Table 6.

Energy to form intramolecular hydrogen bond (kcal/mole)^a

Rb	Sulfur oxidation state
	Thioether	Sulfoxide	Sulfone
3	7.18	13.59	10.39
4	7.25	13.62	10.45
6	7.22	13.64	10.42
8	7.25	13.75	10.45
10	7.28	13.74	10.47

^aValues were calculated as the amount of energy required to break the intramolecular bond in the 5-membered ring for thioether-containing compounds or the 6-membered ring for sulfoxide- and sulfone-containing compounds as shown in Figure 1.

^bR refers to the length of the alkyl chain as shown in Figure 1.