Table 7. Calculated (MP2/6-311+G**) and Experimental ΔHACID Values (kcal/mol). Calculated Gas-Phase σR– Values for the Hydrocarbon Substituents in This Studya.
| acid, R–CH3 | ΔHACID (calc)b | ΔHACID (exp)c | est σR– |
|---|---|---|---|
| 1HC–CH3 | 330.6 | 0.58 | |
| 1CH3C–CH3 | 334.9 | 0.57 | |
| c-C5H4=CH–CH3d | 346.2 | 0.52 | |
| Ph–CH3 | 383.7 | 382.3 | 0.29e |
a
In the same way a σR– value of approximately 1.0 is calculated for the positively charged +CHCH3 group.
b
The ΔHACID values are corrected for zero-point vibrational energy differences.
c
Bartmess, J. E. In NIST Standard Reference Database Number 69; Mallard, W. G., Linstrom, P. J., Eds.; National Institute of Standards and Technology: Gaithersburg, MD, 2003 (http://webbook.nist.gov).
d
6-Methylfulvene.
e
The experimental value is 0.22; see ref (29).