- Biorenewable carbon-supported Ru catalyst for: N -alkylation of amines with alcohols and selective hydrogenation of nitroarenes
-
Herein, we developed a renewable carbon-supported Ru catalyst (Ru/PNC-700), which was facilely prepared via simple impregnation followed by the pyrolysis process. The prepared Ru/PNC-700 catalyst demonstrated remarkable catalytic activity in terms of conversion and selectivity towards N-alkylation of anilines with benzyl alcohol and chemoselective hydrogenation of aromatic nitro compounds. In addition, local anesthetic pharmaceutical agents (e.g., butamben and benzocaine), including key drug intermediates, were synthesized in excellent yields under mild conditions and in the presence of water as a green solvent. Moreover, the prepared Ru/PNC-700 catalyst could be easily recovered and reused up to five times without any apparent loss in activity and selectivity.
- Goyal, Vishakha,Narani, Anand,Natte, Kishore,Poddar, Mukesh Kumar,Ray, Anjan,Sarki, Naina,Tripathi, Deependra
-
p. 14687 - 14694
(2021/08/23)
-
- Simple RuCl3-catalyzed N-Methylation of Amines and Transfer Hydrogenation of Nitroarenes using Methanol
-
Methanol is a potential hydrogen source and C1 synthon, which finds interesting applications in both chemical synthesis and energy technologies. The effective utilization of this simple alcohol in organic synthesis is of central importance and attracts scientific interest. Herein, we report a clean and cost-competitive method with the use of methanol as both C1 synthon and H2 source for selective N-methylation of amines by employing relatively cheap RuCl3.xH2O as a ligand-free catalyst. This readily available catalyst tolerates various amines comprising electron-deficient and electron-donating groups and allows them to transform into corresponding N-methylated products in moderate to excellent yields. In addition, few marketed pharmaceutical agents (e. g., venlafaxine and imipramine) were also successfully synthesized via late-stage functionalization from readily available feedstock chemicals, highlighting synthetic value of this advanced N-methylation reaction. Using this platform, we also attempted tandem reactions with selected nitroarenes to convert them into corresponding N-methylated amines using MeOH under H2-free conditions including transfer hydrogenation of nitroarenes-to-anilines and prepared drug molecules (e. g., benzocaine and butamben) as well as key pharmaceutical intermediates. We further enable one-shot selective and green syntheses of 1-methylbenzimidazole using ortho-phenylenediamine (OPDA) and methanol as coupling partners.
- Sarki, Naina,Goyal, Vishakha,Tyagi, Nitin Kumar,Puttaswamy,Narani, Anand,Ray, Anjan,Natte, Kishore
-
p. 1722 - 1729
(2021/04/19)
-
- Pd/C-catalyzed transfer hydrogenation of aromatic nitro compounds using methanol as a hydrogen source
-
We describe the selective transfer hydrogenation of aromatic nitro compounds to anilines using Pd/C as a heterogeneous catalyst with methanol as a green reductant. Nitroarenes bearing both electron-releasing and electron-deficient groups are amenable to this method and enable the synthesis of corresponding arylamines in moderate to good selectivities including the synthesis of butamben, a local anesthictic drug molecule. This new concise protocol is simple, ligand-free and does not require the supply of external molecular hydrogen.
- Goyal, Vishakha,Sarki, Naina,Natte, Kishore,Ray, Anjan
-
-
- Superhydrophobic nickel/carbon core-shell nanocomposites for the hydrogen transfer reactions of nitrobenzene and N-heterocycles
-
In this work, catalytic hydrogen transfer as an effective, green, convenient and economical strategy is for the first time used to synthesize anilines and N-heterocyclic aromatic compounds from nitrobenzene and N-heterocycles in one step. Nevertheless, how to effectively reduce the possible effects of water on the catalyst by removal of the by-product water, and to further introduce water as the solvent based on green chemistry are still challenges. Since the structures and properties of carbon nanocomposites are easily modified by controllable construction, a one step pyrolysis process is used for controllable construction of micro/nano hierarchical carbon nanocomposites with core-shell structures and magnetic separation performance. Using various characterization methods and model reactions the relationship between the structure of Ni?NCFs (nickel-nitrogen-doped carbon frameworks) and catalytic performance was investigated, and the results show that there is a positive correlation between the catalytic performance and hydrophobicity of catalysts. Besides, the possible catalytically active sites, which are formed by the interaction of pyridinic N and graphitic N in the structure of nitrogen-doped graphene with the surfaces of Ni nanoparticles, should be pivotal to achieving the relatively high catalytic performance of materials. Due to its unique structure, the obtained Ni?NCF-700 catalyst with superhydrophobicity shows extraordinary performances toward the hydrogen transfer reaction of nitrobenzene and N-heterocycles in the aqueous state; meanwhile, it was also found that Ni?NCF-700 still retained its excellent catalytic activity and structural integrity after three cycles. Compared with traditional catalytic systems, our catalytic systems offer a highly effective, green and economical alternative for nitrobenzene and N-heterocycle transformation, and may open up a new avenue for simple construction of structure and activity defined carbon nanocomposite heterogeneous catalysts with superhydrophobicity.
- Duan, Zhiying,Liu, Fangfang,Pang, Shaofeng,Su, Qiong,Wang, Yanbin,Xie, Xin,Zhang, Ping,Zhang, Yujing,Zhou, Feng
-
p. 1996 - 2010
(2020/04/07)
-
- Method for preparing p-aminobenzoic acid alkyl ester
-
The invention discloses a method for preparing p-aminobenzoic acid alkyl ester. The method comprises the following steps: performing an esterification reaction on p-nitrobenzoic acid and a corresponding alkyl alcohol so as to obtain p-nitrobenzoic acid alkyl ester, and further performing catalytic hydrogenation, so as to obtain the p-aminobenzoic acid alkyl ester, wherein the solvent used in the esterification reaction is p-nitrobenzoic acid alkyl ester; the mole ratio of p-nitrobenzoic acid to the p-nitrobenzoic acid alkyl ester is (1:0.5)-(1:1); the alkyl alcohol is a C4-C8 alcohol; the moleratio of the p-nitrobenzoic acid to the alkyl alcohol is (1:0.98)-(1:1.1); the esterification reaction is implemented in the presence of the catalyst; and the catalyst is sulfuric acid or p-toluenesulfonic acid. The invention unexpectedly shows that an esterification reaction product, namely the p-aminobenzoic acid alkyl ester, can be used as a solvent of the esterification reaction, with the esterification reaction solvent, the process that an alcohol or benzene solvent needs to be recycled in a conventional method is avoided, not only is aftertreatment simple, but also solvent consumption is avoided, and the method is environment-friendly.
- -
-
Paragraph 0014; 0017
(2019/10/29)
-
- Room Temperature Carbonylation of (Hetero) Aryl Pentafluorobenzenesulfonates and Triflates using Palladium-Cobalt Bimetallic Catalyst: Dual Role of Cobalt Carbonyl
-
An efficient method for the carbonylation of (hetero) aryl pentafluorobenzenesulfonates and triflates under exceptionally mild conditions using palladium/dicobalt octacarbonyl [Pd/Co2(CO)8] has been developed. Besides acting as carbon monoxide (CO) source, Co2(CO)8enhances the reaction rate by accelerating the CO insertion through an in situ generated bimetallic palladium cobalt tetracarbonyl [Pd-Co(CO)4] complex. Under the optimized reaction condition, carbonylation of a wide range of activated and deactivated, as well as sterically hindered and heteroaromatic, substrates proceeded efficiently at room temperature. The high chemoselectivity and improved synthesis of biologically relevant Isoguvacine and Lazabemide intermediates highlights its scope as a valuable synthetic method. The generality of this protocol was further extended to other electrophiles (bromides, chlorides and tosylates). (Figure presented.).
- Joseph, Jayan T.,Sajith, Ayyiliath M.,Ningegowda, Revanna C.,Shashikanth, Sheena
-
supporting information
p. 419 - 425
(2017/02/10)
-
- Competitive homolytic and heterolytic decomposition pathways of gas-phase negative ions generated from aminobenzoate esters
-
An alkyl-radical loss and an alkene loss are two competitive fragmentation pathways that deprotonated aminobenzoate esters undergo upon activation under mass spectrometric conditions. For the meta and para isomers, the alkyl-radical loss by a homolytic cleavage of the alkyl-oxygen bond of the ester moiety is the predominant fragmentation pathway, while the contribution from the alkene elimination by a heterolytic pathway is less significant. In contrast, owing to a pronounced charge-mediated ortho effect, the alkene loss becomes the predominant pathway for the ortho isomers of ethyl and higher esters. Results from isotope-labeled compounds confirmed that the alkene loss proceeds by a specific γ-hydrogen transfer mechanism that resembles the McLafferty rearrangement for radical cations. Even for the para compounds, if the alkoxide moiety bears structural motifs required for the elimination of a more stable alkene molecule, the heterolytic pathway becomes the predominant pathway. For example, in the spectrum of deprotonated 2-phenylethyl 4-aminobenzoate, m/z 136 peak is the base peak because the alkene eliminated is styrene. Owing to the fact that all deprotonated aminobenzoate esters, irrespective of the size of the alkoxy group, upon activation fragment to form an m/z 135 ion, aminobenzoate esters in mixtures can be quantified by precursor ion discovery mass spectrometric experiments.
- Xia, Hanxue,Zhang, Yong,Pavlov, Julius,Jariwala, Freneil B.,Attygalle, Athula B.
-
p. 245 - 253
(2016/03/15)
-
- Mesomorphism dependence on the combined effect of molecular rigidity and flexibility
-
A novel liquid crystalline (LC) homologous series of azoesters with a laterally substituted methoxy group RO-C6H4-COO-C6H3-(-OCH3)-N═N-C6H4-COO-C4H9(n) has been synthesized and studied with a view to understanding the effect of molecular structure on thermotropic mesomorphism. The novel homologous series consists of thirteen homologues (C1–C18). The C1–C5 homologues are nonliquid crystals. The C6 and C7 homologues are only enantiotropically nematogenic and the rest of the mesomorphic homologues (C8–C18) are enantiotropically smectogenic and nematogenic. Transition temperatures and the textures of the mesophases were determined using an optical polarizing microscope (POM) equipped with a heating stage. The novel azoester homologues were characterised and confirmed using their analytical, spectral and thermometric data. Transition curves Cr-M/I, Sm-N and N-I behaved in normal manner without (Sm-N) and with (N-I) exhibition of odd-even effect respectively in a phase diagram. Thermal stabilities for smectic and nematic are 100.0°C and 127.7°C whose, mesomorphic phase length vary from 13.0°C to 24.0°C and 11.0°C to 33.0°C, respectively. The mesomorpism is compared with other known series.
- Jadeja,Patel
-
-
- Expedient carbonylation of aryl halides in aqueous or neat condition
-
An expedient and versatile, microwave-assisted procedure for the carbonylation of aryl halides with boronic acids, alcohols or amines in water or under neat conditions has been developed. The reaction is catalyzed by fluorous, oxime-based palladacycle 1 that shows an excellent recyclable property and low levels of Pd leaching. To demonstrate the usefulness of the protocol, we applied it to the preparation of compounds of pharmaceutical interest, including a precursor of the reverse transcriptase inhibitor, niacin, benzocaine and butamben.
- Ang, Wei Jie,Lo, Lee-Chiang,Lam, Yulin
-
p. 8545 - 8558
(2014/12/11)
-
- Synthesis and phase behaviors of side-chain liquid-crystalline polymers containing azobenzene mesogen with the different length alkyl tail
-
A series of side-chain liquid-crystal polymers, poly[6-[4-(4′-n-alkyl benzoateazo)phenoxy]-hexylmethacrylate]s (PMAzoCOORm, m = 1, 2, 3, 4, 5, 6, 8, 10, 14, and 18) have been prepared by two synthetic methods. The chemical structure of the monomers was confirmed by 1H NMR and mass spectrometry. The molecular characterizations of the polymers were performed with 1H NMR and gel permeation chromatograph. The phase behaviors of polymers were investigated by the combination of techniques including differential scanning calorimetry, polarized optical microscopy, and small-angle X-ray scattering. For m = 1, 2, 3, 4, 5, and 6, the polymers exhibited a monosmectic A phase in which the smectic layer period was almost identical to the side-chain length. In addition, for m = 2, 3, 4, and 5, they presented the monosmectic C phase in low temperature; moreover, the tilt angle increased from 23.3 to 40.5°. For m = 8, 10, 14, and 18, the polymers showed a bilayer smectic A phase in which the layer spacing was larger than a fully extended side chain but less than two extended chains. On the other hand, for the clearing point, with the increasing of m, it first decreased, and then increased. All of these indicated that the length of alkyl tails played an important role in the phase behaviors of these polymers.
- Chen, Sheng,Ling, Aihua,Zhang, Hai-Liang
-
p. 2759 - 2768
(2013/07/27)
-
- Synthesis and cytotoxicity of some d-mannose click conjugates with aminobenzoic acid derivatives
-
Two sets of new conjugates obtained from d-mannose derivatives and o-, m-, and p-substituted benzoic acid esters interconnected through a triazole ring were synthesized by Cu(I) catalyzed azide-alkyne cycloaddition. All synthesized compounds were tested for their in vitro cytotoxic activity against seven cancer cell lines with/without multidrug resistance phenotype as well as non-tumor MRC-5 and BJ fibroblasts. Butyl ester of 4-aminobenzoic acid 6c showed the highest activity among all tested compounds, however, it was active only against K562 myeloid leukemia cells. N-Glycosyltriazole conjugates, both acetylated and nonacetylated at mannose moiety, were almost completely inactive. In contrast, some of the acetylated O-glycosyl conjugates showed cytotoxic activity which was cell line dependent and strongly affected by position of benzoic acid substitution as well as a length of its ester alkyl chain; the most potent compound was acetylated mannoside conjugated with octyl ester of m-substituted benzoic acid. However, deacetylation resulting in hydrophilicity increase of the glycosides almost completely abolished their cytotoxic potency.
- Hradilová, Ludmila,Poláková, Monika,Dvo?áková, Barbora,Hajdúch, Marián,Petru?, Ladislav
-
-
- Ionic liquids as solvent for efficient esterification of carboxylic acids with alkyl halides
-
The selective esterification of carboxylic acid derivatives with a variety of alkyl halides was carried out using ionic liquid as solvent in the presence of triethylamine. The reaction was found to proceed under relatively mild conditions with excellent conversions (up to 99%) and selectivities. The ionic liquid was recycled and reused. TUeBITAK.
- Goek, Yetkin,Alici, Buelent,Cetinkaya, Enginc,OeZdemir, Ismail,Oezeroglu, Ozlem
-
experimental part
p. 187 - 191
(2010/09/11)
-
- Structure-activity relationships (SAR) research of thiourea derivatives as dual inhibitors targeting both HIV-1 capsid and human cyclophilin A
-
HIV-1 capsid (CA) and human cyclophilin A (CypA) play important roles in HIV-1 assembly and disassembly processes, which are critical in HIV-1 replication. Based on the discovery of thiourea derivatives targeting both of the two proteins and indicating effective inhibitory activities in our group, we designed and synthesized a new class of thiourea derivatives. Their abilities to bind to capsid and cyclophilin A were determined by ultraviolet spectroscopic analysis, fluorescence binding affinity, and PPIase inhibition assay. Furthermore, the newly synthesized compounds were tested for their antiviral activities and cytotoxicities using CEM cells. According to the biological evaluation and subsequent molecular docking analyses, we studied the structure-activity relationships of thiourea derivatives. Three optimal compounds (K17, K24, K25) based on the achieved structure-activity relationships would be the basis for future optimization.
- Chen, Kan,Tan, Zhiwu,He, Meizi,Li, Jiebo,Tang, Shixing,Hewlett, Indira,Yu, Fei,Jin, Yinxue,Yang, Ming
-
scheme or table
p. 25 - 33
(2011/04/17)
-
- Liquid-Phase Hydrogenation of p-Nitrobenzoic Acid Esters on Palladium Catalysts
-
Hydrogenation of some p-nitrobenzoic esters on palladium catalysts (conventional heterogeneous Pd/C and Pd/Al2O3 and polymeric AV-17-8-Pd and AN-1-Pd) is studied. The maximum rate of the hydrogenation reaction was observed in methanol at t = 55°C and PH2 = 0.1 MPa. MNDO calculations of some electronic characteristics of p-nitrobenzoic ester molecules were performed. A two-parameter correlation between the hydrogenation rate constant, the charge of the nitro group, and the steric substituent constant was found for the reaction conducted on the AV-17-8-Pd and AN-1-Pd catalysts.
- Morogina,Nasibulin,Klyuev
-
p. 251 - 255
(2007/10/03)
-
- Change of the Rate-Determining Stage in the Hydrogenation of Nitrobenzene. Effect of Solvent and Catalyst
-
The rate-determining stage in the hydrogenation of nitrobenzene in ethanol over palladium-containing flexible polymers or Pd/C is reduction of the nitro group to nitroso. In 2-propanol, the rate-determining stage is reduction of the nitroso group. When the hydrogenation is performed over palladium-containing hard polymers, change of the solvent does not result in change of the rale-determining stage which is reduction of the nitroso group.
- Voronin,Nasibulin,Klyuev
-
p. 1613 - 1615
(2007/10/03)
-
- An efficient general method for esterification of aromatic carboxylic acids
-
Treatment of a variety of aromatic carboxylic acids with alcohols in the presence of thionyl chloride results in excellent yields of corresponding esters. This esterification system is compatible with a wide assortment of functional groups.
- Hosangadi, Bhaskar D.,Dave, Rajesh H.
-
p. 6375 - 6378
(2007/10/03)
-
- Synthesis and Investigation of Mesomorphic Properties of Some Thiazole Derivatives
-
2,4-Disubstituted thiazoles with liquid crystal properties are synthesized.Influence of the length of the aliphatic chain on the type of mesomorphism and the width of the temperature range of the mesophase existence is investigated.The compounds are shown to possess mesomorphism of smectic type in the range of 36-145 deg C.
- Murza, M. M.,Golovanov, A. S.,Safarov, M. G.
-
p. 1529 - 1532
(2007/10/03)
-
- Smectogenic Salts Formed by Combination of Alkyl p-Aminobenzoates and p-Ethyl- or p-Chlorobenzenesulfonic Acid
-
Two series of smectogenic salts were obtained by combining alkyl p-aminobenzoates with p-ethyl- and p-chlorobenzenesulfonic acids, respectively.The shortest ester alkyl chain required to generate a smectic A phase is nonyl when the former sulfonic acid is employed but the chain may be as short as butyl when the latter is employed.The smectic A-isotropic transition temperature in the second series is significantly higher than that in the first series, indicating that the terminal substituent on the anion is as crucial as that in non-ionic mesogens in determining the mesophase stability. - Keywords: Smectic, alkyl p-aminobenzoates, benzenesulfonates
- Matsunaga, Y.,Sakamoto S.,Togashi, A.,Tsujimoto, M.
-
p. 161 - 166
(2007/10/02)
-
- EFFECTS OF BRANCHING OF THE ALKYL CHAIN ON THE LIQUID CRYSTALLINE PROPERTIES OF N-(p-PHENYLBENZYLIDENE)-p-ALKOXYCARBONYLANILINES.
-
The liquid crystal behavior of twenty-three N-(p-phenylbenzylidene)-p-alkoxycarbonylanilines has been examined by optical microscopy and differential scanning calorimetry in order to study the effects of branching of the alkyl groups.
- Matsunaga,Miyajima
-
p. 353 - 359
(2007/10/02)
-
