Empirical parameters for donor and acceptor properties of solvents

Reevaluation of Donor Number Using Titration Calorimetry

“…The enthalpy changes reported by Gutmann are -26.6 kcal mol -1 for DMF and -18.0 kcal mol -1 for water, 7 thus the ΔH value is expected to be -36.0 kJ mol -1 using Eq. (10).…”

“…20 kJ mol -1 and is much smaller than the corresponding value (111 kJ mol -1 ) estimated from Gutmann's DN (26.6). 7 Gutmann measured the heat of reaction in a batch process using a glass ampule filled with SbCl5, and thus the water content in the solvent was negligible. On the other hand, titration calorimetry is difficult to perform under dried atmosphere and thus the sample solution is reasonably considered to contain a certain amount of water.…”

“…4 These parameters mainly represent the properties of solvents as the electron acceptor, and it is known that they correlate with Mayer's acceptor number (AN). 5 The AN value is defined as the relative chemical shift of 31 P NMR of trimethylphosphine oxide in a solvent, and is widely used as a measure of the accepting property of the solvent molecule when combined with the Gutmann's donor number (DN), 6,7 which is a measure of the donating property. The β and α values of Kamlet-Taft are also proposed as the parameters to measure the solvent-solute interaction, which is related to the donating property.…”

“…Gutmann has experimentally determined the enthalpy change by means of calorimetry and has reported the DN values for many donor molecules that are usually used as solvents. 7 Gutmann's DN is now widely accepted as a good measure of the donating property of solvents, and the values help researchers to understand the solvation structure and the solvation equilibrium of metal ions. The application of these parameters is expanding from the basic solution chemistry into applied materials chemistry, such as the estimation of surface functionality of mesoporous silica.…”

“…Although the DN value of FA (24) is slightly smaller than that of DMF (26.6), such a comparison must be carefully done because the value of FA is estimated by a different method from that used for DMF. 6,7,12 Similarly to the case of FA, although the chemical characteristics of metal ions in TMU such as the solvation structure are compared with those in the other amides on the basis of DN values, [14][15][16] it should be noted that they are not determined by the same experimental method. It has been reported that the solvation number of the metal ion is variable from 4 to 6 according to the ionic size and charge in TMU with the bulky molecular structure.…”