Solvent The major component

Solvent—The major component of a solution, for example, water in sugar water. 

In the following, the solvent (the majority component) A is the material that shall be crystallized, and the minority component B, the solute is, e.g. an impurity. (Commonly, in crystal growth from solution, the minority component B is the... 

In Raman spectroscopy the intensity of scattered radiation depends not only on the polarizability and concentration of the analyte molecules, but also on the optical properties of the sample and the adjustment of the instrument. Absolute Raman intensities are not, therefore, inherently a very accurate measure of concentration. These intensities are, of course, useful for quantification under well-defined experimental conditions and for well characterized samples otherwise relative intensities should be used instead. Raman bands of the major component, the solvent, or another component of known concentration can be used as internal standards. For isotropic phases, intensity ratios of Raman bands of the analyte and the reference compound depend linearly on the concentration ratio over a wide concentration range and are, therefore, very well-suited for quantification. Changes of temperature and the refractive index of the sample can, however, influence Raman intensities, and the band positions can be shifted by different solvation at higher concentrations or... 

Theory. Conventional anion and cation exchange resins appear to be of limited use for concentrating trace metals from saline solutions such as sea water. The introduction of chelating resins, particularly those based on iminodiacetic acid, makes it possible to concentrate trace metals from brine solutions and separate them from the major components of the solution. Thus the elements cadmium, copper, cobalt, nickel and zinc are selectively retained by the resin Chelex-100 and can be recovered subsequently for determination by atomic absorption spectrophotometry.45 To enhance the sensitivity of the AAS procedure the eluate is evaporated to dryness and the residue dissolved in 90 per cent aqueous acetone. The use of the chelating resin offers the advantage over concentration by solvent extraction that, in principle, there is no limit to the volume of sample which can be used. 

A solution is a mixture of two or more substances. The substances involved are mixed so intimately (on the atomic scale) that it is not possible to distinguish their individual properties. A solution constitutes a single phase, as distinct from heterogeneous systems which contain several phases. A solution, however, differs from a chemical compound in that its composition is not fixed but can vary over a range. It is customary to designate the major component of a solution as the solvent, and the minor ones as the solutes. A solvent as well as a solute can be a gas, a solid or a liquid. Depending upon the state of the solute and/or the solvent, several types of solutions may exist. 

The solvent and temperature effects for the Michael addition of amidoxime 7 to DMAD were probed because the reaction itself occurs without any other catalysts. As shown in Table 6.2, the reaction gave a high ratio of 8E in strongly aprotic polar solvents such as DMF and DMSO (entry 1 and 2). 8E was also found as the major product in MeCN (entry 3), dichloromethane (entry 4), and xylenes (entry 5). To our delight, the desired 8Z was obtained as the major component in methanol (entry 6). The stereoselectivity of 8Z versus 8E was better at low temperature (entry 7). A similar result was observed when the reaction was run in THF or dichlo-roethane in the presence of a catalytic amount of DABCO (entries 9 and 10). 

A11 solvents contained 2-methylnaphthalene as the major component. In some cases 18% p-cresol was also present. 

There is no question that the development and commercialization of lithium ion batteries in recent years is one of the most important successes of modem electrochemistiy. Recent commercial systems for power sources show high energy density, improved rate capabilities and extended cycle life. The major components in most of the commercial Li-ion batteries are graphite electrodes, LiCo02 cathodes and electrolyte solutions based on mixtures of alkyl carbonate solvents, and LiPF6 as the salt.1 The electrodes for these batteries always have a composite structure that includes a metallic current collector (usually copper or aluminum foil/grid for the anode and cathode, respectively), the active mass comprises micrometric size particles and a polymeric binder. 

Hydrogen-bond donors have the ability to enhance the selectivities and rates of organic reactions. Examples of catalytic active hydrogen-bond donor additives are urea derivatives, thiourea derivatives (Scheme 10, Tables 12 and 13) as well as diols (Table 14). The urea derivative 7 (Scheme 9) increases the stereoselectivity in radical allylation reactions of several sulphoxides (Scheme 10)171. The modest increase in selectivity was comparable to the effects exerted by protic solvents (such as CF3CH2OH) or traditional Lewis acids like ZnBr2172. It was mentioned that the major component of the catalytic effect may be the steric shielding of one face of the intermediate radical by the complex-bound urea derivative. 

GC-MS spectral analysis. Subsequent extraction of the basified aqueous phase removed another 14% of the aqueous 1 C which contained 10 products as determined by the TLC analysis using solvents (j) and (k). HMI, which accounted for 58.8% of the extract, was the major component of this extract as determined by TLC cochromatography in solvents (j) and (k). Five other unidentified products were still present in the aqueous phase (TLC solvent (h)) after neutral, acidic and basic extraction. 

The EtOH extract of Ipomoea dichroa Choisy was fractionated into different organic solvents. The n-hexane-soluble fraction was resolved by column chromatography to afford dichrosides A-D. The major component dichroside D (hexadecanoic acid, (115)-[(0-6-deoxy-a-L-mannopyranosyl-(1 3)-0-[ S-D-glucopyranosyl-(l—>4)]-0-6-deoxy-a-L-mannopyranosyl-(1 4)-0-6-deoxy-a-L-mannopyranosyl-(l—>2)-6-deoxy-a-L-mannopyranosyl)oxy]) was subjected to catalytic hydrogenation. 

B is introduced gradually over a long period. (B) An example of a steep gradient on the Xtreme Simple by Microtech, in which solvent B is introduced quickly and used for the majority of the elution. In both chromatograms, the gradient ends with solvent A being restored as the major component. 

In both designs, the discharge lamp is filled with krypton and emits 10.6 eV photons, an energy lower than that of the major components of air and some of the commonly used solvents. 

Polybrominated Biphenyls. The photolytic degradation of PBBs in solution has been the subject of several studies. Available data in the literature indicate that brominated biphenyls photodegrade by reduction in solvents capable of proton transfer with the formation of lower brominated biphenyls. For example, the irradiation of FireMaster BP-6 and 2,2, 4,4, 5,5 -hexabromobiphenyl in methanol at wavelengths >286 nm produced mainly penta- and tetrabromobiphenyl (Ruzo and Zabik 1975). FireMaster BP-6 photolyzed7 times faster than its chlorinated counterpart, 2,2, 4,4, 5,5 -hexachloro-biphenyl (Ruzo and Zabik 1975). Although an earlier study tentatively identified dimethoxy tetrabromobiphenyl as a photolysis product of FireMaster BP-6 (Ruzo and Zabik 1975), later work did not detect this compound (Ruzo et al. 1976). Earlier studies indicated that the debromination usually occurs with the stepwise preferential loss of bromine from the ortho and para positions of the biphenyl ring (i.e., 2, 2, 6, and 6 positions) (De Kok et al. 1977 Ruzo and Zabik 1975 Ruzo et al. 1976 Trotter 1977). Thus, the photolysis of 2,2, 4,4, 5,5 -hexachlorobiphenyl, the major component of FireMaster BP-6, would be expected to produce 23, 4,4, 5-pentabromobiphenyl and subsequently... 

Thin layer chromatograms were obtained with silica gel as absorbent and ethyl acetate as developing solvent. The order of elution and Rf values of the major components are as follows menthyl sulfinate (0.65), menthol (0.59), sulfinyl ketal (0.30). 

It has been shown that the redistribution of solvent composition happens even in the case of two solvents having identical interaction parameters with network links Xan = Xbn (Fig. 6, B). In this case when Xab > 0 the sample is enriched by the minority component (i.e. the component with lower content in external solution). In contrast, enrichment of the sample by the majority component occurs if Xab < 0. As a result, if Xab > 0 the additional swelling in comparison with the case of pure solvent happens, while in the case Xab < 0 the additional compression of gel takes place. 

Viscosity Measurements. Although in typical polymer-plasticizer systems, the polymer is the major component, it is possible to use the viscosity of dilute polymer solutions as a measure of the solvent power of the liquid for the polymer. Thus, liquids with high solvent power for the polymer cause a stretching out of the chain molecules, whereas a liquid of poor solvent power causes the chains to coil up. This is because, in the liquid with poor solvent power, the segments of the polymer chain (the monomer units) prefer to stay close to each other, while in a good solvent, interaction between polymer segments and solvent molecules is preferred. 

The spectrophotometer is used to measure absorbance experimentally. This instrument produces light of a preselected wavelength, directs it through the sample (usually dissolved in a solvent and placed in a cuvette), and measures the intensity of light transmitted by the sample. The major components are shown in Figure 5.5. These consist of a light source, a monochromator (including various filters, slits, and mirrors), a sample chamber, a detector, and a meter or recorder. All of these components are usually under the control of a computer. 

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