586-62-9Relevant articles and documents
Sustainable p-cymene and hydrogen from limonene
Martin-Luengo,Yates,Rojo, E. Saez,Huerta Arribas,Aguilar,Ruiz Hitzky
, p. 141 - 146 (2010)
A fine chemical intermediate in a wide range of chemical processes, p-cymene, has been obtained from Limonene, solids based on a natural clay (sepiolite) modified with sodium, nickel, iron or manganese oxides and programmable focalised microwaves. The process has the added bonus of one mol of hydrogen being produced per mol of limonene converted to p-cymene.
Aromatization of Hydrocarbons y Oxidative Dehydrogenation Catalyzed by the Mixed Addenda Heteropoly Acid H5PMo10V2O40
Neumann, Ronny,Lissel, Manfred
, p. 4607 - 4610 (1989)
The mixed addenda heteropoly acid H5PMo10V2O40 dissolved in 1,2-dichloroethane with tetraglyme, forming the (tetraglyme)3-H5PMo10V2O40 complex, catalyzes the aromatization of cyclic dienes at moderate temperatures in the presence of molecular oxygen.Dehydrogenations of exocyclic dienes such as limonene show that dehydrogenation is preceded by isomerization to their endocyclic isomers.Aromatization takes place by succesive one-electron transfers and proton abstractions from the organic substrate to the heteropoly acid, the latter being reoxidized by dioxygen coupled with the formation of water.
Diverse Mechanistic Pathways in Single-Site Heterogeneous Catalysis: Alcohol Conversions Mediated by a High-Valent Carbon-Supported Molybdenum-Dioxo Catalyst
Bedzyk, Michael J.,Das, Anusheela,Kratish, Yosi,Li, Jiaqi,Ma, Qing,Marks, Tobin J.
, p. 1247 - 1257 (2022/02/07)
With the increase in the importance of renewable resources, chemical research is shifting focus toward substituting petrochemicals with biomass-derived analogues and platform-molecule transformations such as alcohol processing. To these ends, in-depth mechanistic understanding is key to the rational design of catalytic systems with enhanced activity and selectivity. Here we discuss in detail the structure and reactivity of a single-site active carbon-supported molybdenum-dioxo catalyst (AC/MoO2) and the mechanism(s) by which it mediates alcohol dehydration. A range of tertiary, secondary, and primary alcohols as well as selected bio-based terpineols are investigated as substrates under mild reaction conditions. A combined experimental substituent effect/kinetic/kinetic isotope effect/EXAFS/DFT computational analysis indicates that (1) water assistance is a key element in the transition state; (2) the experimental kinetic isotopic effect and activation enthalpy are 2.5 and 24.4 kcal/mol, respectively, in good agreement with the DFT results; and (3) several computationally identified intermediates including Mo-oxo-hydroxy-alkoxide and cage-structured long-range water-coordinated Mo-dioxo species are supported by EXAFS. This structurally and mechanistically well-characterized single-site system not only effects efficient transformations but also provides insight into rational catalyst design for future biomass processes.
Preparation method of isopentylene
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Paragraph 0031-0050, (2021/11/10)
The method comprises the following steps: taking dipentene as a raw material, and using acetic acid in a high-pressure carbon dioxide environment. Isoterpinene is prepared by reacting acetate and an axial chiral nitrogen-containing compound as a catalyst. The axial chiral nitrogen-containing compound is one or more of an axial chiral nitrogen-containing binaphthyl or biphenyl compound. The selectivity and yield of terpinene are high.
Thioderivatives of Resorcin[4]arene and Pyrogallol[4]arene: Are Thiols Tolerated in the Self-Assembly Process?
Nemat, Suren J.,Tiefenbacher, Konrad
supporting information, p. 6861 - 6865 (2021/09/14)
Three novel thiol bearing resorcin[4]arene and pyrogallol[4]arene derivatives were synthesized. Their properties were studied with regards to self-assembly, disulfide chemistry, and Br?nsted acid catalysis. This work demonstrates that (1) one aromatic thiol on the resorcin[4]arene framework is tolerated in the self-assembly process to a hexameric hydrogen bond-based capsule, (2) thio-derivatized resorcin[4]arene analogs can be covalently linked through disulfides, and (3) the increased acidity of aromatic thio-substituent is not sufficient to replace HCl as cocatalyst for capsule catalyzed terpene cyclizations.
Preparation of α-terpineol and perillyl alcohol using zeolites beta
?erveny, Libor,Vysko?ilová, Eli?ka,Zítová, Kate?ina
, p. 4297 - 4310 (2021/07/26)
The preparation of α-terpineol by direct hydration of limonene catalyzed by zeolites beta was studied. The same catalyst was used to prepare perillyl alcohol by isomerization of β-pinene oxide in the presence of water. The aim was to optimize the reaction conditions to achieve high conversions of starting material and high selectivity to the desired products. In the case of limonene, it was found that the highest selectivity to α-terpineol was 88% with conversion of 36% under the conditions: 50?wt% of catalyst beta 25, 10% aqueous acetic acid (10?mL) (volume ratio limonene:H2O = 1:4.5), temperature 50?°C, after 24?h. In the case of β-pinene oxide, it was found that the highest selectivity to perillyl alcohol, which was 36% at total conversion, was obtained in the reaction under the following conditions: dimethyl?sulfoxide as solvent (volume ratio β-pinene oxide:DMSO = 1:5), catalyst beta 25 without calcination (15?wt%), demineralized water (molar ratio β-pinene oxide:H2O = 1:8), temperature 70?°C, 3?h. The present study shows that the studied reactions are suitable for the selective preparation of chosen compounds.
STRONGLY LEWIS ACIDIC METAL-ORGANIC FRAMEWORKS FOR CONTINUOUS FLOW CATALYSIS
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Paragraph 0166; 0168, (2021/02/26)
Lewis acidic metal-organic framework (MOF) materials comprising triflate-coordinated metal nodes are described. The materials can be used as heterogenous catalysts in a wide range of organic group transformations, including Diels-Alder reactions, epoxide-ring opening reactions, Friedel-Crafts acylation reactions and alkene hydroalkoxylation reactions. The MOFs can also be prepared with metallated organic bridging ligands to provide heterogenous catalysts for tandem reactions and/or prepared as composites with support particles for use in columns of continuous flow reactor systems. Methods of preparing and using the MOF materials and their composites are also described.
Monoterpenes etherification reactions with alkyl alcohols over cesium partially exchanged Keggin heteropoly salts: effects of catalyst composition
da Silva, Márcio José,Lopes, Neide Paloma Goncalves,Ferreira, Sukarno Olavo,da Silva, Rene Chagas,Natalino, Ricardo,Chaves, Diego Morais,Texeira, Milena Galdino
, p. 153 - 168 (2020/07/21)
In this work, cesium partially exchanged Keggin heteropolyacid (HPA) salts were prepared, characterized, and evaluated as solid catalysts in monoterpenes etherification reactions with alkyl alcohols. A comparison of the activity of soluble HPAs and their insoluble cesium salts showed that among three different Keggin anions the phosphotungstate was the most efficient catalyst. Assessments on the effects of the level of the protons exchange by cesium cations demonstrated that Cs2.5H0.5PW12O40 solid salt was the most active and selective phosphotungstate catalyst, converting β-pinene to α-terpinyl methyl ether. The influences of the main reaction parameters such as reaction temperature, time, catalyst load, substrate nature (i.e., alcohols and monoterpenes) were investigated. We have demonstrated that the simultaneous presence of the cesium ions and protons in the catalyst plays an essential role, being the 2.5–0.5 the optimum molar ratio. The Cs2.5H0.5PW12O40 salt was efficiently recovered and reused without loss of catalytic activity. Graphic abstract: [Figure not available: see fulltext.]
Enantioselective Tail-to-Head Cyclizations Catalyzed by Dual-Hydrogen-Bond Donors
Kutateladze, Dennis A.,Strassfeld, Daniel A.,Jacobsen, Eric N.
, p. 6951 - 6956 (2020/05/19)
Chiral urea derivatives are shown to catalyze enantioselective tail-to-head cyclization reactions of neryl chloride analogues. Experimental data are consistent with a mechanism in which ?-participation by the nucleophilic olefin facilitates chloride ionization and thereby circumvents simple elimination pathways. Kinetic and computational studies support a cooperative mode of catalysis wherein two molecules of the urea catalyst engage the substrate and induce enantioselectivity through selective transition state stabilization.
Multistep Engineering of Synergistic Catalysts in a Metal-Organic Framework for Tandem C-O Bond Cleavage
Brzezinski, Carter,Chen, Justin S.,Feng, Xuanyu,Lin, Wenbin,Song, Yang,Xu, Ziwan
supporting information, p. 4872 - 4882 (2020/04/01)
Cleavage of strong C-O bonds without breaking C-C/C-H bonds is a key step for catalytic conversion of renewable biomass to hydrocarbon feedstocks. Herein we report multistep sequential engineering of orthogonal Lewis acid and palladium nanoparticle (NP) catalysts in a metal-organic framework (MOF) built from (Al-OH)n secondary building units and a mixture of 2,2′-bipyridine-5,5′-dicarboxylate (dcbpy) and 1,4-benzenediacrylate (pdac) ligands (1) for tandem C-O bond cleavage. Ozonolysis of 1 selectively removed pdac ligands to generate Al2(OH)(OH2) sites, which were subsequently triflated with trimethylsilyl triflate to afford strongly Lewis acidic sites for dehydroalkoxylation. Coordination of Pd(MeCN)2Cl2 to dcbpy ligands followed by in situ reduction produced orthogonal Pd NP sites in 1-OTf-PdNP as the hydrogenation catalyst. The selective and precise transformation of 1 into 1-OTf-PdNP was characterized step by step using powder X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, inductively coupled plasma mass spectrometry, infrared spectroscopy, and X-ray absorption spectroscopy. The hierarchical incorporation of orthogonal Lewis acid and Pd NP active sites endowed 1-OTf-PdNP with outstanding catalytic performance in apparent hydrogenolysis of etheric, alcoholic, and esteric C-O bonds to generate saturated alkanes via a tandem dehydroalkoxylation-hydrogenation process under relatively mild conditions. The reactivity of C-O bonds followed the trend of tertiary carbon > secondary carbon > primary carbon. Control experiments demonstrated the heterogeneous nature and recyclability of 1-OTf-PdNP and its superior catalytic activity over the homogeneous counterparts. Sequential engineering of multiple catalytic sites in MOFs thus presents a unique opportunity to address outstanding challenges in sustainable catalysis.
