- P -Xylene from 2,5-dimethylfuran and acrylic acid using zeolite in a continuous flow system
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The continuous flow synthesis of p-xylene (pXL) via Diels-Alder cycloaddition of lignocellulosic biomass-derivable 2,5-dimethylfuran (DMF) and acrylic acid (AA) was performed over different type of zeolites, i.e. Beta, ZSM-5 and Y. Among the tested zeolites, Beta zeolite showed an optimum catalytic performance in pXL synthesis from DMF and AA. In this context, Beta zeolite with a Si/Al molar ratio of 150 which is abbreviated as Beta(150), resulted in complete DMF conversion with a pXL yield of 83% and by-product 2,5-dimethylbenzoic acid (DMBA) with a yield of 17%, at 473 K in 10.1 min residence time (τ), with excess AA (0.7 M). This high catalytic activity is attributed to the high specific surface area of 1180 m2 g-1 with a three-dimensional porous architecture with a pore diameter of 6.6 × 6.7 ? and an acid site density above 40 μmol g-1. The utilized Beta(150) showed a very stable performance up to 10 h time on stream with minor deactivation after 8 h of TOS, while the pXL yield remained above 70%. The original catalytic performance of Beta(150) in the conversion of DMF to pXL was restored by applying a regeneration step for the spent catalyst, which is simple in continuous flow reactors. Finally, this sustainable continuous flow process enables an efficient and selective pXL production from DMF and AA as a dienophile at lower reaction temperature (473 K) and shorter residence time (τ = 10.1 min) in comparison to a batch fashion. This journal is
- Al-Naji, Majd,Antonietti, Markus,Brandi, Francesco,Mendoza Mesa, Jose Alirio,Shekova, Irina
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supporting information
p. 7398 - 7405
(2020/11/25)
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- Palladium-Catalyzed ortho-C-H Methylation of Benzoic Acids
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A palladium-catalyzed methylation of C-H bonds of benzoic acids with di-tert-butyl peroxide as the methylating reagent under an external oxidant and ligand-free conditions has been achieved. The reaction is found to be directed by a weakly coordinating carboxyl group, offering a facile route for the synthesis of highly functionalized ortho-methyl benzoic acids.
- Lv, Weiwei,Wen, Si,Liu, Jing,Cheng, Guolin
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p. 9786 - 9791
(2019/08/26)
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- Preparation method for o-tolylacetic acid aryl formic acid derivative
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The invention discloses a preparation method for an o-tolylacetic acid aryl formic acid derivative. According to the method, new C-C bonds can be formed, the organic o-tolylacetic acid aryl formic acid derivative is obtained, the good functional group tolerance is achieved, and the o-tolylacetic acid aryl formic acid derivative which cannot be easily obtained by adopting other methods can be synthesized; according to the method, adopted raw materials are easy to obtain, the yield is high, the reaction conditions are mild, the substrate range is wide, and after-treatment is simple and green.
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Paragraph 0024-0039
(2019/07/16)
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- Method for preparing aromatic acid by direct carboxylation of CO2
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The invention discloses a method for preparing aromatic acid by direct carboxylation of CO2. The method comprises the following steps: (1) adding aromatic hydrocarbon, organic alkali and lewis acid into a high pressure reaction kettle under an inert gas atmosphere, then feeding CO2 gas into the high pressure reaction kettle for reaction, and obtaining reaction liquid with aromatic acid at the endof the reaction; (2) adding water into the reaction liquid obtained in the step (1), then extracting the aromatic acid in the reaction liquid with an extracting agent to enable the aromatic acid in the reaction liquid to enter an extracting phase, separating the extracting phase from raffinate, and concentrating the extracting phase to obtain the aromatic acid. According to the method, complicatedpreparation of ionic liquid is avoided, and organic alkali is timely neutralized with halogen hydride produced by the reaction, so that the balance moves rightwards; at the end of the reaction, the organic alkali also can be recycled through alkali treatment. The method has the advantages of simple operation, mild conditions, green process, low cost and the like, and is expected to be applied toindustrial production.
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Paragraph 0056; 0057; 0058
(2018/05/16)
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- Ionic liquid, preparation method and application
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The invention relates to an ionic liquid. Cations of the ionic liquid contain hexafluoroisopropyl sulfonic acid groups. According to the ionic liquid provided by the invention, the hexafluoroisopropylsulfonic acid groups are introduced into the cation part of the ionic liquid to give a super acid center to the ionic liquid, through changing anion types, the ionic liquid of which the acidity is greater than that of 98% concentrated sulfuric acid is obtained, and the highest level of the hamlet acidity (H0) in the obtained ionic liquid can reach -14.13.
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Paragraph 0240; 0241; 0242; 0243; 0244
(2018/03/28)
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- Selectivity Control in the Tandem Aromatization of Bio-Based Furanics Catalyzed by Solid Acids and Palladium
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Bio-based furanics can be aromatized efficiently by sequential Diels–Alder (DA) addition and hydrogenation steps followed by tandem catalytic aromatization. With a combination of zeolite H-Y and Pd/C, the hydrogenated DA adduct of 2-methylfuran and maleic anhydride can thus be aromatized in the liquid phase and, to a certain extent, decarboxylated to give high yields of the aromatic products 3-methylphthalic anhydride and o- and m-toluic acid. Here, it is shown that a variation in the acidity and textural properties of the solid acid as well as bifunctionality offers a handle on selectivity toward aromatic products. The zeolite component was found to dominate selectivity. Indeed, a linear correlation is found between 3-methylphthalic anhydride yield and the product of (strong acid/total acidity) and mesopore volume of H-Y, highlighting the need for balanced catalyst acidity and porosity. The efficient coupling of the dehydration and dehydrogenation steps by varying the zeolite-to-Pd/C ratio allowed the competitive decarboxylation reaction to be effectively suppressed, which led to an improved 3-methylphthalic anhydride/total aromatics selectivity ratio of 80 % (89 % total aromatics yield). The incorporation of Pd nanoparticles in close proximity to the acid sites in bifunctional Pd/H-Y catalysts also afforded a flexible means to control aromatic products selectivity, as further demonstrated in the aromatization of hydrogenated DA adducts from other diene/dienophile combinations.
- Genuino, Homer C.,Thiyagarajan, Shanmugam,van der Waal, Jan C.,de Jong, Ed,van Haveren, Jacco,van Es, Daan S.,Weckhuysen, Bert M.,Bruijnincx, Pieter C. A.
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p. 277 - 286
(2017/01/17)
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- A Simple and Mild Approach for the Synthesis of p-Xylene from Bio-Based 2,5-Dimethyfuran by Using Metal Triflates
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The production of aromatic platform chemicals from biomass-derived feedstocks is of considerable importance in biomass conversion. However, the development of effective routes with simple steps and under mild conditions is still challenging. In this work, we report an original route for the direct synthesis of p-xylene from 2,5-dimethylfuran and acrylic acid catalyzed by scandium(III) triflate (Sc(OTf)3) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim]NTf2) under mild conditions. An overall 63 % selectivity towards p-xylene and 78 % selectivity towards aromatics were obtained at 90 % conversion of 2,5-dimethylfuran by enhancing the dehydration and introducing an extra one-pot decarboxylation step. Furthermore, various dienes and dienophiles were employed as reactants to extend the substrate scope. The aromatic compounds were obtained in moderate yields, which proved the potential of the method to be a generic approach for the conversion of bio-based furanics into renewable aromatics.
- Ni, Lingli,Xin, Jiayu,Dong, Huixian,Lu, Xingmei,Liu, Xiaomin,Zhang, Suojiang
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p. 2394 - 2401
(2017/06/13)
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- A carbon dioxide by the method of preparing the arylcarboxylic acid
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The invention discloses a method for preparing arylformic acid from carbon dioxide, belonging to the technical field of comprehensive utilization of carbon dioxide. The method comprises the following concrete steps: reacting sodium arylsulfinate with CO2 (0.1MPa) in a Schlenk tube subjected to dehydration and deoxidation treatment in the presence of a catalytic system comprising copper salt, a nitrogen-containing ligand and alkali, and acidifying reaction liquid by a diluted hydrochloric acid solution to obtain arylformic acid. A catalyst used in the catalytic system is simple and easily available, high in catalytic activity, low in consumption, relatively mild in reaction condition and good in universality on sodium arylsulfinate. Raw materials in the preparation method disclosed by the invention are easily available, the reaction condition is mild, a reaction substrate is good in universality, the reaction time is short, the yield of a target product is high, and the reaction operation and the post-treatment process are simple.
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Paragraph 0048-0049
(2017/03/22)
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- A Facile Solid-Phase Route to Renewable Aromatic Chemicals from Biobased Furanics
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Renewable aromatics can be conveniently synthesized from furanics by introducing an intermediate hydrogenation step in the Diels-Alder (DA) aromatization route, to effectively block retro-DA activity. Aromatization of the hydrogenated DA adducts requires tandem catalysis, using a metal-based dehydrogenation catalyst and solid acid dehydration catalyst in toluene. Herein it is demonstrated that the hydrogenated DA adducts can instead be conveniently converted into renewable aromatics with up to 80 % selectivity in a solid-phase reaction with shorter reaction times using only an acidic zeolite, that is, without solvent or dehydrogenation catalyst. Hydrogenated adducts from diene/dienophile combinations of (methylated) furans with maleic anhydride are efficiently converted into renewable aromatics with this new route. The zeolite H-Y was found to perform the best and can be easily reused after calcination. Just heat and tumble: Furanics-derived hydrogenated Diels-Alder adducts can be conveniently converted, over acidic zeolites, into renewable aromatics using a solid-phase conversion strategy. The zeolite H-Y was found to perform the best and can be easily reused after calcination.
- Thiyagarajan, Shanmugam,Genuino, Homer C.,Van Der Waal, Jan C.,De Jong, Ed,Weckhuysen, Bert M.,Van Haveren, Jacco,Bruijnincx, Pieter C. A.,Van Es, Daan S.
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supporting information
p. 1368 - 1371
(2016/02/12)
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- Iron-Catalyzed Ortho C-H Methylation of Aromatics Bearing a Simple Carbonyl Group with Methylaluminum and Tridentate Phosphine Ligand
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Iron-catalyzed C-H functionalization of aromatics has attracted widespread attention from chemists in recent years, while the requirement of an elaborate directing group on the substrate has so far hampered the use of simple aromatic carbonyl compounds such as benzoic acid and ketones, much reducing its synthetic utility. We describe here a combination of a mildly reactive methylaluminum reagent and a new tridentate phosphine ligand for metal catalysis, 4-(bis(2-(diphenylphosphanyl)phenyl)phosphanyl)-N,N-dimethylaniline (Me2N-TP), that allows us to convert an ortho C-H bond to a C-CH3 bond in aromatics and heteroaromatics bearing simple carbonyl groups under mild oxidative conditions. The reaction is powerful enough to methylate all four ortho C-H bonds in benzophenone. The reaction tolerates a variety of functional groups, such as boronic ester, halide, sulfide, heterocycles, and enolizable ketones.
- Shang, Rui,Ilies, Laurean,Nakamura, Eiichi
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supporting information
p. 10132 - 10135
(2016/08/31)
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- Inclusion complex containing epoxy resin composition for semiconductor encapsulation
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The invention is an epoxy resin composition for sealing a semiconductor, including (A) an epoxy resin and (B) a clathrate complex. The clathrate complex is one of (b1) an aromatic carboxylic acid compound, and (b2) at least one imidazole compound represented by formula (II): wherein R2 represents a hydrogen atom, C1-C10 alkyl group, phenyl group, benzyl group or cyanoethyl group, and R3 to R5 represent a hydrogen atom, nitro group, halogen atom, C1-C20 alkyl group, phenyl group, benzyl group, hydroxymethyl group or C1-C20 acyl group. The composition has improved storage stability, retains flowability when sealing, and achieves an effective curing rate applicable for sealing delicate semiconductors.
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- Direct carboxylation of simple arenes with CO2 through a rhodium-catalyzed C-H bond activation
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Direct carboxylation of simple arenes under atmospheric pressure of CO2 is achieved through a rhodium-catalyzed C-H bond activation without the assistance of a directing group. Various arenes such as benzene, toluene, xylene, electron-rich or electron-deficient benzene derivatives, and heteroaromatics are directly carboxylated with high TONs. This journal is
- Suga, Takuya,Mizuno, Hajime,Takaya, Jun,Iwasawa, Nobuharu
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supporting information
p. 14360 - 14363
(2015/02/19)
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- C-H functionalization logic enables synthesis of (+)-hongoquercin A and related compounds
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The specifics: A synthesis of the sesquiterpenoid antibiotic (+)-hongoquercin A using sequential site-specific C-H methylation and oxidation reactions is described. A key advancement toward this goal was the development of a ligand-accelerated C-H methylation reaction, and enabled the generation of a library of eight structurally diverse analogues. Copyright
- Rosen, Brandon R.,Simke, Leah R.,Thuy-Boun, Peter S.,Dixon, Darryl D.,Yu, Jin-Quan,Baran, Phil S.
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supporting information
p. 7317 - 7320
(2013/07/26)
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- Ortho-methylated tribenzotriquinacenes - Paving the way to curved carbon networks
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The synthesis of sterically crowded tribenzotriquinacenes with complete and partial methylation of the ortho-positions has been achieved using the double cyclodehydration strategy. This leads to a twisted tribenzotriquinacene core and enables further func
- Kirchwehm, Yvonne,Damme, Alexander,Kupfer, Thomas,Braunschweig, Holger,Krueger, Anke
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supporting information; experimental part
p. 1502 - 1504
(2012/03/11)
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- On the Diels-Alder approach to solely biomass-derived polyethylene terephthalate (PET): Conversion of 2,5-dimethylfuran and acrolein into p-xylene
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Polyethylene terephthalate (PET) is a polymeric material with high global demand. Conventionally, PET is produced from fossil-fuel-based materials. Herein, we explored the feasibility of a sustainable method for PET production by using solely bio-renewable resources. Specifically, 2,5-dimethylfuran (derived from lignocellulosic biomass through 5-(hydroxymethyl)furfural) and acrolein (produced from glycerol, a side product of biodiesel production) were converted into the key intermediate p-xylene (a precursor of terephthalic acid). This synthesis consists of a sequential Diels-Alder reaction, oxidation, dehydration, and decarboxylation. In particular, the pivotal first step, the Diels-Alder reaction, was studied in detail to provide useful kinetic and thermodynamic data. Although it was found that this reaction requires low temperature to proceed efficiently, which presents a limitation on economic feasibility on an industrial scale, the concept was realized and bio-derived p-xylene was obtained in 34 % overall yield over four steps. Making PET as green as grass: Polyethylene terephthalate (PET) can be prepared from solely bio-renewable sources by converting 2,5-dimethylfuran and acrolein into the key intermediate p-xylene (see scheme). This atom-economic route consists of a sequential Diels-Alder reaction, oxidation, dehydrative aromatization and decarboxylation. We examined the feasibility of this process with an emphasis on the Diels-Alder reaction step. Copyright
- Shiramizu, Mika,Toste, F. Dean
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p. 12452 - 12457
(2011/12/15)
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- Direct carboxylation of arenes and halobenzenes with CO2 by the combined use of AlBr3 and R3SiCl
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The Lewis acid-mediated direct carboxylation of aromatic compounds with CO2 is efficiently promoted by the addition of silyl chlorides bearing three alkyl and/or aryl substituents in total on the silicon atom. Thus, toluene, xylenes, mesitylene, and some other alkylbenzenes are treated with a 1:1 mixture of AlBr3 and Ph3SiCl in neat substrates under CO2 pressure (3.0 MPa) at room temperature, to give the corresponding carboxylic acids in 60-97% yields, based on AlBr3. Polycyclic arenes, including naphthalene, phenanthrene, and biphenyl, are regioselectively carboxylated in 91-98% yields with the aid of 1 molar equiv of AlBr3 and Ph3SiCl in an appropriate solvent, chosen from benzene, chlorobenzene, and fluorobenzene. These solvents, as well as bromobenzene, resist carboxylation; however, they are also carboxylated in moderate yields when treated with a 1:5 mixture of AlBr3 and iPrSiCl at elevated temperatures. The FT-IR spectrum of a mixture prepared by exposing a suspension of AlBr3 and Ph3SiCl in cyclohexane to CO 2 exhibits an absorption band around 1650 cm-1, assigned to the C=O stretching vibration of a species consisting of CO2, AlBr3, and Ph3SiCl, which suggests that the silyl chlorides activate CO2 in cooperation with AlBr3. 1H NMR analysis of unworked-up reaction mixtures reveals that the products merge as aluminum carboxylates. The mass balance concerning silicon indicates that the silyl chlorides are recycled during the reaction sequence. On the basis of these observations, a feasible mechanism is proposed for the present carboxylation.
- Nemoto, Koji,Yoshida, Hiroki,Egusa, Naoki,Morohashi, Naoya,Hattori, Tetsutaro
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experimental part
p. 7855 - 7862
(2011/02/21)
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- Pd/C and NaBH4 in basic aqueous alcohol: An efficient system for an environmentally benign oxidation of alcohols
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We report the oxidation of a wide range of alcohols using an environmentally benign and economical process. The use of Pd/C heterogeneous catalysts along with NaBH4in aqueous ethanol or methanol and either K2CO3 or KOH as base at room temperature under molecular oxygen or air give the corresponding oxidation products. This protocol is versatile since it is capable of oxidizing alcohols to its desired carbonyl or carboxyl counterpart. Room temperature reaction in aqueous system and recyclability of the catalyst are among the advantages of this manipulation. These advantages make the process safe and cheaper rendering it favorable from both economic and environmental viewpoints. Georg Thieme Verlag Stuttgart New York.
- An, Gwangil,Ahn, Hyunseok,De Castro, Kathlia A.,Rhee, Hakjune
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experimental part
p. 477 - 485
(2010/06/13)
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- Carbonylation of aryl chlorides with oxygen nucleophiles at atmospheric pressure. Preparation of phenyl esters as acyl transfer agents and the direct preparation of alkyl esters and carboxylic acids
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(Chemical Equation Presented) A mild, functional group tolerant method of the preparation of phenyl esters from aryl chlorides via palladium-catalyzed carbonylation is described using atmospheric pressure of carbon monoxide. Phenyl esters are shown to be useful acylating agents, delivering libraries of carbonyl derivatives, including alkyl, allyl and thioesters, under very mild conditions. Direct preparation of alkyl esters and carboxylic acids is also demonstrated, providing the first method for the preparation of methyl and ethyl esters from aryl chlorides without pressured reactors.
- Watson, Donald A.,Fan, Xuexiang,Buchwald, Stephen L.
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supporting information; experimental part
p. 7096 - 7101
(2009/05/09)
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- Environmentally benign oxidation reaction of aldehydes to their corresponding carboxylic acids using Pd/C with NaBH4 and KOH
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Pd/C catalyst in aqueous methanol with sodium borohydride and potassium hydroxide under the air efficiently oxidized aldehydes to their corresponding carboxylic acids at room temperature. The utilization of room temperature reaction, aqueous methanol solvent, and the open-air conditions make this manipulation very interesting for economic and environmental perspectives.
- Lim, Minkyung,Yoon, Cheol Min,An, Gwangil,Rhee, Hakjune
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p. 3835 - 3839
(2008/02/07)
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- Beneficial effect of TMSCl in the Lewis acid-mediated carboxylation of aromatic compounds with carbon dioxide
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The Lewis acid-mediated carboxylation of aromatic compounds with CO 2 is significantly promoted by the addition of a large excess of chlorotrimethylsilane (TMSCl) to give arylcarboxylic acids in good to excellent yields. Copyright
- Nemoto, Koji,Yoshida, Hiroki,Suzuki, Yutaka,Morohashi, Naoya,Hattori, Tetsutaro
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p. 820 - 821
(2007/10/03)
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- Aerobic oxidation of trimethylbenzenes catalyzed by N,N′,N″-trihydroxyisocyanuric acid (THICA) as a key catalyst
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The oxidation of trimethylbenzenes was examined with air or O2 using N,N′,N″-trihydroxyisocyanuric acid (THICA) as a key catalyst. Thus, 1,2,3-, 1,2,4-, and 1,3,5-trimethylbenzenes under air (20 atm) in the presence of THICA (5 mol %), Co(OAc)2 (0.5 mol %), Mn(OAc)2, and ZrO(OAc)2 at 150 °C were oxidized to the corresponding benzenetricarboxylic acids in good yields (81-97%). In the aerobic oxidation of 1,2,4-trimethylbenzene by the THICA/Co(II)/Mn(II) system, remarkable acceleration was observed by adding a very small amount of ZrO(OAc)2 to the reaction system to form 1,2,4-benzenetricarboxylic acid in excellent yield (97%). In contrast, no considerable addition effect was observed in the oxidation of 1,3,5-trimethylbenzene. This aerobic oxidation by the present catalytic system provides an economical and environmentally benign direct method to benzenetricarboxylic acids, which are very important polymer materials.
- Hirai, Naruhisa,Tatsukawa, Yoshinobu,Kameda, Michiko,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 6695 - 6699
(2007/10/03)
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- Oxidation of alcohols and vic-diols with H2O2 by using catalytic amounts of N-methylpyrrolidin-2-one hydrotribromide
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A variety of secondary alcohols, 1,2-diols and primary alcohols were selectively oxidized in excellent yields to their corresponding ketones, 1,2-diketones and aldehydes with aqueous 30 % hydrogen peroxide in refluxing acetonitrile in the presence of catalytic amounts of N-methylpyrrolidin-2-one hydrotribromide (MPHT). Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Joseph, Jomy K.,Jain, Suman L.,Sain, Bir
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p. 590 - 594
(2007/10/03)
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- An efficient Pd(II)-based catalyst system for carboxylation of aromatic C-H bond by addition of a phosphenium salt
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Addition of a phosphenium dramatically improved the reaction yields in the carboxylation of arenes by formic acid catalyzed by Pd(II). Control experiments revealed that the majority of the phosphenium triflate was converted to a mixed anhydride of phosphonic acid and formic acid (7), which however did not substitute for the phosphenium to improve the reaction yield.
- Sakakibara, Ken,Yamashita, Makoto,Nozaki, Kyoko
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p. 959 - 962
(2007/10/03)
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- Efficient chemoselective carboxylation of aromatics to arylcarboxylic acids with a superelectrophilically activated carbon dioxide-Al2Cl6/Al system
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Aromatic carboxylic acids are obtained in good to excellent yield essentially free of diaryl ketones by carboxylation of aromatics with a carbon dioxide-Al2Cl6/Al system at moderate temperatures (20-80°C). To optimize reaction condit
- Olah, George A.,Toeroek, Bela,Joschek, Jens P.,Bucsi, Imre,Esteves, Pierre M.,Rasul, Golam,Prakash, G. K. Surya
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p. 11379 - 11391
(2007/10/03)
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- A new base mediated method for the cleavage of tert-butyl esters
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A new method for the cleavage of tert-butyl esters with NaH in DMF is described.
- Paul, Soumendu,Schmidt, Richard R.
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p. 1107 - 1108
(2007/10/03)
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- Process for preparing an aryl formate and an aromatic carboxylic acid
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A method of producing aryl formate by oxidizing the aromatic aldehyde in an organic solvent having substantially no ability of dissolving water with performic acid generated in situ in the reaction system from the reaction between formic acid and hydrogen peroxide. Optionally the method comprises a second step for decomposing the aryl formate to a phenol compound. This second step may be performed by thermally decomposing the aryl formate to the phenol compound and carbon monoxide at 110 to 350°C in liquid phase in the presence of an alkali metal compound.
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- Oxidative carbonylation of aromatic hydrocarbons in the system containing Pd or Rh compound, trifluoroacetic acid and its anhydride, and MnO2 or Mn2O3
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Manganese(II) and manganese(IV) oxides are effective oxidants for the reaction of oxidative carbonylation of aromatic hydrocarbons proceeding at 0.1-1.5 MPa of CO and 20-100°C in trifluoroacetic acid and its anhydride and catalysed by Pd and Rh compounds. Under these conditions up to 9000 moles of aromatic acid is formed per 1 g-at of platinum. With rhodium catalyst instead of the palladium in the case of toluene content of p-toluic acid in the target product increases from 50 to 90%. Carbonylation of biphenyl at 0.1 MPa of CO and 20°C leads toformation of about 15% of fluorenone together with 4-phenylbenzoic acid (60%).
- Kalinovskii,Pogorelov,Gelbshtein,Akhmetov
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p. 1457 - 1462
(2007/10/03)
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- Aromatic Spiranes XX [1]: Syntheses of Dimethylsubstituted 2-Carboxymethyl-indan-1-ones and Benzylchlorides as Synthones for Syntheses of di- to tetramethylsubstituted Spirobiindandiones
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The isomeric dimethyl methylbenzoates 5, obtained from the bromides via Grignard reactions with dimethylcarbonate, were reduced with LiAlH4 to the hydroxymethyl derivatives 6. The latter were then transformed both to the benzylchlorides 7 (with SOCl2) and to the aldehydes 8 (with pyridinium chlorochromate). Knoevenagel-Doebner reaction of 8 afforded the acrylic acids 9 which (after hydrogenation to 11) were cyclized to the desired indanones 12 with polyphosphoric acid. On the other hand, 12c and 12e were prepared from dimethyl 3-chloropropiophenone (14) by warming with sulfuric acid. After NaH-catalyzed reaction with dimethylcarbonate, the indanones 12 gave the ketoesters 15 which then could be hydrogenated to the indanes 16. All reactions proceeded with satisfactory to excellent yields (60-90%).
- Neudeck
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p. 185 - 200
(2007/10/03)
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- Pd-Catalyzed Regio- and Stereo-selective Carboxylation of Cycloalkanes with CO
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The reactions of cycloalkanes with CO via the C-H bond activation by Pd(OAc)2 catalyst have been found to proceed regio- and stereo-selectively to give corresponding carboxylic acids.The reactivity of C-H bonds of cycloalkanes decreases in the order: tert- > sec- > prim-carbon, and the stereochemistry of the substitutents on the main products is all equatorial.
- Satoh, Ko-ichi,Watanabe, Jun,Takaki, Ken,Fujiwara, Yuzo
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p. 1433 - 1436
(2007/10/02)
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- Photocyclization of -(o-Tolyl)acetophenones: Triplet and 1,5-biradical reactivity
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Several ring-substituted α-(o-tolyl)acetophenones undergo photocyclization to 2-indanol derivatives in high quantum efficiency in solution and in high chemical yield as solids. The mechanism for reaction involves triplet state δ-hydrogen atom abstraction that generates 1,5-biradicals. Quenching studies indicate that the n.π* excited triplets of these ketones react, with rate constants >108 s-1. Variations in triplet reactivity are ascribed to conformational equilibria that populate reactive and unreactive geometries to different extents. The α-aryl ring eclipses the carbonyl in the lowest energy geometry, from which the most favorable geometry for reaction can be reached by small bond rotations. α-(2,4,6-Triisopropylpheny)acetophenone forms the relatively long lived enol as well as indanol in solvent-dependent ratios; deuterium labeling indicates that the 1,5-biradical disproportionates to form enol. This does not happen with α-mesitylacetophenone, so its 54% cyclization quantum efficiency is ascribed to an internal triplet quenching that competes with hydrogen abstraction. This internal quenching is presumed to be of the charge-transfer type and does not appear to lead directly to 1,5-biradicals. 1-Methyl-2-phenyl-2-indanol is formed from α-(o-ethylpheny)acetophenone with a Z/E ratio of 20:1 in benzene and 2:1 in methanol. The 1,5-biradical intermediates were characterized by flash spectroscopy; they have lifetimes between 15 and 45 ns, with those derived from α-(o-isopropylphenyl) ketones being twice as long-lived as those derived from α-(o-methylphenyl) ketones, and show only a small solvent dependence. Biradical lifetimes and the diastereoselectivity of cyclization are interpreted in terms of biradical intersystem crossing occurring preferentially along the reaction coordinate for cyclization, such that the two processes effectively occur concurrently. The applicability of this concept to other biradicals is discussed.
- Wagner, Peter J.,Meador, Michael A.,Zhou, Boli,Park, Bong-Ser
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p. 9630 - 9639
(2007/10/02)
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- Oxidative Coupling of 1-(2,6-Dichlorobenzoyl)pyrroles and -pyrazoles and Alkyl Acrylates by Palladium(II) Acetate
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Treatments of 1-(2,6-dichlorobenzoyl)-, 3-acetyl-1-(2,6-dichlorobenzoyl)-, 1-(2,6-dichlorobenzoyl)-2-formyl-, and 1-(phenylsulfonyl)pyrroles with palladium acetate and alkyl acrylates gave the corresponding α-alkenyl-substituted pyrroles in good yields, while the reaction of 1-(2,6-dichlorobenzoyl)-2,5-dimethylpyrrole gave small amounts of β-alkenyl-substituted pyrroles.Under similar conditions, 1-(2,6-dichlorobenzoyl)pyrazole and 1-(2,6-dichlorobenzoyl)-3,5-dimethylpyrazole reacted with palladium acetate and alkyl acrylates to give the corresponding 4-alkenyl-substituted pyrazoles.The reaction of 1-(2,6-dichlorobenzoyl)-4-methylpyrazole gave 5-alkenyl-substituted pyrazole.
- Itahara, Toshio,Kawasaki, Kazukuni,Ouseto, Fumio
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p. 3488 - 3493
(2007/10/02)
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