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31.
32.
Siegfried Andreae Ernst Schmitz Helmut Sonnenschein Gbor Drnyei Csaba Szntay Jozsef Tams 《Advanced Synthesis \u0026amp; Catalysis》1985,327(3):445-454
N-Amination of Isoquinoline Bases 3, 3-Pentamethylene oxaziridine 1 forms an N N-bond with secondary isoquinoline bases 2a – f to give the cyclohexylidene hydrazines 3a – f . In some cases nitrogen elimination yielding indane derivatives 13b, 13e competes with hydrazone formation. The cyclic Schiff'base 14 and the β-carboline derivative 16 can also be aminated. 相似文献
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34.
Achim Mehlhorn Jürgen Fabian Siegfried Kulpe 《Advanced Synthesis \u0026amp; Catalysis》1984,326(2):303-310
Quantum Chemical Investigations of the Molecular and Electronic Structure of Simple Azomethine Imines and Related Compounds The molecular and electronic structure of simple azomethinimines are investigated by means of MINDO/3 and CNDO/2 calculations. The calculated molecular geometry is compared with X-ray results obtained for these compounds. Except for the NN-bond lengths MINDO/3 satisfactorily describes the molecular structure of azomethinimine and related π-electronic systems. The charges at the atoms along the conjugated chain are alternating as in polymethines. The terminal carbon atom carries a negative charge. This charge brings about an appreciable shielding of this carbon atom such as found in the 13C-n.m.r. spectrum. This result does not contradict a stabilization of azomethinimines in the crystal via = CH…︁OC interactions. 相似文献
35.
36.
Janine Will Lars Schneider Dr. Jonathan Becker Jun.-Prof. Dr. Sabine Becker Andreas Miska Christopher Gawlig Prof. Dr. Siegfried Schindler 《Israel journal of chemistry》2020,60(10-11):999-1003
A new tripodal imine ligand tris(2-(propan-2-ylideneamino)ethyl)amine (imine3tren) was prepared in order to stabilize high valent iron-oxido complexes. Iron complexes were synthesized in template reactions from iron(II) salts, tris(2-aminoethyl)amine (tren) and acetone. Due to the reversibility of the imine formation, complexes with different ligands were obtained depending on the reaction conditions. Three complexes, [Fe(imine3tren)(OAc)2] ( 1 ), [Fe(imine3tren)(OAc)]OTf ( 2 ) and [(imine3tren)2Fe2(F)2](SbF6)2 ( 3 ), could be synthesized and structurally characterized. However, reactions with hydrogen peroxide, iodosobenzene or ozone did not lead to any kind of “oxygen adduct” complex that could be spectroscopically observed. 相似文献
37.
Umberto De Rossi Johannes Moll Monika Spieles Günther Bach Siegfried Dhne Jrg Kriwanek Maria Lisk 《Advanced Synthesis \u0026amp; Catalysis》1995,337(1):203-208
Cyanine dyes ( 1a–d ) with the 5,5′,6,6′-tetrachloro-1,1′-dialkyl-3,3′-di-(3-carboxypropyl)-benzimidocarbocyanine chromophore differing only in the chain length of their alkyl groups in 1,1′-position have been synthesized, spectroscopically characterized, and compared with 5,5′6,6′-tetrachloro-1,1′-diethyl-3,3′-di-(4-sulfobutyl)-benzimidocarbocyanine( TDBC ). In aqueous solution the dyes form J-aggregates which, depending on the alkyl group chain length, exhibit J-bands differing in spectral positions, bandwidth, and in the number of peaks. 相似文献
38.
Wei Li Zhen Yue Artur Lozovoi Oleg Petrov Carlos Mattea Siegfried Stapf 《Journal of Polymer Research》2018,25(11):239
The structure of chain entanglements in the solid state is important for revealing the relationship of structure and properties of polyolefin. In this work, low-field solid-state 1H NMR is used to study the chain dynamics of ultra-high molecular weight polyethylene (UHMWPE) in the solid state. It has been found that the relaxation distribution, analyzed by a multi-exponential inversion program, is an effective method to characterize the heterogeneous chain mobility. It is evidenced from the results that the UHMWPE in a less entangled state presents an obviously heterogeneous distribution of chain mobility in the non-crystalline phase, corresponding to its heterogeneous distribution of entangled points. In comparison, the commercial UHMWPE with a large number of entanglements shows a much more uniform mobility of the non-crystalline components. This heterogeneous distribution of chain mobility becomes even more critical after annealing the samples below the melting point, especially for the less entangled UHMWPE. 相似文献
39.
Siegfried Hring Dieter Kleine Joachim Ulbricht 《Advanced Synthesis \u0026amp; Catalysis》1978,320(3):473-481
On the Free Radical Copolymerization of Unsaturated Isocyanates with Vinylchloride The free radical copolymerization of vinyl-, isopropenyl- and p-vinyl-phenylisocyanate with vinylchloride in mass and tetrahydrofurane solution at 50°C is investigated. The incorporation of the isocyanate monomers in the copolymers is favoured. These monomers effect a great decrease of the rate of copolymerization and a crosslinking of the formed homo- and copolymers, whose extent depends on the kind and the quantity of the incorporated monomers. The crosslinking is caused by the forming of isocyanurate units. 相似文献
40.
Holger Becker Reinhard Caspary Christian Toepfer Manfred V. Schickfus Siegfried Hunklinger 《Journal of Modern Optics》2013,60(9):1715-1723
Abstract We have developed a fixed beam direct writing laser lithography system with a minimum feature size of 400nm at 457nm wavelength and a writing speed of 4·2mm/s with total system costs of less than 100 000 US$. 相似文献