- The first SiHi22+ Complex, Difaydridotetrakis(3-picoline)silicon Dichloride-tetrakis (chloroform)5 [H2Si(3pic)44]Cl2 · CHCl3: Formation chemical equilibria, and structural by NMR spectroscopy and single-crystal X-ray diffraction
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Bis(dichlorosilyl)amine reacts in chloroform solution with 2-picoline to give H3SiCl, H2SiCl2, and HSiCl3 whereas with 3-picoline the two hypervalent silicon compounds H2SiCl2-(3pic)2 and [H2Si(3pic)4]Cl2 ·4 CHCl3 containing hexacoordinated Si atoms are formed. These complexes are in a chemical equilibrium with each other in chloroform solution, from which crystals of [H2Si(3pic)4]Cl2 ·4 CHCl3 could be isolated. The crystal structure of the latter was determined by single-crystal X-ray diffraction. The complex can be regarded as an "contact ion trio" of [H2Si(3pic)4]2+ and two Cl- ions. The N→Si bond lengths, r(Si-N) = 196.9(3} and 197.5(3) pm, are similar to those found in neutral hexacoordinated Si complexes. The data obtained from a 1H1H ROESY experiment suggest that dissolution has no significant impact on the molecular structure of [H2Si(3pic)4]Cl2 ·4 CHCl3. VCH Verlagsgcsellschaft mbH, 1996.
- Fleischer, Holger,Hensen, Karl,Stumpf, Thorsten
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- An efficient and chemoselective deoxygenation of hetero cyclic N-oxides using LiCl/NaBH4
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A practical and novel reagent system LiCl/NaBH4 is used for the deoxygenation of N-Oxides to amines is described.
- Raja Ram,Purushothama Chary,Iyengar
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- Microwave-accelerated direct synthesis of 3-picoline from glycerol through a liquid phase reaction pathway
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A novel route for the synthesis of 3-picoline from glycerol via liquid phase reaction under mild condition, using microwave irradiation, had been well established. The heating mode had a profound effect on the yield of 3-picoline. The formation of 3-picoline could be promoted significantly by microwave heating, however, only very little amount of 3-picoline was generated by conventional heating under the reaction conditions employed in this study. Influencing factors were systemically investigated on the basis of a HAc-catalyzed under microwave irradiation. Additionally, a lot of heterogeneous catalysts were screened. It was found that as high as a 71% yield of 3-picoline was obtained with the mass ratio of pure glycerol/ammonium acetate/acetic acid/TiO2 = 1/3/10/0.2 at 373 K, after only 20 min of microwave irradiation. A catalyst pair (HAc and TiO2) exhibited better catalytic performance relative to other catalysts in this work. Accordingly, microwave assistance together with the catalysts achieved effective transformation of glycerol to 3-picoline under mild conditions. The related plausible reaction mechanisms were also proposed.
- Luo, Cai-Wu,Feng, Xiao-Yan,Chao, Zi-Sheng
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- In situ formation and reaction of 2-pyridylboronic esters
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2-Pyridylboronic esters were generated by cross-coupling 2-bromopyridines with bis(pinacolato)diboron in the presence of a base and palladium catalyst. The boronic esters reacted in situ with unreacted 2-bromopyridines to afford high yields of 2,2′-bipyridines as homocoupled products. Depending upon the reaction conditions, varying amounts of protodeboronated products were also observed. An attempted cross-coupling between two different 2-bromopyridines produced a nearly statistical mixture of homo- and cross-coupled products.
- Fuller, Amelia A.,Hester, Heidi R.,Salo, Eric V.,Stevens, Erland P.
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- Effective charge on the nucleophile and leaving group during the stepwise transfer of the triazinyl group between pyridines in aqueous solution
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Second-order rate constants (kxpy) have been measured for the displacement reaction between substituted pyridines (xpy) and 1′-(2,6-diphenoxy-1,3,5-triazin-2-yl)pyridinium ion in aqueous solution. The rate constants for the reverse reaction (k-xpy) have also been measured for substituted pyridine leaving groups. The plots of log kxpy and log k-xpy against pKaxpy each consist of two intersecting linear correlations consistent with a two-step mechanism involving a Meisenheimer-like intermediate. The overall transfer of the triazin-2-yl group between substituted pyridines has a βeq value of 1.25. There is negligible coupling between the bonding changes in both steps, and the substituent effects indicate that bond formation is half complete in the addition step. Reaction of substituted pyridines with 2,6-diphenoxy-1,3,5-triazin-2-yl chloride has a similar bonding change in the addition step. The 1′-triazin-2-ylpyridinium ion species exist in aqueous solution in equilibrium with the pseudobase formed by addition of water at the 2-position of the pyridinium ring.
- Cullum, Neil R.,Renfrew, A. Hunter M.,Rettura, Donatella,Taylor, John A.,Whitmore, James M. J.,Williams, Andrew
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- Thermal decomposition and ring expansion in 2,4-dimethylpyrrole. Single pulse shock tube and modeling studies
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The thermal decomposition of 2,4-dimethylpyrrole was studied behind reflected shock waves in a pressurized driver single-pulse shock tube over the temperature range 1050-1250 K at overall densities of ~3 × 10-5 mol/cm3. A plethora of decomposition products, both with and without nitrogen, were found in the post-shock mixtures. They were, among the nitrogen containing products: pyridine, two isomers of methylpyrrole, 2-picoline, 5-picoline, HCN, CH3CN, C2H3CN, C2H5CN, and CH≡C-CN. Very small quantities of cis- and trans-CH3CH=CHCN and CH2=CHCH2CN were also found in the post-shock mixtures. Among the products without nitrogen were CH4, C2H4, C2H6, C2H2, CH3H≡CH, CH2=C=CH2, C4H4 and C4H2, and very small quantities of other C4 hydrocarbons and C5 hydrocarbons. The initiation of a chain mechanism in the decomposition of 2,4-dimethylpyrrole takes place via ejection of hydrogen atoms from sp3 carbons and dissociation of the two methyl groups attached to the ring. The H atoms and the methyl radicals initiate a chain mechanism by abstraction of a hydrogen atom from the methyl group and by dissociative recombination of an H atom and removal of a methyl group from the ring. In addition to the dissociation reactions, there are several unimolecular channels that involve ring cleavage. Ring expansion processes that lead to the production of high yields of pyridine and picoline take place from radical species: CH3[C4H2NH]CH2 in the production of picoline and [C4H3NH]CH2 in the production of pyridine. In addition to the chain mechanism, there are unimolecular breakdown processes of the pyrrole ring to yield stable products such as HCN, CH3CN, and others. The total decomposition of 2,4-dimethylpyrrole in terms of a first-order rate constant is given by ktotal = 1016.31 exp(-75.7 × 103/RT) s-1. A reaction scheme containing 36 species and 69 elementary reactions was composed and a computer simulation was performed over the temperature range 1050-1250 K at 25 K intervals. The agreement between the experimental results and the model prediction for most of the species is satisfactory.
- Lifshitz, Assa,Suslensky, Aya,Tamburu, Carmen
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- Evidence for a Single Transition State in the Transfer of the Phosphoryl Group (-PO32-) to Nitrogen Nucleophiles from Pyridino-N-phosphonates
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The reaction of pyridinio-N-phosphonates with pyridines in aqueous buffers has been demonstrated to involve nucleophilic attack at phosphorus.The second-order rate constants obey the equation log kxpy = 0.15pKxpy - 0.86 for attack on isoquinolino-N-phosphonate over a wide range of pyridine basicity indicating a single transition state; this is consistent with a concerted transfer of the phosphoryl group rather than with a stepwise mechanism involving metaphosphate ion in a ternary encounter complex with donor and acceptor.Transfer of the phosphoryl group to pyridine from substituted pyridinio-N-phosphonates obeys the equation log k = -0.92pKxpy + 5.24 and leads to a βeq of 1.07 for substituent effect on the equilibrium constant for transfer.The effective charge at nitrogen, in the transition state, indicated by these values favors weak P-N bonding.An imbalance of -0.77 effective charge units between entering and leaving nitrogen in the transition state is proposed to derive from the charge on the PO3 atoms, which therefore do not bear a full negative charge in the transition state.Transfer of the phosphoryl group from isoquinolinio-N-phosphonate to amines has been investigated kinetically, and the results are also consistent with weak bonding between phosphorus and nitrogen in the transition state.
- Bourne, Nicholas,Williams, Andrew
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- Thermal analysis of complexes of cadmium chloride picoline
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The thermal decomposition of the α, β and γ-picoline complexes of cadmium were studied by means of TG-DTG-DTA. In connection with the preparation of the complex compounds, it was established that the ligand number was influenced by the reaction medium. The thermal decomposition took place stepwise, and intermediates were formed which could be isolated with a derivatograph by the 'freezing-in' method. The structures and properties of these previously unknown compounds were investigated by far-IR spectroscopy and X-ray powder diffraction.
- Liptay, G.,Borbely-Kuszmann, A.,Wadsten, T.,Losonczi, J.
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- Mild and efficient deoxygenation of amine-N-oxides with BiCl3/Indium system
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The BiCl3/indium system was found to be a new reagent for deoxygenation of various amine-N-oxides to the corresponding amines in good to excellent yields under mild conditions.
- Yoo, Byung Woo,Choi, Jin Woo
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- Preparation of pyridine and 3-picoline from acrolein and ammonia with HF/MgZSM-5 catalyst
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Pyridine and 3-picoline were prepared from acrolein and ammonia using HF/MgZSM-5 as catalyst. The HF/MgZSM-5 catalyst was produced from modification of HZSM-5 by HF and Mg(NO3)2. It was found that the micropore structure of the HZSM-5 carrier would be destroyed when Mg and HF were loaded. This corrosion process could be promoted by employing HF onto MgZSM-5 carrier comparing with HZSM-5 one, because of the damage of MgO to ZSM-5 stability. A micro-mesoporous HZSM-5 zeolite with fewer and weaker acid sites was prepared after HF modification. Under the optimized conditions, a total yield of 68% can be reached, with 36% being 3-picoline and 30% being pyridine.
- Zhang, Xian,Wu, Zhen,Liu, Wei,Chao, Zi-Sheng
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- Mechanism of pyridine bases prepared from acrolein and ammonia by in situ infrared spectroscopy
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The in situ infrared spectroscopy of acrolein and ammonia over HF/MgZSM-5 was investigated to check the adsorption reaction of acrolein and ammonia. It was proved that propylene imine intermediate came up during the condensation process of adsorbed acrolein with ammonia. The strong adsorption of C=O helps the formation of propylene imine. The reaction order and active energy were calculated according to the intensity of acrolein infrared spectroscopy. The synthesis of 3-picoline is likely to go through a flat adsorption of propylene imine and a deamination of amino dihydropyridine.
- Zhang, Xian,Wu, Zhen,Chao, Zi-Sheng
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- Thermal activation of solid-state molybdenum halide clusters with an octahedral cluster framework and their application to catalytic synthesis of 3-methylpyridine from piperidine and methanol
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Solid-state molybdenum halide clusters with an octahedral metal framework MoX2 (or [Mo6X8]X2X4/2) (X= Cl, Br, I) are applied to catalysis. When these clusters are thermally activated in a hydrogen stream above 300°C, they exhibit catalytic activity for the dehydrogenative C-methylation of piperidine with methanol, to yield 3-methylpyridine. At 400°C, the selectivity is as high as 74%. This catalytic behavior is different from that of the molecular clusters [(M6Cl12)Cl2(H2O)4]?4H2O (M= Nb, Ta) and (H3O)2[(M6Cl8)Cl6]?6H2O (M= Mo, W), which exhibit Bronsted acidity after thermal activation; piperidine is N-methylated to yield N-methylpiperidine selectively. Elemental analysis and thermogravimetric analysis demonstrate that the solid-state clusters partially eliminate halogen ligands during the activation. Infrared analysis of adsorbed pyridine on the activated clusters shows the presence of a Lewis acid site. This coordinatively unsaturated site of the molybdenum is catalytically active for dehydrogenative C-methylation. The formation of an η3-1-azaallyl species on the molybdenum facilitates the methylation at the 3-position of piperidine, followed by dehydrogenation to yield 3-methylpyridine.
- Kamiguchi, Satoshi,Kajio, Ryu,Yamada, Hitomi,Yuge, Hidetaka,Okumura, Kazu,Iida, Hajime,Nagashima, Sayoko,Chihara, Teiji
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- Mild and Efficient Deoxygenation of Amine-N-oxides with Titanium Tetrachloride-Indium System
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TiCl4/In system was found to be a new reagent for deoxygenation of various amine-N-oxides to the corresponding amines in good to excellent yields under mild conditions.
- Yoo, Byung Woo,Choi, Kwang Hyun,Choi, Kyung Il,Kim, Joong Hyup
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- Crystalline and amorphous aluminosilicates with different pore structures for the synthesis of pyridines
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The heterogeneous catalytic synthesis of pyridine and methylpyridines (picolines) was carried out by the reaction of ethanol with formaldehyde and ammonia over aluminosilicates with different acidic properties and textural characteristics: zeolite framework-type FAU in H-form with microporous (H-Y) and micro-meso-macroporous structure (H-Y-mmm) and mesoporous aluminosilicates, obtained by sol-gel synthesis in an alkaline medium (ASM-1) and under variable pH (ASM-2). It is shown that the highest catalytic activity is characteristic of ASM-2 (Si/Al = 40) with a narrow pore size distribution within the range 2 to 5 nm and containing strongly acidic bridging Si-OH-Al groups on the surface. The products of the reaction of ethanol with formaldehyde and ammonia on the catalysts studied are dominated by picolines; the maximum amount of picolines (60%) is formed on the H-Y-mmm and aluminosilicate ASM-2 samples.
- Grigor'eva, Nellya G.,Filippova, Nadezhda A.,Agliullin, Marat R.,Kutepov, Boris I.,Narender, Nama
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- Thermal conversion of glycerol to value-added chemicals: Pyridine derivatives by one-pot microwave-assisted synthesis
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One-pot syntheses of the value-added heterocyclic compounds 3-methylpyridine and pyridine using a renewablechemical, glycerol, were achieved in acidic medium by thermal conversion reactions. Condensation/cyclization reactions of the thermal degradation products of glycerol were investigated in situ using different ammonia and acidic moiety producing inorganic ammonium salts under pyrolysis or microwave heating conditions. The reaction parameters were studied in detail and satisfying product yields up to 72% were obtained under optimized conditions. Structural identification of all compounds was accomplished by spectroscopic methods. TUeBITAK.
- Bayramoglu, Duygu,Guerel, Goekay,Sinag, Ali,Guellue, Mustafa
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- Interconversion of nicotine enantiomers during heating and implications for smoke from combustible cigarettes, heated tobacco products, and electronic cigarettes
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Physiological properties of (R)-nicotine have differences compared with (S)-nicotine, and the subject of (S)- and (R)-nicotine ratio in smoking or vaping related items is of considerable interest. A Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) method for the analysis of (S)- and (R)-nicotine has been developed and applied to samples of nicotine from different sources, nicotine pyrolyzates, several types of tobacco, smoke from combustible cigarettes, smoke from heated tobacco products, e-liquids, and particulate matter obtained from e-cigarettes aerosol. The separation was achieved on a Chiracel OJ-3 column, 250 × 4.6 mm with 3-μm particles using a nonaqueous mobile phase. The detection was performed using atmospheric pressure chemical ionization (APCI) in positive mode. The only transition measured for the analysis of nicotine was 163.1 → 84.0. The method has been summarily validated. For the analysis, the samples of tobacco and smoke from combustible cigarettes were subject to a cleanup procedure using solid phase extraction (SPE). It was demonstrated that nicotine upon heating above 450°C for several minutes starts decomposing, and some formation of (R)-enantiomer from a sample of 99% (S)-nicotine is observed. An analogous process takes place when a 99% (R)-nicotine is heated and forms low levels of (S)-nicotine. This interconversion has the effect of slightly increasing the content of (R)-nicotine in smoke compared with the level in tobacco for combustible cigarettes and for heated tobacco products. The (S)/(R) ratio of nicotine enantiomers in e-liquids was identical with the ratio for the particulate phase of aerosols generated by e-cigarette vaping.
- Moldoveanu, Serban C.
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p. 667 - 677
(2022/02/02)
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- A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
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The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R′3-nRnX (X = P, N; R′ = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
- García-Domínguez, Andrés,Gonzalez, Jorge A.,Leach, Andrew G.,Lloyd-Jones, Guy C.,Nichol, Gary S.,Taylor, Nicholas P.
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supporting information
(2022/01/04)
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- Synthetic method of 3-methylpyridine
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The invention relates to a synthetic method of 3-methylpyridine, and belongs to the technical field of chemical synthesis. The invention relates to a synthetic method of 3-methylpyridine, which comprises the following steps: by using acetaldehyde or polymer thereof and formaldehyde or polymer thereof as raw materials, reacting in a pipeline reactor or fixed bed reactor at 180-300 DEG C and 4-10MPa under the action of a catalyst, cooling the reacted materials to obtain a 3-methylpyridine reaction solution, extracting, concentrating, and rectifying, and obtaining a 3-methylpyridine product and a catalyst capable of being recycled. According to the synthesis method disclosed by the invention, acid catalyst and continuous production are adopted, so that low-cost, high-yield and high-selectivity 3-methylpyridine synthesis is realized. By changing the catalyst, the application of the catalyst and the change of the reactor are realized, the stable improvement of the product yield is ensured, and the cost is reduced.
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Paragraph 0022-0043
(2021/04/21)
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- Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies
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We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.
- Lecroq, William,Schleinitz, Jules,Billoue, Mallaury,Perfetto, Anna,Gaumont, Annie-Claude,Lalevée, Jacques,Ciofini, Ilaria,Grimaud, Laurence,Lakhdar, Sami
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p. 1237 - 1242
(2021/06/01)
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- Photorelease of Pyridines Using a Metal-Free Photoremovable Protecting Group
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The photorelease of bioactive molecules has emerged as a valuable tool in biochemistry. Nevertheless, many important bioactive molecules, such as pyridine derivatives, cannot benefit from currently available organic photoremovable protecting groups (PPGs). We found that the inefficient photorelease of pyridines is attributed to intramolecular photoinduced electron transfer (PET) from PPGs to pyridinium ions. To alleviate PET, we rationally designed a strategy to drive the excited state of PPG from S1 to T1 with a heavy atom, and synthesized a new PPG by substitution of the H atom at the 3-position of 7-dietheylamino-coumarin-4-methyl (DEACM) with Br or I. This resulted in an improved photolytic efficiency of the pyridinium ion by hundreds-fold in aqueous solution. The PPG can be applied to various pyridine derivatives. The successful photorelease of a microtubule inhibitor, indibulin, in living cells was demonstrated for the potential application of this strategy in biochemical research.
- Dong, Zaizai,Fang, Xiaohong,Kou, Xiaolong,Tan, Weihong,Tang, Xiao-Jun,Wu, Yayun,Zhang, Zhen,Zhao, Rong,Zhou, Wei
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supporting information
p. 18386 - 18389
(2020/08/24)
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- Catalytic Deoxygenation of Amine and Pyridine N-Oxides Using Rhodium PCcarbeneP Pincer Complexes
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Rhodium PCcarbeneP pincer complexes 1-L (L = PPh3, PPh2(C6F5), PCy3) readily facilitate deoxygenation of amine and pyridine N-oxides. The resulting complexes exhibit δ2-C= O coordination of the resulting keto POP pincer ligand. These δ2-Ca? O linkages in the metalloepoxide complexes are readily reduced by isopropyl alcohol and various benzylic alcohols. Thus, efficient catalytic deoxygenation of amine and pyridine N-oxides is possible using complexes 1-L and isopropyl alcohol. This represents a pioneering example of PCcarbeneP pincer complexes being used as catalysts for catalytic deoxygenation.
- Tinnermann, Hendrik,Sung, Simon,Cala, Beatrice A.,Gill, Hashir J.,Young, Rowan D.
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p. 797 - 803
(2020/03/13)
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- Heterogeneously palladium-catalyzed acceptorless dehydrogenative aromatization of cyclic amines
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In this manuscript, we report an efficient heterogeneously catalyzed acceptorless dehydrogenative aromatization of cyclic amines under relatively mild conditions. In the presence of a supported catalyst Pd/LDH (LDH = layered double hydroxide), various kinds of structurally diverse cyclic amines including piperidines, tetrahydro(iso)quinolines, and indolines could be converted into the corresponding heteroarenes. Pd/LDH could be reused several times though its catalytic activity gradually declined due to the increase in the palladium particle size.
- Oyama, Takashi,Yatabe, Takafumi,Jin, Xiongjie,Mizuno, Noritaka,Yamaguchi, Kazuya
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supporting information
p. 517 - 520
(2019/06/11)
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- Mesoporous Aluminosilicates in the Synthesis of N-Heterocyclic Compounds
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Abstract: The catalytic properties of samples of amorphous mesoporous aluminosilicate ASM with different Si/Al molar ratios (40, 80, 160) were studied in the synthesis of practically important pyridines (by the interaction of С2–С5 alcohols with formaldehyde and ammonia, cyclocondensation of acetaldehyde and propionic aldehyde with ammonia), dialkylquinolines and alkyltetrahydroquinolines (by reaction of aniline with C3, C4 aldehydes) and alkyldihydroquinolines (by interaction of aniline with ketones, acetone and acetophenone). It is found that mesoporous aluminosilicate ASM sample with a molar ratio of Si/Al = 40, which has the highest acidity among the studied samples, exhibits the highest activity and selectivity in these reactions.
- Agliullin, M. R.,Bikbaeva, V. R.,Bubennov, S. V.,Filippova, N. A.,Gataulin, A. R.,Grigor’eva, N. G.,Kostyleva, S. A.,Kutepov, B. I.,Narender, Nama
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p. 733 - 743
(2020/02/25)
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- Thermal Behavior Analysis of Two Synthesized Flavor Precursors of N-alkylpyrrole Derivatives
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To expand the library of pyrrole-containing flavor precursors, two new flavor precursors—methyl N-benzyl-2-methyl-5-formylpyrrole-3-carboxylate (NBMF) and methyl N-butyl-2-methyl-5-formylpyrrole-3-carboxylate (NUMF)—were synthesized by cyclization, oxidation, and alkylation reactions. Thermogravimetry (TG), differential scanning calorimeter, and pyrolysis–gas chromatography/mass spectrometry were utilized to analyze the thermal degradation behavior and thermal degradation products of NBMF and NUMF. The TG-DTG curve indicated that the maximum mass loss rates of NBMF and NUMF appear at 310 and 268°C, respectively. The largest peaks of NBMF and NUMF showed by the differential scanning calorimeter curve were 315 and 274°C, respectively. Pyrolysis–gas chromatography/mass spectrometry detected small molecule fragrance compounds appeared during thermal degradation, such as 2-methylpyrrole, 1-methylpyrrole-2-carboxylic acid methyl ester, limonene, and methyl formate. Finally, the thermal degradation mechanism of NBMF and NUMF was discussed, which provided a theoretical basis for their application in tobacco flavoring additives.
- Ai, Lvye,Liu, Mengzhen,Ji, Xiaoming,Lai, Miao,Zhao, Mingqin,Ren, Tianbao
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p. 2389 - 2397
(2019/08/01)
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- Silica-supported silver nanoparticles as an efficient catalyst for aromatic C-H alkylation and fluoroalkylation
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The efficient catalysis of oxidative alkylation and fluoroalkylation of aromatic C-H bonds is of paramount importance in the pharmaceutical and agrochemical industries, and requires the development of convenient Ag0-based nano-architectures with high catalytic activity and recyclability. We prepared Ag-doped silica nanoparticles (Ag0/+@SiO2) with a specific nano-architecture, where ultra-small sized silver cores are immersed in silica spheres, 40 nm in size. The nano-architecture provides an efficient electrochemical oxidation of Ag+@SiO2 without any external oxidant. In turn, Ag+@SiO2 5 mol% results in 100% conversion of arenes into their alkylated and fluoroalkylated derivatives in a single step at room temperature under nanoheterogeneous electrochemical conditions. Negligible oxidative leaching of silver from Ag0/+@SiO2 is recorded during the catalytic coupling of arenes with acetic, difluoroacetic and trifluoroacetic acids, which enables the good recyclability of the catalytic function of the Ag0/+@SiO2 nanostructure. The catalyst can be easily separated from the reaction mixture and reused a minimum of five times upon electrochemical regeneration. The use of the developed Ag0@SiO2 nano-architecture as a heterogeneous catalyst facilitates aromatic C-H bond substitution by alkyl and fluoroalkyl groups, which are privileged structural motifs in pharmaceuticals and agrochemicals.
- Khrizanforov, Mikhail N.,Fedorenko, Svetlana V.,Mustafina, Asiya R.,Kholin, Kirill V.,Nizameev, Irek R.,Strekalova, Sofia O.,Grinenko, Valeriya V.,Gryaznova, Tatiana V.,Zairov, Rustem R.,Mazzaro, Raffaello,Morandi, Vittorio,Vomiero, Alberto,Budnikova, Yulia H.
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supporting information
p. 9608 - 9616
(2018/08/06)
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- Ionic Liquids as “Masking” Solvents of the Relative Strength of Bases in Proton Transfer Reactions
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Equilibrium constants for the proton transfer reaction between pyridines and trifluoroacetic acid were measured in room-temperature ionic liquids (ILs) of different cation–anion compositions. The experimental equilibrium constants for ion-pair formation were corrected according to the Fuoss equation. The calculated equilibrium constants for the formation of free ions were taken as a quantitative measure of the base strength in IL solutions and compared with the relative constants in water. The effect of IL composition is discussed for a series of fixed IL anions and fixed IL cations. Finally, the sensitivity of the proton transfer reaction to the electronic effects of the substituent groups on the pyridine ring was quantified by applying the Hammett equation. A more marked levelling effect on the base strength was observed in ILs than in water. The Hammett reaction constants ρ were then correlated with solvent parameters according to a multi-parametric analysis, which showed that both specific hydrogen-bond donor/acceptor and non-specific interactions play an important role, with α and permittivity being the main parameters affecting the ability of the IL to differentiate the strength of the base.
- Zappacosta, Romina,Di Crescenzo, Antonello,Ettorre, Valeria,Fontana, Antonella,Pierini, Marco,Siani, Gabriella
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- Production method of high-purity 2-chloro-5-trifluoromethylpyridine
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The invention provides a production method of high-purity 2-chloro-5-trifluoromethylpyridine. The production method comprises the following steps: under the action of a silicon dioxide-aluminum oxide-chromic oxide catalyst, gasifying the raw materials acrolein and propyl aldehyde, and reacting with an ammonia gas to generate 3-methylpyridine; gasifying the 3-methylpyridine and carbon tetrachloridetogether, reacting in a chlorine atmosphere to obtain 2-chloro-5-trichloromethylpyridine, and performing fluoro-substitution to obtain a crude product of 2-chloro-5-trifluoromethylpyridine; heating to melt the crude product of 2-chloro-5-trifluoromethylpyridine; refrigerating and circulating in a low-temperature thermostat; cooling and crystallizing and separating to obtain recrystal; sweating the recrystal; repeating the processes of circulating, melting, recrystallizing and sweating to obtain high-purity 2-chloro-5-trifluoromethylpyridine. According to the production method provided by theinvention, 3-methylpyridine is adopted as a raw material, and the 2-chloro-5-trifluoromethylpyridine is molten, recrystallized and purified so that the product has high purity and stable yield.
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Paragraph 0023; 0026-0027; 0031; 0035; 0039
(2018/03/23)
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- A mild and efficient H2O2 oxygenation of N-heteroaromatic compounds to the amine N-oxides and KI deoxygenation back to the tertiary amine with hexaphenyloxodiphosphonium triflate
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A mild and efficient method for the oxidation of N-heteroaromatic compounds to the corresponding N-oxides using H2O2 in the presence of hexaphenyloxodiphosphnium triflate (Hendrickson reagent) in EtOH at room temperature was reported. This methodology presented relatively fast and selective reactions to afford the N-oxides in good yields. The reverse reactions, deoxygenation reactions, were also carried out under the same reaction conditions by KI to produce the tertiary amines.
- Khodaei, Mohammad Mehdi,Alizadeh, Abdolhamid,Hezarkhani, Hadis Afshar
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p. 1843 - 1849
(2018/07/06)
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- Highly Stable and Recyclable Graphene Layers Protected Nickel–Cobalt Bimetallic Nanoparticles as Tunable Hydrotreating Catalysts for Phenylpropane Linkages in Lignin
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Abstract: Nickel–cobalt bimetallic nanoparticles coated with several layers of graphene were developed through direct heating treatment of bimetallic oxide precursor prepared by the modified Pechini-type sol–gel method. These nanomaterials were demonstrated to be versatile catalysts for lignin depolymerization. The catalysts showed unexpectedly tunable selectivity that directly depends on the composition of bimetallic nanoparticles. Dimeric lignin model compounds can be converted totally and the hydrogenolysis selectivities above 85% over Ni–Co@C (Ni:Co = 1:3). During the recycling test, the nanocatalyst showed excellent recyclability in the ten-batch investigation. The deposition of graphene layers over bimetal nanoparticles fosters a subtle balance between protecting effects and surface accessibility to catalytic reactions and significantly improves their stability to air and moisture. Ni–Co@C catalysts were readily separated from the liquid mixtures with high recycling ratio due to their magnetic properties. Graphical Abstract: [Figure not available: see fulltext.] Ni–Co bimetallic nanoparticles are coated with graphene layers. Graphene layers over the nanoparticles protect them from deactivation. Ni–Co@C shows tunable selectivity in the hydrogenolysis of dimeric lignin linkage. The non-precious metal catalyst showed excellent recyclability and can be reused ten times without significant loss of activity.
- Chen, Bingfeng,Li, Fengbo,Yuan, Guoqing
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p. 2877 - 2885
(2017/09/18)
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- Synthetic method of 2-amino-5-methyl pyridine
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The invention provides a synthetic method of 2-amino-5-methyl pyridine and relates to the field of research and development of chemical synthesis of drugs. The synthetic method comprises the following steps: adding methyl groups to pyridine to prepare 5-methyl pyridine; preparing N-oxidative methyl pyridine by 5-methyl pyridine; preparing 2-nitro-5-methyl nitrogen-oxidative pyridine by nitrogen-oxidative pyridine; and preparing the 2-amino-5-methyl pyridine by the 2-nitro-5-methyl nitrogen-oxidative pyridine. The synthetic method provided by the invention has the advantages of high product yield and purity, low in production cost and good in environment-friendly effect.
- -
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Paragraph 0025; 0027; 0033; 0038; 0040
(2017/11/16)
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- Visible-light-responsive catalysis of a zinc-introduced lacunary disilicoicosatungstate for the deoxygenation of pyridine N-oxides
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We herein report the synthesis and photoredox catalysis of a mononuclear zinc-introduced lacunary disilicoicosatungstate TBA7[{Zn(CH3CN)}(γ-SiW10O34){γ-SiW10O32(CH3CONH)}(μ-O)2] (II, TBA = tetra-n-butylammonium). POM II showed efficient photocatalytic activity in the selective deoxygenation of pyridine N-oxides under visible light irradiation (λ > 400 nm).
- Jeong, Jinu,Suzuki, Kosuke,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information
p. 13226 - 13229
(2017/11/27)
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- Producing pyridines: Via thermo-catalytic conversion and ammonization of glycerol over nano-sized HZSM-5
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In this study, nano-sized HZSM-5 catalysts with different Si/Al ratios were synthesized and employed for producing pyridines from glycerol via a thermo-catalytic conversion and ammonization (TCC-A) process. The catalytic performance of micro-sized HZSM-5 and nano-sized HZSM-5 was studied firstly. The nano-sized HZSM-5 showed better catalytic performance in pyridine production in the TCC-A process due to its smaller particle size. When the nano-sized HZSM-5 (Si/Al = 25) served as the catalyst, and the reaction temperature was about 550 °C with the weight hourly space velocity of glycerol to catalyst at 1 h-1 and the ammonia to glycerol ratio at 12:1, the highest yield of pyridines was up to 42.1%, which was much higher than that when using micro-sized HZSM-5 (35.6%) reported before. In addition, nano-sized HZSM-5 also showed a better catalytic performance than micro-sized HZSM-5 in the catalytic conversion of bio-derived furans to produce indoles. After five reaction/regeneration cycles, the catalytic performance of nano-sized HZSM-5 slightly decreased compared with the first run, but was still higher than that of micro-sized HZSM-5.
- Xu, Lujiang,Yao, Qian,Zhang, Ying,Fu, Yao
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p. 86034 - 86042
(2016/11/09)
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- Method for synthesizing 3-picoline
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The invention discloses a method for synthesizing 3-picoline. The method comprises the following process steps: (1) firstly, pretreating a catalyst ZSM-5, and feeding the catalyst ZSM-5 into a tubular reactor, that is, a tubular reactor with a molecular sieve; (2) respectively heating acrolein, acetone, steam and ammonia to 180-210 DEG C, mixing in a certain ratio, diluting with nitrogen, pressurizing to 2.0-2.4MPa, and feeding through the tubular reactor with the molecular sieve at the speed of 9L/minute; and (3) separating in a cooling tower, and refining, thereby obtaining 3-picoline and pyridine. Compared with the prior art, the method is easy in raw material resource, simple to operate, high in yield and high in recycling time of the catalyst ZSM-5.
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Paragraph 0020
(2016/12/01)
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- Palladium Supported on Nanodiamonds as an Efficient Catalyst for the Hydrogenating Deamination of Benzonitrile and Related Compounds
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Palladium nanoparticles were successfully prepared on a nanodiamond (ND) support and used for the hydrogenating deamination of benzonitrile, aromatic imines, and amines for the first time. The developed methodology was further used for the insitu conversion of aldehydes into hydrocarbons, including a biomass-derived model compound. The activity of the catalyst was compared with palladium supported on activated carbon (AC) under identical conditions and the performance of Pd/ND was found to be superior to Pd/AC. The origin of the difference in the catalytic performance was considered. Finally, an attempt has been made to understand the mechanism through the identification of the side products by GCMS analysis. Diamond in the rough: Cleavage of the carbon-nitrogen bond in organic molecules (nitriles, imines, and amines) by palladium supported on nanodiamonds is reported and is linked to the further utilization of biomass.
- Gupta, Neeraj,Ding, Yuxiao,Feng, Zhenbao,Su, Dangsheng
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p. 922 - 928
(2016/03/15)
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- Palladium nanoparticles supported on reduced graphene oxide as an efficient catalyst for the reduction of benzyl alcohol compounds
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Palladium nanoparticles were prepared on reduced graphene oxide (Pd NPs/rGO) by using a sonochemical procedure. Pd NPs with a mean diameter of 37 ± 22 nm were deposited on reduced graphene oxide sheets by the reaction between PdCl42 - and graphene oxide (GO) under sonochemical conditions. The catalyst was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The Pd NPs/rGO nanocomposite was successfully applied as a reusable catalyst for the reduction of benzyl alcohol derivatives into the corresponding methylene compounds in the presence of triethylsilane. The reductive dehydroxylation of benzyl alcohols takes place under mild conditions affording high yields of the corresponding methylene compounds in short reaction times.
- Mirza-Aghayan, Maryam,Molaee Tavana, Mahdieh,Boukherroub, Rabah
-
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- Preparation of an Arenylmethylzinc Reagent with Functional Groups by Chemoselective Cross-Coupling Reaction of Bis(iodoazincio)methane with Iodoarenes
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Palladium-catalyzed cross-coupling reaction of bis(iodozincio)methane with iodoarenes carrying various functionalities such as ester, boryl, cyano, and halo groups proceeded chemoselectively to give the corresponding arenylmethylzinc species efficiently. The moderate reactivity of the gem-dizinc reagent imparted functional group tolerance to the process. The transformations from iodoheteroarenes were also performed; in the case of iodopyridine derivatives, the nickel-catalyzed reaction gave the corresponding organozinc species efficiently. The obtained arenylmethylzinc species underwent the copper-mediated coupling reaction with a range of organic halides.
- Shimada, Yukako,Haraguchi, Ryosuke,Matsubara, Seijiro
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p. 2395 - 2398
(2015/10/19)
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- Unsaturated aldehydes: a novel route for the synthesis of pyridine and 3-picoline
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A novel reaction pathway was developed for the synthesis of pyridine and 3-picoline from the condensation of gas-phase acrolein dimethyl acetal or acrolein diethyl acetal and ammonia over various catalysts in a fixed-bed reactor. ZnO loaded on alkaline-acid sequentially-treated HZSM-5, namely ZnO/HZSM-5-At-acid, was prepared and employed in these reactions for the first time. 3-Picoline, without the generation of 4-picoline, was obtained from the condensation of acrolein dimethyl acetal and ammonia. The ZnO/HZSM-5-At-acid catalyst was proven to be the most promising catalyst relative to other catalysts in this study. The stability of the ZnO/HZSM-5-At-acid catalyst was remarkably higher than that of the ZnO/HZSM-5 catalyst. The catalysts were characterized using XRD, 27Al MAS NMR, XPS, UV-vis DRS, N2-physisorption, NH3-TPD and TG technologies and the results revealed that the pore structure, acidity and location of ZnO had great influence on the total yield of pyridine and 3-picoline, and the catalyst stability.
- Luo, Cai-Wu,Chao, Zi-Sheng
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p. 54090 - 54101
(2015/06/30)
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- PROCESS AND CATALYST FOR THE PRODUCTION OF PYRIDINE AND ALKYL DERIVATIVES THEREOF
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A process for increasing the overall yield of pyridine or its alkyl pyridine derivatives during a base synthesis reaction is disclosed. The process comprises reacting a C2 to C5 aldehyde, a C3 to C5 ketone or a combination thereof, with ammonia and, optionally, formaldehyde, in the gas phase and in the presence of an effective amount of a particulate catalyst comprising a zeolite, zinc, a binder, and clay and optionally a matrix, wherein the catalyst has a L/B ratio of about 1.5 to about 4.0. Preferably, the zeolite is ZSM-5. A process for enhancing the catalytic activity of a zinc and zeolite containing catalyst to increase the overall yield of pyridine and/ or its derivatives during a base synthesis reaction is also disclosed.
- -
-
Paragraph 0039-0040
(2014/05/24)
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- Convenient synthesis of monobenzylated hydrazides via aqueous zinc-mediated addition reactions
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Addition of substituted benzyl bromides to dialkyl azodicarboxylates under aqueous zinc-mediated addition conditions occurs readily to afford monobenzylated hydrazides in good to excellent yields. The reaction is tolerant of a variety of substituents on the benzyl bromide ring. Several dialkyl azodicarboxylates were successfully tested under the reaction conditions. The limitations of the reaction are also addressed.
- Breton, Gary W.
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supporting information
p. 1128 - 1136
(2014/04/03)
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- Amination of allyl alcohol to propionitrile over a Zn30Cr 4.5/γ-Al2O3 bimetallic catalyst via coupled dehydrogenation-hydrogenation reactions
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A Zn30Cr4.5/γ-Al2O3 bimetallic catalyst that can perform coupled dehydrogenation and hydrogenation reactions was prepared for the amination of allyl alcohol to propionitrile. During the catalysis, the hydrogen derived from the dehydrogenation of the alcohol and imine acted as an in situ source for the hydrogenation of the carbon-carbon double bond. The catalyst exhibited good performance for the reaction at atmospheric ammonia pressure. The parameters that affect the catalyst performance were studied thoroughly, and an optimized process for synthesizing propionitrile from allyl alcohol and ammonia over the catalyst was obtained. Under the optimized conditions, the propionitrile yield was greater than 65%. The characterization results indicated that the dehydrogenation reaction mainly occurred on the Lewis acid sites and revealed that ZnAl 2O4 is the active species for the coupled dehydrogenation-hydrogenation reactions. Chromium doping of the γ-Al 2O3-supported zinc catalyst Zn30/γ- Al2O3 resulted in a decrease in the size of the ZnAl 2O4 crystallites, which was favorable for the dehydrogenation-hydrogenation reactions. The characterization results also revealed that the catalyst deactivation was due to carbon deposition on the catalyst during the catalytic run. The catalyst could be reactivated by blowing air into the reactor at a high temperature.
- Zhang, Yuecheng,Wei, Tianyu,Pian, Yanjie,Zhao, Jiquan
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p. 154 - 162
(2013/09/02)
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- A computational, X-ray crystallographic and thermal stability analysis of TETROL and its pyridine and methylpyridine inclusion complexes
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The identification and application of (+)-(2R,3R)-1,1,4,4- tetraphenylbutane-1,2,3,4-tetrol (TETROL) as an efficient and selective host compound is described. Computational and single crystal X-ray diffraction analyses revealed that the butane backbone of TETROL adopts a relatively rigid anti-conformation, with the hydroxy groups oriented syn and connected through a cyclic, homodromic arrangement of their O-H bonds. This structure is stabilised through a pair of 1,3-hydrogen bonding interactions. TETROL forms inclusion complexes with pyridine and 3- and 4-methylpyridine, and does so selectively from mixtures of the pyridines. X-ray diffraction (single crystal and powder) and thermal analyses of the inclusion compounds are described.
- Barton, Benita,Caira, Mino R.,Hosten, Eric C.,McCleland, Cedric W.
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p. 8713 - 8723
(2013/09/23)
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- Molecular products from the thermal degradation of glutamic acid
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The thermal behavior of glutamic acid was investigated in N2 and 4% O2 in N2 under flow reactor conditions at a constant residence time of 0.2 s, within a total pyrolysis time of 3 min at 1 atm. The identification of the main pyrolysis products has been reported. Accordingly, the principal products for pyrolysis in order of decreasing abundance were succinimide, pyrrole, acetonitrile, and 2-pyrrolidone. For oxidative pyrolysis, the main products were succinimide, propiolactone, ethanol, and hydrogen cyanide. Whereas benzene, toluene, and a few low molecular weight hydrocarbons (propene, propane, 1-butene, and 2-butene) were detected during pyrolysis, no polycyclic aromatic hydrocarbons (PAHs) were detected. Oxidative pyrolysis yielded low molecular weight hydrocarbon products in trace amounts. The mechanistic channels describing the formation of the major product succinimide have been explored. The detection of succinimide (major product) and maleimide (minor product) from the thermal decomposition of glutamic acid has been reported for the first time in this study. Toxicological implications of some reaction products (HCN, acetonitrile, and acyrolnitrile), which are believed to form during heat treatment of food, tobacco burning, and drug processing, have been discussed in relation to the thermal degradation of glutamic acid.
- Kibet, Joshua K.,Khachatryan, Lavrent,Dellinger, Barry
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p. 7696 - 7704
(2013/09/02)
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- Generation and reactions of pyridyllithiums via Br/li exchange reactions using continuous flow microreactor systems
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A continuous flow microreactor method for generating and carrying out reactions on pyridyllithiums has been developed based on Br/Li exchange reactions of bromopyridines and dibromopyridines. The reactions can be carried out without using cryogenic conditions by virtue of short residence times and efficient heat transfer, while very low temperatures such as-78 or-110°C are required for conventional batch macro methods. Moreover, sequential introduction of two different electrophiles has been successfully achieved using dibromopyridines in an integrated flow microreactor system composed of four micromixers and four microtube reactors.
- Nagaki, Aiichiro,Yamada, Daisuke,Yamada, Shigeyuki,Doi, Masatomo,Ichinari, Daisuke,Tomida, Yutaka,Takabayashi, Naofumi,Yoshida, Jun-Ichi
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p. 199 - 207
(2013/03/28)
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- METHOD FOR SYNTHESIZING BIO-BASED PYRIDINE AND PICOLINES
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The present invention relates to a method for synthesizing bio-based pyridine and picolines, said method including at least the following steps: a first step involving subjecting a glycerol filler, created from the methanolysis of vegetable oils or animal fats, to a dehydration reaction leading to acrolein; a second step involving partial condensation of the effluent from the first step so as to separate a water-rich flow as well as an acrolein-rich flow; and a third step involving reacting the acrolein from the preceding step with acetaldehyde in the presence of ammonia so as to obtain, by means of a condensation reaction, the biobased pyridine and picolines.
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Page/Page column 4; 6
(2012/11/13)
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- Photodegradation of the isoxazolidine fungicide syp-z048 in aqueous solution: Kinetics and photoproducts
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Previous research has demonstrated that 3-[5-(4-chlorophenyl)-2,3-dimethyl- 3-isoxazolidinyl]pyridine (SYP-Z048), a newly developed nitrogen heterocycle substituted isoxazolidine compound, has good protective and curative activities against a wide range of fungal diseases of fruits and vegetables caused by Ascomycetes, Basidiomycetes, and Deuteromycetes. In this study, the photochemical behavior of SYP-Z048 was investigated in aqueous solution and in response to solar and low-pressure mercury ultraviolet (UV) lamp irradiation. SYP-Z048 photolysis was pH- and temperature-dependent and was described by a first-order degradation reaction. A total of 11 photoproducts were separated by high-performance liquid chromatography (HPLC) and solid-phase extraction (SPE) and were identified on the basis of 1H and 13C nuclear magnetic resonance (NMR) and high-performance liquid chromatography-mass spectrometry (HPLC-MS) spectra. The photoproduct structures and kinetics suggested that the phototransformation of SYP-Z048 occurred via multiple reaction pathways that included the cleavage of the N-O bond in the isoxazolidine ring and the dechlorination of the benzene ring.
- Liu, Pengfei,Xu, Yanjun,Li, Jianqiang,Liu, Junli,Cao, Yongsong,Liu, Xili
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p. 11657 - 11663
(2013/02/23)
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- Electrochemical coupling of mono and dihalopyridines catalyzed by nickel complex in undivided cell
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One step nickel-catalyzed electroreductive homocoupling among 2-bromopicolines and 2-bromopyridine has been investigated by our group in an undivided cell and using zinc or iron as sacrificial anode. In this work, it was developed mono and dihalopyridines coupling to obtain possible products from heterocoupling. A series of reactions were carried out in order to develop a synthetic method for the preparation of unsymmetrical 2,2′-bipyridines and 2,2′:6′,2″-terpyridines. Statistical yields (50%) were observed for 2-bromopyridines/2-bromo-6-methylpyridine heterocoupling. In a preliminary study devoted to terpyridines preparation, good results were obtained for 2,6-dihalopyridines homocoupling, affording 2,6-dichloro-2, 2′-bipyridine (46%) and 2,6-dibromo-2,2′-bipyridine (56%), at controlled reaction time. At major reaction time, it was observed that the direct electroreduction of the 2,6′-dihalo-2,2′-bipyridines intermediates and 2,6″-dihalo-2,2′:6′,2″-terpyridines products on the cathode surface. A reasonable isolated product yield of 6,6″-dimethyl-2,2′:6′,2″-terpyridine (10%) was only observed in the reaction between 2,6-dichloropyridine and 2-bromo-6- methylpyridine (1:2).
- Oliveira, Jadson L.,Silva, Maria J.,Florêncio, Tupolevck,Urgin, Karne,Sengmany, Stéphane,Léonel, Eric,Nédélec, Jean-Yves,Navarro, Marcelo
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experimental part
p. 2383 - 2390
(2012/04/17)
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- CATALYSTS FOR THE PREPARATION OF METHYLPYRIDINE
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Subject of the invention is a dehydrogenation catalyst for dehydrogenating methylpiperidine to methylpyridine. Subject of the invention are also methods for preparing the catalysts obtained thereby and methods, in which the catalysts are used.
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Page/Page column 4
(2011/05/03)
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- Dissection of complex molecular recognition interfaces
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The synthesis of a family of zinc porphyrins and pyridine ligands equipped with peripheral H-bonding functionality has provided access to a wide range of closely related supramolecular complexes featuring between zero and four intramolecular H-bonds. An automated UV/vis titration system was used to characterize 120 different complexes, and these data were used to construct a large of number of different chemical double mutant cycles to quantify the intramolecular H-bonding interactions. The results probe the quantitative structure-activity relationship that governs cooperativity in the assembly of complex molecular recognition interfaces. Specifically, variations in the chemical structures of the complexes have allowed us to change the supramolecular architecture, conformational flexibility, geometric complementarity, the number and nature of the H-bond interactions, and the overall stability of the complex. The free energy contributions from individual H-bonds are additive, and there is remarkably little variation with architecture in the effective molarity for the formation of intramolecular interactions. Intramolecular H-bonds are not observed in complexes where they are geometrically impossible, but there are no cases where excellent geometric complementarity leads to very high affinities. Similarly, changes in conformational flexibility seem to have limited impact on the values of effective molarity (EM). The major variation that was found for all of the 48 intramolecular interactions that were examined using double mutant cycles is that the values of EM for intramolecular carboxylate ester-phenol H-bonds (200 mM) are an order of magnitude larger than those found for phosphonate diester-phenol H-bonds (30 mM). The corresponding intermolecular phosphonate diester-phenol H-bonds are 2 orders of magnitude more stable than carboxylate ester-phenol H-bonds, and the large differences in EM may be due to some kind of compensation effect, where the stronger H-bond is harder to make, because it imposes tighter constraints on the geometry of the complex.
- Hunter, Christopher A.,Misuraca, Maria Cristina,Turega, Simon M.
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supporting information; experimental part
p. 582 - 594
(2011/04/16)
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- PROCESS FOR THE SELECTIVE PREPARATION OF 3-METHYLPYRIDINE (3-PICOLINE) FROM ACROLEIN AND ONE OR MORE AMMONIUM SALTS DISSOLVED IN WATER
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The present invention relates to a process for the selective preparation of 3-methylpyridine, characterized in that acrolein and one or more ammonium salt(s) dissolved in water are reacted continuously under high pressures and at temperatures of 200-400° C.
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Page/Page column 2
(2011/02/25)
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- METHOD FOR RAPIDLY METHYLATING HETEROAROMATIC ARENE AND METHOD FOR PRODUCING TRACER FOR USE IN PET
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Provided is a method whereby a heteroaromatic ring aryl can be very rapidly methylated at a high yield. In an N-alkyl-2-pyrrolidinone, a heteroaromatic ring aryltrialkylstannan is cross-coupled with methyl iodide in the presence of a palladium complex, a phosphine ligand, a cuprous halide, a carbonic acid salt and/or an alkali metal fluoride to thereby rapidly methylate the heteroaromatic ring aryl. (Formula shows a case wherein the heteroaromatic ring aryl is a pyridyl group.)
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Page/Page column 5-6
(2011/11/06)
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- Palladium chloride-catalyzed reductive cleavage of benzylic acetal, ketal and ether compounds with triethylsilane
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Reductive cleavage of benzylic acetal, ketal and ether compounds to the corresponding alkanes using triethylsilane and a catalytic amount of palladium(II) chloride is described. The reductive reaction took place under mild conditions, affording high yields of the corresponding alkane compounds in short reaction times.
- Mirza-Aghayan,Boukherroub,Rahimifard,Zadmard
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experimental part
p. 570 - 573
(2012/06/16)
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- Process for the synthesis of 3-methyl-pyridine
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The present invention discloses a process for the synthesis of 3-methyl-pyridine from formaldehyde, paracetaldehyde, ammonia and acetic acid, whereby said compounds are reacted and said process comprises the following parameters: a) a reaction temperature of 260-300° C.;b) a molar ratio of formaldehyde and paracetaldehyde of 0.7-1-4 Mol/Mol:c) an ammonia concentration of 10-20 weight-%d) an acetic acid concentration of 4-20 weight-%e) a paracetaldehyde concentration of 0.4-1.6 Mol/kgf) a retention time of 10-30 minutes in case of a continuous reaction and 10-90 minutes in case of a discontinuous reaction; andg) a reaction pressure of 30-130 bar
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Page/Page column 1
(2011/01/12)
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- Reduction of amine N-oxides by diboron reagents
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Facile reduction of alkylamino-, anilino-, and pyridyl-N-oxides can be achieved via the use of diboron reagents, predominantly bis- (pinacolato)- and in some cases bis(catecholato)diboron [(pinB)2 and (catB)2, respectively]. Reductions occur upon simply mixing the amine N oxide and the diboron reagent in a suitable solvent, at a suitable temperature. Extremely fast reductions of alkylamino- and anilino-N-oxides occur, whereas pyridyl-N-oxides undergo slower reduction. The reaction is tolerant of a variety of functionalities such as hydroxyl, thiol, and cyano groups, as well as halogens. Notably, a sensitive nucleoside N-oxide has also been reduced efficiently. The different rates with which alkylamino- and pyridyl-N-oxides are reduced has been used to perform stepwise reduction of the N,N-dioxide of (S)-(-)-nicotine. Because it was observed that (pinB)2 was unaffected by the water of hydration in amine oxides, the feasibility of using water as solvent was evaluated. These reactions also proceeded exceptionally well, giving high product yields. In constrast to the reactions with (pinB)2, triethylborane reduced alkylamino-N oxides, but pyridine N-oxide did not undergo efficient reduction even at elevated temperature. Finally, the mechanism of the reductive process by (pinB)2 has been probed by 1H and 11B NMR. (Figure presented) ; 2011 American Chemical Society.
- Kokatla, Hari Prasad,Thomson, Paul F.,Bae, Suyeal,Doddi, Venkata Ramana,Lakshman, Mahesh K.
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experimental part
p. 7842 - 7848
(2011/12/01)
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- METHOD FOR THE PREPARATION OF 3-METHYLPYRIDINE
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The present invention relates to a method for the preparation of 3-methylpyridin by reacting 2-methyl-2,5-diaminopentane and/or 3-methylpiperidin at about atmospheric pressure and a temperature of 180°C to 400°C in a hydrogen atmosphere free of oxygen gas in the presence of a suitable catalyst and of water and/or a volatile alcohol.
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Page/Page column 3-4
(2010/04/27)
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- Microbial biodegradation and metabolite toxicity of three pyridinium-based cation ionic liquids
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Merging the disciplines of green chemistry, ecotoxicology and ecology to develop environmentally-friendly industrial chemicals represents a significant collaborative challenge. This challenge can be met by extending already-informative standard toxicity and biodegradability assays to include further information about the potential persistence and biotransformation of pollutants in the environment. Development of ionic liquids (ILs) provides an ideal and proactive test system to determine several levels of environmental impact using academically interesting and industrially relevant green chemical prototypes. In this study, we investigated the biodegradability of three ILs, 1-butyl-3-methylpyridinium bromide, 1-hexyl-3-methylpyridinium bromide and 1-octyl-3-methylpyridinium bromide, by activated sludge microbial communities. We determined that all three ILs could be fully mineralized, but that only the octyl-substituted cation could be classified as readily biodegradable . We directly examined biodegradation products of the ILs using reverse-phase high performance liquid chromatography/mass spectrometry and MS/MS methods, and identified several unique preliminary degradation products. Finally, we determined that IL-biodegradation products were less toxic than the initial compound to a standard aquatic test organism, Daphnia magna, suggesting that biodegradation in an aquatic environment would decrease toxicity hazards associated with the initial compound. This study provides further information about pyridinium IL-biodegradation and guidelines to structure future IL design and research.
- Docherty, Kathryn M.,Joyce, Michelle V.,Kulacki, Konrad J.,Kulpa, Charles F.
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body text
p. 701 - 712
(2010/08/22)
-
- Basicity of pyridine and some substituted pyridines in ionic liquids
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Figure presented The equilibrium constants for ion pair formation of some pyridines have been evaluated by spectrophotometric titration with trifluoroacetic acid in different ionic liquids. The basicity order is the same in ionic liquids and in water. The substituent effect on the equilibrium constant has been discussed in terms of the Hammett equation. Pyridine basicity appears to be less sensitive to the substituent effect in ionic liquids than in water.
- Angelini, Guido,De Maria, Paolo,Chiappe, Cinzia,Fontana, Antonella,Pierini, Marco,Siani, Gabriella
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experimental part
p. 3912 - 3915
(2010/08/06)
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- DEHYDROGENATION PROCESS
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Processes comprising: providing a dehydrogenatable compound; and subjecting the dehydrogenatable compound to a dehydrogenation reaction at a temperature of from 150 to 400° C., in the presence of oxygen, and at a temperature profile of the dehydrogenation reaction which does not differ substantially from the temperature profile of the dehydrogenation reaction in the absence of oxygen under otherwise identical conditions.
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Page/Page column 5
(2009/04/24)
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- A simple and efficient hydrogenation of benzyl alcohols to methylene compounds using triethylsilane and a palladium catalyst
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Hydrogenolysis of benzyl alcohols using triethylsilane (Et3SiH) and a catalytic amount of palladium(II) chloride (PdCl2) is described. The reaction takes place under mild conditions affording high yields of the corresponding methylene compounds in short reaction times.
- Mirza-Aghayan, Maryam,Boukherroub, Rabah,Rahimifard, Mahshid
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experimental part
p. 5930 - 5932
(2010/01/18)
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