Overall solvent index

The values for each solvent metric, M, are then summed into an overall solvent index (OS I) as shown in Equation 3.9. Prior to their summation, each parameter index can be arbitrarily weighted (a,) to focus on those factors which are more important to a particular industry or process. Equation 3.10 displays the OSI recommended for use by the pharmaceutical industry [1]. 

An alternative approach uses the polarity index, P proposed by Snyder. This is based upon experimentally determined gas chromatographic retention of three test solvents on a large number of stationary phases. The test solvents selected are ethanol, 1,4-dioxane and nitromethane. As well as an overall polarity index (P), three other parameters are calculated, Xe (a proton acceptor parameter), xproton donor parameter) and x (a strong dipole parameter). 

Koppel-Palm solvent parameters Parameters to measure separately the ability of a solvent to enter into nonspecific solvent-solute interactions (permittivity, , and refractive index, nD) and specific solvent-solute interaction (solvent basicity or NUCLEOPHILICITY B and solvent acidity or ELECTROPHILICITY E) as contributing to overall solvent POLARITY. 

The environmental impacts of both the solvent to be replaced and the replacement solvent are considered using two indexes an air index and an overall environmental index. Since the object here is to formulate substitute solvents that have better environmental performance, the indexes for the solvent to be replaced are not matched but are rather treated as an upper bound on the indexes of the acceptable replacement. This insures that the replacement solvent is environmentally better than the original solvent as measured by the indexes. The inherent toxic effects of the solvent and the toxic effects due to volatile organic emissions are considered separately because, when chemicals are mixed, their volatility changes due to the non-idealities in the mixture. Therefore, a chemical that has low risk by inhalation due to low volatility in pure form can have a much higher volatility and a much higher risk when mixed with other chemicals. The air index,... 

Another classification of detector is the bulk-property detector, one that measures a change in some overall property of the system of mobile phase plus sample. The most commonly used bulk-property detector is the refractive-index (RI) detector. The RI detector, the closest thing to a universal detector in lc, monitors the difference between the refractive index of the effluent from the column and pure solvent. These detectors are not very good for detection of materials at low concentrations. Moreover, they are sensitive to fluctuations in temperature. 

Seisakusho differential refractometer). For a solution of known concentration, the difference in refractive index, (n - nj>), between the liquid in the prism and that in the solvent bath causes refraction of the light beam, which is observed as a displacement 8 of the image at a distance d from the prism centre. The overall sensitivity depends on the precision of measuring 8 and the refractive index difference is given by... 

Solubilities, in water, ethanol, and ethanol-water mixtures, have been reported for [Fe(phen)3]-(0104)2, [Fe(phen)3]2[Fe(CN)6], and [Fe(phen)3][Fe(phen)(CN)4]. Solubilities of salts of several iron(II) iiimine complexes have been measured in a range of binary aqueous solvent mixtures in order to estimate transfer chemical potentials and thus obtain quantitative data on solvation and an overall picture of how solvation is affected by the nature of the ligand and the nature of the mixed solvent medium. Table 8 acts as an index of reports of such data published since 1986 earlier data may be tracked through the references cited below Table 8, and through the review of the overall pattern for iron(II) and iron(III) complexes (cf. Figure 1 in Section 5.4.1.7 above) published recently. ... 

Capello et al.16 applied LCA to 26 organic solvents (acetic acid, acetone, acetonitrile, butanol, butyl acetate, cyclohexane, cyclohexanone, diethyl ether, dioxane, dimethylformamide, ethanol, ethyl acetate, ethyl benzene, formaldehyde, formic acid, heptane, hexane, methyl ethyl ketone, methanol, methyl acetate, pentane, n- and isopropanol, tetrahydrofuran, toluene, and xylene). They applied the EHS Excel Tool36 to identify potential hazards resulting from the application of these substances. It was used to assess these compounds with respect to nine effect categories release potential, fire/explosion, reaction/decomposition, acute toxicity, irritation, chronic toxicity, persistency, air hazard, and water hazard. For each effect category, an index between zero and one was calculated, resulting in an overall score between zero and nine for each chemical. Figure 18.12 shows the life cycle model used by Capello et al.16... 

The solvent polarity, which is defined as the overall solvation capability of a liquid derived from all possible, non-specific and specific intermolecular interactions between solute and solvent molecules [4], cannot be represented by a single value encompassing all aspects, but constants such as the refractive index, the dielectric constant, the Hildebrand solubility parameter, the permanent dipole moment, the partition coefficient logP [5] or the normalised polarity parameter TN [6] are generally employed to describe the polarity of a medium. The effect of a solvent on the equilibrium position of chemical reactions, e.g. the keto-enol tautomerism, may also be used. However, these constants reflect only on some aspects of many possible interactions of the solvent, and the assignment to specific interactions is difficult if not impossible. 

The overall tendency of compounds to interact through dispersion forces is related to the refractive index values of the compounds (see Karger et al., 1973) the greater the refractive index the stronger the dispersion interactions. Thus, the dipolar aprotic solvents and pyridine have the strongest influences in dispersion interactions of the compounds listed in Table 1. Where refractive index is used to measure the concentration of solute it is, of course, important to maximize the differences in these values between solute and solvent. 

DMC thus yields very favorable mass indexes (in the range 3-6), indicating a significant decrease of the overall flow of materials (reagents, catalysts, solvents, etc.) and thereby providing safer greener catalytic reactions with no waste. 

The relative PLMA MW was determined by using nonaqueous SEC with THF as solvent and an HP1037A refractive index detector from Hewlett-Packard. A solid-phase extraction cartridge (Waters Sep-Pak) was used to take the PLMA and surfactants from the water phase to THF and to adjust the concentration for SEC. Sodium sulfate was used to dry the THF extract before injection into the SEC columns. For some samples there was too much surfactant present, and it overloaded the cartridge in such cases ion-exchange beads were used to reduce the concentration of the ionic surfactants in the aqueous phase before extraction. The advantage of this extraction procedure is its simplicity. The overall separation scheme is shown in Scheme I. 

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