Electrical Conductances of Tetraphenylphosphonium and Tetraphenylboride Salts in C₁ to C₄ Alcohols

Abstract

The electrical conductances of three large-ion salts, tetraphenylphosphonium chloride (TPPC), tetraphenylphosphonium bromide (TPPB), and sodium tetraphenylboride (STPB), have been measured in water and each of the C 1 to C 4 alcohols at different temperatures. The molar conductivities of the large ions TPP + and TPB -vary inversely with the solvent viscosity η and with the carbon number N of the solvent molecules: (N + 1) 1/2 ηλ 0 ) constant. The value of this constant is slightly dependent on the chain structure of the alcohol: for TPP + , 28.6 (10 -7 Pa‚s‚S‚m 2 /mol) in 1-alkanols, 30.0 in 2-alkanols, 30.4 in isobutanol, 26.9 in tert-butyl alcohol; for TPB -the respective values are 30.0, 31.5, 31.9, and 27.9. In water the values of (N + 1) 1/2 ηλ 0 of TPP + (18.4) and TPB -(17.7) are the lowest, while the values for the small ions (44.6, Na + ; 69.8, Br -; 67.9, Cl -) are the highest among all the solvents. In alcohols and water, the activation energies for molar conductivities (E Λ 0 ) of the three salts are nearly the same as those of E η of the solvents, with one exception. In tert-butyl alcohol the values of E Λ 0 (21 kJ/mol, TPPB; 22, TPPC; 19, STPB) are similar to those of the corresponding salts in other butanols and much lower than E η of tert-butyl alcohol (31 kJ/mol). The activation energy of diffusion of the large tetraphenyl ions through the butanols, the molecular sizes of which are much smaller than the tetraphenyl ions, is relatively insensitive to the molecular structure of the butanols.

Limiting Diffusion Coefficients for Ions and Nonelectrolytes in Solvents Water, Methanol, Ethanol, Propan-1-ol, Butan-1-ol, Octan-1-ol, Propanone and Acetonitrile at 298 K, Analyzed Using Abraham Descriptors

“…Data for ions and ionic species were those that we used before [12]. For nonelectrolytes we supplemented our previous data with a considerable number of extra values of log 10 (D o ) [2,5,7,[30][31][32][33][34], leading to a total of 377 values, including ions, ionic species, zwitterionic amino acids and neutral nonelectrolytes. The list of solutes, diffusion coefficients and solute descriptors are given in Table S1 of the Supplementary Material.…”

“…Diffusion coefficients for ions were obtained from conductance data through Eq. 2 [30,37,43,45]. There is surprisingly little data on diffusion coefficients of nonelectrolytes [4,34], not enough to enable us to obtain a robust equation based on Eq.…”

“…Data are available for ions [30,45], but, again, there is a lack of data on nonelectrolytes [4,10,39,40,42,47]. We adopted the same stratagem as for propan-1-ol solvent and obtained data on a total of 53 solutes, leading to Eq.…”

Solvent effects on reactivity of solvated electrons with ammonium nitrate in 2-propanol/water mixed solvents

“…The technique taken in the specific conductance measurement is similar to that in reference [20]. Conductance meter and cells (YSI 3402 and YSI 3403) were obtained from Yellow Springs Instrument Co.…”