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

Rhenium-oxo-bis(acetylene) anions. Structure, properties, and electronic structure. Comparison of Re-O bonding with that in other rhenium-oxo complexes

Reduction of Re(O)I(RC?CR)2 (2) or [Re(O)(RC?CR)2]2 by two electrons gives Re(O)(RC?CR)2Na (R = Me, 1a; Et, 1b; Ph, 1c). Compounds 1 are unusual oxo complexes, being highly nucleophilic and strongly reducing. X-ray structures of 1a-crypt and 1c-2MeCN reveal Re(O)(RC?CR)2 units, as isolated anions in the former but, in the latter, connected via Na-O-Na bridges into centrosymmetric dimers. The acetylene ligands lie in a plane that is roughly perpendicular to the Re – O bond, but the C?C vectors are splayed rather than parallel. The bond lengths and angles about rhenium are quite similar in the two structures, and quite close to the values found for 2 in which the splaying occurs to accommodate the iodide ligand. Reduction of 2a to 1a¡¤crypt causes a lengthening of the Re-O bond from 1.697(3) to 1.745(7) A and a drop in nuReO from 975 to 869 cm-1, both indicative of a decrease in the Re-O bond order. The Re-C distances and C?C stretching frequencies both decrease on reduction, indicating increased Re ? acetylene back-bonding in 1. Effective core potential calculations on Re(O)(HC?CH)2- (A), Re(O)H(HC?CH)2 (B), Re(O)Cl4- (C), and Re(O)F5 (D) have been performed with excellent agreement between the calculated structures and experimental crystallographic data (A and B are models for 1 and 2). The Re-O bonds in the high-oxidation-state oxo complexes C and D follow the classical Ballhausen-Gray picture, with little mixing between the Re-O orbitals and orbitals on other ligands. In contrast, the frontier molecular orbitals in A and B exhibit significant delocalization over the rhenium, the oxygen, and the acetylene ligands. In A, the HOMO is an orbital largely Re dx(2)-y(2) in character, accounting for the high nucleophilicity at rhenium in 1. The second-highest molecular orbital, only 0.8 eV below the HOMO, has significant Re-O ?-antibonding and Re-acetylene ?-back-bonding character, which provides a rationalization for the reduced Re-O bond order and strong back-bonding observed. There is also a ligand-based nonbonding orbital delocalized over the oxo and the acetylene ligands, as observed in other three-coordinate compounds involving acetylenes. Connections between the calculated electronic structure and the chemistry of 1 are emphasized.

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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 MDR 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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7181-87-5. Chemistry is the experimental science by definition. We want to make observations to prove hypothesis. For this purpose, we perform experiments in the lab. 7181-87-5, Name is 1,3-Dimethyl-1H-benzo[d]imidazol-3-ium iodide,introducing its new discovery.

Sterically Hindered N-Heterocyclic Salts Utilized as Antimicrobial Agents

By the adoption of annulated ring systems for their steric bulkiness, a new series of symmetric N-heterocyclic imidazolium and perimidium salts were synthesized. Also, corresponding asymmetric ferrocenyl N-functionalized series were prepared as salts. All the reported salts were fully characterized. The reported X-ray structure of 4,5-diphenyl-1,3-dimethyl-1H-imidazol-3-ium iodide (2a) shows that it crystallized in the orthorhombic space group P212121. Low to moderate antimicrobial activities were observed with both sets of salts against important clinical isolates of Staphylococcus aureus, Bacillus subtilis, and Enterococcus faecalis and Escherichia coli, Pseudomonas aeruginosa, and Salmonella enterica. The results were benchmarked against meropenem. Both 1,3-propyl-1H-phenanthro[9,10-d]imidazol-3-ium iodide (3b) and 1-ferrocenyl-3-propyl-1H-perimidin-3-ium iodide (9b) showed high antimicrobial activities against all tested Gram-positive bacterial strains, with minimum inhibitory concentration values ranging from 8 to 4?mug/mL (meropenem?=?0.5?0.125?mug/mL), while all the salts showed little or no activity against Gram-negative bacterial strains. In general, the asymmetric ferrocenyl-containing salts exhibited higher activities than the symmetric ones.

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86688-07-5, 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. 86688-07-5, Name is (S)-2,2′-diiodo-1,1′-binaphthalene, molecular formula is C20H12I2. In a Patent, authors is Sinopec Corporation£¬once mentioned of 86688-07-5

Catalytic hydrogenation process for preparing 2, 6 – di-tert-butyl -4 – methyl cyclohexanol (by machine translation)

The invention discloses a catalytic hydrogenation process for preparing 2, 6 – di-tert-butyl – 4 – methyl cyclohexanol, di-tert-butyl – 4 – methylphenol (BHT) with the supported catalyst is added to the high pressure in the reactor, the reaction after the end of the conversion of the BHT is 100%, 2, 6 – di-tert-butyl – 4 – methyl cyclohexanone selectivity is greater than 99.2%; the 2, 6 – di-tert-butyl – 4 – methyl cyclohexanone and compounding chemicals added to the high-pressure in the reactor, after the reaction 2, 6 – di-tert-butyl – 4 – methyl cyclohexanone conversion rate is 100%, 2, 6 – di-tert-butyl – 4 – methyl cyclohexanol selectivity is greater than 98.1%. The invention solves the technical problems of rigorous reaction conditions, the operation is complicated, environmental pollution, industrial application is difficult. (by machine translation)

Enzymes are biological catalysts that produce large increases in reaction rates and tend to be specific for certain reactants and products. I hope my blog about 86688-07-5 is helpful to your research., 86688-07-5

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An article , which mentions 250285-32-6, molecular formula is C27H37ClN2.250285-32-6, The compound – 1,3-Bis(2,6-diisopropylphenyl)imidazolium chloride played an important role in people’s production and life.

A Mechanistically and Operationally Simple Route to Metal?N-Heterocyclic Carbene (NHC) Complexes

We have been puzzled by the involvement of weak organic and inorganic bases in the synthesis of metal?N-heterocyclic carbene (NHC) complexes. Such bases are insufficiently strong to permit the presumed required deprotonation of the azolium salt (the carbene precursor) prior to metal binding. Experimental and computational studies provide support for a base-assisted concerted process that does not require free NHC formation. The synthetic protocol was found applicable to a number of transition-metal- and main-group-centered NHC compounds and could become the synthetic route of choice to form M?NHC bonds.

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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 21436-03-3, Name is (1S,2S)-Cyclohexane-1,2-diamine, 21436-03-3.

Circularly Polarized Luminescence in Nanoassemblies: Generation, Amplification, and Application

Currently, the development of circularly polarized luminescent (CPL) materials has drawn extensive attention due to the numerous potential applications in optical data storage, displays, backlights in 3D displays, and so on. While the fabrication of CPL-active materials generally requires chiral luminescent molecules, the introduction of the ?self-assembly? concept offers a new perspective in obtaining the CPL-active materials. Following this approach, various self-assembled materials, including organic-, inorganic-, and hybrid systems can be endowed with CPL properties. Benefiting from the advantages of self-assembly, not only chiral molecules, but also achiral species, as well as inorganic nanoparticles have potential to be self-assembled into chiral nanoassemblies showing CPL activity. In addition, the dissymmetry factor, an important parameter of CPL materials, can be enhanced through various pathways of self-assembly. Here, the present status and progress of self-assembled nanomaterials with CPL activity are reviewed. An overview of the key factors in regulating chiral emission materials at the supramolecular level will largely boost their application in multidisciplinary fields.

Balanced chemical reaction does not necessarily reveal either the individual elementary reactions by which a reaction occurs or its rate law.21436-03-3. In my other articles, you can also check out more blogs about 21436-03-3

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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 Article, the author is Cusack, Paul A. and a compound is mentioned, 33100-27-5, 1,4,7,10,13-Pentaoxacyclopentadecane, introducing its new discovery. 33100-27-5

Synthetic and Structural Studies of Tin(IV) Complexes of Crown Ethers

Fourteen inorganic tin(IV) and organotin(IV) complexes of crown ethers (L), of general formulae SnX4*L*2H2O, SnCl4*L*4H2O*nCHCl3 ( n = 0 or 1), (SnR2X2)n*L*2H2O ( n = 1 or 2), and (SnPh3X)2*L*2H2O, have been synthesised.The structure and bonding in these adducts are discussed in terms of their i.r. and 119Sn Moessbauer spectroscopic data.These suggest co-ordination to the tin either by one or more of the polyether O atoms, or by the water molecules of hydration (the crown ether acting as a second-sphere ligand).The latter structure is confirmed by a single-crystal X-ray determination of Sn(OH2)2Cl4*18-crown-6*2H2O*CHCl3.The crystals are monoclinic, space group P21/n, with a = 10.315(6), b = 13.630(8), c = 20.649(13) Angstroem, and beta = 94.68(5) deg.The structure was solved using multisolution direct methods and refined by least squares to R = 0.062 (R’ = 0.068) for 3142 observed diffractometer data.The water molecules within the octahedral Sn(OH2)2Cl4 units are found to be cis to each other and are involved in an extensive hydrogen-bonding scheme.The latter links together the 18-crown-6 molecules, unco-ordinated water molecules, and Sn(OH2)2Cl4 octahedra, to give hydrogen-bonded chains which run parallel to the b axis.

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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 1436-59-5, 1436-59-5, Name is cis-Cyclohexane-1,2-diamine, molecular formula is C6H14N2.

Products from a novel reaction of dihydropyrazines with vichinaldiamines

Dihydropyrazines such as 2,3-dihydro-5,6-dimethylpyrazine reacted with 1,2-diamines like ethylenediamine to form cis-tetraazadecalins (TADs) as crystalline products. The NMR spectra of the products in CDCl3 or CD3CN at -20 ~ -60C exhibited the signals due to TAD. However, the NMR spectra at room temperature showed that the TAD had dissociated into its parent materials. Seven TADs were obtained by only a mixing operation at a low temperature.

1436-59-5, Note that a catalyst decreases the activation energy for both the forward and the reverse reactions and hence accelerates both the forward and the reverse reactions. you can also check out more blogs about 1436-59-5

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Let¡¯s face it, organic chemistry can seem difficult to learn. Especially from a beginner¡¯s point of view. Like 21436-03-3, Name is (1S,2S)-Cyclohexane-1,2-diamine. In a document type is Article, introducing its new discovery., 21436-03-3

Syntheses and fully diastereospecific photochromic reactions of thiophenophan-1-enes with chiral bridges

Thiophenophan-1-enes with chiral polyether bridges were prepared and their diastereospecific photochromic reactions were studied. The coupling reaction of substituted dithienylethenes and various chiral synthons afforded thiophenophan-1-enes, namely, bridged dithienylethenes, as single enantiomers without optical resolution, thus indicating that these reactions occurred diastereoselectively. Upon UV irradiation, each optically active thiophenophan-1-ene isomerized to the corresponding enantiomer of the closed form and returned to the initial enantiomer of the open form upon visible irradiation. Because thiophenophan-1-enes never isomerized to other diastereomers even at a high temperature, they underwent diastereospecific photochromic reactions. Large changes were observed in the measurement of the optical rotations of the solutions of thiophenophan-1-enes at 588 nm according to their photochromic reactions. As there was no absorption at this wavelength for both isomers of each thiophenophan-1-enes, the nondestructive readout of the photochromic reaction could be carried out by using these chiral thiophenophan-1-enes. Photo finish: Photochromic reactions of thiophenophan-1-enes with chiral polyether bridges occurred completely in a diastereospecific manner, even at high temperatures. Circular dichroism spectra and optical rotations changed photoreversibly according to the photochromic reactions between the enantiomers of the photoisomers (see figure). Copyright

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1436-59-5, In an article, published in an article,authors is Bennov, Rachel R., once mentioned the application of 1436-59-5, Name is cis-Cyclohexane-1,2-diamine,molecular formula is C6H14N2, is a conventional compound. this article was the specific content is as follows.

Molybdenum complexes of chiral C2-symmetric picchxn-type ligands: Synthesis, characterization, and structural studies

A series of molybdenum complexes based on chiral C2-symmetric picchxn-type ligands (N4 ligands, defined as trans-N,N?-bis(heterocycl-2-ylmethyl)-1,2-diaminocyclohexanes) has been synthesized and characterized. Reported and novel picchxn-type ligands form (kappa3-N4)Mo(CO)3, [(kappa4-N4)Mo(NO)(CO)]PF6, and [(kappa4-N4)Mo(NO)X]PF6 (X = Br, I) compounds. Multiple tridentate (kappa3) and tetradentate (kappa4) ligand configurations were observed, and the favored kappa4 configuration was found to vary with N4 heterocycle identity. Heterocycle variation allowed for directed modification of the molybdenum electronic characteristics, but none of the studied {(kappa4-N4)Mo(NO)}+ fragments was found to be a suitable pi-base for dearomatization chemistry. The crystal structures of eight molybdenum complexes with picchxn-type ligands were determined.

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