Table I.
General Molecular Descriptors of Acids Used as Counterions
| Counterion (acid) | M (g/mol) | pK a1 | Vol (cm3/mol) | CMR | ClogP | PSA | Rotatable bonds | logD | Flex index | H acc | H don |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Phosphoric | 98.0 | 1.96 | 69.4 | 1.427 | −2.174 | 77.8 | 0 | −6.3 | 0.0 | 3 | 4 |
| Citric | 192.1 | 3.13 | 160.9 | 3.680 | −1.998 | 132.1 | 5 | −10 | 26.0 | 4 | 7 |
| Benzenesulfonic | 158.2 | 0.7 | 128.1 | 3.714 | −0.645 | 54.4 | 1 | −4.6 | 6.3 | 1 | 3 |
| Oxalic | 90.0 | 1.27 | 68.7 | 1.483 | −1.745 | 74.6 | 1 | −8.8 | 11.1 | 2 | 4 |
| Sulfuric | 98.1 | −3 | 61.7 | 1.356 | −2.174 | 74.6 | 0 | −10.2 | 0.0 | 2 | 4 |
| Ethanesulfonic | 110.1 | −2.05 | 91.2 | 2.131 | −1.895 | 54.4 | 1 | −5.9 | 9.1 | 1 | 3 |
| Naphthalenesulfonic | 208.2 | 0.17 | 174.4 | 5.402 | 0.529 | 54.4 | 1 | −3.5 | 4.8 | 1 | 3 |
| Toluenesulfonic | 172.2 | −1.34 | 147.2 | 4.178 | −0.146 | 54.4 | 1 | −4.1 | 5.8 | 1 | 3 |
| Formic | 46.0 | 3.75 | 39.8 | 0.830 | −1.316 | 37.3 | 0 | −3.8 | 0.0 | 1 | 2 |
| Methanesulfonic | 96.1 | −1.2 | 72.0 | 1.667 | −2.424 | 54.4 | 0 | −6.4 | 0.0 | 1 | 3 |
| HCl | 36.5 | −6 | 29.1 | 0.000 | −1.316 | 0.7 | 0 | – | 0.0 | 0 | 0 |