Synthesis of highly substituted quinolines via heterocyclization of fluorinated acetylenephosphonates with ortho-aminoaryl ketones

A synthetic route to a series of 4-alkyl- or arylquinolines, bearing in 2- and 3-position fluorinated and phosphonate functions at the same time, is reported for the first time. These compounds are synthesized via regioselective heterocyclization of XCF₂-alkynylphosphonates (X=F, Cl, Br, H, CF₃) with ortho-aminoaryl ketones (R=CH₃, CF₃, Ph) in the presence of K₂CO₃ or Li₂CO₃/TMEDA as mediators. 2-Fluoro- and 3-phosphorus-containing 4-Me, 4-CF₃ or 4-Ph quinolines are obtained in good to excellent yields. The influence of substituents in the aromatic ketone, the XCF₂-group in the alkyne as well as mediators and the reaction medium on the reactivity and specificity of the reaction is also investigated.     

Structural,Magnetic and Catalytic Properties of a New Vacancy Ordered Perovskite Type Barium Cobaltate BaCoO2.67

A new vacancy ordered, anion deficient perovskite modification with composition of BaCoO_2.67 (Ba₃Co₃O₈□₁) has been prepared via a two-step heating process. Combined Rietveld analysis of neutron and X-ray powder diffraction data shows a novel ordering of oxygen vacancies not known before for barium cobaltates. A combination of neutron powder diffraction, magnetic measurements, and density functional theory (DFT) studies confirms G-type antiferromagnetic ordering. From impedance measurements, the electronic conductivity of the order of 10⁻⁴ S cm⁻¹ is determined. Remarkably, the bifunctional catalytic activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is found to be comparable to that of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3–y, confirming that charge-ordered anion deficient non-cubic perovskites can be highly efficient catalysts.     

Formation of poly(ethylene phosphates) in polycondensation of H3PO4 with ethylene glycol. Kinetic and mechanistic study

Conditions of synthesis of poly(ethylene phosphates) in reaction of H₃PO₄ with HOCH₂CH₂OH (EG), the actual path of polycondensation, and structure of the obtained polymers (mostly oligomers) and kinetics of reaction are described. Preliminary kinetic information, based on the comparison of the MALDI‐TOF‐ms and ³¹P{¹H} NMR spectra as a function of conversion is given as well. Because of the dealkylation process fragments derived from di‐ and triethylene glycols are also present in the repeating units. Structures of the end groups (? CH₂CH₂OH or ? OP(O)(OH)₂) depend on the starting ratio of [EG]₀/[H₃PO₄]₀, although even at the excess of EG the acidic end groups prevail because of the dealkylation process. In MALDI‐TOF‐ms products with P_n equal up to 21 have been observed. The average polymerization degrees (P_n) are lower and have been calculated from the proportion of the end groups. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 830–843, 2008     

Differentiation of fluoronitroaniline isomers by negative-ion electrospray mass spectrometry

Tetra- and trifluoronitroanilines were studied by electrospray ionization mass spectrometry. These compounds gave signals only in the negative-ion mode. It was found that the so-called 'in-source' fragmentation, induced by cone voltage increase, enables differentiation of isomers. For para-nitroanilines, in contrast to ortho derivatives, the loss of NO(2) was the most favored process and other fragment ions were characterized by low abundances. For trifluoro conjugates the substitution pattern of aromatic ring by fluorine atoms also affected their fragmentation patterns. For example, in 2,3,6-trifluoro-4-nitroaniline, in contrast to 2,3,5-trifluoro-4-nitroaniline, efficient NO loss, followed by HF loss, took place.     

Catalytic oxidation with air of cyclohexanone to dicarboxylic acids on synthetic carbons. Effect of supported metals and solvents

The oxidation with air of cyclohexanone was conducted in the presence of synthetic carbons catalysts. The effect of carbon activation treatment (CO2 or air burnoff), phosphorus additive, platinum loading, and nature of the solvent (water or water/acetic acid mixture) were studied. Cyclohexanone oxidation at 140 degrees C yielded a mixture of C6, C5, and C4 dicarboxylic acids. Air activated carbons, including those containing phosphorus or those supporting platinum, resulted in a higher yield of adipic acid. The activity and selectivity was associated with the oxygenated functional groups, essentially carbonyl/quinone groups, created during air activation of the carbon. The incorporation of phosphorus into the carbon increased slightly the selectivity to 34.3%, probably because this additive increased the density of oxygenated functional groups. The deposition of platinum by impregnation and liquid-phase reduction with formaldehyde increased the reaction rate and improved the selectivity to adipic acid, where the highest figure was 38.8%. It was suggested that platinum contributed to molecular oxygen activation. In contrast platinum deposition by cationic exchange followed by reduction under H2 resulted often in a detrimental effect probably because the density of the oxygenated groups on carbon is decreased upon H2 reduction in the presence of platinum. When the oxidation of cyclohexanone was carried out in mixtures of water/acetic acid, the selectivity given by the different samples were quite close and generally smaller than those obtained in water which indicates that acetic acid interacts with the oxygenated surface functional groups responsible for the activity and selectivity. Oxidation experiments with methyl-labeled 4-methylcyclohexanone indicated that glutaric acid was produced by oxidative decarbonylation of both the C1 and C2 carbon atoms of the molecule.     

A Raman laser system for multi-wavelength satellite laser ranging

~~A Raman laser system for multi-wavelength satellite laser ranging@K.Hamal$Czech Technical University in Prague,Czech @I.Prochazka$Czech Technical University in Prague,Czech @J.Blazej$Czech Technical University in Prague,Czech1. Yang Fumin, Chen Wanzhen, Zhang Zhongping et al., Satellite laser ranging experiment with sub-centimeter single-shot ranging precision at Shanghai Observatory, Science in China, Ser. A, 2002, 32(10): 935-939. 2. Degnan, J. J., Millimeter accurac…     

Separation of surfactant functionalized single-walled carbon nanotubes via free solution electrophoresis method

This work presents the application of the free solution electrophoresis method (FSE) in the metallic / semiconductive (M/S) separation process of the surfactant functionalized single-walled carbon nanotubes (SWCNTs). The SWCNTs synthesized via laser ablation were purified through high vacuum annealing and subsequent refluxing processes in aqua regia solution. The purified and annealed material was divided into six batches. First three batches were dispersed in anionic surfactants: sodium dodecyl sulfate (SDS), sodium cholate (SC) and sodium deoxycholate (DOC). The next three batches were dispersed in cationic surfactants: cetrimonium bromide (CTAB), benzalkonium chloride (BKC) and cetylpyridinium chloride (CPC). All the prepared SWCNTs samples were subjected to FSE separation process. The fractionated samples were recovered from control and electrode areas and annealed in order to remove the adsorbed surfactants on carbon nanotubes (CNTs) surface. The changes of the van Hove singularities (vHS) present in SWCNTs spectra were investigated via UV-Vis-NIR optical absorption spectroscopy (OAS).     

Synthesis of 2-perfluoroalkyl 4H- and 2H-chromenylphosphonates mediated by amines and phosphines

An efficient synthesis of 2-perfluoroalkyl 4H-chromen-3-ylphosphonates 4a-i (R(F) = CF(3)) and 5a-i (R(F) = C(2)F(5)) has been accomplished via regioselective cycloaddition of 2-hydroxybenzaldehydes to diethyl 3,3,3-trifluoropropyn-1-yl- and diethyl 3,3,4,4,4-pentafluorobutyn-1-ylphosphonate, using trialkyl amines or phosphines as mediators. 2H-Chromen-3-ylphosphonates 6a-i were regioselectively obtained in the presence of triphenylphosphine. A convenient method for the isomerization of 4H-chromen-3-ylphosphonates into 2H-chromen-3-ylphosphonates 6a-i (R(F) = CF(3)) and 7a-i (R(F) = C(2)F(5)) was established.     

High-performance genetic analysis using microfabricated capillary array electrophoresis microplates.

This review focuses on some recent advances in realizing microfabricated capillary array electrophoresis (microCAE). In particular, the development of a novel rotary scanning confocal fluorescence detector has facilitated the high-speed collection of sequencing and genotyping data from radially formatted microCAE devices. The concomitant development of a convenient energy-transfer cassette labeling chemistry allows sensitive multicolor labeling of any DNA genotyping or sequencing analyte. High-performance hereditary haemochromatosis and short tandem repeat genotyping assays are demonstrated on these devices along with rapid mitochondrial DNA sequence polymorphism analysis. Progress in supporting technology such as robotic fluid dispensing and batched data analysis is also presented. The ultimate goal is to develop a parallel analysis platform capable of integrated sample preparation and automated electrophoretic analysis with a throughput 10-100 times that of current technology.