Solution crystallization method

A review on thermal fractionation methods has been presented by Muller and Amal [73], who recall that DSC methods are sensitive to both intra- and intermolecular defects whereas solution crystallization methods, where separation takes place according to crystallizability, are more sensitive to inter- than intramolecular heterogeneity. 

Bottom Up Method 2 (Solution Crystallization Method) We crystallize the NAs from the solution of NA, n-butyl alcohol (n-BuOH) and xylene. The ratio of weight of n-BuOH and xylene is 7 19. We mix xylene to suppress the diffusion of theNA molecules. We control the size by changing the concentration of NA in the solution of NA,n-BuOH,and xylene,CNA/(n-BuOH yiene)-... 

Bottom Up Method 2 (Solution Crystallization Method) When CNA/(n-BuOH+xyiene) increases from 0.38 to 0.61 wt%, the formation of nano-NA (nano-NA-3) and macro-NA (macro-NA-3) are confirmed by WAXS and SEM, respectively, as shown below. We obtain %a of... 

Crystallization Method. Such methods as mechanical separation, preferential crystallisation, and substitution crystallisation procedures are included in this category. The preferential crystallisation method is the most popular. The general procedure is to inoculate a saturated solution of the racemic mixture with a seed of the desired enantiomer. Resolutions by this method have been reported for histidine (43), glutamic acid (44), DOPA (45), threonine (46), A/-acetyl phenylalanine (47), and others. In the case of glutamic acid, the method had been used for industrial manufacture (48). 

Crystallization from Solution. Crystallization techniques are related to the methods used to iaduce a driving force for soflds formation and to the medium from which crystals are obtained. Several approaches are defined ia the foUowiag discussion. 

Since Steiner s aim was to improve immaterial qualities of foods, anthroposophic scientists have developed analytical methods, which aim to visualize this kind of inner quality. This is done by preparing watery solutions of the plant, meat or milk (= juices) which are then brought into reaction with metallic salts like copper chloride (copper chloride crystallization method)... 

A batch cooling crystallization is one of the most commonly used crystallization method. In this process super saturation of a liquid is achieved by means of a cooling process. The solubility of the solute (in the solvent) decreases with a decrease in temperature this leads to precipitation of the solute. 

One-dimensional nanostructures of chalcogens and chalcogenides. An overview of solution-phase methods for generating one-dimensional nanostructures of chalcogens and chalcogenides has been presented by Mayers et al. (2004). Attention was especially focused on Se and Te because of their characteristic crystal structures and their catenation tendency. Basically, reactions were considered such as ... 

Fig. 11.2 Changes in the concentration of Me-est from ethanol solutions using the rapid cooling crystallization method...

There are several companies and groups that are developing bio-based succinic acid production for commercial use. The Showa group possesses a unique technology for purification of succinic acid from fermentation broth. This is the fractional crystallization method starting from sodium succinate. The yield by this method is around 70%, but we can recycle the residual solution so that we can minimize the loss of the product. We also compared the cost-effectiveness of this method with the bipolar electrodialysis method. The cost of our purification process seemed to be about half (our internal data). 

Rubidium alum obtained by either method above is decomposed by treatment with alkali solutions for removal of aluminum and sulfate. Aluminum is precipitated as aluminum hydroxide. Addition of barium hydroxide to the filtrate removes sulfate, precipitating barium sulfate. Evaporation of the solution crystallizes rubidium as hydroxide. 

At the end of the 19th century, Urbain, using the fractional crystallization method, prepared 60g of dysprosium oxide after 10,000 crystallizations then, in 1907, after 15,000 successive nitrate crystallizations from nitric solution, he separated lutetium and ytterbium. 

Figure 6.2. Cathodoluminescence tomograph of an emerald crystal synthesized by the high-temperature solution growth method. Note the regularly spaced faint growth banding appearing in between two distinct bands. (By courtesy of T. Miyata.)...

Among the solution-growth methods, crystallization from aqeous solution is well known. Materials with low water solubility may be brought into solution by the use of complexing agents (mineralizers). Selenium, for instance, can be grown from aqueous sulphide solutions, by making use of the reaction... 

Even a small protein consists of many hundreds of atoms. The primary aim of a structure determination is to place each of these atoms in space by determining the coordinates of each atom relative to a fixed coordinate system. The only techniques that can provide detailed information of this type are based on diffraction methods, and X-ray diffraction is the primary method. We must consider the meaning of the structures derived from these studies. Now X-ray diffraction can only be used to determine structures in crystals. One is, however, really concerned with the structure of proteins in solution, and it is therefore necessary to examine the difference between structure in the solid state and the solution state. We consider differences in general between these two states, and then differences in specific cases. To perform structural studies in solution, spectroscopic methods must be used. These methods are quite different from diffraction methods, being concerned with specific absorption or emission... 

Such a product may be prepared by various methods, e.g. by mixing a coarse crystalline substance derived from crystallization in benzene with a fine crystalline one obtained by the precipitation of tetryl with water from an acetone solution. Another method (according to Crater [22]) consists of pouring the benzene solution into water heated to above the boiling point of benzene. Alternatively, crystallization from dichlorethane (according to Rinkenbach and Regad [23]) may produce an acceptable form of tetryl. 

In another study, Kondrat eva (103) made a determination of the luminescent quantum yield of the 5D4 state of the terbium ion in aqueous solution. The method used was based upon fluorescent-lifetime measurements and had previously been used by Rinck (96) and Geisler and Hellwege (96) to determine the quantum yield of rare earths in crystals. Kondrat eva made his studies on chloride and sulfate solutions, using the electronic shutter technique of Steinhaus et al. (66). 

Crystallization methods starting with a solution and producing a colloid. 

In many cases, the crystal retains enzymatic activity. In some cases, the activity of the enzyme in the crystal is the same as that in solution. The methods used for initiating reactions for study by the Laue method are used to measure activity. For example, pH-jump the acylenzyme indolylacryloyl-chymotrypsin was crystallized at a pH at which it is stable. On changing the pH to increase the reactivity, the intermediate was found to hydrolyze with the same first-order rate constant as occurs in solution the reactions of crystalline ras p21 protein, glycogen phosphorylase, and chymotrypsin have been initiated by photolysis.52 Glyceraldehyde 3-phosphate dehydrogenase has also identical reaction rates in the crystal and solution under some conditions.53... 

Method I.—5 gms. pure p-nitrotoluene, 2 c.cs. of bromine, and a crystal of iodine are placed in a sealed tube. The tube is placed in a bomb furnace and gradually heated up during 40 minutes to 130°, at which temperature it is maintained for 160 minutes. After cooling, the tube is opened and the product extracted with about 60 c.cs. of hot alcohol. From the resulting solution crystals separate on cooling, which are filtered off a second crop is obtained after concentrating and cooling the mother liquor. Water is added to the final mother liquor to precipitate a small quantity of the nitrobenzyl bromide, which is filtered off, dried, and purified by recrystallisation from petroleum ether. The first and second crops should be washed with cold petroleum ether. 

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