Day: December 11, 2020

108-47-4, Chemistry is the experimental science by definition. We want to make observations to prove hypothesis. For this purpose, we perform experiments in the lab. 108-47-4, Name is 2,4-Dimethylpyridine,introducing its new discovery.

Catalytic Reactions of Pyridines. IV. Heterogeneous Vapor-phase Side-chain Alkylation of Pyridines with Alcohols over Na+, K+, Rb+, and Cs+ Exchanged Zeolites

The heterogeneous vapor-phase alkylation of pyridine with methanol over Na+, K+, Rb+, or Cs+ exchanged X- or Y-type zeolite in an atmophere of nitrogen resulted in the formation of 2- and 4-ethylpyridines and 2- and 4-vinylpyridines together with picolines and lutidines.Next, the alkylation of alpha-, beta-, and gamma-picolines with methanol was studied over alkali cation exchanged zeolites and was found to produce mainly the side-chain methylated derivatives: ethylpyridines and vinylpyridines.However, considerable amounts of ring-alkylated derivatives (lutidines) were formed simultaneously.In general, the catalytic activity became observable under reaction conditions involving both a high temperature and a small flow rate of carrier gas (N2).The yields of ethylpyridines were highest when the CsY catalyst was used at 450 deg C, whereas the yields of vinylpyridines were highest when the CsX catalyst was used at 425 deg C.This catalytic side-chain alkylation over alkali cation exchanged zeolites was successfully applied to a variety of picolines, lutidines, and ethylpyridines with either methanol or ethanol.

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Reference£º
Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis¡ªI. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis

108-47-4, Chemistry is an experimental science, and the best way to enjoy it and learn about it is performing experiments.Introducing a new discovery about 108-47-4, Name is 2,4-Dimethylpyridine

Catalytic activity of PdCl2 complexes with pyridines in nitrobenzene carbonylation

Synthesis of square planar palladium(II) complexes of general structure PdCl2(XnPy)2 (where: Py = pyridine; X nPy = 2-MePy; 3-MePy; 4-MePy; 2,4-Me2Py; 2,6-Me 2Py; 2-ClPy; 3-ClPy and 3,5-Cl2Py) has been performed in order to study activity of these complexes as catalysts of nitrobenzene (NB) carbonylation – a process of industrial importance leading to production of ethyl N-phenylcarbamate (EPC). Electron withdrawing/electron donating properties of XnPy ligands (described by experimentally determined acidity parameter pKa) have been correlated with activities of PdCl 2(XnPy)2 complexes during NB carbonylation in presence of catalytic system PdCl2(XnPy) 2/Fe/I2/XnPy. We observed that conversions of substrates and yields of EPC increase within increasing basicity of X nPy ligand (for not sterically hindered XnPy’s). On the basis of current work and our previous studies a detailed mechanism of catalytic carbonylation of NB is proposed.

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Reference£º
Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis¡ªI. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis

108-47-4, Chemistry is the experimental and theoretical study of materials on their properties at both the macroscopic and microscopic levels.In a patent£¬Which mentioned a new discovery about 108-47-4

Sulfonamide compounds and medicinal use thereof

A sulfonamide compound of the formula (I):R 1 –SO 2 NHCO–A–R 2 (I)wherein R 1 is alkyl, alkenyl, alkynyl and the like; A is an optionally substituted heteropolycyclic group except benzimidazolyl, indolyl, 4,7-dihydrobenzimidazolyl and 2,3-dihydrobenzoxazinyl; X is alkylene, oxa, oxa(lower)alkylene and the like; and R 2 is optionally substituted aryl, substituted biphenylyl and the like, a salt thereof and a pharmaceutical composition comprising the same. The sulfonamide compound is effective for the diseases treatable based on their blood sugar level-depressing activity, cGMP-PDE (especially PDE-V)-inhibiting activity, smooth muscle relaxing activity, bronchodilating activity, vasodilating activity, smooth muscle cell suppressing activity, and antiallergic activity.

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Reference£º
Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis¡ªI. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis

108-47-4, Because a catalyst decreases the height of the energy barrier, its presence increases the reaction rates of both the forward and the reverse reactions by the same amount.108-47-4, Name is 2,4-Dimethylpyridine, molecular formula is C7H9N. In a article£¬once mentioned of 108-47-4

Effect of halogen substitution on the enthalpies of solvation and hydrogen bonding of organic solutes in chlorobenzene and 1,2-dichlorobenzene derived using multi-parameter correlations

Enthalpies of solution at infinite dilution at 298 K, DeltasolnHA/Solvent, have been measured by isothermal solution calorimetry for 43 and 72 organic solutes dissolved in chlorobenzene and 1,2-dichlorobenzene, respectively. The measured DeltasolnHA/Solvent data, along with published DeltasolnHA/Solvent values taken from the published literature for solutes dissolved in both chlorobenzene solvents, were converted to enthalpies of solvation, DeltasolvHA/Solvent, using standard thermodynamic equations. Abraham model correlations were developed from the experimental DeltasolvHA/Solvent data. The best derived correlations describe the experimental gas-to-chlorobenzene and gas-to-1,2-dichlorobenzene enthalpies of solvation to within standard deviations of 1.5 kJ mol-1 and 1.9 kJ mol-1, respectively. Enthalpies of X-H?pi (X – O, N, and C) hydrogen bond formation of proton donor solutes (alcohols, amines, chlorinated hydrocarbons, etc.) with chlorobenzene and 1,2-dichlorobenzene were calculated based on the Abraham solvation equation. Obtained values are in good agreement with the results determined using conventional methods.

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Reference£º
Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis¡ªI. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis

108-47-4, Chemistry can be defined as the study of matter and the changes it undergoes. You¡¯ll sometimes hear it called the central science because it is the connection between physics and all the other sciences, starting with biology.108-47-4, Name is 2,4-Dimethylpyridine, molecular formula is C7H9N, introducing its new discovery.

Determination of reversed-phase high performance liquid chromatography based octanol-water partition coefficients for neutral and ionizable compounds: Methodology evaluation

Reversed-phase liquid chromatography (RPLC) based octanol-water partition coefficient (logP) or distribution coefficient (logD) determination methods were revisited and assessed comprehensively. Classic isocratic and some gradient RPLC methods were conducted and evaluated for neutral, weak acid and basic compounds. Different lipophilicity indexes in logP or logD determination were discussed in detail, including the retention factor logkw corresponding to neat water as mobile phase extrapolated via linear solvent strength (LSS) model from isocratic runs and calculated with software from gradient runs, the chromatographic hydrophobicity index (CHI), apparent gradient capacity factor (kg?) and gradient retention time (tg). Among the lipophilicity indexes discussed, logkw from whether isocratic or gradient elution methods best correlated with logP or logD. Therefore logkw is recommended as the preferred lipophilicity index for logP or logD determination. logkw easily calculated from methanol gradient runs might be the main candidate to replace logkw calculated from classic isocratic run as the ideal lipophilicity index. These revisited RPLC methods were not applicable for strongly ionized compounds that are hardly ion-suppressed. A previously reported imperfect ion-pair RPLC method was attempted and further explored for studying distribution coefficients (logD) of sulfonic acids that totally ionized in the mobile phase. Notably, experimental logD values of sulfonic acids were given for the first time. The IP-RPLC method provided a distinct way to explore logD values of ionized compounds.

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Reference£º
Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis¡ªI. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis

Let¡¯s face it, organic chemistry can seem difficult to learn. 126456-43-7. Especially from a beginner¡¯s point of view. Like 126456-43-7, Name is (1S,2R)-1-Amino-2,3-dihydro-1H-inden-2-ol. In a document type is Article, introducing its new discovery.

Enantioselective sensing of chiral amino alcohols with a stereodynamic arylacetylene-based probe

Enantioselective induced circular dichroism analysis of amino alcohols has been accomplished using a conformationally flexible arylacetylene-based probe exhibiting two terminal aldehyde groups. The chirality of the amino alcohol substrates is imprinted on the stereodynamic receptor upon [1 + 2] condensation, which ultimately generates a strong chiroptical response. The distinct induced circular dichroism effects of the diimines obtained can be used for enantioselective sensing and enantiomeric excess determination of a wide range of substrates.

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Reference£º
Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis¡ªI. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis

108-47-4, The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.108-47-4, Name is 2,4-Dimethylpyridine, molecular formula is C7H9N. In a Article, authors is Schrock, Richard R.£¬once mentioned of 108-47-4

Synthesis of Group 4 [(RN-o-C6H4)2O]2- complexes where R is SiMe3 or 0.5 Me2SiCH2CH2SiMe2

Complexes that contain the [(Me3SiN-o-C6H4)2O]2- ligand ([1]2-) of the type [1]M(NMe2)2, [1]MCl2, and [1]MMe2 have been prepared where M=Ti, Zr, or Hf. Although cations prepared by addition of [Ph3C][B(C6F5)4] or [PhNMe2H][B(C6F5)4] to [1]ZrMe2 or [1]HfMe2 could not be observed in NMR studies, addition of [(eta5-C5H4Me)2Fe][B(C 6H5)4] to [1]HfMe2 in the presence of THF led to isolation of {[1]HfMe(THF)2}[B(C6H5)4]. An X-ray study showed the cation to be a distorted octahedron in which the [1]2- ligand is in the mer arrangement and is significantly twisted from a planar NC2OC2N arrangement. The THF ligands are trans to one another. No well-behaved activity for the polymerization of 1-hexene could be observed with activated [1]ZrMe2, while {[1]HfMe(THF)2}[B(C6H5)4] was inactive. The reaction between Li2[O(o-C6H4NH)2] and Me2ClSiCH2CH2SiMe2Cl in THF produced a cyclic diamido/ether ligand H2[2]. The reaction between H2[2] and Zr(NMe2)4 or ZrR4 (R=CH2Ph, CH2SiMe3) gave [2]Zr(NMe2)2(HNMe2) and Zr[2]2, respectively. The dimethylamine in [2]Zr(NMe2)2(HNMe2) could be replaced with pyridine or 2,4-lutidine to give [2]Zr(NMe2)2(L) (L=pyridine or 2,4-lutidine), which then could be converted into [2]ZrCl2(L) with excess Me3SiCl. The reaction between [2]ZrCl2(py) and two equivalents of Me3SiCH2MgCl gave a bimetallic complex in which one of the trimethylsilyl methyl groups has been doubly C-H activated, as confirmed by X-ray crystallography.

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Reference£º
Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis¡ªI. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis

A catalyst don’t appear in the overall stoichiometry of the reaction it catalyzes, 126456-43-7, but it must appear in at least one of the elementary reactions in the mechanism for the catalyzed reaction. 126456-43-7, Name is (1S,2R)-1-Amino-2,3-dihydro-1H-inden-2-ol, molecular formula is C9H11NO. In a Article, authors is Qu, Bo£¬once mentioned of 126456-43-7

A mild dihydrobenzooxaphosphole oxazoline/iridium catalytic system for asymmetric hydrogenation of unfunctionalized dialins

Air-stable P-chiral dihydrobenzooxaphosphole oxazoline ligands were designed and synthesized. When they were used in the iridium-catalyzed asymmetric hydrogenation of unfunctionalized 1-aryl-3,4-dihydronaphthalenes under one atmosphere pressure of H2, up to 99:1 e.r. was obtained. High enantioselectivities were also observed in the reduction of the exocyclic imine derivatives of 1-tetralones.

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Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis¡ªI. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis

Chemistry is the science of change. But why do chemical reactions take place? Why do chemicals react with each other? The answer is in thermodynamics and kinetics.In a document type is Article, the author is Fernandez-Maestre, Roberto and a compound is mentioned, 108-47-4, 2,4-Dimethylpyridine, introducing its new discovery. 108-47-4

Shift reagents in ion mobility spectrometry: The effect of the number of interaction sites, size and interaction energies on the mobilities of valinol and ethanolamine

Overlapping peaks interfere in ion mobility spectrometry (IMS), but they are separated introducing mobility shift reagents (SR) in the buffer gas forming adducts with different collision cross-sections (size). IMS separations using SR depend on the ion mobility shifts which are governed by adduct’s size and interaction energies (stabilities). Mobility shifts of valinol and ethanolamine ions were measured by electrospray-ionization ion mobility-mass spectrometry (MS). Methyl-chloro propionate (M) was used as SR; 2-butanol (B) and nitrobenzene (N) were used for comparison. Density functional theory was used for calculations. B produced the smallest mobility shifts because of its small size. M and N have two strong interaction sites (oxygen atoms) and similar molecular mass, and they should produce similar shifts. For both ethanolamine and valinol ions, stabilities were larger for N adducts than those of M. With ethanolamine, M produced a 68% shift, large compared to that using N, 61%, because M has a third weak interaction site on the chlorine atom and, therefore, M has more interaction possibilities than N. This third site overrode the oxygen atoms’ interaction energy that favored the adduction of ethanolamine with N over that with M. On the contrary, with valinol mobility shifts were larger with N than with M (21 vs 18%) because interaction energy favored even more adduction of valinol with N than with M; that is, the interaction energy difference between adducts of valinol with M and N was larger than that between those adducts with ethanolamine, and the third M interaction could not override this larger difference. Mobility shifts were explained based on the number of SR’s interaction sites, size of ions and SR, and SR-ion interaction energies. This is the first time that the number of interaction sites is used to explain mobility shifts in SR-assisted IMS.

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Reference£º
Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis¡ªI. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis

126456-43-7, A catalyst don’t appear in the overall stoichiometry of the reaction it catalyzes, but it must appear in at least one of the elementary reactions in the mechanism for the catalyzed reaction. 126456-43-7, Name is (1S,2R)-1-Amino-2,3-dihydro-1H-inden-2-ol, molecular formula is C9H11NO. In a Article, authors is Pinxterhuis, Erik B.£¬once mentioned of 126456-43-7

Highly Efficient and Robust Enantioselective Liquid?Liquid Extraction of 1,2-Amino Alcohols utilizing VAPOL- and VANOL-based Phosphoric Acid Hosts

The large-scale production of enantiopure compounds in a cost-effective and environmentally friendly manner remains one of the major challenges of modern-day chemistry. The resolution of racemates through enantioselective liquid?liquid extraction was developed as a suitable solution but has remained largely underused, owing to a lack of highly efficient and robust chiral hosts to mediate the process. This paucity of hosts can in part be attributed to a poor understanding of the underlying principles behind these processes hindering the design of more efficient selectors. A previously untested class of hosts, VAPOL and VANOL derived phosphoric acids, has been studied in depth for the efficient enantioselective liquid?liquid extraction of 1,2-amino alcohols. A systematic investigation of extraction parameters was conducted, revealing many key interactions and DFT calculations illustrate the binding modes for the 1:1 complexes that are involved in chiral recognition. The resulting, now-optimized, procedures are highly robust and easy to implement. They are also easily scalable, as demonstrated by U-tube experiments.

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Reference£º
Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis¡ªI. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis