In this work, the electrogeneration of peroxodisulfate from a 1 M H2SO4 solution on boron-doped diamond microelectrodes array has been studied. The peroxodisulfate is detected at the vicinity of the boron doped diamond electrode, with the SECM probe, only when the polarization of the microarray is greater than 2.1 V versus AgCl/Ag. The main electrochemical interest of working with microarrays comes from the fact that current densities and efficiencies are comparable to those observed in the peroxodisulfate industrial production. The local Scanning Electrochemical Microscopy studies have shown that the peroxodisulfate reaction is related to a surface mediated oxidation of sulfate anions into peroxodisulfate according to a complex reactional mechanism.

The packing of large-diameter columns for liquid chromatography is still difficult and numerous publications have reported results from tests which prove the packing is heterogeneous. The slurry is more compact in the wall region and this reduces the flow of the mobile phase, leading to distortion of the sample zone in the column and generation of peak tailing. A new type of injection system for the head of the column has been developed which divides the flow of the solvent from the pump into two parts. One, without sample, is directed to a crown injector, close to the wall. By adjusting the ratio of this flow to that of the bulk flow it is possible to increase the speed of the mobile phase in this part of the stationary phase and reduce distortion of the sample zone. The other part of the solvent carries the sample to the stationary phase through a distributor. The results demonstrate the benefits of this annular injection system, which include increased efficiency and improved column stability.

Silica-polypyrrole particles have been used as a composite stationary phase for liquid chromatography. Determination of capacity factors (k') of a wide number of polycyclic aromatic hydrocarbon (PAH) molecular probes allows the characterisation of the chromatographic properties of the silica-polypyrrole stationary phase. Capacity factors in the range of 0.10 up to 6.1 were determined, thus demonstrating the high affinity of the PAH probes towards the stationary phase. The selectivity of the composite stationary phase was also evaluated as a function of the planarity of the molecular probes injected. Capacity factors determined for PAHs (two-dimensional molecular probes) are higher than those measured for phenyl-substituted PAHs (phenyl-PAHs, three-dimensional molecular probes). Determination of capacity factors, dependence on the composition of the mobile phase demonstrates the reverse alpha-phase properties of the composite stationary phase. The acid-base properties of the composite silica-polypyrrole stationary phase were investigated using benzene derivative molecular probes (i.e., toluene, phenol, benzoic acid and aniline). Capacity factors in the range of 0.45 to 1.0 were determined. This study clearly demonstrates that this composite stationary phase exhibits selective interactions towards PAHs and phenyl-substituted PAHs and strong acid-base properties depending on the structure, the geometry and the acid-base properties of the molecular probes eluted.

Axial compression of the stationary phase is an easy technique for packing preparative liquid chromatography columns. However, the compression piston often needs an important external device to move the external jack. A new type of column is described which uses an auto-compression system to move the piston and compress the packing material. The system is fitted with a new annular injector which is known to reduce the peak tailing. The results of the tests demonstrate the ease of use of this column, its efficiency and stability.

A simple HPLC method has been developed for the determination of organic acids adsorbed on particles of maghemite. The advantage of this described technique is the possibility to identify and measure the ratios of differents acids bounded on the same particle. The chromatographic analysis is achieved on a sulphonated copolymer column in acidic form. Good recoveries of the acids were obtained by dosing the free acids in the supernatant and the acids adsorbed on the particles.

Under mild basic conditions, Chaetoglobosin M leads to the formation of two new bridged chaetoglobosins with preservation of the epoxide function, The structures of these new toxins are proposed on the basis of high-resolution MS and NMR data and supported by molecular modelling.

From culture on maize of the strain MRC 2654 of Phomopsis leptostromiformis, two fungal metabolites, unusual to this fungus, have been isolated in the methanolic extract. The acute toxicity for rats of these compounds justifies the present structural investigation. H-1 and C-13 NMR spectra allow to establish for these molecules some partial structures containing an indole unit and several condensed cycles. On the basis of these NMR results, the compound F = 185-degrees-C is identified to the term M of the chaetoglobosin series and the more polar compound, F = 205-degrees-C, named chaetoglobosin N, appears to be a new term in this series.

A l'issue de la culture sur mais de la souche MRC 2654 de Phomopsis leptostromiformis, deux metobolites fongiques inhabituels chez ce champignon ont ete isoles de l'extrait methanolique. La toxicite aigue provoquee chez le rat par ces composes justifie l'etude structurale presentee. Les spectroscopies RMN 1 H et 13 C permettent d'etablir pour ces molecules, des structures partielles contenant un noyau indolique et plusieurs cycles condenses. Sur la base de ces resultats RMN, le compose F=185 o C a ete identifie au terme M de la serie des chaetoglobosines et le second compose, plus polaire, F=205 o C nomme chaetoglobosine N apparait comme un nouveau terme de cette serie

Attempts to obtain the toxin phomopsin A, usually isolated from Phomopsis leptostromiformis fungus, failed when infesting maize with the strain MRC2654 of this fungus. However, taking into account the acute toxicity for rats of the crude methanol extract, mycotoxins less polar than phomopsins were searched for by checking other separation procedures. Preparative thin layer chromatography on silica (TLC) entailed the localisation of the toxicity in the fraction soluble in isopropylic ether. Finally, the preparative high performance liquid chromatography (HPLC) on silica allowed the purification of two toxins, which are demonstrated to belong to the chaetoglobosin series, as described elsewhere. An LC method for the direct monitoring of these toxins' production in liquid media resulted in a first optimization of the culture conditions. It appeared that the yields of these toxins can be approximately increased four-fold by reducing the culture of Phomopsis leptostromiformis in darkness from a 28-day period to 10 days.

The effects of the chemical hybridizing agent RH0007 (CHA or gametocide) on the fatty acid composition of mature seeds, anthers and leaves of Triticum aestivum were investigated. The fatty acid composition of seeds of treated plants showed small but significant variations compared with control material. Total lipid content of treated seeds decreased markedly with gametocide treatment. Fatty acid composition and repartition of polar lipids of anthers were not drastically altered by the treatment. In anthers of treated plants, linoleic acid content rose as oleic and linolenic acid percentages fell. Foliar sprays of CHA induced drastic decreases in chlorophyll and carotenoid contents of treated leaves. Changes in fatty acid composition were not so marked as for pigment levels. Changes observed for anthers and leaves could be correlated with a secondary herbicide effect of the gametocide but not with a primary action.

A simple HPLC method has been developed for the quantification of chemical hybridizing agent (CHA) in grains, leaves, straw and glumes of traited wheat. The procedure included acido-basic extractions of wheat grains and tissues and derivatization of CHA residue as methyl ester compound. The chromatographic separation was achieved with Spherisorb silica using ethyl acetate-methanol (98:2) and UV detection at 285 nm. Good recoveries of CHA for fortified wheat grains and leaves were obtained. Recoveries of CHA in traited wheat demonstrated accumulation of the agent in reproductive organs.

Abstractγ‐Hydroxybutyric acid (GHB) is known to act as a neuromodulator or neurotransmitter in the CNS.

A new route to 2-N-(carboxypropylamino)-2-deoxy-D-glucopyranose synthesis is reported, involving the Schiff-base derivative of beta-D-glucosamine with benzyl 4-oxobutyrate. Improvement in the synthesis of benzyl-4-oxobutyrate is also described. Biological compounds action was investigated by evaluating sedative and dopaminergic activities on male mice.

The syntheses of 2-carboxamido 2-deoxy 1,3,4,6-tetra O-acetyl β-D-glucose and 2-carboxamido 2-deoxy D-glucose derivatives are described. These compounds are proposed as 4-hydroxybutyric acid (GHB) derivatives in attempt to test whether modifications in GHB structure could lead to more active biological substances.

AbstractKetoxime (I) lassen sich nach zweifacher Metallierung an Aldimine (III) zu Azetidinderivaten (IV) addieren.

AbstractDie Umsetzung der Silylester (I) von in γ‐Stellung bromierten α,β‐ungesättigten Carbonsäuren mit Zink und Aldehyden (II)in einer oder zwei Stufen führt zu unterschiedlichen Ergebnissen.

The regiospecificity of Reformatsky reactions of γ-bromocrotonic and γ-bromosenecioic timethylsilyl esters are discussed. One-step reactions lead to a majority of α-substituted derivatives, while in two-step reactions, the γ-substituted products are obtained exclusively.

Ivanov reagent add several analogous reagents (phenyl acetique serie) have been studied by NMR. In all the cases, an enolate-structure is revealed; no carbaneniate-species could be detected, even in very solvating solvents.