Cinchona based squaramide catalysed enantioselective Michael addition of α-nitrophosphonates to aryl acrylates: enantioselective synthesis of quaternary α-aminophosphonates

Several cinchona based squaramide catalysts were applied to the asymmetric Michael addition of α-nitroethylphosphonates to acrylic acid aryl esters, resulting in high yields and enantioselectivities. The absolute configuration of one of the quaternary α-nitrophosphonate adducts was deduced from its experimental and calculated CD spectra. The adducts were reduced to their cyclic aminophosphonates by catalytic hydrogenation.     

Scope and Limitation for the Reaction of α,β-Unsaturated Carbonyl Compounds with Phosphorus Nucleophiles by Determination of the Half-Wave Potential

Abstract

During the formation of oxaphospholenes the phosphorus in the reagent gets oxidized and the double bond in the enones gets reduced.     

P-Mannich Reaction on Wool Fibre for Activation in Dyeing

Abstract

Chemical modification of wool by means of dimethyl phoaphitc and D-glucose results in an increase in dye pickup, while colour and light fastness properties did not decrease, in fact some features bccpme more favourable. Our invesigations showed that increase in fibre diameter occurred. which could rise the rate of dye penetration. Amino acid analysis of the treated wool sample h w e d a decrease in lysine and arginim content, which allows of supposing covalent bond formation betweecl dimcthyl phosphite, D-glucose and the amino and guanidino groups of wool.     

Dissipation of the herbicide active ingredient glyphosate in natural water samples in the presence of biofilms

Dissipation of the herbicide active ingredient glyphosate was investigated in natural waters. To assess combined effects, glyphosate was applied in its pure form (glyphosate isopropylammonium salt) and in preparation Roundup Classic® formulated with polyethoxylated tallowamines (POEA). Standing and running surface water samples originated from Lake Balaton and River Danube between early May and mid-June of 2015. The kinetics of dissipation of glyphosate, measured by high-performance liquid chromatography combined with UV-VIS absorbance detection or tandem mass spectrometry, was investigated under laboratory conditions in aquaria with or without the presence of biofilms. The quantity and the biofilm structure of algal biomass were determined by in vivo fluorimetry and scanning electron microscopy. The presence of POEA affected the dissipation of glyphosate, and dissipation profiles differed in the investigated natural waters. Significantly higher initial concentrations of glyphosate were measured in River Danube for treatment with formulated glyphosate (101.4 ± 6.2 µg L^?1), than with glyphosate alone (79.9 ± 6.6 µg L^?1), and dissipation to a residual level (57.6 ± 1.4 µg L^?1) consequently took longer (approximately by 1 day). Degradation of glyphosate from the initial level (91.24 ± 5.9 µg L^?1) in Lake Balaton was not detected. Phytotoxic effects of glyphosate, particularly if enhanced by a formulant on algal biomass, were observed. Thus, 5–18% and 11–33% of algal biomass reduction was determined in River Danube upon treatments with glyphosate and Roundup Classic®, respectively. Corresponding biomass decreases in Lake Balaton were 1.3–13% and 9–14%, respectively, accompanied by an overall decay in the algal biofilms. In River Danube, treatments resulted in the occurrence of 1.4–5.8% of green algae in the algal biomass in 28 days, while green algae were not detected in the untreated control. The results indicate that glyphosate is capable of modifying the structure of the algal community and to induce increased secretion of extracellular polymeric substances matrix in the biofilms assessed.     

Beziehungen zwischen den Verdampfungsw?rmen bin?rer Gemische

Ohne Zusammenfassung     

Direct determination of oxygen in organic materials-I A study of the carbon reduction method

The results of an investigation into the nature of the carbon reduction process in the Unterzaucher method for the microdetermination of oxygen are reported and discussed. The reaction between carbon dioxide and carbon is discussed, and its relation to the specific surface area, which contrary to belief has been found not to contribute to the efficiency of the reaction. It is shown that carbon-oxygen complexes give rise to errors in the results, and that an intermediate, SiO(OH), formed on the inner surface of the silica pyrolysis tube might be a precursor to the formation of carbon monoxide as a source of blank error and of the apparent oxygen content of pure hydrocarbons.     

Application of curve fitting in thin-layer chromatography-flame ionization detection analysis of the carbohydrate fraction in marine mucilage and marine snow samples from Italian seas

This paper presents a thin-layer chromatographic-flame ionization detection (TLC-FID) procedure to characterize the carbohydrate fraction of marine mucilage and marine snow samples from the Italian Seas. The identification of the different carbohydrate subfractions is supported by the application of a deconvolution procedure based on a new mathematical function for describing chromatographic peaks and enhancing their resolution. The joint-approach TLC-FID analysis and deconvolution procedure allows for the characterization of the carbohydrate fraction of the marine samples in a single step without using the different derivatization procedures requested by the most common gas chromatography and high-performance liquid chromatographic methods for carbohydrate analysis. In fact, the results obtained by the TLC-FID procedure show that different neutral, uronic acid, and aminosugar subfractions can be present simultaneously in these samples. Moreover, the results support some hypotheses about the causes of the presence of mucilages in the Italian Seas.     

Quantum ratchet effect for vortices

We have measured a quantum ratchet effect for vortices moving in a quasi-one-dimensional Josephson junction array. In this solid-state device the shape of the vortex potential energy, and consequently the band structure, can be accurately designed. This band structure determines the presence or absence of the quantum ratchet effect. In particular, asymmetric structures possessing only one band below the barrier do not exhibit current rectification at low temperatures and bias currents. The quantum nature of transport is also revealed in a universal/nonuniversal power-law dependence of the measured voltage-current characteristics for samples without/with rectification.     

Three-dimensional elastic wave scattering by a layer containing vertical periodic fractures

Elastic wave scattering off a layer containing a single set of vertical periodic fractures is examined using a numerical technique based on the work of Hennion et al. [J. Acoust. Soc. Am. 87, 1861-1870 (1990)]. This technique combines the finite element method and plane wave method to simulate three-dimensional scattering off a two-dimensional fractured layer structure. Each fracture is modeled explicitly, so that the model can simulate both discrete arrivals of scattered waves from individual fractures and multiply scattered waves between the fractures. Using this technique, we examine changes in scattering characteristics of plane elastic waves as a function of wave frequency, angle of incidence, and fracture properties such as fracture stiffness, height, and regular and irregular spacing.