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991.
LUMIFLAVIN-SENSITIZED PHOTOOXYGENATION OF INDOLE 总被引:1,自引:0,他引:1
Abstract— The lumiflavin-sensitized photooxygenation of indole in aqueous solutions has been investigated by means of steady light photolysis and flash photolysis. The semiquinone of lumiflavin and the half-oxidized radical of indole were formed by the reaction between triplet lumiflavin and indole (3.7 times 109 M -1 s-1 ). The semiquinone anion radical of lumiflavin reacted with oxygen to form superoxide radical. The triplet state of lumiflavin also reacted with oxygen forming singlet oxygen, 1 O2 . But the reaction between 1 O2 and indole (7 times 107 M_l s_1 ; estimated from steady light photolysis using Rose Bengal as a sensitizer) was far less efficient than the reaction between indole and triplet lumiflavin. The quantum yield of the lumiflavin-sensitized photooxygenation of dilute indole via radical processes was much higher than that via 1 O2 processes, though appreciable 1 O2 was formed. 相似文献
992.
The reaction of [Ni[Co(aet)(2)(pyt)](2)](2+) (aet = 2-aminoethanethiolate, pyt = 2-pyridinethiolate) with [PtCl(4)](2)(-) gave an S-bridged Co(III)Pt(II)Co(III) trinuclear complex composed of two [Co(aet)(2)(pyt)] units, [Pt[Co(aet)(2)(pyt)](2)](2+) ([1](2+)). When a 1:1 mixture of [Ni[Co(aet)(2)(pyt)](2)](2+) and [Ni[Co(aet)(2)(en)](2)](4+) was reacted with [PtCl(4)](2)(-), a mixed-type S-bridged Co(III)Pt(II)Co(III) complex composed of one [Co(aet)(2)(pyt)] and one [Co(aet)(2)(en)](+) units, [Pt[Co(aet)(2)(en)][Co(aet)(2)(pyt)]](3+) ([2](3+)), was produced, together with [1](2+) and [Pt[Co(aet)(2)(en)](2)](4+). The corresponding Co(III)Pt(II)Co(III) trinuclear complexes containing pymt (2-pyrimidinethiolate), [Pt[Co(aet)(2)(pymt)](2)](2+) ([3](2+)) and [Pt[Co(aet)(2)(en)][Co(aet)(2)(pymt)]](3+) ([4](3+)), were also obtained by similar reactions, using [Ni[Co(aet)(2)(pymt)](2)](2+) instead of [Ni[Co(aet)(2)(pyt)](2)](2+). While [Pt[Co(aet)(2)(en)](2)](4+) formed both the deltalambda (meso) and deltadelta/lambdalambda (racemic) forms in a ratio of ca. 1:1, the preferential formation of the deltadelta/lambdalambda form was observed for [1](2+) (ca. deltalambda:deltadelta/lambdalambda = 1:3) and [2](3+) (ca. delta(en)lambda(pyt)/lambda(en)delta(pyt):deltadelta/lambdalambda = 1:2). Furthermore, [3](2+) and [4](3+) predominantly formed the deltadelta/lambdalambda form. These results indicate that the homochiral selectivity for the S-bridged Co(III)Pt(II)Co(III) trinuclear complexes composed of two octahedral [Co(aet)(2)(L)](0 or +) units is enhanced in the order L = en < pyt < pymt. The isomers produced were separated and optically resolved, and the crystal structures of the meso-type deltalambda-[1]Cl(2).4H(2)O and the spontaneously resolved deltadelta-[4](ClO(4))(3).H(2)O were determined by X-ray analyses. In deltalambda-[1](2+), the delta and Lambda configurational mer(S).trans(N(aet))-[Co(aet)(2)(pyt)] units are linked by a square-planar Pt(II) ion through four aet S atoms to form a linear-type S-bridged trinuclear structure. In deltadelta-[4](3+), a similar linear-type trinuclear structure is constructed from the delta-mer(S).trans(N(aet))-[Co(aet)(2)(pymt)] and delta-C(2)-cis(S)-[Co(aet)(2)(en)](+) units that are bound by a Pt(II) ion with a slightly distorted square-planar geometry through four aet S atoms. 相似文献
993.
The ruthenium catalyzed N-alkylation and N-heterocyclization of aniline using alcohols and aldehydes
Aniline reacts with saturated and 2,3-unsaturated alcohols in the presence of ruthenium catalyst at 180°C to give N-alkylanilines and 2,3-alkylquinolines in good yields. 相似文献
994.
Gamma ray waste water radiation monitor has been improved by using multichannel analyzer. Maximum permissible concentrations of 125I are one thousandth lower than 51Cr. This condition, the radioactive waste water cannot be pumped out occasionally. Gamma ray energy spectrum is measured by microcomputer based multichannel analyzer by which 125I photo-peak counts is separated from other radionuclide counts. Also detecting vessel is washed with pressured fresh water to prevent contamination. 相似文献
995.
Horiguchi Y Kodama H Nakamura M Yoshimura T Hanezi K Hamada H Saitoh T Sano T 《Chemical & pharmaceutical bulletin》2002,50(2):253-257
A synthesis of 1,1-disubstituted 1,2,3,4-tetrahydroisoquinolines (6) was achieved in a highly efficient manner via Pictet-Spengler reaction of arylethylamines (1) and acyclic and cyclic ketones (2) using titanium (IV) isopropoxide and acetic-formic anhydride. The cyclization of the in situ formed acyliminium ion (4) to N-formyl 1,2,3,4-tetrahydroisoquinoline (5) was greatly facilitated by using trifluoroacetic acid as an additional reagent. The Pictet-Spengler reaction was carried out by one pot procedure, providing a convenient and effective method for preparing various 1,2,3,4-tetrahydroisoquinolines. 相似文献
996.
Yukio Yoshimura Masahiro Nomoto 《Journal of polymer science. Part A, Polymer chemistry》1986,24(9):2351-2372
A method of determining the molecular species composition distributions of products obtained by reaction of tung oil with various phenols in the presence of acid catalyst has been studied. Methyl α-eleostearate was used as a model substance in place of tung oil. The product composition analysis of methyl α-eleostearate reactions with phenols was done by HLC. From these results, the molecular weight distributions and molecular species composition distributions of the reaction products were calculated according to a statistical procedure. Good agreement was found between the calculated and experimental molecular weight distribution, which enabled prediction of the molecular species composition distribution. 相似文献
997.
Electrochemical formation of barium tungstate (BaWO4) was studied as a model case of electrochemical formation of an advanced oxide material for electronics. BaWO4 is formed on the surface of tungsten electrode during oxidation in alkaline media (pH > 12) containing a corresponding cation.
The analysis of electrochemical as well as electrochemical quartz crystal microbalance (EQCM) data taken during these experiments
identifies at least three qualitatively different steps composing the electrode process. Effects of the potential, applied
current density and alkaline earth metal cation concentration are demonstrated using cyclic voltammetry and galvanostatic
experiments. Specific constraints of the ECC formalism for the electrochemical oxide deposition following from the galvanostatic
data are discussed.
Received: 2 October 1997 / Accepted: 4 December 1997 相似文献
998.
Kodera Y Ichikawa M Yoshida J Kashimoto N Uda N Sumioka I Ide N Ono K 《Chemical & pharmaceutical bulletin》2002,50(3):354-363
The pharmacokinetic behavior of allixin (3-hydroxy-5-methoxy-6-methyl-2-penthyl-4H-pyran-4-one) was investigated in an experimental animal, mice. Allixin was administered using an inclusion compound because the solubility of allixin in aqueous solution is very low. The allixin content in serum and in the organs of administered animals was analyzed by liquid chromatography (LC)-MS. Most of the administered allixin disappeared within 2 h, and the bioavailability of allixin was estimated to be 31% by obtained area under the blood concentration-time curve (AUC). The metabolites of allixin were studied using the metabolic enzyme fraction of liver and liver homogenate. Several new peaks corresponding to allixin metabolites were observed in the HPLC chromatoprofile. The chemical structure of the metabolites was investigated using LC-MS and NMR. Three of them were identified as allixin metabolites having a hydroxylated pentyl group. 相似文献
999.
Ion-exchanger colorimetry with 1-(2-pyridylazo)2-naphthol (PAN) has been developed for the determination of nickel at the mug/l. level in natural water. With 1 litre of sample the detection limits are 1.3 x 10(-9)Mi.e., 0.077 mug/l. for fresh water and 5.8 x 10(-9)Mi.e., 0.34 mug/l. for sea-water. The distribution ratio is 5 x 10(4). Copper and zinc, which form coloured species with PAN in the resin phase, can be completely eluted with a masking solution composed of EDTA and thioglycollic acid (pH 7.8). Cobalt can be determined simultaneously by measurement at 628 nm. 相似文献
1000.
Melting behavior of poly(3-hydroxybutyrate) investigated by two-dimensional infrared correlation spectroscopy 总被引:4,自引:0,他引:4
Padermshoke A Katsumoto Y Sato H Ekgasit S Noda I Ozaki Y 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(4):541-550
The melting behavior of a bacterially synthesized biodegradable polymer, poly(3-hydroxybutyrate) (PHB), was investigated by using generalized two-dimensional infrared (2D IR) correlation spectroscopy. Temperature-dependent spectral variations in the regions of the C-H stretching (3100-2850 cm(-1)), C=O stretching (1800-1680 cm(-1)), and C-O-C stretching (1320-1120 cm(-1)) bands were monitored during the melting process. The asynchronous 2D correlation spectrum for the C=O stretching band region resolved two crystalline bands at 1731 and 1723 cm(-1). The intense band at 1723 cm(-1) may be due to the highly ordered crystalline part of PHB, and the weak band at 1731 cm(-1) possibly arises from the crystalline part with a less ordered structure. These crystalline bands at 1731 and 1723 cm(-1) share asynchronous cross peaks with a band at around 1740 cm(-1) assignable to the C=O band due to the amorphous component. This observation indicates that the decreases in the crystalline components do not proceed simultaneously with the increase in the amorphous component. In the 3020-2915 cm(-1) region where bands due to the asymmetric CH3 stretching and antisymmetric CH2 stretching modes are expected to appear, eight bands are identified at 3007, 2995, 2985, 2975, 2967, 2938, 2934, and 2929 cm(-1). The bands at 2985 and 2938 cm(-1) are ascribed to the amorphous part while the rest come from crystal field splitting, which is a characteristic of polymers with a helical structure. 相似文献