Table 1.

The HNP and the corresponding pK_a values of compounds 2a–f in isopropyl alcohol, tert-butyl alcohol, acetone and N,N- dimethylformamide.

Compd.	N,N-Dimethyl formamide		Acetone		Isopropyl alcohol		tert-butyl alcohol
	HNP (mV)	pK a	HNP (mV)	pK a	HNP (mV)	pK a	HNP (mV)	pK a
2a	−218	11.02	−279	12.44	−119	9.46	−168	10.36
2b	−200	10.68	−282	12.43	−119	9.46	−212	11.06
2c	−241	11.67	−237	11.46	−163	9.76	−253	11.80
2d	−152	10.15	−279	12.44	−156	9.90	−267	12.05
2e	−218	11.23	−242	11.72	−133	9.28	−183	10.51
2f	−237	11.41	−259	12.08	−191	10.43	−172	10.46