Nonpolar solvent, defined

Nitrosamlnes, ascorbic acid and, 915-916 N-1 Inked glyCOptOtKins, 59 NMDA tcceplor, 252 n minus nomenclature, fatty acids, 640 Non-lnsuiln-dependent diabetes mellitus (NIDDM), 171,173-174 obesity as risk factor, 380 weight loss and, 389-391 Nonpolar solvent, defined. 26 Nonspecific nitrogen, 460 Noiepinepbrlne, 185,623 NO synthase, 200 NPU, see Not protein utilization... 

In the past few years, a range of solvation dynamics experiments have been demonstrated for reverse micellar systems. Reverse micelles form when a polar solvent is sequestered by surfactant molecules in a continuous nonpolar solvent. The interaction of the surfactant polar headgroups with the polar solvent can result in the formation of a well-defined solvent pool. Many different kinds of surfactants have been used to form reverse micelles. However, the structure and dynamics of reverse micelles created with Aerosol-OT (AOT) have been most frequently studied. AOT reverse micelles are monodisperse, spherical water droplets [32]. The micellar size is directly related to the water volume-to-surfactant surface area ratio defined as the molar ratio of water to AOT,... 

An isolated ion-pair, of initial separation r0 at time t0 = 0, in a nonpolar solvent may recombine or separate and ultimately escape. At a time t, the probability that the ion-pair will have recombined is < (t r0, t0 = 0) and that it is still extant p(t r0) f0 = 0). A short while later, the probability that the ion-pair has not recombined is p t + df r0, t0 =0). The change in survival probability is the probability that the ion-pair recombined during the time interval t to t + df, that it had a lifetime between t and t -f df. Defining the lifetime distribution function as f(f), then... 

Lipids are defined as water-insoluble compounds extracted from living organisms by weakly polar or nonpolar solvents. This definition is based on a physical property, in contrast to the definitions of proteins, carbohydrates, and nucleic acids, which are based on chemical structure. Consequently, the term lipid covers a structurally diverse group of compounds, and there is no universally accepted scheme for classifying lipids. 

Simple 2,2-dibutyl-l,3,2-dioxastannolanes form solid complexes of monomer units with certain nucleophiles, such as pyridine and dimethyl sulfoxide, that have 1 1 stoichiometry and pentacoordinate tin atoms.62 Such complexes are less stable for more-substituted stannylene acetals, such as those derived from carbohydrates.62 Unfortunately, the precise structures of these complexes have not yet been defined. Addition of nucleophiles to solutions of stannylene acetals in nonpolar solvents has been found to markedly increase the rates of reaction with electrophiles,63 and transient complexes of this type are likely intermediates. Similar rate enhancements were observed in reactions of tributylstannyl ethers.57 Tetrabu-tylammonium iodide was the nucleophile used first,57 but a wide variety of nucleophiles has been used subsequently tetraalkylammonium halides, jV-methylimidazole,18 and cesium fluoride64,65 have been used the most. Such nucleophilic solvents as N,N-dimethylformamide and ethers probably also act as added nucleophiles. As well as increasing the rates of reaction, in certain cases the added nucleophiles reverse the regioselectivity from that observed in nonpolar solvents.18,19... 

Most alkenes do not polymerize in the presence of only hydrogen halides. One noticeable exception is JV-viny] carbazole, the most nucleophilic alkene, which is successfully polymerized by HI, HBr, and HC1 [111], Polymerization by HI produces well-defined polymers [112], Cyclohexyl vinyl ether also produces well-defined polymers when initiated by HI, although the polymerization is slow [113]. Other vinyl ethers form 1 1 a-alkoxyiodoethanes adducts with hydrogen iodide rather than polymer, especially in nonpolar solvents [Eq. (27)]. 

Chemical structures of sporaviridins are described in Fig. 1. They are only soluble in polar solvents such as water, methanol, and n-butanol. Therefore, a two-phase solvent system containing n-butanol was examined. A nonpolar solvent such as diethyl ether has been added to the n-butanol-water system to decrease the solubility of molecules in n-butanol and to obtain partition coefficients close to 1. The partition coefficients, K, are defined as the ratio of the solute concentration in the upper phase (butanol rich) to its concentration in the lower one (water rich). A two-phase solvent system oin-butanol-diethyl ether-water (10 4 12, v/v/v) was selected because it allows one to obtain the almost equally dispersed partition coefficients among six components (C2, B2, A2, Cl, Bl, Al). The preparative separation of six components from sporaviridin complex by HSCCC was performed in 3.5 h (500 mL of elution volume). The six components were eluted in the order of their partition coefficients, yielding pure components Al (1.4 mg), A2 (0.6 mg), Bl (0.7 mg), B2 (0.5 mg). Cl (1.1 mg), and C2 (1.4 mg) from 15 mg of the sporaviridin complex. 

Regular solution theory characterises nonpolar solvents in terms of solubility parameter, 6y which is defined as... 

The same initiator was also used to produce a three-arm PBd star.26 Complete monomer consumption was observed, but SEC analysis showed a bimodal distribution. This behavior was attributed to the strong association effects of the trifunctional initiator in a nonpolar solvent. The problem was overcome when s-BuOLi was added in the reaction mixture in a ratio [s-BuLi] [s-BuOLi] = 2. s-BuOLi was shown to be capable of disrupting the initiator association without affecting appreciably the microstructure of the PBd chains. Therefore, a well-defined star polymer with low molecular weight distribution was obtained. 

A solvent for ultraviolet/visible spectroscopy must be transparent in the region of the spectrum where the solute absorbs and should dissolve a sufficient quantity of the sample to give a well-defined analyte spectrum. In addition, we must consider possible interactions of the solvent with the absorbing species. For example, polar solvents, such as water, alcohols, esters, and ketones, tend to obliterate vibration spectra and should thus be avoided to preserve spectral detail. Nonpolar solvents, such as cyclohexane, often provide spectra that more closely approach that of a gas (compare, for example, the three spectra in Figure 24-14). In addition, the polarity of the solvent often influences the position of absorption maxima. For qualitative analysis, it is therefore important to compare analyte spectra with spectra of known compounds measured in the same solvent. 

Lipids (or fats) are a heterogeneous group of organic compounds defined by their solubility in nonpolar solvents such as chloroform, ether, and benzene and by their poor solubility in water. 

Lipids can best be defined as biomolecules which are soluble to a great extent in nonpolar solvents. In contrast to carbohydrates, proteins and nucleic acids, lipids do not have polymeric forms. By virtue of their hydrophobic nature they aggregate into large complexes, held together to a significant degree by nonpolar interactions. 

Few studies have been conducted heretofore on sulfonated ionomers in solvents which can be considered relatively polar, as defined by a high dielectric constant. A recent study (13) on acrylonitrile-methallyl sulfonate copolymers in dimethyl-formamide is a notable exception. S-PS is readily soluble in a wide variety of solvents, some of them exhibiting rather high values of dielectric constant, such as dimethylformamide (DMF) or dimethylsulfoxide (DMSO). The reduced viscosity-concentration behavior of sulfonated polystyrene is markedly different in polar solvents from that in nonpolar-solvent systems. Typically there is a marked upsweep in reduced viscosity at low polymer concentrations and clearly a manifestation of classic polyelectrolyte behavior. ( 7)... 

Photoacidity may be defined regardless of proton dissociation occurring or not during the finite lifetime of the photoacid in the excited state. Photoacidity may also be defined in nonpolar solvents using the Forster cycle. 

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