Table 3. Rate of change of pK values of substituted benzoic acids with change in solvent composition.

Substituent	(ΔpK)/ Δ (percent EtOH)
	0–12.2%	12.2–25.2	25.2–44.1	44.1–54.8
Hydrogen	1.92 × 10−2	3.65 × 10−2	4.10 × 10−2	3.54 × 10−2
m-Allyl	2.03 × 10−2	4.01 × 10−2	4.09 × 10−2	3.50 × 10−2
p-Allyl	1.94 × 10−2	3.83 × 10−2	3.97 × 10−2	3.57 × 10−2
m-Propenyl	1.94 × 10−2	3.75 × 10−2	4.19 × 10−2	3.45 × 10−2
p-Propenyl	2.43 × 10−2	2.84 × 10−2	3.70 × 10−2	3.68 × 10−2