271-89-6Relevant articles and documents
On the way to biofuels from furan: Discriminating Diels-Alder and ring-opening mechanisms
Vaitheeswaran,Green, Sara K.,Dauenhauer, Paul,Auerbach, Scott M.
, p. 2012 - 2019 (2013)
We performed kinetics experiments and quantum calculations to investigate the reaction of furan to benzofuran catalyzed by the acidic zeolite HZSM-5, which is a key step in the conversion of biomass to biofuels through catalytic fast pyrolysis. The reaction was studied experimentally by placing the zeolite in contact with solution-phase furan and detecting the benzofuran product over the temperature range 270-300 C, yielding an apparent activation energy of 72 ± 3 kJ/mol. The reaction was modeled in gas and zeolite phases to determine the energetics of the following two competing pathways: a Diels-Alder mechanism often assumed in interpretations of experimental data and a ring-opening pathway predicted by the chemoinformatic software RING. Quantum calculations on the zeolite/guest system were performed using the ONIOM embedded cluster approach. We computed the energetics of reactants, products, and all intermediate steps. Locating relevant transition states fell beyond our computational resources because of system size and the ruggedness of the energy landscape. The Diels-Alder mechanism in the gas phase was found to pass through a high-energy intermediate roughly 380 kJ/mol above the reactant energy, which reduces to approximately 200 kJ/mol in HZSM-5. In contrast, the ring-opening mechanism passes through a gas-phase intermediate roughly 500 kJ/mol above the reactant energy, which falls to approximately 50 kJ/mol in HZSM-5. The energy of the ring-opening mechanism over HZSM-5 fits into the experimentally determined energy budget of 72 ± 3 kJ/mol. These experimental and computational results highlight the importance of the ring-opening mechanism for this key step in making biofuels. Our results strongly indicate that, in the cavities of HZSM-5, the condensation of two furan molecules to form benzofuran and water does not proceed by a Diels-Alder reaction between the reactants.
Thermal Decomposition of Chroman. Reactivity of o-Quinone Methide
Dorrestijn, Edwin,Pugin, Raphae?l,Nogales, M. Victoria Ciriano,Mulder, Peter
, p. 4804 - 4810 (1997)
The gas phase thermal decomposition of 3,4-dihydro-2H-1-benzopyran (chroman, 1) has been studied between 760 and 1110 K in different bath gases and hydrogen donors. In nitrogen, the unimolecular rate parameters are k1 (s-1) = 1015.3 exp(-263 (kJ mol-1)/RT). The activation energy is slightly higher than the bond dissociation energy (BDE) of the phenoxylic C - O bond. The decomposition starts with elimination of ethene and formation of 6-methylene-2,4-cyclohexadien-1-one (o-quinone methide, 2). Quinone methides are important intermediates in the chemistry of lignin. In the high temperature range (860-980 K) 2 decomposes cleanly into CO, benzene, and small amounts of fulvene, obeying k2 (s-1) = 1014.8 exp(-281 (kJ mol-1)/RT. Reverse radical disproportionation of 2 with toluene is mainly responsible for o-cresol formation. In cis-2-butene at 770 K, exclusively cis-2,3-dimethylchroman is formed. This stereospecificity suggests a concerted retro-Diels - Alder mechanism and is not compatible with the high Arrhenius parameters, indicative of a stepwise, biradical mechanism.
3-Nitrocoumarins as Dienophiles in the Diels-Alder Reaction in Water. An Approach to the Synthesis of Nitrotetrahydrobenzo[c]chromenones and Dihydrodibenzo[b,d]furans
Amantini, David,Fringuelli, Francesco,Piermatti, Oriana,Pizzo, Ferdinando,Vaccaro, Luigi
, p. 9263 - 9268 (2003)
The [4 + 2] cycloadditions of 3-nitrocoumarin (1a), 6-chloro-3-nitrocoumarin (1b), and 6-, 7-, and 8-hydroxy-3-nitrocoumarins (1c, 5, and 6) with (E)-piperylene (7), isoprene (8), 2,3-dimethyl-1,3-butadiene (9), 2-methoxy-1,3-butadiene (10), 2,3-dimethoxy-1,3-butadiene (11), and cyclopentadiene (12) were investigated in aqueous medium, in organic solvent and under solventless conditions. The reactions performed in water occurred in heterogeneous phase but were faster than those executed in toluene or dichloroethane (DCE). 1a-c, 5, and 6 behaved as 2π components in the Diels-Alder cycloadditions with 7-10 and 12, and exo adducts were preferentially or exclusively produced. Surprisingly 1a, behaved as a 4π component in the cycloaddition in water with 11 and 4-substituted 3-nitrochromanones 20 and 21 were isolated. The cycloadditions of hydroxy-3-nitrocoumarins 1c, 5, and 6 with 1,3-diene 9 did not work in water or in organic solvent, but did work under solventless conditions. Nitrotetrahydrobenzo[c]chromenones 13-16, 24, and 25, originating from the normal electron-demand Diels-Alder reactions, were converted into dihydrodibenzo[b,d]furans 27-31 in water, via one-pot Nef-cyclodehydration reactions.
Characteristic flavor formation of thermally processed N-(1-deoxy-α-D-ribulos-1-yl)-glycine: Decisive role of additional amino acids and promotional effect of glyoxal
Zhan, Huan,Cui, Heping,Yu, Junhe,Hayat, Khizar,Wu, Xian,Zhang, Xiaoming,Ho, Chi-Tang
, (2021/09/28)
The role of amino acids and α-dicarbonyls in the flavor formation of Amadori rearrangement product (ARP) during thermal processing was investigated. Comparisons of the volatile compounds and their concentrations when N-(1-deoxy-α-D-ribulos-1-yl)-glycine r
Biomass to drugs: Green production of salicylic acid from 2-furoic acid in two steps
Jiang, Jun,Li, Teng,Sun, Guangyu,Wang, Yantao,Xiong, Lu,Yang, Weiran,Yu, Pengxin,Zheng, Boying
, (2022/03/07)
Salicylic acid, generally produced by chemical synthesis based on petrochemical products, is a vital organic acid and widely used in the pharmaceutical synthesis. This work developed a new and green route for the production of salicylic acid from biomass-derived 2-furoic acid in two steps. Firstly, 2 mmol 2-furoic acid was creatively converted to 2,3-benzofuran using HZSM-5 (Si/Al=130) at 280 °C for 1.5 h under 100 psi N2; and then the oxidation of 2,3-benzofuran to salicylate was conducted with tert?butyl hydroperoxide under basic condition without metal catalyst at 120 °C for 1 h. The stability of the catalyst for the first step and the possible reaction pathway for the second step based on the control experiments was properly envisioned. Regardless of limited salicylic acid yield (16%) from 2-furoic acid, this work paves a potentially feasible pathway for the preparation of drugs from biomass.
Ruthenium-Catalyzed Dehydrogenation Through an Intermolecular Hydrogen Atom Transfer Mechanism
Huang, Lin,Bismuto, Alessandro,Rath, Simon A.,Trapp, Nils,Morandi, Bill
supporting information, p. 7290 - 7296 (2021/03/01)
The direct dehydrogenation of alkanes is among the most efficient ways to access valuable alkene products. Although several catalysts have been designed to promote this transformation, they have unfortunately found limited applications in fine chemical synthesis. Here, we report a conceptually novel strategy for the catalytic, intermolecular dehydrogenation of alkanes using a ruthenium catalyst. The combination of a redox-active ligand and a sterically hindered aryl radical intermediate has unleashed this novel strategy. Importantly, mechanistic investigations have been performed to provide a conceptual framework for the further development of this new catalytic dehydrogenation system.
A donor-acceptor complex enables the synthesis of: E -olefins from alcohols, amines and carboxylic acids
Chen, Kun-Quan,Shen, Jie,Wang, Zhi-Xiang,Chen, Xiang-Yu
, p. 6684 - 6690 (2021/05/31)
Olefins are prevalent substrates and functionalities. The synthesis of olefins from readily available starting materials such as alcohols, amines and carboxylic acids is of great significance to address the sustainability concerns in organic synthesis. Metallaphotoredox-catalyzed defunctionalizations were reported to achieve such transformations under mild conditions. However, all these valuable strategies require a transition metal catalyst, a ligand or an expensive photocatalyst, with the challenges of controlling the region- and stereoselectivities remaining. Herein, we present a fundamentally distinct strategy enabled by electron donor-acceptor (EDA) complexes, for the selective synthesis of olefins from these simple and easily available starting materials. The conversions took place via photoactivation of the EDA complexes of the activated substrates with alkali salts, followed by hydrogen atom elimination from in situ generated alkyl radicals. This method is operationally simple and straightforward and free of photocatalysts and transition-metals, and shows high regio- and stereoselectivities.
Preparation method of 2,3-dihydrobenzofuran
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Paragraph 0027-0028, (2020/07/02)
The invention discloses a preparation method of 2,3-dihydrobenzofuran. The preparation method comprises the following steps: with phenol and 2-bromoacetaldehyde diethyl acetal as initial raw materials, carrying out condensing to obtain 2-phenoxyacetaldehyde diethyl acetal; carrying out cyclizing to obtain benzofuran; and finally, conducting hydrogenating to obtain 2,3-dihydrobenzofuran. The methodprovided by the invention can be used for preparing 2,3-dihydrobenzofuran, and has the advantages of easily available raw materials, mild reaction conditions, easy operation, good product quality, high yield, low cost, small environmental pollution and relatively high economic benefits.
Metal-free and base-free decarboxylation of substituted cinnamic acids in a deep eutectic solvent
Chen, Chen,Jian, Yuqing,Lei, Yuxin,Li, Bin,Peng, Caiyun,Sheng, Wen-Bing,Sumera, Yasmin,Wang, Wei,Zhang, Ming
, p. 558 - 563 (2020/01/24)
A metal-free and base-free strategy was developed in DES to synthesize styrenes for the first time by decarboxylation of cinnamic acid derivatives, which provided a renewable and cost efficiently protocol to access various styrenes including those with functional groups such as 4-vinylphenol and 1-chloro-4-vinylbenzene.
Catalytic Aerobic Dehydrogenatin of N-Heterocycles by N-Hydoxyphthalimide
Chen, Weidong,Tang, Hao,Wang, Weilin,Fu, Qiang,Luo, Junfei
supporting information, p. 3905 - 3911 (2020/08/10)
Catalytic methods for the aerobic dehydrogenation of N-heterocycles are reported. In most cases, indoles are accessed efficiently from indolines using catalytic N-hydroxyphthalimide (NHPI) as the sole additive under air. Further studies revealed an improved catalytic system of NHPI and copper for the preparation of other heteroaromatics, for example quinolines. (Figure presented.).
