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11.
Colin Eaborn 《Journal of organometallic chemistry》1985,290(3):c42-c43
The [CuPPh3CCPh]4 tetramer, obtained by treatment of [Cu(PPh3)2BH4] with phenylacetylene and KOH (molar ratio 1/1/1) in 1/1 benzene/benzyl alcohol, consists of a tetrahedral skeleton of metal atoms bonded to four terminal phosphine molecules and to four μ-3 -bridging phenylacetylide ligands which behave essentially as 2e donors. 相似文献
12.
Colin Eaborn 《Journal of organometallic chemistry》1985,282(1):C27-C28
13.
14.
Interpretation of the chemical and spectral (IR., UV., 1H- and 13C-NMR.) properties of the antitumor antibiotic hedamycin (C41H50N2O11) suggests that the molecule contains a methyl substituted 1-hydroxyanthraquinone nucleus, an α, β-unsaturated ketone, two sugar-like tetrahydropyran rings ( 4 and 8 ) and an aliphatic chain 2 , presumably with an epoxy group (see the Scheme). 相似文献
15.
Norbert V. Fehringer Dalia M. Gilvydis Stephen M. Walters Colin F. Poole 《Journal of separation science》1992,15(2):124-127
The combination of open tubular column gas chromatography with electrolytic conductivity detection has been evaluated for the determination of nitrogen-containing pesticide residues in food extracts. Optimization of the column position at the column-detector interface was crucial to the successful operation of the detector. The signal-to-noise ratio and response stability of the detector are greatly influenced by the composition of the electrolyte solvent. Large volume splitless injections using retention gaps and optimized detector operating conditions enabled pesticide residues in food extracts to be determined at sub parts-per-million levels. Although the electrolytic conductivity detector is less sensitive than the thermionic ionization detector, its greater nitrogen selectivity can he crucial to the determination of nitrogen-containing contaminants in food extracts, particularly in complex mixtures where phosphorus-containing contaminants or matrix compounds are also present. 相似文献
16.
A universal temperature controlled membrane interface (TCMI) has been constructed for hollow-fibre membranes. The membrane temperature is controllable in the range -70 to 250 degrees C using an electric heater and a flow of cooled nitrogen or helium gas. Volatile and semi-volatile organic compounds may be detected either by continuous diffusion across the membrane or by in-membrane pre-concentration followed by thermal desorption into the detector. The TCMI interface is demonstrated in combination with mass spectrometry and GC-MS, for the determination of VOCs and SVOCs in aqueous and air samples and for the on-line monitoring of a bioreactor. 相似文献
17.
Imines of (1S,9S)-t-butyl-9-amino-octahydro-6,10-dioxo-6H-pyridazino[1,2-a][1,2]diazepine-1-carboxylate undergo thermal (toluene, 110°C) or LiBr-DBU catalysed (MeCN, room temperature) regio- and stereo-specific cycloaddition to a range of chiral dipolarophiles giving enantiopure spiro-cycloadducts in excellent yield. The reactions proceed via intermediate NH azomethine ylides and litho azomethine ylides, respectively and results in the multiplication of chiral centres from 2 (one of which is lost in the process) to 5. 相似文献
18.
The preparation of the η4-4-2,3,5,6-tetramethyl-1,4-benzoquinonecomplex [CO(C5Me5)(C10H12O2)] (I) is reported. Complex I undergoesreversible protonation to yield the 2-6-η-4-hydroxy-1-oxo-2,3,5,6-tetramethylcyclohexadienyl complex [Co(C5Me5)(C10H13O2)BF4 (II) and diprotonation to yield the η6-6-1,4-dihydroxy-2,3,5,6-tetramethylbenzene complex [Co(C5Me5)(C10H14O2)] (BF4)2 (III). Methylation of complex I with MeI/AgPF6 gives the 2---6-η-4-methoxy-1-oxo-2,3,5,6-tetramethylcyclohexadienyl complex [Co(C5Me5)(C11H15O2])PF6 (IV). In trifluoroacetic acid solution complex IV is protonated to form the η6-1-hydroxy-4-methoxy-2,3,5,6-tetramethylbenzene cation [Co(C5Me5)-(C11H16O2)]2+ 相似文献
19.
The geometry of the linear molecule HBO, has been investigated within the restricted Hartree-Fock LCAO-MO-SCF approximation. The calculated bond lengths for the near Hartree-Fock calculation were R(H-B)=2.1913 bohr, R(B-O)=2.2284 bohr. Several one electron properties have been calculated for the minimum energy configuration. 相似文献
20.
[reaction: see text] The title alkaloid was synthesized in racemic form from 3,7-diallyl-2,4,6,8-tetraoxo-3,7-diazabicyclo[3.3.1]nonane (7) by a regioselective diallylation reaction followed by double ring-closing olefin metathesis and exhaustive reduction. Tetraoxobispidine 7 was itself prepared in three simple operations from dimethyl malonate. The entire sequence to alpha-isosparteine was conducted on a multigram scale and proceeded without recourse to chromatography. 相似文献