Search results for "pane"
showing 10 items of 1074 documents
Part II. Chiral dirhodium (II) catalysts with ortho-metalated arylphosphane ligands in the enantioselective intramolecular cyclopropanation of a race…
2006
Abstract In this report, chiral dirhodium (II) with ortho -metalated phosphane ligands, namely ( M )-Rh 2 (O 2 CR) 2 (PC) 2 [PC = ortho -metalated aryl phosphane, O 2 CR = carboxylate bridging ligands) ( 1a–g ), have been used for the intramolecular cyclopropanation of racemic1-diazo-6-methyl-3-(2-propenyl)-5-hepten-2-one ( 2 ), containing both a tri- and monosubstituted carbon–carbon double bond, in pentane. The highest level of regiocontrol has been obtained with chiral catalyst Rh 2 (O 2 CCH 3 ) 2 [( p -MeC 6 H 3 )P( p -MeC 6 H 4 ) 2 ] 2 ( M )- 1c , affording favorably trisubstituted cyclopropane 3 versus monosubstituted cyclopropane 4 in 74:26 ratio. An exceptional diastereoselectivity…
SiO2-supported vanadium magnesium mixed oxides as selective catalysts for the oxydehydrogenation of short chain alkanes
2001
Abstract Unsupported and SiO 2 -supported VMgO mixed oxides catalysts have been prepared, characterized and tested in the oxidation of propane, n -butane and propylene. Mg-vanadates are observed by XRD, IR and Raman spectroscopy in both pure and supported VMgO catalysts, although the effective Mg/V ratio, in the VMgO phases formed, depends on the silica content. Since SiO 2 reacts partially with MgO during the calcination step, forming Mg 2 SiO 4 , the effective Mg/V ratio depends on the silica content. In this sense, pyro -Mg 2 V 2 O 7 is mainly formed on supported catalysts with Mg/V atomic ratios lower than 4, while ortho -Mg 3 V 2 O 8 is observed on supported catalysts with Mg/V atomic …
Inhibitoren der Korrosion 10 (1). Nachweis der Sekundärinhibition durch Allyl-triphenyl-phosphonium- bzw. arsoniumbromid und N-Allyl-chinaldiniumbrom…
1971
Triphenyl-allyl-phosphonium- (1) und -arsoniumsalze (2) sowie Allyl-chinaldinium-bromid (4) sind Korrosionsinhibitoren mittlerer Wirksamkeit. Sie werden von Carbonyleisenpulver im sauren Medium zu Triphenylphosphin bzw. Triphenylarsin bzw. Chinaldin reduziert. Triphenylphosphin und Triphenylarsin, die sich als Schicht auf dem Carbonyleisenpulver befinden, konnen nach Extraktion dunnschichtchromatographisch identifiziert werden. Die Allylgruppe wird aus den Verbindungen 1, 2 und 4 durch Eisen als Propen, Propan und wahrscheinlich als Cyclopropan abgelost. Die gaschromatographisch bestimmten Mengen an Kohlenwasserstoffen stehen in guter Ubereinstim-mung mit den gravimetrisch ermittelten Werte…
Studies on the diurnal courses of the contents of abscisic acid, 1-aminocyclopropane carboxylic acid and its malonyl conjugate in needles of damaged …
1993
Summary The diurnal courses of the contents of 1-aminocyclopropane carboxylic acid (ACC), its malonyl conjugate (MACC) and abscisic acid (ABA) in the two-year-old needles of damaged and undamaged spruce trees (Picea abies L.) were investigated. The contents of ACC and MACC were significantly higher in the needles of the damaged trees as compared with the undamaged ones. In the needles of the damaged spruce trees, the ACC and MACC contents, and ABA contents as well, fluctuated to a greater extent than those in the undamaged spruce trees during the day. The relationships between ACC-ABA and MACC-ACC contents as well are also discussed.
Propane-1,3-diammonium molybdate
2019
The reaction between equimolar amounts of propane-1,3-diamine and molybdenum trioxide in water led to the formation of single crystals of the title salt, (C3H12N2)[MoO4]. The asymmetric unit is comprised of one propane-1,3-diammonium cation and one molybdate anion. The latter is isolated in the structure and has a slightly distorted tetrahedral configuration. An extensive network of N—H...O hydrogen bonds connects anions and cations, giving rise to a compact three-dimensional packing.
Heterogeneous salt distribution in hot snacks enhances saltiness without loss of acceptability
2013
clef UT: 000318667000026; International audience; Abstract Health issues have led worldwide organisations to encourage the food industry to reduce salt in processed foods. Therefore, different strategies for salt reduction have been investigated. Here, the effect of heterogeneous salt distribution on saltiness perception intensity was assessed to compensate for salt reduction in snack foods. Two models of hot-served baked foods were developed. One model is made of two layers that vary in composition (cream-based and cereal-based layers) and salt (NaCl) concentration; the other one is made of four cream-based layers that vary in salt concentrations. Consumer panels rated the saltiness intens…
Separation of Enantiomers in a Monolayer of Racemic 3-Hexadecyl-oxy-propane-1,2-diol
1993
Monolayers of a racemic mixture and of the pure S enantiomer of 3-hexadecyloxy-propane-1,2-diol have been characterized by thermodynamic measurements at the air/water interface as well as by fluorescence microscopy. The critical temperatire T c , the limiting molecular area at high pressure and the pressure π c corresponding to the observed main phase transition, derived from the isotherms, slightly depend on chiral purity
Toward an understanding of the selectivity in domino reactions. A DFT study of the reaction between acetylenedicarboxylic acid and 1, 3-Bis(2-furyl)p…
2000
The mechanism of the domino reaction between acetylenedicarboxylic acid and 1,3-bis(2-furyl)propane has been theoretically studied in the framework of density functional theory. This domino process comprises two consecutive cycloaddition reactions: the first one is initialized by the nucleophilic attack of the C5 position of the furan ring to a conjugate position of acetylenedicarboxylic acid to give a zwitterionic intermediate, which by a subsequent ring-closure process affords an oxanorbornadiene intermediate. The second reaction is an intramolecular concerted cycloaddition of this intermediate to give the final dioxapentacyclic adduct. For the second cycloaddition, which corresponds to t…
Synthesis of 1,3-Oxazolidines and 1,3-Dioxolanes by Reaction of (2R,3R)-3-Methylamino-3-phenyl-1,2-propanediol with Electrophiles.
2004
Abstract The chemoselective reaction of (2R, 3R)-3-methylamino-3-phenyl-1,2-propanediol 1 with dimethoxypropane and dichloromethane under different conditions are reported as useful preparative procedures, for the synthesis 1,3-oxazolidines and 1,3-dioxolanes.