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991.
Oxidative addition of 1-chloro-1-nitroethane to trans-IrCl(CO)-[P(CH3)2C6H5]2 followed by treatment of the initial product with pyridine yields a new iridium(III) complex IrCl(py)[COC(NO2)CH3][P(CH3)2C6H5]2, whose structure has been confirmed by X-rays crystallography. Two intermediate products have been observed by NMR spectroscopy; their structures have been tentatively assigned. The reaction of the corresponding bromine derivatives yields two isomers of the composition IrBr2(CO)[CH(NO2)CH3][P(CH3)2C6H5]2, and these are not affected by pyridine. The reaction of 1-chloro-1-nitroethane with Pt[P(C6H5)3]4 takes a completely different course in that yields nitrorethane and cis-PtCl2[P(C6H5)3]2 as the main products, with no detectable formation of the products of oxidation addition. A brief mechanistic investigation points towards the participation of radicals and radical anions as transient intermediates and a mechanism is proposed which explains most of the experimental results. 相似文献
992.
The synthesis of N-acyl derivatives of γ - keto - α - amino acids (3, 4, 5) by the amidoalkylation of 1,3-dicarbonyl compounds with glyoxylic acid-amide adducts (1, 2) is described. The γ - keto - α - amino acid derivatives (4, 5) were further converted to the corresponding butenolides (6, 7) and to pyrazolylglycine (12). 相似文献
993.
C.P. Boekel A. Jelsma J.H. Teuben H.J. De Liefde Meijer 《Journal of organometallic chemistry》1977,136(2):211-218
The thermolysis of compounds of the type Cp2VR (R = aryl) in the solid state has been studied. A distinct increase in thermal stability is observed upon substitution of the ortho-position of the aryl group. Thermal decomposition occurs with formation of RH, Cp2 V, a vanadocene homologue with the group R substituted in one of the Cp rings and, probably, a vanadocene homologue with two substituted Cp rings. It is shown that the abstraction of the hydrogen atom from the cyclopentadienyl ring, necessary for the formation of RH, is an intermolecular process, whereas the substitution of the aryl group in the Cp ring is intramolecular. A decomposition mechanism is proposed in which the group R is transferred from the vanadium atom to the C5H5 ring of the same molecule by interaction with an aryl group of another molecule. The thermal decomposition of Cp2VR is compared with that of the analogous titanium compounds. 相似文献
994.
We look for possible ordered geometrical configurations with bicontinuous or cellular topologies, optimizing the frustration of a periodic system of frustrated fluid films. The solutions found have the same symmetries as those observed for cubic phases of amphiphilic molecules. This agreement leads to consider cubic structures as structures of defects of rotation, or disclinations.This paper was presented at the workshop Ringing gels and Cubic phases, University of Bayreuth, October 25–26th, 1988. 相似文献
995.
A preparative route to cis- and trans-1,2-dibromocyclopropane () was developed via the Hunsdiecker reaction of silver cyclopropane-1,2-dicarboxylate (). Cis- and trans- gave the same ratio of cis- and trans- (1:3.2). The mechanism of this reaction is briefly discussed. 相似文献
996.
The internal structure of the disk-like aggregate of a lyotropic nematic phase formed by two amphiphiles, potassium laurate and decanol, in the presence of water was studied by neutron scattering with contrast variation method. These experiments show that the two amphiphiles are not distributed uniformly in the aggregate. The potassium laurate concentration is higher in the rim of the disk, where the interface exhibits a semitoroidal curvature, than in its central core, where the curvature is lower. This segregation of the two amphiphiles within the aggregate may be invoked to explain the existence of finite bilayered aggregates which had been suggested to be unstable relative to infinite bilayers by previous models. 相似文献
997.
M. Kabešová I. Vargová T. Šramko J. Gažo 《Journal of Thermal Analysis and Calorimetry》1978,13(1):65-70
The influence of the position of the CH3 group in picoline and lutidine ligands on the degree of chemical change of the NCS groups in coordination compounds of the type Cu(NCS)2L2 (whereL=2-, 3- and 4-picoline, and 2,3-, 2,4-, 2,5-, 2,6-, 3,4- and 3,5-lutidine) is dealt with. The most marked effect of the CH3 group is found to be exerted in position 4. This effect of the methyl group on the degree of chemical change points to the mutual influence of the ligands in coordination compounds of Cu(II).
Zusammenfassung Der Artikel befaßt sich mit dem Einfluß der Lage der CH3 Gruppe in Pikolinen und Lutidinen als Liganden auf den Grad der chemischen Änderungen der Gruppen NSC in Koordinationsverbindungen des Typs Cu(NCS)2L2 (L=2-, 3- und 4-Pikoline, 2,3-, 2,4-, 2,5-, 2,6-, 3,4- und 3,5-Lutidine). Der ausgeprägteste Effekt der CH3 Gruppe wurde in der Position 4 beobachtet. Dieser Einfluß der Methylgruppe auf das Ausmaß der chemischen Änderungen deutet auch auf die gegenseitige Wirkung der Liganden in Koordinationsverbindungen von Cu(II).
Résumé L'article a trait à l'influence de la position du groupe CH2 dans les picolines et lutidines, en tant que ligands, sur le degré des changements chimiques des groupes SCN dans les composés de coordination du type Cu(SCN)2L2 (L=2-, 3 et 4-picoline, 2,3-, 2,4-,2,5-, 2,6-, 3,4- et 3,6-lutidine). L'effet le plus prononcé du groupe CH3 s'observe en position 4. Cette influence du groupe méthyle sur le degré des changements chimiques indique aussi l'influence mutuelle des ligands dans les composés de coordination du Cu(II).
- , , NCS Cu(NCS)2,L2, L=2-, 3- 4- , 2.3-, 2.4-, 2.5-, 2.6-, 3.4- 3.5-. , 4. Cu(II).相似文献
998.
The alkylhalide-halide association ions, [RX2]? that are observed in the negative chemical ionization mass spectra of alkyl halides appear to be directly related to the corresponding SN2 transition states in solution. ‘Frontside’ association of halide ions with bridgehead alkyl halides does not occur in our system. The Change in heats and entropies of association for the chloromethane series is consistent with delocalization in the [RX]2? ions. 相似文献
999.
Examination of a large number of spectra indicates that bis-unsaturated compounds commonly undergo a skeletal rearrangement in which part or all or the bridging moiety is eliminated, often with concomitant loss of hydrogen atoms. The spectra of labeled azobenzene, diphenyl sulfide, and their p,p′-dimethyl derivatives show that scrambling of hydrogen atoms precedes or accompanies such rearrangements, in contrast to the loss of a p-methyl group from the latter derivatives. These results are rationalized in terms of the radical site formed on one unsaturated functional group attacking the polarizable π-electrons of the other unsaturated group. 相似文献
1000.
Zusammenfassung Die photometrische Methode zur quantitativen Bestimmung der Phenole mit 4-Aminoantipyrin wurde auf Naphthole und einige Naphtholsulfosäuren ausgedehnt. Die 1-Naphtholsulfosäuren geben in wäßriger Lösung eine beständige Rotfärbung, die Reaktion folgt bis zu einer Konzentration von 10 g/ml dem Beerschen Gesetz. Bei der 2-Naphtholreihe kann man die Methode nur bei 2-Naphthol und 2-Naphthol-8-sulfosäure anwenden. In den Fällen wo der gebildete Farbstoff in Chloroform löslich ist, wird durch Überführung in die organische Phase die Empfindlichkeit der Methode etwa 10fach gesteigert. 相似文献