Table 1.
Key Thermodynamic Constants in Common Solvents
| solvent | TS∘(H•)a,b | ΔG∘f(H•)a,c | E∘(H+/H2)d,e | C G e |
|---|---|---|---|---|
| gas phase | 8.17f | 48.59f | -- | -- |
| water | 2.9549 | 52.849 | 0.00g | 52.850,g |
| acetone | 6.5047 | 51.947 | -- | -- |
| acetonitrile (MeCN) | 6.3747 | 52.047 | −0.02819 | 52.619 |
| benzene | 6.2348 | 52.148 | -- | -- |
| CCl4 | 6.1648 | 51.948 | -- | -- |
| chlorobenzene | 5.8348 | 52.148 | -- | -- |
| N,N-dimethylacetamide (DMA) | -- | -- | −0.7951 | -- |
| N,N-dimethylformamide (DMF) | 6.0747 | 52.347 | −0.66219 | 67.619 |
| dimethyl sulfoxide (DMSO) | 6.1649 | 52.649 | −0.6752,h | 68h |
| 1,4-dioxane | 6.2547 | 52.247 | -- | -- |
| n-hexane | 6.3047 | 51.747 | -- | -- |
| isopropanol (IPA) | -- | -- | −0.49419 | -- |
| methanol (MeOH) | 5.7149 | 51.949 | −0.50153 | 63.4 |
| toluene | 6.1047 | 52.047 | -- | -- |
| tetrahydrofuran (THF) | 6.4347 | 52.047 | −0.343i | 59.9 |
Values in kcal mol−1 at 298 K.
TS∘(H•) = T[S∘(H•(g)) + ΔSsolv∘(H•)], where H2 data are used to approximate H• solvation, and the standard state is 1 M in solution unless otherwise specified.
Adapted and expanded from ref 19.
Potentials are in V.
E∘ and CG are vs Cp2Fe+/0 unless otherwise stated.
Values involve H•(g) at 1 atm gaseous standard state from ref 42.
Value referenced to SHE.
E∘(H+/H2) in DMSO was determined from the E1/2 of a quasi-reversible wave, and therefore both it and the corresponding CG are not reported to the same level of accuracy as other values in this table.
Value is an average of those presented in refs 19, 54, and 55 with corrections for TS∘(H•) where necessary. [The value of TS∘(H·) in THF in ref 55 was corrected from unit mole fraction to 1 M standard state, giving 6.43 kcal mol−1 and E∘(H+/H2) = −0.33 V (values that were then averaged with those from the citations noted just above).] Standard state is defined by an absolute pKa scale.56