Search results for "Methanol"
showing 10 items of 1026 documents
Identification and quantification of carotenoids including geometrical isomers in fruit and vegetable juices by liquid chromatography with ultraviole…
2004
A method was established for the identification and quantification of carotenoids including geometrical isomers in fruit and vegetable juices by liquid chromatography with an ultraviolet−diode array detector, using a C18 Vydac 201TP54 column. The mobile phase used was the ternary methanol mixture (0.1 M ammonium acetate), tert-butyl methyl ether and water, in a concentration gradient, and a temperature gradient was applied. Retinol palmitate was added as an internal standard. An extraction process (ethanol/hexane, 4:3, v/v) was performed, followed by saponification with diethyl ether/methanolic KOH (0.1%, w/v, BHT) (1:1, v/v) for 0.5 h at room temperature. Seventeen different (cis and trans…
"Partial oxidation of methane and methanol on FeOx-, MoOx- and FeMoOx -SiO2 catalysts prepared by sol-gel method: a comparative study"
2020
[EN] FeOx-, MoOx and FeMoOx-SiO2 materials prepared by a sol-gel procedure have been evaluated as catalysts for the partial oxidation of methane and methanol. The effect of decreasing the pH of the synthesis gel on the chemical nature of FeOx and MoOx species has been investigated. Characterization results show that low pH improves the dispersion of metal oxide species present in SiO2 matrix. For FeOx/SiO2 materials, the presence of dispersed FeOx species (rather than bulk Fe2O3) improves the selectivity to formaldehyde in the partial oxidation of methane and methanol. For FeMoOx/SiOx catalysts, dispersed species favor the selectivity to formaldehyde only for methane oxidation. In contrast,…
HPLC: a tool for the analysis of T-2 toxin and HT-2 toxin in cereals.
1984
An analytical procedure for the determination of trichothecenes in various cereals is described. HPLC was performed with a reversed-phase (C18) column eluted with methanol:water (60:40, v/v). Compounds were detected with a refractive index detector. The elution patterns of free and contaminated samples were compared. The recovery of added T-2 toxin (2 and 5 micrograms/g) in rye and wheat was approximately 80%. The application of this method allows for combined use with other sensitive methods such as mass spectrometry and gas chromatography. The described method is operationally simple, relatively inexpensive, and requires no derivatization.
Complexes of organometallic compounds XXVIII. The solution chemistry of bis(acetylacetone)ethylenediimine adducts of organotin(IV) halides
1971
Abstract The nature of methanol solutions of a series of bis(acetylacetone)ethylenediimine adducts of organotin(IV) halides has been studied by electronic and PMR spectroscopy and by osmometry and conductivity. Effectively complete dissociation to the free ligand and solvated organotin(IV) halide moieties is inferred.
Synthesis and characterization of the first diorganotin(IV) complexes containing mixed arylazobenzoic acids and having skew trapezoidal bipyramidal g…
2005
Abstract Three diorganotin(IV) complexes of the type, [R 2 Sn(L a H)(L b H)] (R = n Bu or Me and, L a H and L b H are two different 5-[( E )-2-(aryl)-1-diazenyl]-2-hydroxybenzoate residues; a: aryl = 4′-Cl-(held constant) and b: aryl = 4′-Me or 4′-Br) have been prepared either by reacting n Bu 2 SnO, L a HH′ and L b HH′ (1:1:1) in anhydrous toluene or by reacting Me 2 SnCl 2 , L a HNa and L b HNa (1:1:1) in anhydrous methanol. The products were characterized by microanalysis, IR, NMR ( 1 H, 13 C, 119 Sn) and 119m Sn Mossbauer spectroscopy. A full characterization of the structures of the complexes [ n Bu 2 Sn(L a H)(L b H)] ( 1 and 2 ) and [Me 2 Sn(L a H)(L b H)] ( 3 ) in the solid state w…
Aryl carbinols as nerve agent probes. Influence of the conjugation on the sensing properties
2012
Two new aryl carbinols (1 and 3) have been synthesised and characterised and their ability as OFF-ON probes for the chromogenic detection of the nerve agent simulant in acetonitrile has been tested. In addition compound 2 has been also studied. The carbinols suffered a phosphorylation reaction followed by an elimination process giving rise to the corresponding carbocations. This transformation of the carbinol into the carbocation is responsible for a significant color change. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012.
Dimeric resorcinarene salt capsules with very tight encapsulation of anions and guest molecules
2015
Crystallization of N-cyclohexyl ammonium resorcinarene triflate from methanol results in a dimeric capsule capable of trapping two triflate anions and two methanol molecules within a 341 A3 cavity while with 1,4-dioxane as a guest it forms a new larger dimeric capsule with volume of 679 A3 encapsulating four 1,4-dioxane and four water molecules, resulting in packing coefficients of 0.75 and 0.67, respectively.
The static dielectric constant of solutions of water inn-alcohols at 15, 25, 35, and 45°C
1979
Dielectric constants (measured at 1 MHz) are reported for solutions of water (concentration range 0 to 0.2 mole fraction) in 1-propanol at 25°C, and in 1-butanol, 1-pentanol, and 1-hexanol at 15, 25, 35, and 45°C. These results, together with literature values for solutions of water in methanol, ethanol, 1-heptanol, and 1-octanol, show that water interacts with alcohols in at least two ways: (1) it can participate in the formation of dynamic hydrogen-bonded chains, thereby raising the polarizability; (2) it can form relatively stable structures such as H2O(ROH)4 which have zero net dipole moment and consequently diminish volume polarizability. For C n H 2n+1 OH alcohols,n≥4, most of the ini…
Dalton communication. Crystal structure and oxo-transfer properties of [NH4]2[WVIO2{O2CC(S)Ph2}2]
1994
The complex [NH4]2[WVIO2{O2CC(S)Ph2}2] is the first example of a non-dithiolene tungsten complex capable of oxidising benzoin to benzil in methanol; the reduced complex product formed, presumably a monomeric WVIO species, was reoxidised with nitrate ions, regenerating the starting WVIO2 complex which then acts as a true homogeneous catalyst.
Determination of the composition of isomeric mixtures of allylstannanes by means of 119Sn and 13C NMR measurements
1993
Abstract Allylstannanes of the type Bun3Sn(C3H3) ((C3H3 = allenyl and propargyl) Me3Sn(C4H7), Bun3Sn(C4H7), Ph3Sn(C4H7), Me3Sn(C4H7)2 and Bun3Sn(C4H7)2 [C4H7 = (E)-but-2-enyl, (Z-but-2-enyl, and but-1-en-3-yl] were prepared via Grignard reactions as isomeric mixtures whose compositions can be directly determined by 119Sn and 13C NMR spectrometry. The 119Sn and 13C δ-values of all possible isomers together with the isomeric compositions of freshly prepared compounds and after isomerization in dry methanol under reflux are reported. The course of isomerization of some compounds in anhydrous methanol at room temperature or in the presence of Bu3SnCl was followed by 119Sn NMR spectrometry.