Upon irradiation through Pyrex with a xenon lamp (hν>300 nm), terminal acetylenes undergo highly selective selenoperfluoroalkylation with perfluoroalkyl iodide and diphenyl diselenide. In this reaction, perfluoroalkyl and phenylseleno groups are selectively introduced into the terminal and internal positions of acetylenes, respectively. 相似文献
Using the ns pulse radolysis, we studied the characteristic absorption spectrum and kinetic decay of cytosine anion radical (Cyt-). Results showed that the characteristic absorption of Cyt- was located at λ=355±5 nm, and decayed following the first order kinetics with τ1/2=265 ns at pH=7.0. The decay became slower and τ1/2 rapidly rised with the increment of pH value, Cyt- protonated at C6 in acidic solution, and the characteristic absorption was located at λ=310±5 nm, and decayed following the second order kinetics: Cyt- protonated at N3 in aqueous solution of pH≥7, and the characteristic absorption was located at λ=295±5 nm, and decayed following the second order kinetics. 相似文献
A novel synthetic method combining chemo and enzymatic synthesis strategies was employed to prepare a vinyl acetate type monomer, 6‐(4‐methoxybiphenyl‐4′‐oxy)hexyl vinyl hexanedioate (VA‐LC). Homo‐ and copolymers of VA‐LC with maleic anhydride (MAn) were prepared by conventional free radical polymerization using 2,2′‐azobisisobutyronitrile (AIBN) and 1,1′‐azobis (cyclohexane carbonitrile) (AHCN) as an initiator at 95 and 60 °C, respectively. The thermal properties of the generated polymeric material were investigated by differential scanning calorimetry (DSC), and the optical texture was inspected by polarizing optical microscopy (POM). While the monomer VA‐LC does not exhibit liquid‐crystalline properties, poly(VA‐LC), and the alternating copolymer of VA‐LC with maleic anhydride both displayed such properties.
The reaction of the dimethoxyaminyl radical with functionally substituted nitrosoalkanes (2) in a 2:1 ratio at 20°C gives the corresponding N-alkyl-N-methoxydiazene N-oxides (3) as a single isomer in preparative yields.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2443–2445, October, 1992. 相似文献
Photoreduction of o-benzoquinones in the presence of p-bromo-N,N-dimethylaniline under irradiation ( > 500 nm) affords the corresponding pyrocatechols and hydroxyphenyl ethers. The latter are unstable and, in turn, decompose in the dark reaction to pyrocatechols. The ratio between pyrocatechol and hydroxyphenyl ether formed upon the photoreaction is determined by the structure of o-quinone, namely, the presence and bulk of substituents in positions 3 and 6 of the ring. The yield of pyrocatechol is maximal (60—65%) if the substituents are the same (H and H, But and But) or insignificantly differ (Pri and But), regardless of its bulk. 相似文献
An O-methylated analog of protonated phenazine-di-N-oxide radical anion abstracts hydrogen from primary and secondary alcohols
in a slow (k1 < 500 M−1 s−1) bimolecular reaction. No kinetic evidence has been found for the unimolecular release of free methoxyl radicals through
the homolytic N-OMe bond cleavage in these species. DFT calculations at the UB3LYP 6-31G(d) level indicate that protonated
and O-alkylated radical anions of pyrazine, quinoxaline and phenazine di-N-oxides are close analogues of aromatic nitroxyl
radicals with the highest spin density localized on the oxygen and nitrogen of the nitrone moiety. 相似文献