Table I.
Experimental and theoretical gas-phase free energy of deprotonation of thiols and nitrogen heteroaromatics (in kcal/mol) and pKa in water
| Thiols | Gg expa | Gg theor | pKa expb | pKa theor |
|---|---|---|---|---|
| C2H5SH | 348.9 | 352.0 | 10.5 | 10.14 |
| C6H5SH | 333.8 | 336.0 | 7.78 | 6.58 |
| SH2 | 344.4 | 346.7 | 7.0 | 5.49 |
| t-C4H9-SH | 346.2 | 350.6 | 11.05 | 11.50 |
| n-C4H9-SH | 347.4 | 351.7 | 10.65 | 10.37 |
| nitrogen heteroaromatics |
Gg exp | Gg theor | pKa exp | pKa theor |
| 4-Me-imidazole | 220.0 | 221.2 | 7.45 | 7.49 |
| pyridine | 214.6 | 214.8 | 5.30 | 5.95 |
| pyrimidine | 204.4 | 204.3 | 1.30 | 1.04 |
| thiazole | 208.3 | 206.4 | 2.80 | 2.20 |
| 4-aminopyridine | 226.4 | 226.9 | 9.70 | 9.38 |
| pyrazine | 202.3 | 201.2 | 0.70 | 1.10 |