO2composites, containing Pd or PdO nanoparticles, were prepared using an original one-step methodology. These nanocomposites catalyze the hydrogenation of acetophenone (AP) at 1 bar and 10 bar of H2in an aqueous solution. Compared to unsupported Pd or PdO nanoparticles, a remarkable increase in their activity was achieved as a result of interaction with zirconia. An unsupported PdO hydrogenated AP mainly to ethylbenzene (EB), while excellent regioselectivity towards 1-phenylethanol (PE) was obtained with PdO/ZrO2and it was preserved during recycling. Similarly, regioselectivity to PE was higher with Pd/ZrO2compared to unsupported Pd NPs. PdO and zirconia resulted in high selectivity to alcohols in the hydrogenation of substituted acetophenones.
Reductive Deamination with Hydrosilanes Catalyzed by B(C6F5)3
Fang, Huaquan,Oestreich, Martin
supporting information, p. 11394 - 11398 (2020/05/25)
The strong boron Lewis acid tris(pentafluorophenyl)borane B(C6F5)3 is known to catalyze the dehydrogenative coupling of certain amines and hydrosilanes at elevated temperatures. At higher temperature, the dehydrogenation pathway competes with cleavage of the C?N bond and defunctionalization is obtained. This can be turned into a useful methodology for the transition-metal-free reductive deamination of a broad range of amines as well as heterocumulenes such as an isocyanate and an isothiocyanate.
Lewis-Pair-Mediated Selective Dimerization and Polymerization of Lignocellulose-Based β-Angelica Lactone into Biofuel and Acrylic Bioplastic
Hong, Miao,Wang, Xiao-Jun
supporting information, p. 2664 - 2668 (2020/01/24)
This contribution reports an unprecedentedly efficient dimerization and the first successful polymerization of lignocellulose-based β-angelica lactone (β-AL) by utilizing a selective Lewis pair (LP) catalytic system, thereby establishing a versatile bio-refinery platform wherein two products, including a dimer for high-quality gasoline-like biofuel (C8–C9 branched alkanes, yield=87 %) and a heat- and solvent-resistant acrylic bioplastic (Mn up to 26.0 kg mol?1), can be synthesized from one feedstock by one catalytic system. The underlying reason for exquisite selectivity of the LP catalytic system toward dimerization and polymerization was explored mechanistically.
Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
supporting information, p. 16490 - 16494 (2019/11/03)
Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
