Reactions CO/H2 en phase liquide. Synthese de precurseurs de l'ethanol par homologation du methanol.: I. Influences de la temperature et de la pression

The CO/H₂ homologation of methanol to acetaldehyde and subsequently to its dimethyl acetal in the presence of cobalt acetate promoted by iodine was examined under various conditions. Temperature and pressure were found as critical parameters. High pressures (140 MPa) and low temperatures (160–170°C) give optimal yields and selectivity to acetaldehyde. According to pressure, temperature, contact time, gas ratio and ligand/catalyst ratio, the reaction is oriented towards acetaldehyde, its dimethyl acetal or methyl acetate.     

Raman spectroscopic study of the hydration of short-chain poly(oxyethylene)s C <Subscript>1</Subscript>E<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>C <Subscript>1</Subscript> (<Emphasis Type="Italic">n</Emphasis>=1−4)

The hypothesis that the degree of hydration of poly(oxyethylene) (POE) in aqueous solution depends on the mole ratio of water molecules to ether oxygen atoms in the molecule has been verified by studying the isotropic Raman spectra in the O−H stretching region for four short-chain POEs (C ₁E _n C ₁ withn=1−4). Excellent coincidence of the O−H stretching Raman band for all four POEs studied in the range of mole ratio H₂O/O _ether from 25 to 0.6 was observed, thus confirming the assumption stated above. A conclusion that all ether oxygen atoms in the POE molecule participate in hydrogen bonding with water molecules has been made.     

Straightforward route for anchoring a glucosyl moiety onto nucleophilic species: reaction of amines and alcohols with carboxymethyl 3,4,6-tri-O-acetyl-alpha-D-glucopyranoside 2-O-lactone

The base-catalyzed reaction of carboxymethyl 3,4,6-tri-O-acetyl-alpha-D-glucopyranoside 2-O-lactone (prepared from isomaltulose) with amino acids and fatty amines under basic catalysis gave a series of new pseudoglucopeptides, nonionic amphiphiles, and polymerizable derivatives. The same reaction applied to alcohols provided the corresponding 2-(alpha-D-glucopyranosyloxy)acetyl esters with either basic or acidic catalysts.     

Mass spectral behavior of some homoleptic and mixed aryldichalcogenide bis(diphenylphosphino)ferrocenenickel(II), palladium(II), and platinum(II), and bis(diisopropylphosphino)ferrocenepalladium(II) complexes

The mass spectral behavior of a number of organometallic complexes containing the Group 10 metals Ni, Pd, and Pt, together with various thiolate ligands were studied. For Pd, two main types of complexes, differing by the substituents on the phosphorus atom were studied. Types I and II were substituted with bis(diphenylphosphino)ferrocene and bis(diisopropylphosphino)ferrocene ligands, respectively. The Ni complexes, except for one, and the Pd Type I complexes had no molecular radical cations (M(+.)) in their EI spectra. On the other hand, all the Pt complexes showed intense M(+.) ions in their EI spectra indicating that these complexes were more stable as radical cations than those of Ni and Pd. The FAB and MALDI spectra of all the complexes displayed intense quasi-molecular ions (MH(+)) and the fragmentations in both modes were similar. The MALDI spectra of several complexes displayed only M(+.) ions while one gave evidence of both MH(+) and M(+.) ions. Several Pd Type II complexes yielded intense M(+.) in their EI spectra.     

Stabilization of γ‘ phase in Bi<Subscript>4</Subscript>V<Subscript>2-x</Subscript>Fe<Subscript>x</Subscript><Superscript>II</Superscript>O<Subscript>11-1.5x</Subscript> series

Summary This work reports the room-temperature stabilization of the Bi₄V_2-xFe_x^IIO_11-1.5x γ ‘ phase, a promising ionic conductive material that finds application in solid oxide fuel cell and oxygen sensor devices. The Fe(II) cation proved to be a better stabilizer than Fe(III), which was previously used, since a lower substitution degree of V⁵⁺ is needed for the former. Powder X-ray diffraction, Fourier-transform infrared spectroscopy and differential scanning calorimetry were used in these experiments.     

A new approach in assessing microbiological results in water analysis proficiency testing

Due to the relatively large spread in the results of microbiological proficiency tests, the z-scores are often not able to detect zero or low results as being ‘bad’ results. This paper describes an adapted z-score based on the average or the standard deviation of the 50% ‘highest’ results. The combination of the adapted z-scores of four samples enables a better judgement of the performance of each laboratory. Papers published in this section do not necessarily reflect the opinion of the Editors, the Editorial Board or the Publisher.     

Trennung,Identifizierung und Bestimmung von Bactericiden auf der Basis von halogenierten Aromaten mittels Gas-Chromatographie

The separation of a mixture of 22 bactericides has been achieved by gas chromatography on columns with silicone rubber W-982 as stationary phase with temperatures between 100° and 300°C. The unchanged compounds as well as their silylation products have been used. The latter are more conveniently used especially for the quantitative determination. To be able to calculate the retention indices after Kovats gas chromatography has been performed isothermally at 180°C for the more volatile compounds and at 250°C for all other bactericides.The retention indices obtained under these conditions are tabulated together with the limits of detection.     

Tying together the ultrastructural modifications of wood fibre induced by pulping processes with the mechanical properties of paper

The composition and ultrastructural arrangement of cell wall polymers in wood fibres have determining influence on the properties of wood derived materials. It is therefore important to improve our understanding of the relationship between fibres organisation, the modifications induced by pulping treatments, and the resulting paper sheet mechanical properties. The different treatments to which fibres are subjected during the manufacturing of pulps and papers induce morphological and micro-structural alterations due to the removal of wall constituents and of microfibrillar elements. The impact of pulping processes on fibres was investigated at the ultrastructural scale of transmission electron microscopy. Particular attention was given to the effects of beating in refiners at various intensities on the ultrastructure of fibres. The most characteristic effects consisted of delaminations, microfibril disorganisation, and even fractures, of varying importance depending on the intensity of the mechanical refining. The consequences of internal alterations and surface modifications of the fibres were examined in relation to the paper sheet mechanical properties. Correlations between the type of alteration observed in the fibres and its possible impact on a given paper mechanical property are suggested. With similar approaches, the effects of drying and recycling were studied.     

Stereoselectivity of (−)-(1<Emphasis Type="Italic">R</Emphasis>,2<Emphasis Type="Italic">S</Emphasis>)-2-methylamino-1-phenylpropan-1-ol preparation

Stereoselectivity of reductive amination of (R)-1-hydroxy-1-phenylpropan-2-one by methylamine was studied. From the four isomers possible, only two are produced by this reaction. These are marked as (−)-(1R,2S)-ephedrine (desired product) and (+)-(1S,2R)-ephedrine. The reaction stereoselectivity depends both on the type of the catalyst and reaction conditions. The most suitable type is the supported platinum. However, this catalyst rapidly deactivates. With a decreasing activity of Pt catalyst, the stereoselectivity decreases. It is also decreased during the production of the second liquid phase (water) in the reaction mixture.     

The effect of amino acid deletions and substitutions in the longest loop of GFP

Background  

The effect of single and multiple amino acid substitutions in the green fluorescent protein (GFP) from Aequorea victoria has been extensively explored, yielding several proteins of diverse spectral properties. However, the role of amino acid deletions in this protein -as with most proteins- is still unknown, due to the technical difficulties involved in generating combinatorial in-phase amino acid deletions on a target region.