Experimental determination of dissociation constants (pKa) for N‐(2‐aminoethyl)‐1,3‐propanediamine, 2‐methylpentamethylene diamine, N,N‐dimethyldipropylenetriamine, 3,3′‐diamino‐N‐methyldipropyl‐amine, Bis[2‐(N,N‐dimethylamino)ethyl]ether, 2‐[2‐(dimethyl‐amino) ethoxy] ethanol, 2‐(dibutylamino) ethanol, and N‐propylethanol‐amine and modeling with artificial neural network

Abstract

AbstractThe dissociation constants (pKa) of the eight amines, namely, N‐(2‐aminoethyl)‐1,3‐propanediamine, 2‐methylpentamethylene diamine, N,N‐dimethyldipropylene‐triamine, 3,3′‐diamino‐N‐methyl‐dipropylamine, Bis[2‐(N,N‐dimethylamino) ethyl]ether, 2‐[2‐(dimethyl‐amino)ethoxy] ethanol, 2‐(dibutylamino) ethanol, and N‐propylethanolamine were measured between 298.15 and 313.15 K with 5 K increment. Based on the experimental values and using the van't Hoff equation, thermodynamic properties such as the standard state changes of enthalpy, entropy, and Gibbs free energy were calculated. Using computational chemistry calculations, the amine that is protonated first was predicted. Furthermore, computer‐free group contribution methods such as the original Perrin–Dempsey–Serjeant (PDS), the modified PDS, and the Qian–Sun–Sun–Gao (QSSG) model were used to estimate the dissociation constants of the studied amines at 298.15 K. The QSSG provided the most accurate results. Finally, this work utilized an artificial neural network for estimating the pKa values, which were in excellent agreement with the experimental data.