Physical Properties of Solvent

The physical properties of solvents greatly influence the choice of solvent for a particular application. The solvent should be liquid under the temperature and pressure conditions at which it is employed. Its thermodynamic properties, such as the density and vapor pressure, temperature and pressure coefficients, as well as the heat capacity and surface tension, and transport properties, such as viscosity, diffusion coefficient, and thermal conductivity, also need to be considered. Electrical, optical, and magnetic properties, such as the dipole moment, dielectric constant, refractive index, magnetic susceptibility, and electrical conductance are relevant, too. Furthermore, molecular 

For the majority of the solvents listed in this book as green solvents, many of the properties have been listed and annotated in numerous reference texts, as for example Riddick et al. (1986) and Ash and Ash (1996). The use of these references to provide necessary data for determination of the appropriateness of these solvents will help tremendously in solvent selection. 

A fundamental guide to understanding the manner in which solvents influence chemical reactions is sketched out in table 3.1 (Marcus, 1998a). 

In a solution of a solute in a solvent there can exist noncovalent intermolecular interactions of solvent-solvent, solvent-solute, and solute-solute pairs. The noncovalent attractive forces are of three types, namely, electrostatic, induction, and dispersion forces. We speak of forces, but physical theories make use of intermolecular energies (Connors, 1990). 

Heat capacity of solvents Molecular sizes of solvents Electrical and optical properties 

The physical properties of the solvents which are concerned in NMR determinations are density, melting point, boiling point, refraction index, dielectric constant, permanent electric moment and magnetic volume susceptibilities. The first five properties have been compiled for 911 organic solvents (S 26) and the list is available on request. Dipole moments are found in ref. (M 34) and volume susceptibilities in ref. (L 43). 

Limited tables containing the physical properties of selected solvents are presented in specialized monographs dealing with solvent effect (R 18a) or NMR (M 31). 

There are many physical properties of solvents for electrolytes that have been compiled ([1-3] and elsewhere) but are of less interest in the context of the solvation of the ions and the properties of electrolyte solutions in the solvents. Such properties include the critical temperature, pressure, and density on the one hand, when the solvent is heated, and the glass transition temperature, when the solvent is cooled and forms a glass on the other hand. The glass is homogeneous and isotropic and has a viscosity 10 Pa s, but is not in internal equilibrium. 

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Table 1. Physical properties of solvents for lithium batteries...

Physical Properties of Solvents and Half-Wave Potential E1/2 of Bis-biphenylchromium (BBCr), in 0.1 M NaClO. Solution... 

In order to obtain better separations it is very important to know the bulk physical properties of solvents (viscosity, refractive index, dielectric constant, dipole moment. 

Brillouin scattering Absolute Requires knowledge of certain physical properties of solvent several concentrations necessary 2... 

Small amounts of impurities in solvents usually do not have serious effects on the physical properties of solvents (Section 2.5). However, they often have drastic effects on the chemical properties of solvents, changing the reaction mechanisms or making electrochemical measurements impossible. The extent of the effect of an impurity differs considerably, depending on the properties of the impurity and those of the solvent in which it exists. Impurities that have significant effects on chemical reactions or on electrochemical measurements are called reactive impurities. 

Physical properties of solvents commonly used in dry-cleaning processes... 

What physical properties of solvents have been used to parameterize them for continuum calculations ... 

Table 1 Physical Properties of Solvents at 25°C (unless noted)... 

Also, in this case, conductivity data were analyzed by Fuoss-On-sager-Skinner equations and limiting equivalent conductances A<> and association constants KA are collected in Table II together with physical properties of solvent mixtures. Furthermore, Table III shows ethanol and tert-butanol concentration in the mixture [ROH], the relevant dielectric constant c, and the pK of picric acid. 

In the past decade a number of physical techniques have been used to evaluate the unique barrier properties of mammalian skin [1]. This chapter deals with the use of another physical technique, fluorescence spectroscopy, to study the barrier properties of the human stratum corneum (SC), specifically with respect to the transport of ions and water. The SC is the outermost layer of the human epidermis and consists of keratinized epithelial cells (comeo-cytes), physically isolated from one another by extracellular lipids arranged in multiple lamellae [2]. Due to a high diffusive resistance, this extracellular SC lipid matrix is believed to form the major barrier to the transport of ions and water through the human skin [3-5]. The objective of the fluorescence studies described here is to understand how such extraordinary barrier properties are achieved. First the phenomenon of fluorescence is described, followed by an evaluation of the use of anthroyloxy fatty acid fluorescent probes to study the physical properties of solvents and phospholipid membranes. Finally, the technique is applied to the SC to study its diffusional barrier to iodide ions and water. 

Table 3.4 illustrates some of the physical properties of solvents directly nebulised and the effects that they have on the torch. 

Table 3.5 List of the physical properties of solvents considered for ICP-OES analysis. In all cases silicone tubing of 1.02 mm internal diameter was used...

Table 5.5 Physical properties of solvents used for dissolving Conostan high viscosity oil and low viscosity oil blends for analysis of oils using ICP-AES...

Many equations have been suggested to express the effect of the solvent on the rate of chemical reactions (25-25). Quantitative correlations are based on various physical properties of solvents or on empirical and semiempirical parameters. The LFER has been applied in this field because it was obvious that no simple physical characteristic of the solvent could adequately describe all interactions between molecules of the substrate and solvent (25, 29). 

It has been found in many papers (91-97) that the solvent may considerably affect also the relative adsorptivity of substrates. The majority of these authors, however, only point out differences in the relative adsorp-tivities of substrates in competitive hydrogenations under various conditions, or attempt to correlate these adsorptivities with the physical properties of solvents. In order to predict the effect of solvents on the selectivity of heterogeneously catalyzed hydrogenations, it is of course very important to obtain more general information on the effect of solvents on the adsorption coefficients of reacting compounds, based on a qualitative basis. Cerveny, Prochazka, and Ruzicka (70) suggested, for correlation of the effect of solvent on the relative adsorptivity of compounds, an equation in the form... 

A typical approach, in which the ionic strength is established by a 1-1 salt, and the pH is adjusted by an acid or base that has an ion in common with the inert electrolyte and is measured by means of a glass electrode, was used to study the following systems by titration, electrophoresis, and electroacoustics. A purely aqueous system was usually studied as a reference. The physical properties of solvents relevant to the interpretation of electrokinetic data (viscosity and permittivity) may be very different from those of water, and they have to be taken into account in the interpretation of results. 

The solution chemistry of nonaqueous solvents is very different from that of water-rich mixed solvents. pH measurement in nonaqueous solvents is difficult or impossible. Salts often show a limited degree of dissociation and limited solubility (see [132] for solubility of salts in organic solvents). Ions that adsorb nonspecifically from water may adsorb specifically from nonaqueous solvents, and vice versa. Therefore, the approach used for water and water-rich mixed solvents is not applicable for nonaqueous solvents, with a few exceptions (heavy water and short-chain alcohols). The potential is practically the only experimentally accessible quantity characterizing surface charging behavior. The physical properties of solvents may be very different from those of water, and have to be taken into account in the interpretation of results. For example, the Smoluchowski equation, which is often valid for aqueous systems, is not recommended for estimation of the potential in a pure nonaqueous solvent. Surface charging and related phenomena in nonaqueous solvents are reviewed in [3120-3127], Low-temperature ionic liquids are very different from other nonaqueous solvents, in that they consist of ions. Surface charging in low-temperature ionic liquids was studied in [3128-3132]. 

Table 3 contains the physical properties of solvents that are used for dissolving alkali metals. Besides boiling point (b.p.) and viscosity (the data enable one to judge on the experimental potentialities inherent in a solvent) the Table contains values of dielectric constant and of donor and acceptor numbers (DN, AN). It is hard to notice any correlation between the macroscopic properties of the solvents, on the one hand, and their ability to dissolve alkali metals and the possibility of electrochemical generation of solvated electrons, on the other hand. 

At the laboratory scale, the economics, toxicological, or operational hazards of the solvent are usually not determining factors. Key criteria at laboratory scale are typically selectivity and solubility. However, if there is a probability that a laboratory procedure will be scaled up, then other factors (e.g., cost, toxicity, recoverability) should also be considered in the early laboratory development. Table 5 lists physical properties of solvents commonly used for... 

Many physical properties of solvents depend on their molecular weight, such as boiling and freezing points, density, heat of evaporation, flash point, and viscosity. The relationship between these properties and molecular weight for a large number of solvents of different chemical composition is affected by numerous other influences but within the same chemical group (or similar stmcture) molecular weight of solvent correlates well with its physical properties. 

And while water-based cleaning agents have been much improved in recent times, their performance does not always match fliat of their solvent forerunners. In fact, an ideal water-based cleaning agent would combine the physical properties of solvent-based cleaning agents with the safety and convenience of water-based materials. 

A generally accepted viewpoint is that the deviation from the log-linear solubilization is mainly caused by the non-ideality of the solvent mixture. This is supported by the similarities in the patterns of observed log and activities of the cosolvent in solvent mixture, when they are graphically presented as functions of f Based on the supposition that solvent non-ideality is the primary cause for the deviation, Rubino and Yalkowsky examined the correlations between the extent of deviation and various physical properties of solvent mix-... 

Table 15.1.1. Typical chemical and physical properties of solvents included in their specifications...

To facilitate engineering calculations, it is essential to know the physical properties of solvents, and so properties such as the density and viscosity of aqueous amine solutions have been widely studied in the hterature. However, veiy few literature data are available for C02-loaded aqueous amine systems. Our study therefore focuses on the effect of dissolved CO2 on key thermophysical properties of aqueous amine solutions. 

Many physical properties of solvents depend on their molecular weight, such as... 

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