Abstract
The equilibrium constants for 1:1 proton transfer complex formation between chloranilic acid (CA) and quinoline, α-picoline, benzyl amine (BA), triethyl amine (TEA) and diethyl amine (DEA) have been measured in 1,4-dioxan by using UV spectroscopy. A linear correlation between the logarithm of the proton-transfer equilibrium constant and the pK of the amine has been found, except for primary and secondary amines. The results support the concept of amine-solvent hydrogen bond formation, which increases the reactivity of tha amine as a base. Such hydrogen bonds increase amine basicity more than would the inductive effect of an added alkyl group. The thermodynamic parameters were found in agreement with these results. Moreover, the thermodynamic data showed that the strength of the hydrogen bonds involved are among the strongest hydrogen bonds known.