A kinetic investigation into the removal of carbobenzyloxy group from protected amines via hydrogenolysis reaction

Hydrogenolysis of a carbobenzyloxy group (CBz) was studied utilizing molecular hydrogen in the presence of carbon-supported palladium catalyst. It was demonstrated that the kinetics of the reaction are greatly influenced by the presence of the CO₂ by-product. It was found out that the presence of CO₂ determines whether the reaction is first or zero order since it causes deactivation of the catalyst via inhibition. The effect of potassium carbonate (K₂CO₃) and triethylamine (TEA) as additives was investigated. A considerable solvent effect was also observed that may be explained by the variation of dispersion of the catalyst from one solvent to another.     

Characterization of zero locations of polytopes of real polynomials

Given a stability region of a polytope of polynomials, the edge theorem can be used to verify certain root-clustering properties of the polytope. The authors consider the inverse problem; starting with a polytope of real polynomials, they present a result that allows the construction of the smallest set of regions in the complex plane which characterizes its zero location     

Editorial

Ohne Zusammenfassung     

Management of rhesus isoimmunization by preimplantation genetic diagnosis

Intracranial osteolipomas are rare lesions which occur in the region of the tuber cinereum. All cases reported to date have been incidental autopsy findings. We describe a patient who presented with a variety of neurological symptoms and had a typical osteolipoma surgically removed.     

Multisource-sputtered ErBa2Cu3O7−x films on single-crystal and buffered crystalline substrates

High-quality superconducting films of erbium-barium-copper-oxide have been produced in a multisource sputtering system on a variety of substrates, including buffered sapphire and silicon wafers as well as various single-crystal materials. Fine-grained polycrystalline films with narrow (<4 K) resistive transitions have been grown on a number of different substrates. The use of erbium in the 12–3 compound leads to improved film morphology and to more forgiving conditions for establishing of the superconducting phase. Sputtered neutral mass spectroscopy (SNMS) yields useful information about the compositional profile of the films.     

Analysis of the MSS51 region on chromosome XII of Saccharomyces cerevisiae.

We have localized gene MSS51 on chromosome XII of Saccharomyces cerevisiae between the RDN1 and CDC42 loci. 'Head to head' with MSS51 is another gene, QRI5, the function of which is unknown. However, the proximity of these genes, the structure of the intergenic region and the presence of an ABF1 binding site right in the middle of this region suggest that the MSS51 and QRI5 expressions are submitted to a common regulatory process.     

Tannins/melamine–urea–formaldehyde (MUF) resins substitution of chrome in leather and its characterization by thermomechanical analysis

A new sulfonated melamine–urea–formaldehyde (MUF) resin of relatively low melamine content, prepared according to a sequential formulation, has been shown to be highly effective when coupled with different natural vegetable tannins to produce leather with the same good characteristics of leather prepared with chrome salts. In particular, the antishrinkage effectiveness of the leather prepared according to the new approach is comparable to that obtained with chrome tanned leathers. The comparison of the traditional leather shrinkage temperatures test method with a new thermomechanical analysis (TMA) test method in tension yields thermograms presenting three major modulus of elasticity (MOE) peaks. These are closely connected to molecular level phenomena determining the shrinkage temperature of leather. The three determining parameters appear to be as follows: (1) The average value of the temperatures at which the three MOE peaks occur: the higher the value of this average, the lower is the shrinkage of leather. (2) The average of maximum MOE values of the TMA peaks: the higher this average is, the better is the leather in regard to antishrinkage effectiveness. This means the leather maximum MOE at each peak is a measure of the resistance to the contraction force induced by heat. (3) The relative intensity of the first TMA peak in relation to the second: the higher the value of the MOE for the first TMA peak is in relation to the second peak, the lower the leather shrinkage appears to be. However, it has not been possible to better define or quantify this latter effect. This new TMA test method in tension has also yielded a mathematical relationship correlating the thermogram peak temperatures and MOE averages with the traditional shrinkage temperature to a high degree of confidence. A previous TMA test method, in compression, has proven to yield more problematic and finally not very reliable results when one needs to apply it to a wide variety of different cases. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1889–1903, 2003