Table 5. Rate Constants for the Quaternization of 3- and 4-Substituted Pyridines with Ethyl Iodide^a Compared to Δν(OH)_exp Shifts of 4-Fluorophenol upon Hydrogen Bonding.

species	log k2a	Δν(OH)expb
pyridine	1.408	286
3-bromopyridine	0.487	241
3-cyano	–0.020	203
3-methyl	1.609	300
4-methyl	1.672	304
4-ethyl	1.743	306
4-methoxy	1.776	312
4-acetyl	0.765	255
4-cyano	0.152	214
4-phenyl	1.497	293
4-amino	2.477	347
4-methylamino	2.812	354
r, cor. coef. (linear)		0.996

^aIn nitromethane solvent, from ref (20).

^bFrom ref (21).