Table 2.
Experimental and calculated pKa’s of a series of dicarboxylic acids.
| Acid | Expt.1 | E+CL2 | GB3 | E−CL4 | |
|---|---|---|---|---|---|
| n5 | pK1 | ||||
| Azelaic | 7 | 4.55 | 4.4 | 4.20 | 4.2 |
| Suberic | 6 | 4.52 | 4.6 | 4.19 | 4.3 |
| Pimelic | 5 | 4.48 | 4.5 | 4.17 | 4.2 |
| Adipic | 4 | 4.42 | 4.7 | 4.04 | 4.1 |
| Glutaric | 3 | 4.34 | 4.0 | 3.57 | 3.7 |
| AAE | 0.18 | 0.43 | 0.38 | ||
| pK2 | |||||
| Azelaic | 7 | 5.41 | 5.3 | 5.18 | 7.1 |
| Suberic | 6 | 5.40 | 5.2 | 5.25 | 7.1 |
| Pimelic | 5 | 5.42 | 5.3 | 5.25 | 7.0 |
| Adipic | 4 | 5.41 | 5.4 | 5.42 | 7.1 |
| Glutaric | 3 | 5.42 | 5.0 | 5.05 | 6.6 |
| AAE | 0.18 | 0.19 | 1.55 | ||
| ΔpKa6 | |||||
| Azelaic | 7 | 0.86 | 0.8 | 0.98 | 2.9 |
| Suberic | 6 | 0.88 | 0.6 | 1.06 | 2.8 |
| Pimelic | 5 | 0.94 | 0.8 | 1.08 | 2.8 |
| Adipic | 4 | 0.99 | 0.7 | 1.38 | 2.9 |
| Glutaric | 3 | 1.08 | 1.0 | 1.48 | 2.9 |
| AAE | 0.19 | 0.24 | 1.9 | ||
1
Experimental data are taken from Ref. 34.
2
E+CL refers to the simulations based on explicit solvent with charge leveling.
3
GB refers to the simulations based on the GB implicit-solvent model.
4
E−CL refers to the simulations based on explicit solvent without charge leveling.
5
n refers to the number of methylene groups in the dicarboxylic acid HO2C–(CH2)n–CO2H.
6
In all simulations, the microscopic pK1a of azelaic acid (4.85) was used as the model pKa (see Sec. 3).