Thermal behaviour and thermochemistry of ethanaminium iodides

Abstract

Dynamic thermoanalytical methods (DTA, TG, DTG) have been applied to the investigation of the thermal features of compounds of general formula (EtnNHa-n)I, with n = 0-4. The primary decomposition step of these derivatives is accompanied by the release of amine and HI to the gaseous phase. The enthalpies of this process have been evaluated on the basis of the van't Hoff equation and analytical TG curves. Values thus derived together with the available literature data were used to estimate the enthalpies of formation and the energies of the crystal lattice of the compounds. Further information regarding this latter quantity was also drawn from the Kapustinskii-Yatsimirskii formula.Owing to the rather strong base character of alkanamines they form salttype compounds with typical inorganic acids. The halogenide salts of such amines are one of the simplest ionic derivatives of organic compounds. Such derivatives are, thus very convenient model systems for studying the influence of the structure of cations on the features of parent molecules. In our previous note we turned our attention to the thermochemistry and thermal properties of numerous chloride salts of nitrogen organic bases [1][2][3]. The present note is devoted to similar studies for ammonium and ethanaminium iodides. Salts of alkanamines appear to have some industrial applications [4][5]. Nitrogen organic bases also commonly appear in biological systems. Thus, the present studies are of considerable scientific and practical importance.Experimental N, N, N-triethyl-ethanaminium iodide was purchased from Fluka AG and Bush SG. Other compounds studied were synthesized by mixing an aqueous solution of appropriate bases with an almost stoichiometric amount of hydroiodic acid. The resulting crystals were separated and purified by John Wiley & Sons, Limited, Chichester Akad~tiai Kiad6, Budapest