Search results for "Formate"
showing 10 items of 111 documents
Conformation resolved induced infrared activity: trans- and cis-formic acid isolated in solid molecular hydrogen
2011
We report combined experimental and theoretical studies of infrared absorptions induced in solid molecular hydrogen by different conformers of formic acid (HCOOH, FA). FTIR spectra recorded in the H(2) fundamental region (4120-4160 cm(-1)) reveal a number of relatively strong trans-FA induced Q-branch absorptions that are assigned by studying both FA-doped parahydrogen (pH(2)) and normal hydrogen (nH(2)) samples. The induced H(2) absorptions are also studied for HCOOD doped nH(2) crystals for both the trans and cis conformers that show resolvable differences. Samples containing90% of the higher energy cis-HCOOD conformer are produced by in situ IR pumping of the OD stretching overtone of tr…
Capillary electrophoresis–inductively coupled plasma-mass spectrometry hyphenation for the determination at the nanogram scale of metal affinities an…
2012
Abstract A screening strategy based on hyphenated capillary electrophoresis and inductively coupled plasma mass spectrometry (CE–ICP-MS) was developed to classify phosphorylated ligands according to their europium(III) binding affinity in a hydro-organic medium (sodium formate, pH 3.7, H2O/MeOH 90:10, v/v). Taking advantage of the high sensibility of ICP-MS for detecting phosphorus, this method enabled to assess the affinity of a variety of phosphorylated compounds, including phosphine oxides, thiophosphines, phosphonates, and phosphinates, in less than 1 h and using less than 5 ng of substance. By varying the total europium concentration, complexation constants could be determined accordin…
Synthesis of β- and γ-carbolines via ruthenium and rhodium catalysed [2+2+2] cycloadditions of yne-ynamides with methylcyanoformate
2011
A flexible approach towards substituted β- and γ-carbolines based on transition metal catalysed [2+2+2] cycloaddition reactions between functionalised yne-ynamides and methylcyanoformate is described. The versatility of this new reaction sequence is demonstrated by its application in the total synthesis of the marine natural product eudistomin U.
Ammonium formate-Pd/C as a new reducing system for 1,2,4-oxadiazoles. Synthesis of guanidine derivatives and reductive rearrangement to quinazolin-4-…
2021
1,2,4-Oxadiazole is a heterocycle with wide reactivity and many useful applications. The reactive O-N bond is usually reduced using molecular hydrogen to obtain amidine derivatives. NH4CO2H-Pd/C is here demonstrated as a new system for the O-N reduction, allowing us to obtain differently substituted acylamidine, acylguanidine and diacylguanidine derivatives. The proposed system is also effective for the achievement of a reductive rearrangement of 5-(2′-aminophenyl)-1,2,4-oxadiazoles into 1-alkylquinazolin-4(1H)-ones. The alkaloid glycosine was also obtained with this method. The obtained compounds were preliminarily tested for their biological activity in terms of their cytotoxicity, induce…
Formateur académique. Un nouveau métier
2019
International audience; Dans Formateur académique : un nouveau métier ?, Denis Loizon livre les compétences indispensables au formateur du second degré, montre comment les développer et donne une représentation réaliste de ce métier.
Le pilotage par l'Etat de la formation des enseignants du début des années 1990 à nos jours et les incidences sur le métier de formateur
2013
L'objet de cet article est de questionner, dans une perspective historique, la manière dont l'État a organisé et a fait évoluer la formation des enseignants du début des années 1990 à nos jours. Il s'attache à mettre en lumière les ambitions qui ont présidé aux réformes et tente de montrer la manière dont le métier de formateur d'enseignants s'est constitué et a évolué. Le formateur avait acquis un certain nombre de savoir-faire, et plus généralement une certaine culture, qui pourraient conduire à affirmer qu'un processus de professionnalisation était en cours, et ce jusqu'au milieu des années 2000. Ce processus tendait à rassembler sous une même dénomination, celle de " formateur ", des in…
Former ou accompagner : une tension difficile à vivre pour les formateurs en IFSI
2019
International audience
Être militaire aujourd'hui : combattant, formateur, éducateur.
2017
International audience
Boron Nitride‐supported Sub‐nanometer Pd6 Clusters for Formic Acid Decomposition: A DFT Study
2017
A periodic, self-consistent planewave DFT study was carried out to explore the potential use of Pd6 clusters supported on a boron nitride sheet as a catalyst for the selective decomposi- tion of formic acid (HCOOH) to CO2 and H2. The competition between formate (HCOO) and carboxyl (COOH) paths on cata- lytic sites, with different proximities to the support, was stud- ied. Based on energetics alone, the reaction may mainly follow the HCOO route. Slightly lower activation energies were found at the lateral sites of the cluster as compared to top face sites. This is particularly true for the bidentate to monodentate HCOO conversion. Through comparison of results with similar studies on HCOOH d…
Fumarate respiration of Wolinella succinogenes: enzymology, energetics and coupling mechanism.
2002
Wolinella succinogenes performs oxidative phosphorylation with fumarate instead of O2 as terminal electron acceptor and H2 or formate as electron donors. Fumarate reduction by these donors ('fumarate respiration') is catalyzed by an electron transport chain in the bacterial membrane, and is coupled to the generation of an electrochemical proton potential (Deltap) across the bacterial membrane. The experimental evidence concerning the electron transport and its coupling to Deltap generation is reviewed in this article. The electron transport chain consists of fumarate reductase, menaquinone (MK) and either hydrogenase or formate dehydrogenase. Measurements indicate that the Deltap is generat…