- Intermolecular cyclization of diethanolamine and methylamine to N,N′-dimethylpiperazine over zeolites under high pressure
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Synthesis of N,N′-dimethylpiperazine via intermolecular cyclization of diethanolamine and methylamine has been investigated under high pressure conditions using zeolites and montmorillonite K10 for the first time. The HZSM-5(30) is particularly effective
- Narender,Srinivasu,Kulkarni,Raghavan
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Read Online
- Continuous N-alkylation reactions of amino alcohols using γ-Al2O3 and supercritical CO2: Unexpected formation of cyclic ureas and urethanes by reaction with CO2
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The use of γ-Al2O3 as a heterogeneous catalyst in scCO2 has been successfully applied to the amination of alcohols for the synthesis of N-alkylated heterocycles. The optimal reaction conditions (temperature and substrate flow rate) were determined using an automated self-optimising reactor, resulting in moderate to high yields of the target products. Carrying out the reaction in scCO2 was shown to be beneficial, as higher yields were obtained in the presence of CO2 than in its absence. A surprising discovery is that, in addition to cyclic amines, cyclic ureas and urethanes could be synthesised by incorporation of CO2 from the supercritical solvent into the product.
- Streng, Emilia S.,Lee, Darren S.,George, Michael W.,Poliakoff, Martyn
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- N-methylation of nitrogen-containing heterocycles with dimethyl carbonate
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Reactivity of dimethyl carbonate, the environmentally friendly reagent, as methylating agent for nitrogen-containing heterocyclic compounds has been studied. Reactions of imidazole, pyrazole, pyrrole, morpholine, and piperazine with dimethyl carbonate to afford N-methylated products were reported. The reactions were carried out with neither catalyst nor solvent at a temperature range of 110-170°C under atmospheric pressure. Copyright Taylor & Francis, Inc.
- Ouk, Samedy,Thiebaud, Sophie,Borredon, Elisabeth,Chabaud, Bernard
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Read Online
- An enthalpic scale of hydrogen-bond basicity. 3. Ammonia, primary, secondary, and tertiary amines
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A reliable enthalpic scale of hydrogen-bond acceptor strength (basicity) is built for aliphatic amines by means of a new infrared method, from the temperature variation of hydrogen-bond equilibrium constants. Enthalpies of hydrogen bonding to a reference hydrogen-bond acceptor, 4-fluorophenol, have been determined in CCl4 and/or C2C14 for ammonia and 68 primary, secondary, and tertiary amines. The scale spans from -23.8 kJ mol -1 for i-Pr2NCH(Et)2 to -39.4 kJ mol -1 for Et3N. This large variation is mainly explained by the basicity-enhancing electronic effects of alkyl groups, which can be overcompensated by dramatic basicity-decreasing steric effects. Relationships between ΔH° and the change in electronic energy or the infrared shift of the OH stretching upon hydrogen bonding are studied and found useful in the prediction of the hydrogen bond enthalpies of amines with several hydrogen-bond acceptor sites. A careful statistical analysis of the enthalpy-entropy relationship shows an isoentropic tendency. The entropies of 65% of hydrogen-bonding reactions between aliphatic amines and 4-fluorophenol have a mean value of -55.1 ± 4.2 J K-1 mol-1. Amines excluded from the isoentropic set are mainly severely hindered ones. The hydrogen-bond enthalpic scale can be useful in measuring the electrostatic character of Lewis bases.
- Graton, Jerome,Berthelot, Michel,Besseau, Francois,Laurence, Christian
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- A METHOD FOR THE ALKYLATION OF AMINES
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The present invention pertains to a method for the alkylation of amines. In particular, the present invention relates to a method for preparing N, N, N', N , N -pentamethyldiethylenetriamine by reacting diethylenetriamine with methanol in the presence of hydrogen and a metal catalyst.
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Page/Page column 22-23
(2021/09/11)
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- A METHOD FOR PREPARING ALKYLATED AMINES
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The present invention pertains to a method for preparing an alkylated amine by reacting a primary or secondary amine with an alcohol in the presence of hydrogen, a metal catalyst supported by photosensitive titanium oxide, and UV irradiation. Advantageously, the reaction can be carried out under mild reaction conditions.
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Page/Page column 31; 32
(2021/09/11)
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- Method for synthesizing N-methyl fatty amine
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The invention discloses a method N - for synthesizing,methyl fatty amine with fatty amine and methanol as a raw material, to catalyze N - methylation reaction. by using a transition metal iridium catalyst as a solvent, to avoid using the organic agent; to react and only generate water as a byproduct, without environmental hazard; and has wide application prospects.
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Paragraph 0034-0038
(2020/03/12)
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- N-Methylation of Amines with Methanol in Aqueous Solution Catalyzed by a Water-Soluble Metal-Ligand Bifunctional Dinuclear Iridium Catalyst
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The N-methylation of amines with methanol in aqueous solution was proposed and accomplished by using a water-soluble metal-ligand bifunctional dinuclear iridium catalyst. In the presence of [(Cp*IrCl)2(thbpym)][Cl]2 (1 mol %), a range of desirable products were obtained in high yields under environmentally benign conditions. Notably, this research exhibited the potential of transition metal-catalyzed activation of methanol as a C1 source for the construction of the C-N bond in aqueous solution.
- Han, Xingyou,Li, Feng,Liu, Peng,Meng, Chong,Tung, Nguyen Thanh
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p. 5815 - 5824
(2020/05/26)
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- Electroactivated alkylation of amines with alcohols: Via both direct and indirect borrowing hydrogen mechanisms
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A green, efficient N-alkylation of amines with simple alcohols has been achieved in aqueous solution via an electrochemical version of the so-called "borrowing hydrogen methodology". Catalyzed by Ru on activated carbon cloth (Ru/ACC), the reaction works well with methanol, and with primary and secondary alcohols. Alkylation can be accomplished by either of two different electrocatalytic processes: (1) in an undivided cell, alcohol (present in excess) is oxidized at the Ru/ACC anode; the aldehyde or ketone product condenses with the amine; and the resulting imine is reduced at an ACC cathode, combining with protons released by the oxidation. This process consumes stoichiometric quantities of current. (2) In a membrane-divided cell, the current-activated Ru/ACC cathode effects direct C-H activation of the alcohol; the resulting carbonyl species, either free or still surface-adsorbed, condenses with amine to form imine and is reduced as in (1). These alcohol activation processes can alkylate primary and secondary aliphatic amines, as well as ammonia itself at 25-70 °C and ambient pressure.
- Appiagyei, Benjamin,Bhatia, Souful,Keeney, Gabriela L.,Dolmetsch, Troy,Jackson, James E.
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supporting information
p. 860 - 869
(2020/02/21)
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- UiO-type metal-organic frameworks with NHC or metal-NHC functionalities for: N-methylation using CO2 as the carbon source
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We demonstrate the first metal-organic framework (MOF) that catalyzes N-methylation of amines using 1 atm CO2 and phenylsilane under ambient conditions. Compared with its homogeneous analog, the incorporation of N-heterocyclic carbene (NHC) into the MOF provides more efficient catalysis with improved reaction kinetics, turnover numbers and recyclability. Moreover, the metalated NHC functionalized MOF achieves direct N-methylation of amines bearing carboxylate moieties, which are common building blocks in pharmaceutical chemistry.
- Zhang, Xu,Jiang, Yilin,Fei, Honghan
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supporting information
p. 11928 - 11931
(2019/10/11)
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- Biocatalytic Access to Piperazines from Diamines and Dicarbonyls
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Given the widespread importance of piperazines as building blocks for the production of pharmaceuticals, an efficient and selective synthesis is highly desirable. Here we show the direct synthesis of piperazines from 1,2-dicarbonyl and 1,2-diamine substrates using the R-selective imine reductase from Myxococcus stipitatus as biocatalyst. Various N- and C-substituted piperazines with high activity and excellent enantioselectivity were obtained under mild reaction conditions reaching up to 8.1 g per liter.
- Borlinghaus, Niels,Gergel, Sebastian,Nestl, Bettina M.
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p. 3727 - 3732
(2018/04/14)
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- Method for selectively preparing N-monomethylamine compound
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The invention discloses a method for selectively preparing an N-monomethylamine compound. The method takes an amine compound, formaldehyde and H2 as reaction raw materials; the raw materials react in a reaction medium in the presence of a compound catalyst at 30 DEG C-180 DEG C for 2h-48h, so as to obtain the N-monomethylamine compound; and the compound catalyst is composed of oxides of at least two of the following metal or oxides of least one of the following metal and at least one metal simple substance: aluminum, copper, nickel, cobalt and iron. According to the method for preparing the N-monomethylamine compound, the conversion ratio and the selectivity of N-monomethylamine are relatively high; the H2 is used as a reducing agent and is clean, cheap and environment-friendly; the catalyst utilized by the method is cheap, simple to prepare and high in catalysis efficiency; and the method has mild preparation and reaction conditions and the catalyst has no corrosiveness, is easy to separate and can be repeatedly used.
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Paragraph 0034-0035
(2017/08/29)
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- Ionic liquid/H2O-mediated synthesis of mesoporous organic polymers and their application in methylation of amines
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Mesoporous Tr?ger's base-functionalized polymers (Meso-TBPs) were prepared using a sulfonic acid group functionalized ionic liquid/H2O system, with surface areas up to 431 m2 g-1 and pore sizes of 3-15 nm. Ir(ii) coordinated Meso-TBPs exhibited extraordinary catalytic performance in the N-methylation of amines using methanol.
- Yu, Xiaoxiao,Yang, Zhenzhen,Zhang, Hongye,Yu, Bo,Zhao, Yanfei,Liiu, Zhenghui,Ji, Guipeng,Liu, Zhimin
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supporting information
p. 5962 - 5965
(2017/07/10)
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- Efficient Cobalt-Catalyzed Methylation of Amines Using Methanol
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The methylation of amines using methanol is a promising route to synthesize N-methylamines, and the development of cheap and efficient catalytic system for this reaction is of great significance. Herein, we reported a cobalt (Co)-based catalytic system, which was in situ formed from commercially available Co precursor and a tetradentate phosphine ligand P(CH2CH2PPh2)3 combined with K3PO4. This catalystic system was very effective for the selective production of dimethylated products from aliphatic amines and monomethylated ones from aromatic amines. The reaction mechanism was further investigated by control and isotope labelling experiments. (Figure presented.).
- Liu, Zhenghui,Yang, Zhenzhen,Yu, Xiaoxiao,Zhang, Hongye,Yu, Bo,Zhao, Yanfei,Liu, Zhimin
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supporting information
p. 4278 - 4283
(2017/10/23)
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- N-Methylation of Amines with Methanol Catalyzed by a Cp?Ir Complex Bearing a Functional 2,2′-Bibenzimidazole Ligand
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A new type of Cp?Ir complex bearing a functional 2,2′-bibenzimidazole ligand was designed, synthesized, and found to be a highly effective and general catalyst for the N-methylation of a variety of amines with methanol in the presence of a weak base (0.3 equiv of Cs2CO3).
- Liang, Ran,Li, Shun,Wang, Rongzhou,Lu, Lei,Li, Feng
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supporting information
p. 5790 - 5793
(2017/11/10)
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- N-Methylation of amines with methanol in a hydrogen free system on a combined Al2O3-mordenite catalyst
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N-Methyl amines play a major role in the production of medicines, pesticides, surfactants and dyes. N-Methylation of primary or second amines with methanol is considered to be a green path for the synthesis of N-methyl amines and the catalyst is key. In this article, the combined Al2O3-mordenite catalyst (mass fraction of alumina is 40%) with good activity, selectivity, lifetime and stability was prepared for N-methylation of various amines with methanol in a hydrogen free system in a fixed bed reactor, and characterized by XRD, N2 adsorption and NH3-TPD. Furthermore, the methanol adsorption was investigated by in situ FTIR, and the result indicated that methoxyl species may be the active species for the N-methylation of amines.
- Su, Jiahui,Li, Xungang,Chen, Yunbin,Cui, Yuancun,Xu, Jingwei,Qian, Chao,Chen, Xinzhi
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p. 55643 - 55649
(2016/07/06)
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- Light-promoted N,N-dimethylation of amine and nitro compound with methanol catalyzed by Pd/TiO2 at room temperature
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A series of TiO2 supported nano-Pd catalysts (Pd/TiO2) were prepared and used for the N,N-dimethylation of different amines and nitro compounds with methanol under UV irradiation at room temperature. A wide range of N,N-dimethyl amines were one-pot synthesized with up to 98% by applying aliphatic secondary amines, aromatic primary amines, aliphatic primary amines and aromatic nitro compounds as starting materials. It is noteworthy that up to 90% yield of 4-chloro-N,N-dimethylaniline was obtained by adjusting the Pd loadings on the TiO2 and the dehalogenation reaction was inhibited. Finally, a reaction mechanism is discussed, involving PhN = CH2 and PhNHCH3 as reaction intermediates.
- Zhang, Lina,Zhang, Yan,Deng, Youquan,Shi, Feng
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p. 14514 - 14521
(2015/03/05)
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- PROCESS FOR PRODUCING N-METHYL OR N,N-DIMETYL AMINES
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A process for producing N-methyl or N,N-dimethyl amines, which comprises using amine compound, nitro-containing compound or nitrile compound as a starting material, carbon dioxide as a methylating agent and hydrogen gas as a reducing agent, and allowing them to react in a sealed reactor for 6 to 48 h in a reaction medium at a reaction temperature of 80 to 180 ° C. in the presence of a composite catalyst, so as to provide N-methyl or N,N-dimethyl amines. The process of the present invention is simple and under relative mild reaction conditions. By means of the process of the invention, the target products can be prepared at low cost with a high yield. The catalysts used have a high catalytic activity and can be separated from the reaction system simply and reused. Furthermore, the whole process of the present invention is environmental-friendly and facilitates the cycling use of carbon dioxide.
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Paragraph 0059
(2015/02/18)
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- RANEY nickel-catalyzed reductive N-methylation of amines with paraformaldehyde: Theoretical and experimental study
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RANEY Ni-catalyzed reductive N-methylation of amines with paraformaldehyde has been investigated. This reaction proceeds in high yield with water as a byproduct. RANEY Ni can be easily recovered and reused with a slight decrease of the yield. Using density functional theory (DFT), the mechanism of RANEY Ni-catalyzed reductive N-methylation is discussed in detail. The reaction pathway involves the addition of amine with formaldehyde, dehydration to form the imine and hydrogenation. In the transition state of hemiaminal dehydration, the C-O bond cleavage of the aromatic amine is more difficult than that of the aliphatic amine. For the aromatic amine, a higher energy barrier must be overcome, which results in a relatively low yield. After addition of amine with formaldehyde and dehydration, imine is obtained and preferred to adsorb on the bridge site of the Ni(111) surface. The preferential pathways of imine hydrogenation involve the pre-adsorbed hydrogen atom attacking the nitrogen atom of the imine. The energy barrier of hydrogenation is much lower than that of addition and dehydration. Thus, the hydrogenation of imine is a relatively rapid reaction step. In the reductive N-methylation of secondary amine, the possible dehydration pathway is different from the one of the primary amine. In the dehydration of the secondary amine, the intermediate hemiaminal is initially adsorbed on the bridge site of the Ni(111) surface, then undergoes C-O bond cleavage, and eventually the hydroxyl is located in the bridge site. With the final hydrogenation, the product is obtained by adsorption on the top site of the Ni(111) surface.
- Ge, Xin,Luo, Chenxi,Qian, Chao,Yu, Zhiping,Chen, Xinzhi
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p. 43195 - 43203
(2015/02/19)
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- N-Methylation of amine and nitro compounds with CO2/H2 catalyzed by Pd/CuZrOx under mild reaction conditions
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An active Pd/ZrCuOx catalyst was prepared for the reductive amination of CO2. The N-methylation of amines and nitro compounds with CO2/H2 can be realized with up to 97% yield under relatively mild reaction condi
- Cui, Xinjiang,Zhang, Yan,Deng, Youquan,Shi, Feng
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supporting information
p. 13521 - 13524
(2015/01/09)
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- Methylation of amines, nitrobenzenes and aromatic nitriles with carbon dioxide and molecular hydrogen
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CO2/H2 was successfully employed in alkylation reactions by performing CO2 reduction and amine N-methylation in one-pot. In the presence of a simple CuAlOx catalyst, N-methyl or N,N-dimethyl amines with different structures can be selectively synthesized with up to 96% yields by applying amine, nitrobenzene and nitrile as starting materials.
- Cui, Xinjiang,Dai, Xingchao,Zhang, Yan,Deng, Youquan,Shi, Feng
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p. 649 - 655
(2014/01/17)
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- Sulfur, oxygen, and nitrogen mustards: Stability and reactivity
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Mustard gas, bis(β-chloroethyl) sulfide (HD), is highly toxic and harmful to humans and the environment. It comprises one class of chemical warfare agents (CWAs) that was used in both World Wars I and II. The three basic analogues or surrogates are: the monochloro derivative, known as the half mustard, 2-chloroethyl ethyl sulfide (CEES); an oxygen analogue, bis(β-chloroethyl) ether (BCEE); and several nitrogen analogues based on the 2,2′-dichlorodiethylamine framework (e.g., HN1, HN2, and HN3). The origin of their toxicity is considered to be from the formation of three-membered heterocyclic ions, a reaction that is especially accelerated in aqueous solution. The reaction of these cyclic ion intermediates with a number of important biological species such as DNA, RNA and proteins causes cell toxicity and is responsible for the deleterious effects of the mustards. While a number of studies have been performed over the last century to determine the chemistry of these compounds, early studies suffered from a lack of more sophisticated NMR and X-ray techniques. It is now well-established that the sulfur and nitrogen mustards are highly reactive in water, while the oxygen analog is much more stable. In this study, we review and summarize results from previous studies, and add results of our own studies of the reactivity of these mustards toward various nonaqueous solvents and nucleophiles. In this manner a more comprehensive evaluation of the stability and reactivity of these related mustard compounds is achieved.
- Wang, Qi-Qiang,Begum, Rowshan Ara,Day, Victor W.,Bowman-James, Kristin
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supporting information
p. 8786 - 8793
(2013/01/15)
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- PROCESS FOR PREPARING A CYCLIC TERTIARY METHYLAMINE
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Process for preparing a cyclic tertiary methylamine of the formula I where A is a C4-alkylene group, a C5-alkylene group or a —(CH2)2—B—(CH2)2—group, where B is oxygen (O) or an N—R1 radical and R1 is C1-C5-alkyl, aryl or C5-C7-cycloalkyl, wherein an amino alcohol II from the group consisting of 1,4-aminobutanol, 1,5-aminopentanol, aminodiglycol (ADG) or aminoethylethanolamine of the formula IIa where R1 is as defined above or is hydrogen (H), in which case R1═CH3 in the amine I, is reacted with methanol in a reactor at a temperature in the range from 150 to 270° C. in the liquid phase in the presence of a copper-comprising heterogeneous catalyst.
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Page/Page column 8
(2012/06/30)
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- Synthesis and antimicrobial activity of N-alkyl and N-aryl piperazine derivatives
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A series of substituted piperazine derivatives have been synthesized and tested for antimicrobial activity. The antibacterial activity was tested against Staphylococcus aureus (MTCCB 737), Pseudomonas aeruginosa (MTCCB 741), Streptomyces epidermidis (MTCCB 1824) and Escherichia coli (MTCCB 1652), and antifungal activity against Aspergillus fumigatus, Aspergillus flavus and Aspergillus niger. All synthesized compounds showed significant activity against bacterial strains but were found to be less active against tested fungi. In vitro toxicity tests demonstrated that compounds 4d and 6a showed very less toxicity against human erythrocytes.
- Chaudhary, Preeti,Kumar, Rupesh,Verma, Akhilesh K.,Singh, Devender,Yadav, Vibha,Chhillar, Anil K.,Sharma,Chandra, Ramesh
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p. 1819 - 1826
(2007/10/03)
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- Cyclopentadienyl RuII Complexes as Highly Efficient Catalysts for the N-Methylation of Alkylamines by Methanol
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The ruthenium(II) half-sandwich complex [RuCl(η5-C5H5)(PPh3)2] (1) catalyses the reaction between methanol and alkylamines RNH2 or R1R2NH to afford RN(CH3)2 and R1R2NCH3 products, respectively. The reaction is quantitative and generally fast, at the methanol reflux temperature, for a wide spectrum of substrates. Starting form primary amines, the stepwise formation of RN=CH2, RNHCH3, and RN(CH3)2 has been observed. Both PPh3 and Cl- dissociation from 1 are key-steps in forming the effective catalytic species. The catalytic activity of several half-sandwich neutral or cationic complexes (2-15) related to 1 is also discussed.
- Zotto, Alessandro Del,Baratta, Walter,Sandri, Mauro,Verardo, Giancarlo,Rigo, Pierluigi
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p. 524 - 529
(2007/10/03)
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- Reaction of 1,2-dibromoethane with primary amines: Formation of N,N′-disubstituted ethylenediamines RNH-CH2CH2-NHR and homologous polyamines RNH-[CH2CH2NR]n-H
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The reaction of primary amines RNH2 (R: Me, Et, iPr, tBu and Ph) with 1,2-dibromoethane gave N,N′-disubstituted ethylenediamines R-NH-CH2CH2-NH-R (1) in yields ranging from 10% (1a; R=Me) to 70% (1d, R=tBu; 1e, R=Ph). Pipe
- Denk, Michael K.,Krause, Mike J.,Niyogi, Debyani F.,Gill, Nachhattarpal K.
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p. 7565 - 7570
(2007/10/03)
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- Antiatherosclerotic and antithrombotic 1-benzopyran-4-ones and 2-amino-1,3-benzoxazine-4-ones
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This invention relates to compounds of Formula I STR1 which are useful in association with a pharmaceutical carrier as antiatherosclerotic agents. In addition, various compounds of Formula I are useful inhibitors of cell proliferation.
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- Process for converting heat stable amine salts to heat regenerable amine salts
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Processes are disclosed for converting heat stable amine salts to heat regenerable amine salts using a modified electrodialysis zone (140). The processes of the present invention can be used to reduce the level of heat stable salts in a lean solvent stream in an acid gas removal process and can be integrated with the acid gas removal process to utilize process streams as a source of ions.
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- Antiatherosclerotic and antithrombotic 2-amino-6-phenyl-4H-pyran-4-ones
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This invention relates to compounds of Formula I STR1 which are useful as antiatherosclerotic agents and inhibitors of cell proliferation for the treatment of proliferative diseases. In addition, various compounds of Formula I are useful inhibitors of platelet aggregation.
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- A flash photolysis study of the oxidation of aliphatic amines by phosphate radical
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Rate constants for the reaction of the phosphate radical (PO42-) with various aliphatic amines have been measured by flash kinetic spectrophotometry.Phosphate radical can react with aliphatic amines by hydrogen atom abstraction or electron transfer, the general reactivity order being tertiary secondary primary.For tertiary amines, a good correlation has been obtained when the logarithm of rate constants are plotted against the oxidation peak potentials of the amines, providing clear evidence for an electron transfer mechanism.In the case of tertiary amines, electron transfer from the nitrogen takes place.The identification of aminium cation radicals in the case of cyclic tertiary amines like, 1,4-diazabicyclooctane (DABCO) and 1,3,6,8-tetraazatricyclododecane (TATCD) provides additional proof for electron transfer.Primary and secondary amines get oxidized mainly by hydrogen atom abstraction as shown by the poor correlation with Taft substituent constants, but electron transfer cannot be completely ruled out.In the case of t-butylamine, electron transfer takes place and t-butylalcohol has been identified as the end product.
- Subramanian, P,Rajaram, J,Ramarkrishnan, V,Kuriacose, J C
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p. 913 - 919
(2007/10/02)
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- Ruthenium catalyzed reactions of ethylene glycol with primary amines: steric factors and selectivity control
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The selectivity of reactions of ethylene glycol with primary amines in the presence of RuCl2(PPh3)3 at 120 deg C is highly dependent on the steric nature of the amine.Selectivity to di-amination is favored by smaller alkyl groups on the amine while large amines cleanly yield ethanolamines.This contrasts with the results obtained with secondary amines at this temperature, in which ruthenium-triphenylphosphine catalyst systems always favor mono-amination.In the case of sec-butyl amine, where almost equal amounts of mono- and di-aminated product are obtained, the selecti vity can be shifted to mono-amination by the addition of excess triphenylphosphine.The steric effects seen in these reactions are consistent with standard steric parameters availble from the literature.
- Marsella, John A.
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- Process for preparing N-substituted piperazines from ethylene glycol and amines
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N,N'-dialkylpiperazines are prepared by contacting ethylene glycol and a primary amine in the presence of a homogeneous ruthenium-phosphine catalyst. For example, ethylene glycol and aniline are reacted in the presence of ruthenium trichloride and triphenylphosphine to produce N,N'-diphenylpiperazine.
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- RAPID REDUCTIVE-CARBOXYLATION OF SECONDARY AMINES. ONE POT SYNTHESIS OF TERTIARY N-METHYLATED AMINES
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Various tertiary N-methylated amines were synthesized by using a new reductive-carboxylation approach.Secondary amines, on carboxylation with carbon dioxide under moderate reaction conditions, afforded their corresponding carbamate esters, which, on in situ lithium aluminum hydride reduction, gave desired tertiary N-methylated amines in high yield.
- Ram, Siya,Ehrenkaufer, Richard E.
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p. 5367 - 5370
(2007/10/02)
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- Deprotonation de N-oxydes d'amines aliphatiques: schema reactionnel general et nouvelle synthese de pyrrolidines
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Amine oxides, 1, 5, 10, 15, 21, 23, when treated by lithium diisopropylamide undergo deprotonation.Monodeprotonation gives rise either to secondary amines and benzaldehyde resulting from the hydrolysis of an intermediate immonium (I) or to hydroxylamines via a Stevens-like rearrangement observed for the first time on an amine oxide.Double deprotonation gives an immonium ylid (Y) which, depending upon the structure of the initial tertiary amine yields either "head to head" piperazines (biradical-like behavior of (DD)) or aziridines.The immonium ylid (Y5) derived from trimethylamine oxide, whose formation and reactivity are reported for the first time, has remarkable property of undergoing cycloaddition reactions with unactivated olefins, leading to a new and efficient synthesis of various pyrrolidines.
- Beugelmans, Rene,Benadjila-Iguertsira, Leila,Chastanet, Jacqueline,Negron, Guillermo,Roussi, Georges
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p. 725 - 734
(2007/10/02)
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- Transalkylation Reaction. Homogeneous Catalytic Formation of C-N Bonds
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We have performed kinetic and mechanistic studies on homogeneous ruthenium-catalyzed transalkylation of tertiary amines.From these studies we have derived a kinetic expression for transalkylation catalysis based on initial reaction rates.We find that transalkylation proceeds most efficiently in alcoholic solvents (e.g., MeOH or EtOH), under a slight pressure of CO, with a mixed-metal, iron-ruthenium catalyst.The mechanism appears to be in one which a metal cluster of at least two and most probably three atoms binds the amine through insertion into an α C-H bond to give a metallazacyclopropane or metal-iminium complex.Nucleophilic attack by free amine on the complex, or an immediate derivative, follows, and subsequent rearrangement of the intermediate formed gives transalkylation products.The catalyst system has been tested as a synthetic tool for the oligomerization and cyclization of tertiary diamines.These preliminary studies have been quite succesful.Thus, N,N,N',N'-tetramethylethylenediamine can be transformed into Me3N and N,N'-dimethylpiperazine with good conversion and high selectivity.N,N,N',N'-Tetraethylethylenediamine can be transformed into Et3N and the linear, perethyl, ethylenediamine dimer, trimer, tetramer, and pentamer with excellent conversion.
- Wilson, Robert B.,Laine, Richard M.
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p. 361 - 369
(2007/10/02)
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- Derivatives of leukotrienes A and C
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The present invention provides novel derivatives of leukotrienes A and C which are useful in inhibiting the smooth muscle contracting effects of SRS-A; inhibiting platelet aggregation; and inhibiting the biosynthesis of thromboxane A2.
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- AMINE RADICAL CATIONS : AN ELECTRON SPIN RESONANCE STUDY OF CATIONS GENERATED BY RADIOLYSIS
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Amine radical cations have been generated by exposing dilute solutions of amines to 60Co γ-rays at 77 K.They are well characterised by their e.s.r. spectra, the method and interpretation being established by showing that the e.s.r. data for Me3N(.+) cations are indentical with literature values.Results for the triethylammonium cation show that the β-protons do not occupy the most favourable sites for maximum hyperconjugation, in contrast with other radical cations.This is explained in terms of steric factors, and an equilibrium between two preferred conformations. 1,1-Diamines, R2NCH2NR2, give cations having localised structures, R2N(.+)CH2NR2, rather than the delocalised structure adopted by acetal cations.Possible evidence for weak N-N bonding and delocalisation is adduced for NN'-dimethylpiperazine cations, but we confirm that the cation of triethylenediamine has a truly delocalised ?(*) structure.There is no tendency for R3N(+.) cations to react with neutral amines to give ( dimer cations, in marked constrast with results for corresponding trialkylphosphine systems.
- Eastland, George W.,Rao, D. N. Ramakrishna,Symons, Martyn C. R.
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p. 1551 - 1558
(2007/10/02)
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- Transition Metal-catalysed N-Alkylation of Amines by Alcohols
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Primary and secondary alcohols effect alkylation of primary and secondary amines in the presence of rhodium, iridium, and ruthenium compounds at = 100 deg C, whereby selective monoalkylation of primary amines can be achieved, and heterocyclic rings can be constructed by both inter- and intra-molecular processes.
- Grigg, R.,Mitchell, T. R. B.,Sutthivaiyakit, S.,Tongpenyai, N.
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p. 611 - 612
(2007/10/02)
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- 19-Hydroxy-PGI2 compounds
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Prostacyclin and prostacyclin-type derivatives having a 19-hydroxy feature are disclosed, including processes for preparing them and the appropriate intermediates. The compounds are useful for pharmacological purposes such as inhibition of blood platelate aggregation.
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- 2-Decarboxy-2-hydroxymethyl-19-hydroxy-PG1 analogs
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Prostaglandin derivatives having a 19,20-didehydro, a 19-hydroxy, or a 19-keto feature are disclosed, including processes for preparing them and the appropriate intermediates. A typical 19-hydroxy compound of this invention is 19-hydroxy-19-methyl-PGF2α, methyl ester, represented by the formula STR1
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