- Significant effect of base on the improvement of selectivity in the hydrogenation of benzoic acid over NiZrB amorphous alloy supported on γ-Al2O3
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This study presents a facile way to improve the selectivity for cyclohexanecarboxylic acid by adding a base in the hydrogenation of benzoic acid over a non-noble metal NiZrB amorphous alloy supported on γ-Al2O3. It is found that alkali metal carbonates exhibit an excellent selectivity improvement from 50.3% to a range of 93.5-95.7%, with the conversion of benzoic acid higher than 92.3%. Even a very small amount of K2CO3 (1 mol% benzoic acid) was efficient for improving the selectivity for cyclohexanecarboxylic acid. In addition, a lower reaction temperature was beneficial to the improvement of selectivity. Based on the results of temperature programmed desorption of NH3 and inductively coupled plasma analysis, the improvement of selectivity in the presence of a base was attributed to the neutralization of the acidic sites on the surface of the catalyst by the in situ generated potassium benzoate, inhibiting the hydrodeoxygenation of carbonyl and resulting in a high selectivity for cyclohexanecarboxylic acid.
- Wen, Xin,Cao, Yingying,Qiao, Xianliang,Niu, Libo,Huo, Li,Bai, Guoyi
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Read Online
- Singlet oxygen production in the reaction of superoxide with organic peroxides
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A selective chemiluminescent probe for singlet oxygen has been employed to detect and quantify singlet oxygen in the reactions of superoxide with organic peroxides. The production of singlet oxygen has been quantified in the reaction of superoxide with benzoyl peroxide (BP). No singlet oxygen was detected in the reactions of superoxide with cumyl peroxide, tert-butyl peroxide, or tert-butyl hydroperoxide. On the basis of these results and on the temperature dependence of the reaction, we proposed a mechanism for singlet oxygen formation in the reaction of superoxide with BP.
- MacManus-Spencer, Laura A.,Edhlund, Betsy L.,McNeill, Kristopher
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Read Online
- An Anionic, Chelating C(sp3)/NHC ligand from the Combination of an N-heterobicyclic Carbene and Barbituric Heterocycle
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The coordination chemistry of the anionic NHC1-based on an imidazo[1,5-a]pyridin-3-ylidene (IPy) platform substituted at the C5 position by an anionic barbituric heterocycle was studied with d6(Ru(II), Mn(I)) and d8(Pd(II), Rh(I), Ir(I), Au(III)) transition-metal centers. While the anionic barbituric heterocycle is planar in the zwitterionic NHC precursor 1·H, NMR spectroscopic analyses supplemented by X-ray diffraction studies evidenced the chelating behavior of ligand 1-through the carbenic and the malonic carbon atoms in all of the complexes, resulting from a deformation of the lateral barbituric heterocycle. The complexes were obtained by reaction of the free carbene with the appropriate metal precursor, except for the Au(III) complex 10, which was obtained by oxidation of the antecedent gold(I) complex [AuCl(1)]?with PhICl2as an external oxidant. During the course of the process, the kinetic gold(I) intermediate 9 resulting from the oxidation of the malonic carbon of the barbituric moiety was isolated upon crystallization from the reaction mixture. The νCOstretching frequencies recorded for complex [Rh(1)(CO)2] (5) demonstrated the strong donating character of the malonate-C(sp3)/NHC ligand 1-. The ruthenium complex [Ru(1)Cl(p-cymene)] (11) was implemented as a precatalyst in the dehydrogenative synthesis of carboxylic acid derivatives from primary alcohols and exhibited high activities at low catalyst loadings (25-250 ppm) and a large tolerance toward functional groups.
- Benaissa, Idir,Gajda, Katarzyna,Vendier, Laure,Lugan, No?l,Kajetanowicz, Anna,Grela, Karol,Michelet, Véronique,César, Vincent,Bastin, Stéphanie
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p. 3223 - 3234
(2021/09/30)
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- Ruthenium-catalyzed ester reductions applied to pharmaceutical intermediates
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Ruthenium pincer complexes were synthesized and used for catalytic ester reductions under mild conditions (～5 bar of hydrogen). An experimental design approach was used to optimize the conditions for yield, purity, and robustness. Evidence for the catalytically active ruthenium dihydride species is presented. Observed intermediates and side products, as well as time-course data, were used to build mechanistic insight. The optimized procedure was further demonstrated through scaled-up reductions of two pharmaceutically relevant esters, both in batch and continuous flow.
- Shaalan, Youssef,Boulton, Lee,Jamieson, Craig
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supporting information
p. 2745 - 2751
(2020/11/30)
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- A Diaminopropane Diolefin Ru(0) Complex Catalyzes Hydrogenation and Dehydrogenation Reactions
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New ruthenium (0) complexes with a cooperative diolefin diaminopropane (DAP) or the dehydrogenated iminopropenamide ligand (IPA) were synthesized for comparison with their diaminoethane (DAE)/ diazadiene (DAD) ruthenium analogues. These DAP/IPA complexes are efficient catalysts in dehydrogenation reactions of alkaline aqueous methanol which proceeds under mild conditions (T=70 °C) and of higher alcohols, forming the corresponding carbonate and carboxylates, respectively. The scope of the reaction includes an example of a 1,2-diol as model for biomass derived alcohols. Their catalytic applications are extended to the atom-efficient dehydrogenative coupling of alcohols and amines to amides. The reaction proceeds without any additives and is applicable to the synthesis of formamides from methanol. Moreover, DAP/IPA complexes catalyze the hydrogenation of a series of esters, lactone, ketone, activated olefin, aldehyde and imine substrates. The diaminopropane Ru catalyst exhibits higher activity compared to the dehydrogenated β-ketiminate (IPA) and previously studied DAD/DAE based catalysts. We present studies on their stoichiometric reactivity with relevance to their possible catalytic mechanisms and the isolation and full characterization of key reaction intermediates.
- Casas, Fernando,Trincado, Monica,Rodriguez-Lugo, Rafael,Baneerje, Dipshikha,Grützmacher, Hansj?rg
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p. 5241 - 5251
(2019/11/16)
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- Lanthanoid complexes supported by retro-Claisen condensation products of β-triketonates
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β-Triketonates have been recently used as chelating ligands for lanthanoid ions, presenting unique structures varying from polynuclear assemblies to polymers. In an effort to overcome low solubility of the complexes of tribenzoylmethane, four β-triketones with higher lipophilicity were synthesised. Complexation reactions were performed for each of these molecules using different alkaline bases in alcoholic media. X-ray diffraction studies suggested that the ligands were undergoing decomposition under the reaction conditions. This is proposed to be caused by in situ retro-Claisen condensation reactions, consistent with two examples that have been reported previously. The lability of the lanthanoid cations in the presence of a varying set of potential ligands gave rise to structures where one, two, or three of the molecules involved in the retro-Claisen condensation reaction were linked to the lanthanoid centres. These results, along with measurements of ligand decomposition in the presence of base alone, suggest the solvent used will modulate the impact of the retro-Claisen condensation in these complexes.
- Abad Galán, Laura,Sobolev, Alexandre N.,Zysman-Colman, Eli,Ogden, Mark I.,Massi, Massimiliano
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supporting information
p. 17469 - 17478
(2019/01/03)
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- Mechanistic investigation of imine formation in ruthenium-catalyzed N-alkylation of amines with alcohols
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Imines are observed frequently in ruthenium-catalyzed N-alkylation of amines with alcohols. Herein, nitrogen–phosphine functionalized carbene ligands were developed and used in ruthenium-catalyzed N-alkylation to explore the mechanism of imine formation. The results showed that strongly electron-donating ligands were beneficial for imine formation and alcohol dehydrogenation to generate acid. In addition, with an increase of electron density of nitrogen atom in substituted amines, the yield of imines in N-alkylation was improved. At the same time, with electron-rich imines as substrates, the transfer hydrogenation of imines became difficult. It is suggested that strongly electron-donating ligands and substrates caused an increase of electron density on the ruthenium center, which resulted in the elimination of hydrogen atoms in active species [LRuH2] as hydrogen gas rather than transfer onto the imine coordinated with the ruthenium center.
- Yu, Xiaojun,Li, Yaqiu,Fu, Haiyan,Zheng, Xueli,Chen, Hua,Li, Ruixiang
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- Efficient Method for Aromatic-Aldehyde Oxidation by Cleavage of Their Hydrazones Catalysed by Trimethylsilanolate
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The reactions of hydrazones, derived from various aromatic aldehydes bound to Rink resin and hydrazines, with trimethylsilanolate have been studied. In this process, the aldehydes were oxidized to the corresponding carboxylic acids. The reaction was also tested with success in solution, with various aromatic aldehydes easily being oxidized in one pot via hydrazone formation and trimethylsilanolate treatment. A mechanism for the hydrazone cleavage is proposed. The reaction may be used as an alternative method for aldehyde oxidation with the selectivity complementary to that of currently used reactions.
- Burglova, Kristyna,Okorochenkov, Sergei,Budesinsky, Milos,Hlavac, Jan
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p. 389 - 396
(2017/01/24)
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- One-pot odourless synthesis of thioesters via in situ generation of thiobenzoic acids using benzoic anhydrides and thiourea
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An efficient and odourless procedure for a one-pot synthesis of thioesters by the reaction of benzoic anhydrides, thiourea and various organic halides (primary, allylic, and benzylic) or structurally diverse, electron-deficient alkenes (ketones, esters, and nitriles) in the presence of Et3 N has been developed. In this method, thiobenzoic acids were in situ generated from the reaction of thiourea with benzoic anhydrides, which were subjected to conjugate addition with electron-deficient alkenes or a nucleophilic displacement reaction with alkyl halides.
- Abbasi, Mohammad,Khalifeh, Reza
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p. 1265 - 1273
(2015/08/18)
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- Facile and direct synthesis of symmetrical acid anhydrides using a newly prepared powerful and efficient mixed reagent
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An efficient mixed reagent for direct synthesis of symmetrical carboxylic anhydrides from carboxylic acids has been prepared. Carboxylic acids are converted to anhydrides using triphenylphosphine/ trichloroisocyanuric acid under mild reaction conditions at room temperature. Short reaction time, excellent yields of products, low cost, availability of reagents, simple experimental procedure, and easy work-up of the products are the main advantages of the presented method.
- Rouhi-Saadabad, Hamed,Akhlaghinia, Batool
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p. 479 - 485
(2015/01/30)
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- Noncovalent catch and release of carboxylates in water
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Association constants of a bis-(acetylguanidinium)ferrocene dication to various (di)carboxylates were determined through UV-vis titrations. Association constant values greater than 104 M-1 were determined for both phthalate and maleate carboxylates to the bis-(acetylguanidinium)ferrocene salt in pure water. Density functional theory computations of the binding enthalpy of the rigid carboxylates for these complexes agree well with the experimentally determined association constants. Catch and release competitive binding experiments were done by NMR for the cation-carboxylate ion-pair complexes with cucurbit[7]uril, and they show dissociation of the ion-pair complex upon addition of cucurbit[7]uril and release of the free (di)carboxylate.
- Beck, Christie L.,Winter, Arthur H.
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p. 3152 - 3158
(2014/05/06)
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- Synthesis of aryl ethers from benzoates through carboxylate-directed C-H-activating alkoxylation with concomitant protodecarboxylation
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One in, one out: In the presence of a copper/silver bimetallic catalyst system, aromatic carboxylate salts undergo ortho C-H alkoxylation with concomitant loss of the carboxylate directing group in a protodecarboxylation step (see scheme, FG=functional group). This process provides a convenient synthetic access to the important class of aromatic ethers from widely available carboxylic acids. Copyright
- Bhadra, Sukalyan,Dzik, Wojciech I.,Goo?en, Lukas J.
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supporting information
p. 2959 - 2962
(2013/04/10)
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- Catalytic nanoreactors for ester hydrolysis
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Hydrolysis of 4-nitrophenyl benzoate (PNPB) in the presence of ionene nanoreactors was studied comparing the ionenes, poly[(dimethyl)-2-hydroxy propanodiyl chloride] (2-OH-33R1), poly[(methylbutyliminium)-2-hydroxy propanodiyl chloride] (2-OH-33R4) and poly[(methyloctyliminium)-2-hydroxy propanodiyl chloride] (2-OH-33R8). Methyl orange incorporation and study of viscosity showed that increase of the side chain length of the ionene enhances the ability to form globular hydrophobic microdomains. Catalytic hydrolysis of PNPB follows the order 2-OH-33R8 2-OH-33R4 > 2-OH-33R1, and 2-OH-33R8 has the lowest pKa that may reflect its higher hydrophobicity, which apparently influences the ionene nanoreactor reactivity. A lower pKa indicates easier deprotonation of the alkoxide group, which participates more effectively in the reaction and the 2-OH-33R8 functionalized ionene acts as a specially effective catalytic homogeneous nanoreactor.
- Berlamino, Alexanders T.N.,Orth, Elisa S.,Mello, Renata S.,Medeiros, Michelle,Nome, Faruk
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experimental part
p. 7 - 12
(2011/02/16)
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- NOVEL BENZOOXAZOL- AND BENZOOXATHIOL-2-ONE DERIVATIVES AND THEIR USE AS MONOAMINE NEUROTRANSMITTER RE-UPTAKE INHIBITORS
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This invention relates to novel benzooxazol- and benzooxathiol-2-one derivatives useful as monoamine neurotransmitter re-uptake inhibitors. In other aspects the invention relates to the use of these compounds in a method for therapy and to pharmaceutical compositions comprising the compounds of the invention.
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Page/Page column 11
(2009/04/25)
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- NOVEL PHENOXAZIN-3-ONE DERIVATIVES AND THEIR USE AS MONOAMINE NEUROTRANSMITTER RE-UPTAKE INHIBITORS
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This invention relates to novel phenoxazin-3-one derivatives useful as monoamine neurotransmitter re-uptake inhibitors. In other aspects the invention relates to the use of these compounds in a method for therapy and to pharmaceutical compositions comprising the compounds of the invention.
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Page/Page column 11
(2009/04/25)
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- NOVEL CHROMEN-2-ONE DERIVATIVES AND THEIR USE AS MONOAMINE NEUROTRANSMITTER RE-UPTAKE INHIBITORS
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This invention relates to novel chromen-2-one derivatives of formula (I) useful as monoamine neurotransmitter re-uptake inhibitors. In other aspects the invention relates to the use of these compounds in a method for therapy and to pharmaceutical compositions comprising the compounds of the invention. Formula (I) wherein Q represents a chromen-2-one group; which chromen-2-one group is optionally substituted with one or more substituents independently selected from the group consisting of: halo, trifluoromethyl, trifluoromethoxy, cyano, hydroxy, amino, nitro, alkoxy, cycloalkoxy, alkyl, cycloalkyl, cycloalkylalkyl, alkenyl and alkynyl; R1 represents hydrogen or alkyl; which alkyl is optionally substituted with one or more substituents independently selected from the group consisting of: halo, trifluoromethyl, trifluoromethoxy, cyano, hydroxy, amino, nitro, alkoxy, cycloalkoxy, alkyl, cycloalkyl, cycloalkylalkyl, alkenyl and alkynyl; and R2 and R3 together form -(CH2)-(CH2)- or -(CH)=(CH)-.
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Page/Page column 15
(2008/06/13)
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- Surfactant-mediated solvent-free dealkylative cleavage of ethers and esters and trans-alkylation under neutral conditions
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A simple, surfactant-mediated, one-pot, solvent-free dealkylative cleavage of aryl ethers and esters followed by subsequent optional trans-alkylation under essentially neutral conditions has been developed.
- Bhattacharya, Apurba,Patel, Nitin C.,Vasques, Tomas,Tichkule, Ritesh,Parmar, Gaurang,Wu, Jiejun
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p. 565 - 567
(2007/10/03)
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- Reaction of benzoyl peroxide with bromide anion
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The reaction of benzoyl peroxide with a complex of potassium bromide and 18-crown-6 in acetonitrile at 293-308 K was investigated. The reagents in the course of reaction are consumed in stoichiometric quantities. The main reaction products are the complex of potassium benzoate with the 18-crown-6 and benzoic acid arising due to decomposition of the intermediately formed unstable benzoyl hypobromite. The reaction with the above complex was compared to that with tetraethylammonium bromide. The latter demonstrated higher reactivity toward benzoyl peroxide than the complex of potassium bromide with 18-crown-6.
- Opeida,Turovskii,Maksyuta
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p. 1646 - 1649
(2007/10/03)
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- The positional reactivity order in the sulfur trioxide sulfonation of benzene and naphtalene derivatives containing an electron-withdrawing substituent
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The reaction of sulfur trioxide with derivatives of benzene and naphthalene containing an electron-withdrawing substituent, viz.-SO3H, -SO2Ph, -NO2, -CHO, -COPh, -CO2H, and -CO2Me, in dichloromethane as solvent at ca. 22 deg C has been studied by analysis of the resulting mixtures of the sulfo derivatives with 1H-NMR.The initial sulfonation of the benzene derivatives yields the corresponding 3-sulfonic acid (3-S) and subsequently, with the exception of nitrobenzene and methyl benzoate, small amounts of 3,5-S2.Benzenesulfonic acid in addition undergoes sulfonylation giving 3,3'-di- and 3,5,3'-trisulfodiphenyl sulfone.Monosulfonation of naphtalene-1-S yields the 1,5-S2, 1,6-S2 and 1,7-S2 derivatives in a ratio of 71:20:9.On using a large excess of SO3, the eventual products are 1,3,5-S3, 1,3,6-S3 and 1,3,5,7-S4.Monosulfonation of naphthalene yields 5-S, 6-S, 7-S and 8-S in a 55:9:6:30 ratio, that of 1-benzoylnaphthalene 5-S, 6-S and 7-S in a ratio of 83:11:6, and 1-nitronaphtalene only the 5-S.The absence of peri sulfonation with 1-sulfo-, 1-benzoyl- and 1-nitronaphthalene is due to prohibitive steric hidrance. 1-Naphthoic acid and its methyl ester upon SO3 sulfonation and aqueous work-up both yield 5- and 8-sulfonaphthoic acid in a ratio of 65:35 and 77:21, respectively.The initially formed peri-substituted product is the intramolecular anhydride of 8-sulfo-1-naphthoic acid (5).All the 2-substituted naphthalenes yield 5-S and 8-S upon SO3 sulfonation of which the former sulfo isomer is far in excess.The positional reactivity orders for the SO3 sulfonation of the monosubstituted naphthalene derivatives are discussed in terms of the difference in reactivity of the α- and β-positions, and the steric and electronic effects of the deactivating substituent.
- Cerfontain, Hans,Zou, Yousi,Bakker, Bert H.
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p. 403 - 410
(2007/10/02)
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- Photochemical Decomposition of Dibenzoyl Peroxide and Phenyl Benzoate in Solid KBr Matrix
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Physical and photochemical properties of dibenzoyl peroxide (DBPO) and phenyl benzoate (PB) in a solid KBr matrix were investigated.The photoinduced decompositions of DBPO and PB were monitored with infrared spectroscopy and HPLC.The organic molecules at different locations in the matrix contribute to the overall IR absorption differently.Therefore, they are affected differently during a photochemical decomposition.The bromide ions in the matrix intercept some of the radical intermediates in the decomposition of DBPO but have no influence on the radical pair in the rearrangement of phenyl benzoate.
- Owen, David J.,O'Donnell, Jennifer,Schutt, Wendy,Morrow, Jeffrey,Li, Yuzhuo
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p. 6203 - 6207
(2007/10/02)
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- Preparation of anhydrous organic acid salts
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One-step process for preparing anhydrous, organic acid alkali or alkaline earth metal salts by contacting and reacting an organic or polymeric acid fluoride, anhydride or ester and an organic alkali or alkaline earth metal silanolate.
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- Method for producing terephthalic acid
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A low viscosity slurry of aggregates of crystals in a dispersant is prepared by first making aggregates of crystals by the method of direct precipitation, the shape of the aggregates being granular, and then mixing the aggregates and the dispersant.
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- METAL SILANOLATES: ORGANIC SOLUBLE EQUIVALENTS FOR O-2
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Alkali metal trimethylsilanolates, M+ -OSiMe3, convert carboxylic acid derivatives into their corresponding anhydrous acid salts under mild non-aqueous conditions.
- Langanis, E. D.,Chenard, B. L.
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p. 5831 - 5834
(2007/10/02)
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- OXIDATIVE BENZOIN REACTIONS
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A one-pot synthesis (yields over 50percent) of methyl and ethyl esters from aldehydes (and the corresponding alcohol), using aromatic nitrocompounds as oxidizing agents under the catalytic action of cyanide ion or of a conjugate base of a thiazolium ion, is described.A variety of by-products (α-hydroxybenzylidenaniline (16), α-methoxybenzylidenaniline (21), α-cyanobenzylidenaniline (27), N1-hydroxy-N1,N2-diphenylbenzamidine (28), and others) have been identified.
- Castells, J.,Pujol, F.,Llitjos, H.,Moreno-Manas, M.
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p. 337 - 346
(2007/10/02)
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- Carbanions. Electron Transfer vs. Proton Capture. 7. Electron-Transfer Oxidation of an Amino Acid Derived Carbanion
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The dimethylamide of phenylalanine, 1, reacts with potassium tert-butoxide and nitrobenzene in tert-butyl alcohol at 50 deg C in argon atmosphere.The products are potassium nitrobenzenide (PhNO2-*K+)and degradative fragments of the amino amide, including ammonia, dimethylamine, potassium benzoate, potassium carbonate, and potassium cyanide.The yields of these isolated degradation products are relatively low when the reaction is run anaerobically but are improved when the reaction is carried out under oxygen.The oxygen-mediated reaction does not produce cyanide or nitrobenzenide but its products are otherwise the same with the addition of oxalate.Conversions are essentially quantitative when the oxygen-mediated reaction is followed by vigorous, acid-catalyzed, hydrolytic workup.The reaction is believed to begin with the one-electron oxidation of the α-amino carbanion, proceeding through a ketimine and/or enamine which is rapidly oxidized to the eventual products.The rate of oxidation of 1 is approximately the same as its ionization rate but the reaction becomes less efficient if the N-pivalyl derivative of 1 is used.Experiments with the dimethylamide of alanine give qualitatively similar results, with potassium formate replacing potassium benzoate in the products.
- Guthrie, Robert D.,Hrovat, David A.,Prahl, Fredrick G.,Swan, James
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p. 498 - 501
(2007/10/02)
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