Unified pH Values Under Standard Conditions
Standard Gibbs Energies of Transfer are suitable to obtain the Standard Gibbs Energies of Solvation as anchor points for the PPM using the main anchor point of the Standard Gibbs Energy of Solvation of the proton in water. Unified pH values can be calculated from these values.
All values of the Standard Gibbs Energies of Transfer ΔtrG°(H+, H2O → S) and Standard Gibbs Energies of Solvation ΔsolvG°(H+, S) are given in kJ mol−1.
| Solvent S | ΔtrG°(H+, H2O → S) / kJ mol−1 | ΔsolvG°(H+, S) / kJ mol−1 | pH°abs
| pH°absH2O
| pe°abs (H+/H2, S)
| E°abs(H+/H2, S) / V |
|---|---|---|---|---|---|---|
| H2O | 0.0 | −1104.5 | 193.5 | 0.0 | 72.3 | 4.28 |
| MeCN | 46.4 a | −1058.1 | 185.4 | −8.1 | 80.4 | 4.76 |
| (23.0) | (−1081.5) e | (189.5) | (−4.0) | (76.3) | (4.52) | |
| DMSO | −19.4 a | −1123.9 | 196.9 | 3.1 | 68.9 | 4.08 |
| (−31.8) | (−1136.3) e | (199.1) | (5.6) | (66.7) | (3.95) | |
| NH3 | −97.0 a | −1201.5 | 210.5 | 17.0 | 55.3 | 3.27 |
| (−97.5) | (−1202) f | (210.6) | (17.1) | (55.2) | (3.27) | |
| DCE | 244.5 | −860.0 c | 150.7 | −42.8 | 115.1 | 6.81 |
| (53) g | (−1051.5) | (184.2) | (−9.3) | (81.6) | (4.83) | |
| (56) h | (−1048.5) | (183.7) | (−9.8) | (82.1) | (4.86) | |
| EMIM Br | 2.6 | −1101.9 d | 193.0 | −0.5 | 72.7 | 4.30 |
| Et2O | 106.5 | −998.0 c | 174.8 | −18.7 | 91.0 | 5.39 |
| HF | 196.5 | −908 c | 159.0 | −34.5 | 106.7 | 6.31 |
| MeOH | 10.4 a | −1094.1 | 191.6 | −1.9 | 74.1 | 4.38 |
| (9.2) | (−1095.3) e | (191.9) | (−1.6) | (73.9) | (4.37) | |
| (1.7) | (−1102.8) i | (193.2) | (−0.3) | (72.6) | (4.29) | |
| (28.5) | (−1076) k | (188.5) | (−5.0) | (77.3) | (4.57) | |
| (42.7) | (−1061.8) l | (186.0) | (−7.5) | (79.8) | (4.72) | |
| EtOH | 11.1 a | −1093.4 | 191.5 | −2.0 | 74.2 | 4.39 |
| 1-PrOH | 9 a | −1095.5 | 191.9 | −1.6 | 73.8 | 4.37 |
| 1-BuOH | 3 a | −1101.5 | 192.9 | −0.6 | 72.8 | 4.31 |
| EG | 5 a | −1099.5 | 192.6 | −0.9 | 73.1 | 4.33 |
| PG | 6.5 b | −1098.0 | 192.3 | −1.2 | 73.4 | 4.34 |
| DMF | −14.4 b | −1118.9 | 196.0 | 2.5 | 69.7 | 4.13 |
| PC | 50 a | −1054.5 | 184.7 | −8.8 | 81.0 | 4.79 |
| NMPy | −25 a | −1129.5 | 197.8 | 4.3 | 67.9 | 4.02 |
| MeNO2 | 95 a | −1009.5 | 176.8 | −16.7 | 88.9 | 5.26 |
| PhNO2 | 33 a | −1071.5 | 187.7 | −5.8 | 78.0 | 4.62 |
| Py | −28 a | −1132.5 | 198.3 | 4.8 | 67.4 | 3.99 |
| HMPT | 40 a | −1064.5 | 186.4 | −7.1 | 79.3 | 4.69 |
| [a] Values according to Marcus.[1] [b] Values according to Marcus.[2] [c] Values calculated with the rCCC model.[3] [d] Values according to COSMO-RS model. [e] Values in parenthesis according to Kelly et al.[4] [f] Values in parenthesis according to Tuttle et al.[5] [g] Values in parenthesis according to Sabela et al.[6] [h] Values in parenthesis according to Olaya et al.[7] [i] Values in parenthesis according to Hwang et al.[8] [k] Values in parenthesis according to Fifen et al.[9] [l] Values in parenthesis according to Pliego et al.[10] [m] At a(H+) = 1 mol L-1 → pK'e = peabs. | ||||||
Bibliography:
[1] Y. Marcus, M. J. Kamlet, R. W. Taft, Journal of Physical Chemistry 1988, 92, 3613-3622.
[2] C. Kalidas, G. Hefter, Y. Marcus, Chem. Rev. 2000, 100, 819.
[3] D. Himmel, S. K. Goll, I. Leito, I. Krossing, Chemistry A European Journal 2011, 17, 5808.
[4] C. P. Kelly, C. J. Cramer, D. G. Truhlar, Journal of physical Chemistry B 2007, 111, 408-422.
[5] T. R. Tuttle, S. Malaxos, J. V. Coe, The Journal of Physical Chemistry A 2002, 106, 925-932.
[6] A. Sabela, V. Mareček, Z. Samec, R. Fuoco, Electrochimica Acta 1992, 37, 231-235.
[7] A. J. Olaya, M. A. Méndez, F. Cortes-Salazar, H. H. Girault, Journal of Electroanalytical Chemistry 2010, 644, 60-66.
[8] S. Hwang, D. S. Chung, Bulletin of the Korean Chemical Society 2005, 26, 589-593.
[9] J. J. Fifen, M. Nsangou, Z. Dhaouadi, O. Motapon, N.-E. Jaidane, Journal of Chemical Theory and Computation 2013, 9, 1173-1181.
[10] J. R. Pliego, E. L. M. Miguel, The Journal of Physical Chemistry B 1013, 117, 5129-5135.