Search results for "alkane"
showing 10 items of 162 documents
Cascade complex formation by phosphate in the cobalt(II)/[30]aneN10 anaerobic system
1993
Abstract The interaction of phosphate with the mono- and binuclear cobalt(II) complexes of [30]aneN 10 (1,4,7,10,13,16,19,22,25,28-decaazacyclotriacontane) has been studied by potentiometry in 0.15 mol dm −3 NaClO 4 solution at 298.15 K under anaerobic conditions. The stable species [CoH 2 ([30]aneN 10 )PO 4 ] + , [CoH 4 ([30]aneN 10 )PO 4 ] 3+ , [Co 2 H([30]aneN 10 )PO 4 ] 2+ , [Co 2 H 2 ([30]aneN 10 )PO 4 ] 3+ and [Co 2 H 3 ([30]aneN 10 )PO 4 ] 4+ , where the phosphate anion is directly bound to the metal ions or acts as a second sphere ligand, are formed and their stability constants have been determined. The results obtained allowed for the selection of suitable conditions for the study…
Influence of Copper(II) and Nickel(II) Ions in the Topology of Systems Based on a Flexible Bis-Oxamate and Bipyridine Building Blocks
2014
Single crystals of the mononuclear bis-oxamate nickel(II) complex [Ni(bipy)(H2edpba)]·dmso (1) are obtained by reacting [Ni(bipy)Cl2]·H2O and the flexible K2(H2edpba) ligand [bipy = 2,2′-bipyridine; H4edpba = N,N′-2,2′-ethylenediphenylenebis(oxamic acid)]. The reaction of 1 with copper(II) ions resulted in two products in which the replacement of the nickel(II) ion by copper(II) took place: the chain compound [Cu(bipy)(H2edpba)]n·3nH2O·ndmso [dmso = dimethyl sulfoxide] (2) and the analogous chain compound without dmso crystallization molecules [Cu(bipy)(H2edpba)]n·1.5nH2O (3a) in its polycrystalline form. The reaction of [Cu(bipy)Cl2] and K2(H2edpba) yielded single crystals of [Cu(bipy)(H2e…
Degradation of long-chain n-alkanes in soil microcosms by two actinobacteria
2012
The ability of two recently isolated actinobacteria, that degrade medium and long chain n-alkanes in laboratory water medium, was investigated in soil microcosms using different standard soils that were artificially contaminated with n-alkanes of different length (C(12)- C(20)- C(24)- C(30)). The two strains, identified as Nocardia sp. SoB and Gordonia sp. SoCp, revealed a similar high HC degradation efficiency with an average of 75% alkane degraded after 28 days incubation. A selectivity of bacteria towards n-alkanes of different length was detected as well as a consistent effect of soil texture and other soil physical chemical characteristics on degradation. It was demonstrated the specif…
Sequence similarity of mammalian epoxide hydrolases to the bacterial haloalkane dehalogenase and other related proteins Implication for the potential…
1994
Direct comparison of the amino acid sequences of microsomal and soluble epoxide hydrolase superficially indicates that these enzymes are unrelated. Both proteins, however, share significant sequence similarity to a bacterial haloalkane dehalogenase that has earlier been shown to belong to the alpha/beta hydrolase fold family of enzymes. The catalytic mechanism for the dehalogenase has been elucidated in detail [Verschueren et al. (1993) Nature 363, 693-698] and proceeds via an ester intermediate where the substrate is covalently bound to the enzyme. From these observations we conclude (i) that microsomal and soluble epoxide hydrolase are distantly related enzymes that have evolved from a co…
Conformational polymorphs of 1,1,2,2-tetrachloroethane: pressure vs. temperature.
2011
Directional Cl···Cl type I and II interactions govern the low-density aggregation of 1,1,2,2-tetrachloroethane molecules in synclinal conformation in the crystalline state at low temperature, whereas the dense molecular packing in high-pressure is achieved for the antiperiplanar conformers and electrostatically less favored Cl···Cl contacts. The mechanism of transformation between loose and dense associations involves the collapse of Cl···Cl contacts and conformational conversion.
A raman spectroscopic determination of the interlamellar forces in crystalline n-alkanes and of the limiting elastic modulus Ec of polyethylene
1976
A simple treatment based on continuum mechanics shows that weak interlamellar forces in crystalline n-alkanes should result in a characteristic upward shift of the frequencies of the longitudinal acoustical (LA) modes, which is independent of the chain length and decreases inversely with the mode order. A raman spectroscopic determination of the LA mode frequencies of a series of different n-alkanes confirms the theoretical conclusion and permits a derivation of a force constant characteristic of the interlamellar forces. The discussion results in a new formula valid for the LA mode frequencies of the orthorhombic n-alkanes in the acoustical limit and yields a new determination of the limit…
Size-activity relationship of iridium particles supported on silica for the total oxidation of volatile organic compounds (VOCs)
2019
12 Figures, 2 Tables.-- Datos suplementarios disponibles en línea en la página web del editor.-- © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Exploring long chain n-alkane metabolism in Gordonia sp. strain SoCg
2009
Many microorganisms are able to degrade aliphatic hydrocarbons and a relationship between n-alkane utilization and storage compound synthesis has been described in bacteria. The Gram positive GC-rich n-alkane degrader Gordonia sp. strain SoCg, isolated from a long-term accidentally contaminated beach in Sicily, is able to grow on long n-alkanes up to. It carries a single copy of the alkane hydroxylase gene alkB on its chromosome and its alk cluster revealed a genomic organization similar to other alk clusters of alkane-degrading Gram positive bacteria. The alk gene expression, analysed by Real-time RT-PCR, is induced by n-hexadecane and n-triacontane and coupled to alkane consumption. Inter…
Die kristallstruktur von cycloalkanen
1982
An X-ray structure analysis was performed on single crystals of the cycloalkane (CH2)36. The lattice belongs to the space group Aa and is arranged in layers. The unit cell has the dimensions α = 1,033 nm, b = 0,824 nm, c = 4,22 nm, β = 107, 1° and contains four molecules. The molecules consist of two stretched stems which are linked by sharp folds at each end. The folds have the conformation …t(g g t g g) t… lying parallel to the b-axis. Raman measurements suggest that the stems are slightly twisted. A comparison of the homologous series (CH2)n, n = 36, 48, 60, and 72 using X-ray powder methods showed that the (CH2)36-structure, including the fold conformation, is also representative for th…
A Stereocontrolled Protocol to Highly Functionalized Fluorinated Scaffolds through a Fluoride Opening of Oxiranes
2016
A novel selective and substrate-dependent synthetic protocol has been developed towards the synthesis of various fluorine-containing, highly functionalized cycloalkane derivatives. The method involves the stereoselective epoxidation of some unsaturated cyclic beta-amino acid derivatives as model compounds, followed by a regioselective fluoride opening of oxiranes under various conditions with Deoxofluor and XtalFluor-E reagents, thereby offering an insight into this new epoxide opening methodology with fluoride.