Cry stallization

Attempts to prepare the mono(cyclopenta-dienyl) derivatives are sometimes frustrated by a Schlenk-type equilibrium (see p. 132), but judicious choice of ligands, solvent etc. occasionally permits the isolation of such compounds, e.g. the centrosymmetric halogen-bridged dimer (t - -C5Me5)Ca(/i-l)(lhf)2 2] which cry.stallizes from toluene solution. The complex is isostruc-tural with the dimeric organosamarium(ll) analogue. - ... 

Impinging jets, which consist of a cylindrical chamber with two spray nozzles that enter from opposite sides of the chamber, provide small particles with narrow size distribution. The solution oi the material is fed through one nozzle and the crystallization agent through the second nozzle. Finasteride has been cry.stallized in this way a solution of the material in acetic acid plus some water was fed from one nozzle and water from the other the average crystal size was 10 to 15 pm. 

Phenylmenthol (1), 11. 412-41.5. The material obtained from commercial ( + )-pule-gone by the original procedure of Corey and Ensley consists of (- )-8-phcnylmenthol and the Ci.Cfi-diastereomicr in the ratio 88 12. Separation of the pure reagent can be accomplished by column chromatography or, more conveniently, by cry.stallization of the 3,5-dinitrobenzoate ester, m.p. 119°, ao -217°. ... 

SYNS POTASSIUM monosulfide POTASSIUM SULFIDE, anhydrous (UN 1382) (DOT) POTASSIUM SULFIDE, hydrated with not <30% water of cri stallization (UN 1847) (DOT) POTASSIUM SULFIDE with <30% water of cri stallization (UN 1382) (DOT)... 

Deliquescence. — Many substances, cry.stallized and uncrystallized, absorb water when exposed to moist air, or often even to ordinary air, which always contains a little water vapor. This is called deliquescence, and such substances are said to deliquesce, or to be deliquescent... 

The manufacture of the industrially important zeolite types A, X and Y is generally carried out by mixing sodium aluminate and sodium silicate solutions, whereupon a sodium aluminosilicate get is formed. In this gel Si02- and Al203-containing compounds pass into the liquid phase, from which the zeolites are formed by cry.stallization. As the zeolite growth components are removed from the solution more gel dissolves. The reaction mechanism for zeolite formation is presently not yet fully understood. There is experimental evidence that, depending upon the reaction conditions, different mechanisms are possible. 

Michel, H. 1990. General and practical aspects of membrane protein cry stallization. In Crystallization of Membrane Proteins, (ed. H. Michel), pp. 73. CRC Press, Boca Raton, FL. 

This operation should be carried out in a well-ventilated hood. S( ratching the. sides of the beakers at the surface of th< wat(T promoters cry.stallization. I he beakers are stirred... 

Chemical treatment may be replaced by cry.stallization or ion-exchange units. However, their investment and operating costs are substantial and negatively influence the economics of the entire process. In addition, crystallization and ion exchange are delicate operations that may require specialized personnel. 

Regularity per se is not sufficient to ensure crystallizability in polymers. The spatial regularity and packing are important. To illustrate this, let us consider two examples of stereoregular polymers. Table 3.8 shows the properties of two isomers cis- and /raw5-polyisoprene. It is obvious from the table that the stereoregular trans form is more readily packed and cry stallizable and has properties of crystalline polymers. 

Correlations of nucleation rate with crystallizer variables have been developed for several sterns. For example. Bennett et al. examined the effect of slurry circulation rate on nucleation and developed a correlation based on the tip speed of the impeller. Crootsdiolten et al. considered the scale-up of nud ion kinetics for sodium chloride cry.stallization, and they provide an analysis of the role of mixii and mixer characteristics in contact nucleation. Garside and Sh reviewed published kinetic correlations though about 1979. 

From XRD (Figure 14.33) it is found that cry stallization of the polymer blend is taking place after irradiation increasing in optical band gap. The electronic energy loss plays a crucial role in the modification of properties of polymers after irradiation. 

Other developments were taking place among LTCC merchants. Hartmann and Booth announced a lo w-K cry stallizable dielectric tape that could be cofired with copper. Properties are shown in Table 1.13. Alexander described a tape with similar characteristics, although it was not cofirable with copper. Gupta discussed the issues involved in the synthesis of a low-firing tape system that offered low dielectric constant, low loss, and CTE matched to silicon. A later paper described the results of his research. " ... 

Cry stallization of cis- 1,4-polybutadiene between rollers during shearing has been modeled (214) using a novel procedure in which the influences of shear flow on lateral heat conduction is approximately avoided. This technique permits the crystalline layer build-up to be determined as a function of time, temperature, and shear rates in on-line processing. The morphology ereated under these conditions was studied. This is not an easy kinetic problem to handle theoretically. 

For pH <6, and pH >8, solubility of aluminum is appreciable. Gel transformation can occur via matter transport in the solution, in a dissolution-cry.stallization proce.ss (see Section 2.3.4). Slowly generated soluble species in small concentration, probably monomers, feed the formation of Al(OH)3 which is more stable than bochmite at room temperature (ACf29gK 01 ) Al(OH)j —546, 7-AIOOH = -436). 

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