1.2- Dichloroethane Dielectric constant

Triphenylmethyl Chloride. The ionization of triphenylmethyl chloride (Ph3CCl) in 1,2-dichloroethane (dielectric constant of 10.4 at 25°C) (75) has not been measured directly, but an extrapolation from experimental data (76,77) allows the following estimates ... 

Current option 136, 214 density matrix 263 l,2-dichloro-l,2-difluoroethane 24 dichloroethane 239, 242 dielectric constant 239 diffuse functions 99 difluoroethylene 45 dihedral angles 290 valid range 288 n,n-dimethylformamide 105 dipole moment 20... 

On the assumption that = 2, the theoretical values of the ion solvation energy were shown to agree well with the experimental values for univalent cations and anions in various solvents (e.g., 1,1- and 1,2-dichloroethane, tetrahydrofuran, 1,2-dimethoxyethane, ammonia, acetone, acetonitrile, nitromethane, 1-propanol, ethanol, methanol, and water). Abraham et al. [16,17] proposed an extended model in which the local solvent layer was further divided into two layers of different dielectric constants. The nonlocal electrostatic theory [9,11,12] was also presented, in which the permittivity of a medium was assumed to change continuously with the electric field around an ion. Combined with the above-mentioned Uhlig formula, it was successfully employed to elucidate the ion transfer energy at the nitrobenzene-water and 1,2-dichloroethane-water interfaces. 

In this way, the concept of donicity explains some properties of substances usually defined apolar from their usual parameters of polarity (dielectric constant, dipolar moment, Et parameter value) but which presents high possibilities of interaction (and of solvatation) with positively charged centres. This is the case of tertiary amines such as triethylamine (or of ethers such as THF, dioxane) which shows usual polarity parameters near that of apolar solvents (benzene, chloroform, chlorobenzene, 1,2-dichloroethane, etc.) but high ability to coordinate positive charges. 

Solvents, base electrolytes As solvents for the organic phase, liquids with relative dielectric constants above 10 are suitable. So far, nitrobenzene has been used almost exclusively, but dichloroethane can also be employed [7]. Tetra-butylammonium tetraphenylborate [ 1 ] is the most commonly used base... 

Fig. 9.4.23 Dispersibility of colloidal systems of a kind of metals in various organic liquids. er. Relative dielectric constant of liquids A, electron affinity disp, dispersion (O) floe, flocculation ( ) upon stirring, the suspension becomes turbid then particles slowly sediment) coag, coagulation ( immediately after stirring of the suspension, particles aggregate again to sediment). ( ) Boundary between disp and floe ( ) boundary between Hoc and coag. Broken lines divide each region, (a) Hexane, (b) benzene, (c) diethyl ether, (d) ethyl acetate, (e) letrahydrofuran. (0 dichloroethane. (g) benzyl alcohol, (h) 2-butanol, (i) butanol, (j) acetone, (k) ethanol. (From Ref, 23.)...

The authors prefered the latter explanation. They argue that the difference in the dielectric constant of the medium, when a hydrocarbon rich mixture is compared with that rich in sulfur dioxide, affects the ratio of gauche to trans conformations of the polymer chain. Such effects were observed in other systems, e.g. in 1,2 dichloroethane (38). Hence,... 

Enantioselectivity is highly dependent on the solvent employed. A screening of appropriate solvents for the oxidation of methyl p-tolyl sulfide showed a dramatic solvent effect (Table 6C.4) [22], The best solvents were dichloromethane and 1,2-dichloroethane, which have similar dielectric constants, that is, 1.6 and 1.44, respectively. 

The influence of solvents was extensively studied [38, 40b, 42], with reactions shown capable of being performed in neat, or, virtually in any polar medium. Whilst high dielectric constant oxygenated solvents such as tetrahydrofuran (THF), 1,4-dioxane, acetone (Et20), dimethyl sulfoxide (DMSO), and dimethyl-formamide (DMF) are used in non-asymmetric MBH reactions, dichloroethane (CH2C12) or acetonitrile are preferred for asymmetric transformations. MBH re-... 

On the other hand, C0CI2 is insoluble in pure liquid SbClg since cation stabilization cannot take place. The majority of solvents that are extensively used in solution chemistry (particularly in the field of organic chemistry) are typical EPD solvents. Gutmann (25-28) has introduced the so-called donor number or donicity (DN) as a measure of the EPD properties of donor solvents. This is defined as the negative AH values for formation of the 1 1 adduct of the EPD with SbClg as reference standard EPA in a dilute solution of 1,2-dichloroethane. Donicities for various solvents are listed in Table I together with their dielectric constants e. 

Sn(CH3)3l dissolved in nitrobenzene as a function of concentration of various EPD solvents added (35). In noncoordinating or weakly coordinating solvents, such as hexane, earbon tetrachloride, 1,2-dichloroethane, nitrobenzene, or nitromethane, Sn(CH3)3l is present in an unionized state (tetrahedral molecules). Addition of a stronger EPD solvent to this solution provokes ionization, presumably with formation of trigonal bipju amidal cations [Sn(CH3)3 (EPD)2J. Table II reveals that the molar conductivities at a given mole ratio EPD Sn(CH3)3l are (with the exception of pyridine) in accordance with the relative solvent donicities. No relationship appears to exist between conductivities and the dipole moments or the dielectric constants of the solvents. 

Fig. 22. Plots of the parameters S vs. dielectric constants of solvents at 25 °C. a dichlorometha-ne, b chloroform c 1,2-dichloroethane, d 1,2-dichloropropane, e 1,1,1,1,2-tetrachloroethane, f 1,2,3-trichIoropropane, g pentachloroethane, h tetrahydrofuran, i N,N-dimethylformamide, j 1,4-dioxane, k m-cresol...

The partition between solute and solvent is performed by defining a cavity in the polarizable medium the solute is placed inside the cavity, where the relative dielectric constant is 1 (i. e. the value of vacuum), while outside the dielectric constant has the macroscopic value of the solvent (for example 78.39 for water at 298 K, 10.36 for 1,2-dichloroethane and so on). The shape and the size of the cavity are important parameters of the method. 

Figure 4-9. Conformation energy of 1,2-dichloroethane as a function of the relative permittivity (dielectric constant) in the liquid phase ( ) in various solvents (O) and in the gas phase ( ),...

The rate law for dimerisation of RuX2(CO)4, in a range of solvents including nitromethane, 1,2-dichloroethane, chloroform, nitrobenzene, dioxan, and methyl isobutyl ketone, is first-order. The suggested ratedetermining step is formation of the five-co-ordinate species RuX2(CO)3. Rates are affected little by the nature of the solvent, and do not correlate with dielectric constant or co-ordinating ability. ... 

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