Table 1.

Calculated gas-phase O–H Bond Dissociation Enthalpies (BDEs), Ionization Potentials (IPs) and acidities of acetaminophen and some of its analogs

	O–H BDEa (kcal/mol)	IPb (kcal/mol)	Acidityc (kcal/mol)
1	82.5	176.2	342.7
2	83.2	184.7	337.6
3	83.7	193.1	331.9
4a	76.0	157.7	347.2
5a	77.0	164.6	345.6
6a	78.3	174.6	340.8
4b	72.3	152.3	346.1
5b	73.5	157.7	345.2
6b	74.1	167.0	341.4

^aO–H BDEs of 1, 2 and 3 were calculated using the B3LYP density functional as in ref. 22. The values for 4–6 were taken from ref. 18c.

^bIPs of 1, 2 and 3 were calculated using the B3LYP density functional as in ref. 23. The values for 4–6 were taken from ref. 18c.

^cAcidities were calculated using the B3LYP functional as in ref. 22.