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1.
K. Dimroth A. Berndt F. Br A. Schweig R. Volland 《Angewandte Chemie (International ed. in English)》1967,6(1):34-40
The distribution of the unpaired electron over the oxygen and the 24 carbon atoms in the free 2,4,6-triphenylphenoxy radical was determined by electron spin resonance spectroscopy and quantum-mechanical approximation methods. The hyperfine splitting was evaluated with the aid of the spectra of triphenylphenoxyls deuterated in some or all of the substituent phenyl groups. The results of the quantum-mechanical approximations were checked by recording the ESR spectra of triphenylphenoxyls labeled with 13C in positions 1,2,3, or 4 of the central ring. The spin density distribution permits a first discussion of the 17O-coupling constants of correspondingly labeled triphenylphenoxyl and other organic free radicals. 相似文献
2.
Summary Tokaj wines (Szamorodni and Aszu wines) of Hungarian origin were investigated on the basis of free amino acids and biogenic
amines. The separation and determination of these compounds was performed by an amino acid analyser equipped with an ion-exchange
resin column. The total amount of free amino acids and biogenic amines was higher in Aszu wines than in Szamorodni wines.
The main amino acids were proline and arginine, while the major biogenic amines were tyramine and putrescine. The free amino
acid and biogenic amine content of Aszu wines depended on the vineyards the wines originated from.
Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001 相似文献
3.
Fausi?RassoulEmail author Heinz?L?ster Volker?Richter 《Monatshefte für Chemie / Chemical Monthly》2005,136(8):1501-1507
Summary. L-Carnitine, L-(−)-β-hydroxy-γ-trimethylaminobutyrate, plays an important role as a factor necessary for the transport of long-chain fatty acids into the mitochondria. In order to investigate the influence of L-carnitine on hyperlipidaemias, the experimental model of the sucrose-induced hypertriglyceridaemia of the rat was used. In these experiments L-carnitine in the dose of 11 mg per day and 100 g body weight (over the period of 1 week) was able to antagonize the sucrose-induced hypertriglyceridaemia and the increase of serum free fatty acid level in female rats of the Wistar strain. Carnitine administration did not change the activities of lipogenic enzymes and fatty acid synthesis in the liver. However, L-carnitine increases the rate of hepatic fatty acid oxidation. Our results indicate a hypotriglyceridemic and free fatty acid lowering effect of L-carnitine, and suggest the use of this compound in the therapy of hyperlipidaemias. 相似文献
4.
Vitaliy Petrik 《Tetrahedron letters》2007,48(19):3327-3330
The easy radical trifluoromethylation of a series of 1,3-dicarbonyl compounds with CF3I is described. The reaction occurs in the presence of a nitrogen base and sodium dithionite in CH3CN-H2O solution. Additionally, we report a new access to ammonium triflinates. 相似文献
5.
Jing-kun Xu Gao-quan Shi Feng-en Chen Xiao-yin Hong Department of Chemistry Bio-organic Phosphorous Chemistry Laboratory Tsinghua University Beijing China 《高分子科学》2002,(5):425-430
The Raman spectra of poly(3-methylthiophene) (PMeT) films with different thicknesses, which have beenelectrochemically deposited on a flat stainless steel electrode surface by direct oxidation of 3-methylthiophene in borontrifluoride diethyl etherate (BFEE) at a constant applied potential of 1.38 V (versus SCE), have been investigated byexcitation with a 633-nm laser beam. The spectroscopic results demonstrated that the doping level of PMeT film wasincreasing during film growth. This finding was also confirmed by electrochemical examination. Moreover, the Raman bandsassigned to radical cations and dications in doped PMeT films were found approximately at 1420 and 1400 cm~(-1),respectively. Radical cations and dications coexist on the backbone of PMeT as conductive species and their concentrationsincrease with the increase of doping level. Successive cyclic voltammetry was proved to be an effective approach toimproving the doping level of as-grown thin compact PMeT film. 相似文献
6.
Yuehai ShenJianxun Wen 《Journal of fluorine chemistry》2002,113(1):13-15
A new and efficient route has been developed to synthesize 17β-(1-methyl-3-perfluoroalkyl)propyl-3β-androsterol (1) in nine steps from hyodeoxycholic acid via selective addition of 1-perfluoroalkyl iodide to 24-norchola-5,22-dien-3β-ol. From (1), the first series of steroidal liquid crystalline aliphatic esters (smectic A) with fluorocarbon side chains has been prepared. 相似文献
7.
Nikolay T. Tzvetkov 《Tetrahedron letters》2005,46(45):7751-7755
Bicyclic cyclopentafuranols were formed by photoinitiated radical cyclization of allyl- and propinyloxymethyl substituted cyclopentanones with high regioselectivity. The irradiations were carried out at a wavelength of 300 nm in aprotic solvents such as benzene and acetonitrile. We could also show that reductive photoinduced electron transfer (PET) of the propynyloxymethyl substituted cyclopentanone 5 does not lead to any cyclization. The starting materials were synthesized in good yields following known procedures. 相似文献
8.
旨在剖析祖仁教授主编的《高分子化学》第四版的教学思想和撰写特点,涉及章节、内容的选择和安排、逻辑思维和教学方法,以及一些技术术语等。同时也指出了新版教材的一些印刷错误等。 相似文献
9.
《Tetrahedron》2019,75(12):1639-1646
An efficient visible-light photocatalytic protocol for the vicinal heteroarylsulfonylation and oximinosulfonylation of unactivated olefins is described. The addition of sulfonyl radicals to alkenes triggers the intramolecular migration of remote heteroaryl and oximino groups via CC bond cleavage. The transformation features a good functional group tolerance and a broad substrate scope. A variety of valuable heteroaryl- and oximino-substituted alkyl sulfones are obtained under mild conditions in synthetically useful yields. 相似文献
10.
Nariman M. A. Nahas 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2327-2335
Thermal fragmentation of O-Aryl-N,N-diphenylhydroxylamines I and II were investigated. Neat heating in an atmospheric nitrogen afforded arenes, biaryl, diaryl sulfide, diphenylamine, diaryl sulfone, phenols, arenesulfonic acid, carbazole, and thianthrene. In the presence of isoquinoline as a radical trap, I gave 1-phenylisoquinoline as well as the previous products. Analogous results were obtained on heating of I in boiling tetraline, which lead to the formation of 1-hydroxytetraline, α -tetralone, and 1,1′-bitetralyl as the major products. A free-radical mechanism has been postulated to take place through the initial homolysis of N─O and S─O bonds to account for the identified products. 相似文献