1719-82-0Relevant articles and documents
Synthesis of terephthalic acid via Diels-Alder reactions with ethylene and oxidized variants of 5-hydroxymethylfurfural
Pacheco, Joshua J.,Davis, Mark E.
, p. 8363 - 8367 (2014)
Terephthalic acid (PTA), a monomer in the synthesis of polyethylene terephthalate (PET), is obtained by the oxidation of petroleum-derived p-xylene. There is significant interest in the synthesis of renewable, biomass-derived PTA. Here, routes to PTA starting from oxidized products of 5- hydroxymethylfurfural (HMF) that can be produced from biomass are reported. These routes involve Diels-Alder reactions with ethylene and avoid the hydrogenation of HMF to 2,5-dimethylfuran. Oxidized derivatives of HMF are reacted with ethylene over solid Lewis acid catalysts that do not contain strong Br?nsted acids to synthesize intermediates of PTA and its equally important diester, dimethyl terephthalate (DMT). The partially oxidized HMF, 5-(hydroxymethyl)furoic acid (HMFA), is reacted with high pressure ethylene over a pure-silica molecular sieve containing framework tin (Sn-Beta) to produce the Diels-Alder dehydration product, 4-(hydroxymethyl)benzoic acid (HMBA), with 31% selectivity at 61% HMFA conversion after 6 h at 190°C. If HMFA is protected with methanol to form methyl 5-(methoxymethyl)furan-2-carboxylate (MMFC), MMFC can react with ethylene in the presence of Sn-Beta for 2 h to produce methyl 4-(methoxymethyl) benzenecarboxylate (MMBC) with 46% selectivity at 28% MMFC conversion or in the presence of a pure-silica molecular sieve containing framework zirconium (Zr-Beta) for 6 h to produce MMBC with 81% selectivity at 26% MMFC conversion. HMBA and MMBC can then be oxidized to produce PTA and DMT, respectively. When Lewis acid containing mesoporous silica (MCM-41) and amorphous silica, or Br?nsted acid containing zeolites (Al-Beta), are used as catalysts, a significant decrease in selectivity/yield of the Diels-Alder dehydration product is observed.
Auto-Tandem Catalysis with Frustrated Lewis Pairs for Reductive Etherification of Aldehydes and Ketones
Bakos, Mária,Gy?m?re, ádám,Domján, Attila,Soós, Tibor
supporting information, p. 5217 - 5221 (2017/04/27)
Herein we report that a single frustrated Lewis pair (FLP) catalyst can promote the reductive etherification of aldehydes and ketones. The reaction does not require an exogenous acid catalyst, but the combined action of FLP on H2, R-OH or H2O generates the required Br?nsted acid in a reversible, “turn on” manner. The method is not only a complementary metal-free reductive etherification, but also a niche procedure for ethers that would be either synthetically inconvenient or even intractable to access by alternative synthetic protocols.
Catalysis by framework zinc in silica-based molecular sieves
Orazov, Marat,Davis, Mark E.
, p. 2264 - 2274 (2016/03/05)
Microporous and mesoporous zincosilicates (e.g., CIT-6, VPI-8, Zn-MFI, and Zn-MCM-41) synthesized in the presence of alkali cations contain two broad types of Zn sites: one that is a dication analog of the monocation ion-exchangeable Al-site in aluminosilicates, while the other resembles isolated Zn sites on amorphous silica. The ratio of these sites varies, depending on the synthesis conditions of the zincosilicate. Post-synthetic strategies based on ion-exchange can alter the site distribution towards either population. Furthermore, post-synthetic introduction of isolated Zn sites of the latter type is possible for materials possessing silanol nests. Both types of sites behave as Lewis acid centers in probe-molecule IR spectroscopy, but have very different catalytic properties. Due to the unusually high adsorption energies of Lewis bases on such materials, Lewis acid catalysis is difficult at low temperatures and in solvents bearing Lewis basic functionality. However, at high temperatures, in hydrocarbon solvents, CIT-6 (Zn-beta) is able to selectively catalyze the Lewis-acid-catalyzed Diels-Alder cycloaddition-dehydration reactions of ethylene with methyl 5-(methoxymethyl)furan-2-carboxylate, a furan that can be derived quantitatively by partial oxidation of biomass-based 5-hydroxymethylfurfural. Additionally, zinc in silica-based molecular sieves is shown here to enable chemistries previously not accessible with framework Sn-, Ti- and Zr-based Lewis acid sites, e.g., the direct production of dimethyl terephthalate by Diels-Alder cycloaddition-dehydration reactions of ethylene and the dimethyl ester of furan-2,5-dicarboxilic acid.
Base-free oxidation of alcohols to esters at room temperature and atmospheric conditions using nanoscale Co-based catalysts
Zhong, Wei,Liu, Hongli,Bai, Cuihua,Liao, Shijun,Li, Yingwei
, p. 1850 - 1856 (2015/03/14)
The direct oxidation of alcohols to esters with molecular oxygen is an attractive and crucial process for the synthesis of fine chemicals. To date, the heterogeneous catalyst systems that have been identified are based on noble metals or have required the addition of base additives. Here, we show that Co nanoparticles embedded in nitrogen-doped graphite catalyze the aerobic oxidation of alcohols to esters at room temperature under base-free and atmospheric conditions. Our Co@C-N catalytic system features a broad substrate scope for aromatic and aliphatic alcohols as well as diols, giving their corresponding esters in good to excellent yields. This apparently environmentally benign process provides a new strategy with which to achieve selective oxidation of alcohols.
Route to Renewable PET: Reaction Pathways and Energetics of Diels-Alder and Dehydrative Aromatization Reactions between Ethylene and Biomass-Derived Furans Catalyzed by Lewis Acid Molecular Sieves
Pacheco, Joshua J.,Labinger, Jay A.,Sessions, Alex L.,Davis, Mark E.
, p. 5904 - 5913 (2015/10/12)
Silica molecular sieves that have the zeolite beta topology and contain framework Lewis acid centers (e.g., Zr-β, Sn-β) are useful catalysts in the Diels-Alder and dehydrative aromatization reactions between ethylene and various renewable furans for the production of biobased terephthalic acid precursors. Here, the main side products in the synthesis of methyl 4-(methoxymethyl)benzene carboxylate that are obtained by reacting ethylene with methyl 5-(methoxymethyl)-furan-2-carboxylate are identified, and an overall reaction pathway is proposed. Madon-Boudart experiments using Zr-β samples of varying Si/Zr ratios clearly indicate that there are no transport limitations to the rate of reaction for the synthesis of p-xylene from 2,5-dimethylfuran and ethylene and strongly suggest no mass transport limitations in the synthesis of methyl p-toluate from methyl 5-methyl-2-furoate and ethylene. Measured apparent activation energies for these reaction-limited systems are small (13C kinetic isotope effects (KIE) in the synthesis of MMBC and MPT measured by gas chromatography/isotope-ratio mass spectrometry in reactant-depletion experiments support the Madon-Boudart result that these systems are not transport-limited and the KIE values agree with those previously reported for Diels-Alder cycloadditions.
DIELS-ALDER REACTIONS CATALYZED BY LEWIS ACID CONTAINING SOLIDS: RENEWABLE PRODUCTION OF BIO-PLASTICS
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Paragraph 0173, (2015/01/06)
The present disclosure is related to silica-based Lewis acid catalysts, being essentially devoid of strong Br?nsted acid character, and their ability to effect the [4+2] cycloaddition and dehydrative aromatization of dienes and dienophiles containing oxygenated substituents to form substituted benzene products. In some embodiments, the processes comprise contacting biomass-derived substrates with ethylene to form terephthalic acid and its derivatives.
Birch Reductive Alkylation of Methyl m-(Hydroxymethyl)benzoate Derivatives and the Behavior of o- and p-(Hydroxymethyl)benzoates under Reductive Alkylation Conditions
Fretz, Samuel J.,Hadad, Christopher M.,Hart, David J.,Vyas, Shubham,Yang, Dexi
, p. 83 - 92 (2013/03/29)
Birch reductive alkylation of methyl m-(hydroxymethyl)benzoate derivatives, using lithium in ammonia-tetrahydrofuran in the presence of tertbutyl alcohol, can be achieved without significant loss of benzylic oxygen substituents. Similar treatment of o- and p-(hydroxymethyl)benzoate derivatives results largely in loss of benzylic oxygen substituents. The results are rationalized by computations describing electron density patterns in the putative radical anion intermediate involved in these reactions.
Environmentally benign metal triflate-catalyzed reductive cleavage of the C-O bond of acetals to ethers
Zhang, Yin-Jie,Dayoub, Wissam,Chen, Guo-Rong,Lemaire, Marc
experimental part, p. 2737 - 2742 (2011/11/29)
A protocol is described for the reductive cleavage of the C-O bond of aromatic and aliphatic acetals to ethers catalyzed by Cu(OTf)2 or Bi(OTf)3 at room temperature in excellent yields, without affecting aromatic rings, nitro, nitrile, ester and hydroxyl groups. This protocol represents an improvement in terms of atom economy compared to the previous methods, by distinctly decreasing the amount of the reducing reagent, 1,1,3,3-tetramethyldisiloxane (TMDS), and using a small amount of catalyst.
HYDROXYMETHYLBORON COMPOUNDS
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Page/Page column 38-39, (2010/11/29)
The present invention provides compounds which are useful as safe substitutes for the organotin reagent used in coupling reaction for the oxymethylation of aromatic rings, such as alkoxymethylation or hydroxymethylation, with a palladium catalyst and which can dispense with chromatographic purification with silica gel in the production and are suitable for mass production; and compounds applicable even to the oxymethylation of aromatic ring substrates which do not permit coupling reaction by conventional technique or have low reactivity.
High yielding methyl esterification catalyzed by indium(III) chloride
Mineno, Tomoko,Kansui, Hisao
, p. 918 - 919 (2007/10/03)
The carboxylic acids are efficiently converted into the methyl esters in methanol using indium(III) chloride as the catalyst. This method is applicable for aromatic and aliphatic carboxyl moieties as well as amino acids in high yields.
