Table 2. The activation (ΔG^‡) and reaction (ΔG‡R) Gibbs free energies for the formation of four semimercaptals (kcal mol^–1). ΔΔG‡R = ΔG‡R – ΔG^‡.

	ΔG‡	ΔG‡R	ΔΔG‡R
1	34.2	–6.6	–1.5
2	31.1	–6.5	2.5
3	34.3	–6.2	–2.0
4	24.5	–3.9	8.4