Category: chiral-catalyst

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 Dranka, Maciej and a compound is mentioned, 33100-27-5, 1,4,7,10,13-Pentaoxacyclopentadecane, introducing its new discovery. 33100-27-5

Coordination Abilities of 4,5-Dicyano-2-(trifluoromethyl)imidazolate Anion toward Sodium Cation: Structural and Spectroscopic Studies of Solid and Liquid Glyme-Solvated Electrolyte Systems

Comprehensive structural analysis of sodium 4,5-dicyano-2-(trifluoromethyl)imidazolate (NaTDI) solvates with glymes (1-4), tetrahydrofuran, and crown ethers has been performed. Several structural motifs obtained from single-crystal X-ray analysis of complementary series of crystalline adducts with varying O:Na ratios were correlated with spectroscopic and thermal data to provide new information about the coordination ability of heterocyclic anions toward sodium cations. Presented results provide a basis for developing models of poly(ethylene oxide) electrolytes and liquid systems for sodium ion battery electrolytes. We have found a wide variety of anion-cation coordination types which allow us to compare them with analogous lithium solvates in terms of Brown’s valence-matching principle and Lewis acid strength (Sa) parameters. Noticed aggregation modes of sodium salts confirm the occurrence of a solvate disproportionation conductivity mechanism at high salt concentrations which can be used for developing new heterocyclic salt systems for sodium batteries.

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Chiral Catalysts,
Chiral catalysts – SlideShare

 

14187-32-7, An article , which mentions 14187-32-7, molecular formula is C20H24O6. The compound – Dibenzo-18-crown-6 played an important role in people’s production and life.

The effect of crown ethers, tetraalkylammonium salts, and polyoxyethylene amphiphiles on pirarubicin incorporation in K562 resistant cells

The basic distinguishing feature of all cells expressing functional P-glycoprotein-multidrug resistance (P-gp-MDR) is a decrease in steady-state accumulation drug levels as compared to drug-sensitive controls. In an attempt to identify mechanism(s) by which MDP can be circumvented, we examined the cellular accumulation, in resistant cells, of 4′-O-tetrahydropyranyl-doxorubicin (pirarubicin) alone and in conjunction with various molecules belonging to three different classes: the crown ethers, the tetraalkylammonium salts, and the polyoxyethylene amphiphiles. The present study was performed using a spectrofluorometric method which enabled us to follow the uptake and release of fluorescent molecules by living cells while the cells were being incubated with the drug. Erythroleukemia K562 cell lines were used. Our data show that the compounds of these three completely different classes were able to increase the incorporation of pirarubicin provided they had a minimum degree of lipophilicity. Study of the growth inhibitory activity of these compounds revealed that cross-resistance to the tetraalkyl ammonium salt increased with the lipophilicity and was equal to 58 for tetraoctylammonium salt, the most lipophilic compound of this series. This demonstrates that neither the presence of a positive charge nor an aromatic moiety is required for MDR recognition.

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Chiral Catalysts,
Chiral catalysts – SlideShare

 

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 Dalko, Peter I. and a compound is mentioned, 21436-03-3, (1S,2S)-Cyclohexane-1,2-diamine, introducing its new discovery. 21436-03-3

A concise synthesis of (-)-mesembrine

(-)-Mesembrine 11 was synthesized in 7 steps, in 19.4% overall yield and with ee>95%. The key step of the sequence is a stereoselective alkylation reaction of dianion derived from C2 symmetric imidazolines allowing efficient formation of quaternary benzylic center. Chiral auxiliaries derived from (S,S)-1,2-diamino-1,2-diphenylethane 1a and (S,S)-1,2-diaminocyclohexane 1b were compared. This synthesis provided unambiguous correlation of the newly formed stereocenter.

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Chiral Catalysts,
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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 Review, the author is Di Stefano, Stefano and a compound is mentioned, 21436-03-3, (1S,2S)-Cyclohexane-1,2-diamine, introducing its new discovery. 21436-03-3

The canonical behavior of the entropic component of thermodynamic effective molarity. An attempt at unifying covalent and noncovalent cyclizations

This review article is concerned with the measurement, significance and applications of the concept of effective molarity (EM) in a large variety of cyclization reactions ranging from the formation of giant macromolecules in polymeric equilibrates to the self-assembly of cyclic supermolecules and supramolecular aggregates. Based on a dissection of EM into enthalpic and entropic components (EM = EMH ¡Á EMS), a careful examination of a large number of often overlooked quantitative studies of reversible cyclizations led to the definition of a set of “canonical” values of the entropic component EMS, expressed in graphical form by the plot of EMS? vs. n, where the asterisk denotes statistically corrected quantities, and n is the number of single bonds in the ring product. It is proposed that, to a useful approximation, all cyclization reactions comply with the “canonical” EMS? values, independent of the chemical nature of end groups and of the intervening chain, but solely dependent on the number n of rotatable bonds. The entropic component EMS? is approximately the same for cyclizations carried out under kinetic or thermodynamic control, and does not appear to be altered to a very significant extent by replacement of covalent with noncovalent bonds.

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Chiral Catalysts,
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Chemistry is an experimental science, and the best way to enjoy it and learn about it is performing experiments.Introducing a new discovery about 14098-44-3, Name is Benzo-15-crown-5, 14098-44-3.

Synthesis of concave receptors derived from diphenylglycoluril

Improved synthtic methods are described for the synthesis of concave receptor molecules.These receptors consist of a diphenylglycoluril unit, flanked by two aromatic moieties.The most versatile synthetic method consists of Lewis-acid-catalyzed reaction of a tetrakis(chloromethyl) derivative of diphenylglycoluril with the appropriate benzene or naphthalene derivative.

14098-44-3, A reaction mechanism is the microscopic path by which reactants are transformed into products. Each step is an elementary reaction. In my other articles, you can also check out more blogs about 14098-44-3

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Chiral Catalysts,
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Chemistry is the experimental science by definition. We want to make observations to prove hypothesis. For this purpose, we perform experiments in the lab. 1806-29-7, Name is 2,2-Biphenol1806-29-7, introducing its new discovery.

Synthesis, characterization, and crystal structures of n-alkyldiorganodithiophosphates RS2P(OC6H4)2

Treatment of KS2P(OC6H4)2 (1) with five n-alkyl halides afforded the stable n-alkyldithiophosphate compounds RS2P(OC6H4)2 (2-6). Single crystal X-ray analysis revealed that the PS2 fragment in 1 displays an isobidentate coordination pattern; compounds 2-4 display a monodentate binding pattern. The crystal packing of title compounds is stabilized by cation-pi, weak hydrogen bonding C-H-O, as well as aromatic non-bonded interactions.

Sometimes chemists are able to propose two or more mechanisms that are consistent with the available data.1806-29-7, If a proposed mechanism predicts the wrong experimental rate law, however, the mechanism must be incorrect.Welcome to check out more blogs about 1806-29-7, in my other articles.

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Chiral Catalysts,
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33100-27-5. Let¡¯s face it, organic chemistry can seem difficult to learn. Especially from a beginner¡¯s point of view. Like 33100-27-5, Name is 1,4,7,10,13-Pentaoxacyclopentadecane. In a document type is Article, introducing its new discovery.

Solution state chemistry of scandium(III): A study of scandium-crown ether complexes by 45Sc -NMR spectroscopy

Addition of SbCl5 (1 mol) to ScCl3 (THF)3 (1 mol) in acetonitrile followed by in situ addition of a crown ether (1 mol) provides the [ScCl2 (crown)][SbCl6] complexes where crown = 15-crown-5, dibenzo-24-crown-8, dibenzo-30-crown-10, 1-aza-15-crown-5 and 1-aza-18-crown-6. In the particular case of crown = 12-crown-4, both [ScCl2 (crown)]+ and [Sc (crown)2]3+ cations are produced. Characterisation of these various cationic Sc(III) species in terms of solution structures has been established by 45Sc-NMR spectroscopic studies.

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Chiral Catalysts,
Chiral catalysts – SlideShare

 

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 D’Aprano, Alessandro and a compound is mentioned, 33100-27-5, 1,4,7,10,13-Pentaoxacyclopentadecane, introducing its new discovery. 33100-27-5

Solvent Effects on Complexation of Crown Ethers with LiClO4, NaClO4 and KClO4 in Methanol and Acetonitrile

The thermodynamic formation constants Kf for complexation of Li+, Na+ and K+ with the crown ethers 12C4 and 15C5 have been determined in methanol and acetonitrile at 25 deg C using precision conductivity data.The method permits evaluation of very small Kf values (e.g., Kf = 6.98 mol-1-dm3 for LiClO4 + 12C4 in methanol) as well as fairly large values (e.g., Kf 0 2.73*104 mol-1-dm3 for NaClO4 + 15C5 in acetonitrile).The determination fo Kf values from condcutivity data takes into consideration the often neglected ion pair formation of both the uncomplexed and the complexed cations.Our results for Kf are generally consistent with previously reported values based on potentiometry, calorimetry, and polarography, but there are significant differences in several cases which we attribure to neglect of ion association both for uncomplexed or “free” cation Ka and the macrocyclic complexed cation Ka2.Our results are also consistent with the well known concept relating the magnitude of Kf to both the cavity diameter and ion-solvent interactions.Limiting molar conductivities Lambda2 for the complex salt (M-crown ether) (ClO4) in both solvents were generally found to be smaller or very close to the corresponding quantity Lambda1 for the binary MClO4-solvent system.However, in methanol, single ion limiting molar conductivities for the cationic complexes lambda2 exhibit anomalous behavior which is attributed to solvation differences between “free” cations and complexed cations. – Key words: Electrolytic, molar and ionic conductance; ion pair and complex ion formation; 12-crown-4; 15-crown-5; lithium, sodium and potassium perchlorate; acetonitrile; methanol; solvation effects; ion solvation; Gibbs energies of transfer.

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Chiral Catalysts,
Chiral catalysts – SlideShare

 

Let¡¯s face it, organic chemistry can seem difficult to learn. Especially from a beginner¡¯s point of view. Like 33100-27-5, Name is 1,4,7,10,13-Pentaoxacyclopentadecane. In a document type is Article, introducing its new discovery., 33100-27-5

Crown ether adducts of light alkali metal triphenylsilyls: Synthesis, structure and hydrosilylation catalysis

Alkali metal triphenylsilyls [Li(12-crown-4)SiPh3]¡¤(thf)0.5(2), [Na(15-crown-5)SiPh3]¡¤(thf)0.5(3) and [K(18-crown-6)SiPh3(thf)] (4) were synthesized using 1,1,1-trimethyl-2,2,2-triphenyldisilane (Ph3SiSiMe3) and isolated in high yields. Solid state structures were determined by single crystal X-ray diffraction. These alkali metal silyls catalyzed the regioselective hydrosilylation of 1,1-diphenylethylene to give the anti-Markovnikov product. The presence of crown ethers enhanced the reactivity of the metal silyls in hydrosilylation catalysis.

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Chiral Catalysts,
Chiral catalysts – SlideShare

 

23190-16-1, Children learn through play, and they learn more than adults might expect. Science experiments are a great way to spark their curiosity, get their minds active, and encourage them to do something that doesn¡¯t involve a screen. 23190-16-1, C6H5CH(NH2)CH(C6H5)OH. A document type is Article, introducing its new discovery.

1,1?-Bis(oxazolin-2-yl)ferrocenes: An investigation of their complexation behavior toward [Pd(eta3-allyl)Cl]2

The coordination behavior of several aryl- and alkyl-bis(oxazolinyl) ferrocenes, which were prepared in high yields from ferrocene-1,1?- dicarbonyl dichloride and enantiomerically pure or racemic amino alcohols via the corresponding bis(beta-hydroxyamide)s and dimesylates or ditosylates as intermediates, toward [Pd(eta3-allyl)Cl]2 was investigated by ESI mass spectrometry. The synthesized compounds were characterized by NMR spectroscopy and elemental analysis and the molecular structures of 1,1?-bis[(R)-4-isopropyloxazolin-2-yl]-ferrocene (6b), 1,1?-bis[(S)-4-isopropyloxazolin-2-yl]ferrocene (7b), 1,1?-bis[(S)- 4-sec-butyloxazolin-2-yl]ferrocene (11b), 1,1?-bis[(S)-4-tert- butyloxazolin-2-yl]ferrocene (12b), 1,1?-bis[(R)-4-phenyloxazolin-2-yl] ferrocene (13b), and 1,1?-bis[(S)-4-phenyloxazolin-2-yl]ferrocene (14b) were determined by single-crystal X-ray diffraction analysis. The coordination behavior studies by ESI-MS show a strong preference for monodentate complex formation. This result is supported by theoretical studies carried out at the B3LYP level of theory. It was found that the latter coordination type of 1,1?-bis[(S)-4-methyloxazolin-2-yl]ferrocene (1b) to an allylpalladium moiety is kinetically favored over the bidentate one.

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Chiral Catalysts,
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