Lattice potential energy and standard molar enthalpy in the formation of 1-dodecylamine hydrobromide (1-C12H25NH3•Br) (s)

This paper reports that 1-dodecylamine hydrobromide (1-C12H25NH3 center dot Br)(s) has been synthesized using the liquid phase reaction method. The lattice potential energy of the compound 1-C12H25NH3 center dot Br and the ionic volume and radius of the 1-C12H25NH3+ cation are obtained from the crystallographic data and other auxiliary thermodynamic data. The constant-volume energy of combustion of 1-C12H25NH3 center dot Br(s) is measured to be Delta U degrees(m)(1-C12H25NH3 center dot Br, s) =-(7369.03 +/- 3.28) kJ center dot mol(-1) by means of an RBC-II precision rotating-bomb combustion calorimeter at T=(298.15 +/- 0.001) K. The standard molar enthalpy of combustion of the compound is derived to be Delta H-c(m degrees)(1-C12H25NH3 center dot Br, s)=-(7384.52 +/- 3.28)kJ center dot mol(-1) from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound is calculated to be Delta H-f degrees(m)(1-C12H25NH3 center dot Br, s)=(1317.86 +/- 3.67) kJ center dot mol(-1) from the standard molar enthalpy of combustion of the title compound and other auxiliary thermodynamic quantities through a thermochemical cycle.