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31.
2-(9H-Xanthen-9-ylmethyl)-1H-benzimidazole ( 2a ) was prepared by condensing 9H-xanthene-9-acetic acid ( 1a ) with 1,2-benzenediamine. Similarly, 2-(9H-thioxanthen-9-ylmethyl)-1H-benzimidazole ( 2b ) and its S,S-dioxide ( 2d ) were obtained. Compound 2d was also prepared by oxidizing 2b with hydrogen peroxide in acetic acid. Heating of 9H-thioxanthene-9-acetic acid 10-oxide ( 1c ) with 1,2-benzenediamine gave 9-methylene-9H-thioxanthene ( 3 ). 2-(9H-Thioxanthen-9-ylmethyl)-1H-benzimidazole S-oxide ( 2c ) was obtained by oxidizing 2b with m-chloroperbenzoic acid in acetone. 相似文献
32.
33.
Michael H. Gold Hidetoshi Kutsuki Meredith A. Morgan 《Photochemistry and photobiology》1983,38(6):647-651
Oxidation of specifically radiolabeled 14C-lignins by UV/H202. Fenton's reagent, photosesitizing riboflavin. UV- and γ-irradiation was examined. In the presence of UV/H2O2, a hydroxyl radical (·OH) generating system. 14C-methoxy. 2-[14C-sidechain] and 14C-ring labeled lignin were rapidly and extensively degraded as measured by gel filtration of the reaction products on Sephadex LH-20. This suggested that exposure to OH leads to rapid, nonspecific lignin degradation. Rapid degradation of 14C-methoxy, 2-[14C-sidechain] and 14C-ring labeled lignin also occurred in the presence of the ·OH generating system, Fenton's reagent, confirming the primary role of ·OH in these reactions. Photosensitizing riboflavin, also capable of effecting transformation of organic compounds via Type I hydrogen radical abstractions, caused extensive oxidative degradation of 14C-methoxy labeled lignin and significant degradation of 2-(14C-sidechain] and 14C-ring labeled lignin. In addition, UV- and γ-irradiation caused slower but extensive degradation of the polymers, probably via radical type mechanisms. All of these results indicate that ·OH as well as organic radical generating systems are effective agents for the purpose of degrading this heterogeneous, optically inactive and random biopolymer. 相似文献
34.
T Sato T Fujiwara Y Abe M Itoh H Fukuda J Hatazawa K Kubota T Ido T Matsuzawa 《Radioisotopes》1989,38(1):7-12
We investigated glucose and amino acid metabolism in tumors and other organs using whole body autoradiography with a short-lived positron emitter and a long-lived beta emitter. The radioactive compounds used were 2-deoxy-2-[18F]-fluoro-D-glucose (18F-FDG) with a half life of 109.8 min and L-[methyl-14C]-methionine (14C-MET) with a half life of 5,730 years. A Donryu rat weighing about 150 g was subcutaneously inoculated at the back with experimental tumors of AH109A and AH272. 74 MBq (2 mCi) of 18F-FDG and 740 kBq (20 microCi) of 14C-MET was administered and after 30 min, the rat was sacrificed. Whole body frozen sections were obtained using autocryotome. For the 18F-FDG autoradiogram, the frozen sections were exposed to an X-ray film for 6 h. After seven days, these frozen sections were again exposed to 14C-MET for a week. Cross-contamination was minimized by adjusting the exposure time, the interval of exposures and the administered dose. The accumulation of the tracers was represented as the optical density ratio of the tissue of interest to the muscle. The tumor ratios were 12.5 for 18F-FDG and 8.6 for 14C-MET showing the highest accumulation in the whole body autoradiogram. In contrast the inflammatory tissue ratios were 1.27 for 18F-FDG and 0.77 for 14C-MET showing very low amino acid metabolism. With the present double tracer whole body autoradiogram, 18F-FDG accumulation was seen in the brain and the heart but not to the liver as against 14C-MET accumulation which was seen to the liver but not to the brain and the heart. 相似文献
35.
36.
The molecular displacements on the M011-->M101 phase transition of n-hexatriacontane (n-C36H74) have been investigated with an IR microscope designed for the oblique infrared transmission method. It has been clarified that two polytypic structures of the M011 modification, single-layered structure (Mon) and double-layered one (Orth II), both transform to the M101 modification of single-layered structure with their respective mechanisms. On the M011(Mon)-->M101 transition, the inclination direction of molecular axis is changed by 90 degrees through an intermediate state in which the molecular chain is set perpendicular to the basal plane of the single crystal. On the other hand, a polymorphic-polytypic composite structural change on the M011(Orth II)-->M101 transition is accomplished through two kinds of molecular displacements occurring alternately along the stacking direction of molecular layers. 相似文献
37.
The thermodynamic properties of the two polytypes of n-hexatriacontane (n-C36H74), single-layered structure Mon and double-layered structure Orth II have been investigated by means of solubility measurements and incoherent inelastic neutron scattering. The solubility measurements reveal that Orth II is more stable than Mon by 1.2 kJ/mol because of the advantage of larger entropy. The neutron scattering measurements show that the vibrational modes of Orth II shift to the lower frequencies compared with those of Mon in the frequency region below 120 cm(-1). The advantage of Orth II in vibrational entropy due to the low-frequency shifts is estimated to be 9.6 J K(-1)/mol at 288 K under the harmonic approximation, which nearly agrees with the entropy difference of 6.8 J K(-1)/mol between Mon and Orth II determined by solubility measurements. These results suggest that the difference in vibrational entropy due to low-frequency modes mainly contributes to the relative thermodynamic stabilities of polytypic structures of long-chain compounds. From the frequency of methyl torsional mode, it is suggested that the cohesive force at the lamellar interface is stronger in Mon than in Orth II. 相似文献
38.
Kawai H Katoono R Fujiwara K Tsuji T Suzuki T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(3):815-824
The molecular recognition of catecholamines by hydrindacene-based receptors 1 and 2, as well as the durene-based receptor 3, and the guest-induced conformational changes are reported. These receptors selectively bind adrenaline and dopamine salts through the guests' ammonium group and 3-hydroxyl group on the aromatic ring. In the case of adrenaline, an additional hydrogen bond with a benzylic hydroxyl group is formed. In 2 % CD3CN/CDCl3, the association constants are of the order of 10(4) M(-1), which is much larger than with guests without the 3-hydroxyl groups (10(3) M(-1)). The two amide groups of receptor 1 can rotate freely around the C(aromatic)--C(amide) bond, whereas the tert-amide in 2 changes between two stable conformations at a slow enough rate to allow detection by (1)H NMR spectroscopy. In the absence of a guest molecule, the syn-conformer is less stable than the anti-conformer. On complex formation with adrenaline, the syn-conformer becomes dominant due to an intramolecular dipole-reversal effect in addition to multipoint hydrogen bonding. 相似文献
39.
M. Kubota 《Journal of Radioanalytical and Nuclear Chemistry》1983,78(2):295-305
Ion exchange resins are widely used in the field of nuclear industry. The present work aimed at the development of a method
for complete decomposition of cation exchange resins with H2O2 in the presence of Fe3+ ion. The decomposition reaction proceeded at ambient temperature and decomposition time was greatly shortened with increasing
concentration of Fe3+ ion rather than that of H2O2. The catalytic action of Fe3+ ion was suppressed with increase of HNO3 concentration. As much as 4 g of the air-dried resin could be decomposed with 8 ml of 30% H2O2, and the use of about 60 ml of 30% H2O2 resulted in the complete decomposition of organic carbon to CO2. Absence of any orgnaic carbon in the residual solution will simplify the final disposal. 相似文献
40.
Edwards KW Ogg M Bellerive A Britton DI Hyatt ER MacFarlane DB Patel PM Spaan B Sadoff AJ Ammar R Baringer P Bean A Besson D Coppage D Copty N Davis R Hancock N Kelly M Kotov S Kravchenko I Kwak N Lam H Kubota Y Lattery M Momayezi M Nelson JK Patton S Poling R Savinov V Schrenk S Wang R Alam MS Kim IJ Ling Z Mahmood AH O'Neill JJ Severini H Sun CR Wappler F Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Sung M White C Wolf A Zoeller MM Butler F Fu X Nemati B 《Physical review letters》1995,74(17):3331-3335