Recrystallization method

The enantioselective inclusion complexation of the reaction product with lOa-c in aqueous medium is more efficient than that by the recrystallization method. For example, inclusion complexation of rac-65e with 10a,b did not occur by recrystallization from an organic solvent however, enantioselective complexation occurred efficiently in aqueous medium to give finally optically active 65e [12]. 

Materials. All phosphors used In this study were prepared by solid state methods previously reported. LaOBr Tb and LaOBr Tm phosphors were prepared by a molten KBr flux recrystallization method (8) which gives clear, single crystal... 

Zhang and co-workers reported partial conversion of a mesoporous starting material (SBA-15) into a mesoporous aluminosilicate with zeolitic characteristics in a so-called vapour phase transport method.[82] In this process, Al is firstly introduced onto the mesoporous surface, followed by a filling of the mesopores with a carbonaceous species, and finally a partial recrystallization of aluminosilicate in the vapour of the SDA is conducted. The advantage of this method, compared with the hydrothermal recrystallization method of Kloetstra et al., lies in the fact that the mesopore structure collapses to a lesser extent as the crystallization is limited to the surface of the mesoporous precursor. 

Hexachloro-p-xylylene(HCX) is prepared by passing 2,5,7,7,7,8,8,8-octachloro-p-xylene vapor over a copper mesh at 500 °C at a reduced pressure58 Pure yellow crystalline HCX is obtained by the same recrystallization method used... 

Comparatively pure linoleic acid can be obtained, for example, by the purification of safflower oil fatty acid such as low temperature recrystallization method, distillation method, urea method, salt recrystallization method, etc. Source Seki 1971... 

Moreover, the intercalation method was applied to the enantioresolution of racemic alcohols. The amide derivative of cholic add, called cholamide, serves as an excellent host for enantioresolution of 2,2-dimethyl-3-hexanol among secondary aliphatic alcohols. The intercalation method gave highly effective enantioresolution of the alcohol, as in the case of the recrystallization method. For example, dioxane molecules were exchanged with the alcohol molecules in channels of the bilayers with a high enantioselectivity of 96% ee, which was close to the value (98% ee) obtained by the recrystallization method. X-ray diffraction studies proved that the host bilayer framework has an anti-parallel arrangement on the lipophilic side in the case of dioxane, while the framework has a parallel one after intercalation of the alcohol. This indicates that the intercalation accompanies a layer-reversion. Such dynamical enantioresolution confirms the effidency of the intercalation method. 

The reaction of 2-oxopropanal with 2,5,6-triaminopteridin-4(37/)-one has been extensively studied.54 59 In neutral, or mildly acidic solution, a mixture of 2-amino-7-methylpteridin-4(3//)-one (7) and its 6-methyl isomer 8 are formed, but the 7-isomer is greatly preponderant. Separation may be achieved by recrystallization methods. Separation has also been achieved by utilizing the different propensity to form adducts with hydrogen sulfite.272... 

The major advantage of the recrystallization method is that alloys can be prepared of the desired composition by arc melting or some other suitable method of melting and then heat treated without changing composition. This is even true of metals with wide differences in vapor pressure. Alloys with a volatile component can be heat treated under pressure or in a sealed refractory metal crucible. McEwen and Touborg (1973) used an overpressure of 4 atmospheres while arc melting Tm alloys to prevent excessive vaporization of Tm. The alloys were then sealed in Ta to prevent loss during heat treatment. They also produced crystals of Y, Sm, Gd, Tb, Dy, Ho, Er, Tm, and many other intra-rare earth alloys. 

During the first decade of the insulin era, only an acid solution of an impure form of the hormone was available for therapy. When it became possible to crystallize insulin, the purity, and hence the biological potency, of the hormone improved substantially (Table I). These improvements were mainly achieved by introduction of Ztf+-crystallization (Scott, 1934) and recrystallization methods, the latter based on the observation that insulin recrystallized several times was better tolerated by patients suffering from allergic reactions (Jorpes, 1949). Until the late 1960s, recrystallized insulin was considered to be an essentially pure substance, but the introduction of new analytical methods made it possible to detect the presence of significant amounts of protein impurities by disc electrophoresis (Mirsky and... 

Due to the different orientations reciystallized films are not very suitable for solar cell applications. Recrystallization methods which require even higher temperatures can not be applied if glass substrates are used /26/. Furthermore the films are incorporating doping materials which affect the performance of the cells. 

Even today, drugs based on digitalis extract, such as Digitoxin and Digoxin, are some of the best-known treatments to control the heart rate. Nowadays, preparations from digitalis leaves are made using modern recrystallization methods and are carefully standardized by bio-assay. 

In conclusion, this study demonstrates that the polymorphic inclusion compounds can selectively be obtained by changing the recrystallization methods. An identical unsaturated nitriles were accommodated into the different inclusion spaces. This face would enable us to evaluate an effect of molecular-level spaces for the reaction, such as inclusion polymerization. 

In the case of CeP, no sharp peak in p versus T was observed (Hulliger and Ott 1978). Kwon etal. (1991) grew very good single crystals using a recrystallization method with an excess of P. The temperature dependence of the electrical resistivity of CeP is shown in fig. 121 (Kwon et al. 1991). This result is very similar to that obtained for CeAs (see fig. 120), and in fact the carrier concentration determined by the de Haas-van Alphen (dHvA) effect is nearly the same as that obtained for CeAs (0.001 electron/Ce-atom). 

In Method A, the steroids are reacted with acrlyoyl chloride in the presence of triethylamine at low temperatures to provide the desired monomers. In Method B, acrylic acid is condensed with the steroids in the presence of dicyclohexylcarbodiimide and N,N-dimethylaminopyridine to give the same monomers. In both cases the crude monomers need to be purified first by flash chromatography and, finally, by recrystallization. Method B has been found to be more efficient and the crude products obtained are cleaner than those obtained from Method A. The monomers are... 

Liu and co-workers extended this precipitation and recrystallization method to non-aqueous solutions/ Supercritical COg/ethanol was used as a solvent with high diffusivity and strong salvation strength, which are good for the recrystallization of ID nanostructures. 

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