Dissociation constants of eight amines: Experimental measurements and modeling

Abstract

In this study, the dissociation constants of the eight amines, namely, N-(2-aminoethyl)-1,3-propanediamine, 2-methylpentamethylene diamine, N, n-dimethyldipropylene-triamine, 3,3’-Diamino-n-methyldipropylamine, Bis[2-(n, n-dimethylamino) ethyl]ether, 2-[2-(Dimethylamino) ethoxy] Ethanol, 2-(dibutylamino) Ethanol and N-propylethanolamine were determined from 298.15 K to 313.15 K. 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 amino group 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. In these methods, the QSSG provided the most accurate results as the database used in this method was updated with additional the functional groups as well as information about group positions. Finally, an artificial neural network was used to predict the pKa values.

Thermodynamic Modeling of an Aqueous N, N‐Dimethyldipropylenetriamine and Benzylamine Blend for Efficient CO2 Capture

“…It has a high pKa value of (9.99 at 313 K), confirming its affinity to react with acidic CO 2 . [21] It exhibits high CO 2 absorption capacity with a moderate of ~70 kJ/mol. [22] In a study, DMDPTA displayed comparable CO 2 absorption rate, negligible vapor pressure, much greater cyclic capacity and almost 3 times higher CO 2 loading compared to MEA at CO 2 partial pressures of 0.1-19 kPa at 313 K. [23] These great characteristics encouraged us to examine the CO 2 capture capabilities of aqueous DMDPTA blended Benzylamine solutions.…”