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71.
A rapid and effective synthesis of propylene carbonate using a supercritical CO2-ionic liquid system 总被引:1,自引:0,他引:1
Kawanami H Sasaki A Matsui K Ikushima Y 《Chemical communications (Cambridge, England)》2003,(7):896-897
The synthesis of propylene carbonate from propylene oxide and carbon dioxide under supercritical conditions in the presence of 1-octyl-3-methylimidazolium tetrafluoroborate was achieved in nearly 100% yield and 100% selectivity within 5 minutes, whose TOF value is 77 times larger than those so far reported. 相似文献
72.
Viau L Bidault S Maury O Brasselet S Ledoux I Zyss J Ishow E Nakatani K Le Bozec H 《Journal of the American Chemical Society》2004,126(27):8386-8387
A new type of 4,4'-bis(styryl)-2,2'-bipyridine functionalized by a dialkylamino-azobenzene group has been prepared. This ligand has allowed the preparation of photoisomerizable octupolar tris(bipyridyl)zinc(II) complexes and the corresponding star-shaped polymer by atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). The photoisomerization properties of such new metallo-chromophores have been studied. The macroscopic molecular orientation of the corresponding doped and grafted NLO-polymer films is reported for the first time. 相似文献
73.
Keitaro Senga Misuzu Ichiba Hashime Kanazawa Sadao Nishigaki 《Journal of heterocyclic chemistry》1982,19(1):77-80
Synthesis and properties of hitherto unknown thiazolo[5,4-d]pyrimidine 1-oxides are described. For example, the reaction of 6-chloro-1,3-dimethyl-5-nitrouracil (I) with methyl thioglycolate in the presence of excess triethylamine afforded 2-methoxycarbonyl-4,6-dimethylthiazolo[5,4-d]pyrimidine-5,7-(4H,6H)dione 1-oxide (IIIa), which is a versatile intermediate for the preparation of various thiazolo[5,4-d]pyrimidine derivatives. 相似文献
74.
The reaction of 6-arylidenehydrazino-1,3-dimethyluracils with thionyl chloride in benzene afforded purine, thiazolo[4,5-d]pyrimidine, pyrimido[4,5-e][1,3,4]thiadiazine, pyrazolo[3,4-d]pyrimidine, and [1,2,3]thiadiazolo[4,5-d]pyrimidine derivatives, while the treatment of 6-(benzylidene-1′-methylhydrazino)-1,3-dimethyluracil with thionyl chloride in benzene gave 4-methylpyrimido[4,5-e][1,3,4]thiadiazine and 1-methylpyrazolo-[3,4-d]pyrimidine derivatives. Plausible mechanisms for the formation of these fused pyrimidines are also described. 相似文献
75.
Faria Luis F. Figueiredo Gimenes Maria Antonieta P. Nobrega Ronaldo Pereira Nei 《Applied biochemistry and biotechnology》2002,98(1-9):449-458
Oxygen availability is the most important environmental parameter in the production of xylitol by yeasts, directly affecting
yields and volumetric productivity. This work evaluated the cell behavior in fermentations carried out with different dissolved
oxygen concentrations (0.5–30.0% of saturation), as well as a limited oxygen restriction (0% of saturation), at several oxygen
volumetric transfer coefficients (12 ≤ k
L
a ≤ 70 h−1). These experiments allowed us to establish the specific oxygen uptake rate limits to ensure high yields and volumetric productivity.
When oxygen availability was limited, the specific oxygen uptake rate values were between 12 and 26 mg of O2/of g cell·h, resulting in a yield of 0.71 g of xylitol/xylose consumed, and 0.85 g/[L·h] for the volumetric productivity.
According to the results, the effective control of the specific oxygen uptake rate makes it possible to establish complete
control over this fermentative process, for both cell growth and xylitol production. 相似文献
76.
The first coordination polymer of 2,2′‐((4‐carboxymethyl‐1,3‐phenylene)bis(oxy)) diacetic acid (H3L) with europium(III) ion, [Eu(L)(H2O)]·3H2O ( 1 ), has been hydrothermally synthesized and structurally characterized. Complex 1 exhibits a 3D coordination polymer with helical chain and rtl topology of the point symbol (4·62)2(42·610·83) based on [Eu2(COO)4] as secondary building unit (SBU). Furthermore, the luminescent and magnetic properties of complex 1 are studied. 相似文献
77.
Desmond V. OConnor Minoru Sumitani John M. Morris Keitaro Yoshihara 《Chemical physics letters》1982,93(4):350-354
Two-component fluorescence decay has been observed in isolated pentafluorobenzene and hexafluorobenzene excited at 266 nm. From the temperature and pressure dependence of the decay constants an attempt has been made to separate sequence congestion effects from other possible causes of non-exponential behavior. 相似文献
78.
79.
80.
Optical Review - We have realized a multifunctional aerial display. An aerial image of a polarization-processing display is formed through aerial imaging by retro-reflection. By changing the... 相似文献