Tag: M.W:200-300

Synthetic Route of 18531-99-2, Catalysts are substances that increase the reaction rate of a chemical reaction without being consumed in the process. 18531-99-2, Name is (S)-[1,1′-Binaphthalene]-2,2′-diol, molecular formula is C20H14O2. In a Article£¬once mentioned of 18531-99-2

Acetyl-BINOL as mimic for chiral beta-diketonates: A building block for new modular ligands

alpha-Acetyl-(S)-BINOL was prepared by ortho-lithiation and subsequent acetylation of acetal-protected (S)-BINOL. The beta-hydroxyketone moiety of this compound is herein a structural mimic for a beta-diketonate and forms six-membered chelates with transition metal ions. The second hydroxy-function was submitted to esterification with several carboxylic acids bearing another donor function, thus, new tridentate chiral ligands were obtained. Out of this library the l-proline-alpha-acetyl-(S)-BINOL-ester was identified to be most effective for the titanium-mediated addition of Et2Zn to PhCHO yielding the respective secondary alcohol with up to 93% ee, which is better than with using (S)-BINOL itself. Besides a solvent dependency (use of MeCN is optimal), the proper choice of the counter-ion is crucial: anion exchange of bromide by trifluoroacetate gave a significant increase of enantioselectivity. Copyright

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Catalysts function by providing an alternate reaction mechanism that has a lower activation energy than would be found in the absence of the catalyst. In some cases, the catalyzed mechanism may include additional steps.In a article, 5197-95-5, molcular formula is C13H22BrN, introducing its new discovery. Quality Control of: Benzyltriethylammonium bromide

Microwave-assisted alkylation of phenols by quaternary onium salts

The alkylation of cresol and its analogues was accomplished by quaternary onium salts under solventless and microwave(MW) conditions using Cs 2CO3 as the base. The beneficial energy absorbing ability of the onium saltscould be clearly observed under MW conditions as compared to the thermal experiments and was relevant in the range of 110-125 C.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Catalysts function by providing an alternate reaction mechanism that has a lower activation energy than would be found in the absence of the catalyst. In some cases, the catalyzed mechanism may include additional steps.In a article, 117408-98-7, molcular formula is C12H16N2O, introducing its new discovery. SDS of cas: 117408-98-7

Site-Selective Ni-Catalyzed Reductive Coupling of alpha-Haloboranes with Unactivated Olefins

A mild, chemo- and site-selective catalytic protocol that allows for incorporating an alkylboron fragment into unactivated olefins is described. The use of internal olefins enables C-C bond-formation at remote sp3 C-H sites, constituting a complementary and conceptually different approach to existing borylation techniques that are currently available at sp3 centers.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Application of 18531-94-7, 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. 18531-94-7, Name is (R)-[1,1′-Binaphthalene]-2,2′-diol, molecular formula is C20H14O2. In a Patent£¬once mentioned of 18531-94-7

PROCESS FOR PRODUCTION OF DISULFONIC ACID COMPOUND, ASYMMETRIC MANNICH CATALYST, PROCESS FOR PRODUCTION OF -AMINOCARBONYL DERIVATIVE, AND NOVEL DISULFONATE SALT

Hexamethylphosphoramide (HMPA) was added to a reaction vessel containing (R)-1,1′-binaphthyl-2,2′-dithiol and potassium hydroxide. The vessel was purged with oxygen and stirred at 80C for 5 days under 7 atmospheres of oxygen. After being cooled to room temperature, the reaction product was purified to yield potassium (R)-1,1′-binaphthyl-2,2′-disulfonate. The (R)-1,1′-binaphthyl-2,2′-disulfonic acid obtained from the disulfonate and 2,6-diphenylpyridine were stirred in acetonitrile, and then the solvent was evaporated under reduced pressure. Subsequently, magnesium sulfate and distilled CH2Cl2 were added to the reaction product, and the mixture was stirred at room temperature for 30 minutes. The resulting solution was cooled to 0C. Benzaldehyde imine whose nitrogen is protected with Cbz and subsequently acetyl acetone were dropped into the solution over a period of 1 hour. The resulting mixture was further stirred at 0C for 30 minutes. A corresponding beta-aminocarbonyl derivative was thus produced with an yield of 91% and an enantiomeric excess of 90% ee.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

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High-Dimensional Mutant and Modular Thermodynamic Cycles, Molecular Switching, and Free Energy Transduction

Understanding how distinct parts of proteins produce coordinated behavior has driven and continues to drive advances in protein science and enzymology. However, despite consensus about the conceptual basis for allostery, the idiosyncratic nature of allosteric mechanisms resists general approaches. Computational methods can identify conformational transition states from structural changes, revealing common switching mechanisms that impose multistate behavior. Thermodynamic cycles use factorial perturbations to measure coupling energies between side chains in molecular switches that mediate shear during domain motion. Such cycles have now been complemented by modular cycles that measure energetic coupling between separable domains. For one model system, energetic coupling between domains has been shown to be quantitatively equivalent to that between dynamic side chains. Linkages between domain motion, switching residues, and catalysis make nucleoside triphosphate hydrolysis conditional on domain movement, confirming an essential yet neglected aspect of free energy transduction and suggesting the potential generality of these studies.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

A catalyst don’t appear in the overall stoichiometry of the reaction it catalyzes, Application In Synthesis of (S)-[1,1′-Binaphthalene]-2,2′-diol, but it must appear in at least one of the elementary reactions in the mechanism for the catalyzed reaction. 18531-99-2, Name is (S)-[1,1′-Binaphthalene]-2,2′-diol, molecular formula is C20H14O2. In a Article, authors is Schanz, Hans-Joerg£¬once mentioned of 18531-99-2

Improved resolution methods for (R,R)- and (S,S)-cyclohexane-1,2-diamine and (R)- and (S)-BINOL

Starting from inexpensive L-(+)-tartaric acid, it was possible to resolve and obtain pure both enantiomers of trans-cyclohexane-1,2-diamine 1 and thence both enantiomers of BINOL 2, two of the most powerful, chiral inducing backbones in asymmetric catalysis. The modified method is very economic, not only due to an almost doubling of the overall yields of enantiomerically pure compounds (86% 1, 83% 2) but also due to the easy recovery of resolving agent 1 [66% (R,R)-1, 79% (S,S)-1] in the BINOL resolution. An improvement in the yield of the preparation of racemic BINOL is also recorded.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Catalysts function by providing an alternate reaction mechanism that has a lower activation energy than would be found in the absence of the catalyst. In some cases, the catalyzed mechanism may include additional steps.In a article, 1941-30-6, molcular formula is C12H28BrN, introducing its new discovery. Recommanded Product: Tetrapropylammonium bromide

Synthesis and catalytic performance of bimetallic NiMo-and NiW-ZSM-5/MCM-41 composites for production of liquid biofuels

This work presents a synthesis of bimetallic NiMo and NiW modified ZSM-5/MCM-41 composites and their heterogeneous catalytic conversion of crude palm oil (CPO) to biofuels. The ZSM-5/MCM-41 composites were synthesized through a self-assembly of cetyltrimethylammonium bromide (CTAB) surfactant with silica-alumina from ZSM-5 zeolite, prepared from natural kaolin by the hydrothermal technique. Subsequently, the synthesized composites were deposited with bimetallic NiMo and NiW by impregnation method. The obtained catalysts presented a micro-mesoporous structure, confirmed by XRD, SEM, TEM, EDX, NH3-TPD, XRF and N2 adsorption-desorption measurements. The results of CPO conversion demonstrate that the catalytic activity of the synthesized catalysts decreases in the series of NiMo-ZSM-5/MCM-41>NiW-ZSM-5/MCM-41>Ni-ZSM-5/MCM-41>Mo-ZSM-5/MCM-41>W-ZSM-5/MCM-41>NiMo-ZSM-5>NiW-ZSM-5>ZSM-5/MCM-41>ZSM-5>MCM-41.It was found that the bimetallic NiMo-and NiW-ZSM-5/MCM-41 catalysts give higher yields of liquid hydrocarbons than other catalysts at a given conversion. Types of hydrocarbon in liquid products, identified by simulated distillation gas chromatography-flame ionization detector (SimDis GC-FID), are gasoline (150-200?; C5-12), kerosene (250-300?; C5-20) and diesel (350?; C7-20). Moreover, the conversion of CPO to biofuel products using the NiMo-and NiW-ZSM-5/MCM-41 catalysts offers no statistically significant difference (P>0.05) at 95% confidence level, evaluated by SPSS analysis.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Electric Literature of 5197-95-5, The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.5197-95-5, Name is Benzyltriethylammonium bromide, molecular formula is C13H22BrN. In a Article£¬once mentioned of 5197-95-5

A Simple Procedure for the Preparation of 6-Aminothieno<2,3-d>-1,3-dithiole-2-thiones

O-Ethyl-S-cyanomethyl-dithiocarboxylate 1 reacts with carbon disulfide under phase transfer conditions to the 5-cyano-2-thioxo-1,3-dithiole-4-thiolate 2, giving with alpha-halocarbonyl compounds R1CH2X 6-aminothieno<2,3-d>-1,3-dithiole-2-thiones 3. 2 can be alkylated to 4.These compounds 3 or 4 were transformed into the 1,3-dithiole-2-ones 5 or 6 respectively by heating with mercuric acetate in chloroform-acetic acid.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Catalysts function by providing an alternate reaction mechanism that has a lower activation energy than would be found in the absence of the catalyst. In some cases, the catalyzed mechanism may include additional steps.In a article, 150-61-8, molcular formula is C14H16N2, introducing its new discovery. Quality Control of: N1,N2-Diphenylethane-1,2-diamine

The 5′,6-oxomethylene transglycosidic tether for conformational restriction of pyrimidine ribonucleosides. Investigation of 6-formyl- and 6-(hydroxymethyl)uridine 5′-carboxaldehydes

In an effort to develop a new motif for the transglycosidic tethering of the pyrimidine nucleoside framework, the 2′,3′-O-isopropylidenated and unprotected versions of 6-formyl- and 6-(hydroxymethyl)uridine 5′-carboxaldehyde were prepared and these were examined for their ability to adopt 5′,6-oxomethylene tethered solution structures. In aqueous solution, the 2′,3′-O-isopropylidenated nucleosides readily generated spiro-dihydrouridines via proximity-induced transglycosidic intramolecular reactions. In stark contrast, their unprotected counterparts existed mainly as the untethered aldehyde hydrates. Based on these findings, the 5′,6-oxomethylene transglycosidic tether appears to constitute a useful conformational restriction motif for the pyrimidine ribonucleoside framework, but only when the 5′-OH group is functionalized. (C) 2000 Elsevier Science Ltd.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Chemistry is traditionally divided into organic and inorganic chemistry. Safety of Titanocenedichloride. The former is the study of compounds containing at least one carbon-hydrogen bonds.In a patent£¬Which mentioned a new discovery about 1271-19-8

Synthesis and structures of titanium and yttrium complexes with N,N?-tetramethylguanidinate ligands: Different reactivity of the M-N bonds toward phenyl isocyanate

A salt elimination reaction of bis(cyclopentadienyl)titanium dichloride (C5H5)2TiCl2 with one equiv. of N,N?-tetramethylguanidinate lithium [LiNC(NMe2)2] proceeded in THF at room temperature to yield a bis(cyclopentadienyl)titanium mono-guanidinate chloride (C5H5) 2TiCl(NC(NMe2)2) (1). However, treatment of two equiv. of LiNC(NMe2)2 with (C5H 5)2TiCl2 under the same conditions resulted in the elimination of one cyclopentadienyl ring to form an unexpected mono(cyclopentadienyl)titanium bis(guanidinate) chloride (C5H 5)TiCl[NC(NMe2)2]2 (2), in which only one Ti-Cl bond is broken, with the other Ti-Cl bond retained. Reaction of [(C5H5)2YCl]2 with LiNC(NMe 2)2 gave the corresponding product {(C5H 5)2Y[mu-eta1:eta2-NC(NMe 2)2]}2 (3). On further investigations on the reactivity of 1-3 toward phenyl isocyanate, we found phenyl isocyanate only inserts into the Y-N(mu-Gua) bonds of 3 to yield [(C5H 5)2Y(mu-eta1:eta2- OC(NC(NMe2)2)NPh)]2 (4). Complexes 1-4 were characterized by elemental analysis and spectroscopic properties and their solid-state structures were determined by X-ray single-crystal diffraction.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI