Wen-Yan Dan

Investigation on phase transitions of 1-decylammonium hydrochloride as the potential thermal energy storage material

1-Decylammonium hydrochloride was synthesized by the method of liquid phase synthesis. Chemical analysis, elemental analysis, and X-ray single crystal diffraction techniques were applied to characterize its composition and structure. Low-temperature heat capacities of the compounds were measured with a precision automated adiabatic calorimeter over the temperature range from 78 to 380 K. Three solid–solid phase transitions have been observed at the peak temperatures of 307.52 ± 0.13, 325.02 ± 0.19, and 327.26 ± 0.07 K. The molar enthalpies and entropies of three phase transitions were determined based on the analysis of heat capacity curves. Experimental molar heat capacities were fitted to two polynomial equations of the heat capacities as a function of temperature by least square method. Smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K based on the fitted polynomials.

n-Dodecyl­ammonium bromide monohydrate

In the title compound, C12H28N+·Br−·H2O, the ionic pairs formed by n-dodecylammonium cations and bromide anions are arranged into thick layers; these layers are linked in a nearly perpendicular fashion [the angle between the layers is 85.84 (5)°] by hydrogen-bonding interactions involving the water molecules. The methylene part of the alkyl chain in the cation adopts an all-trans conformation. In the crystal structure, molecules are linked by intermolecular N—H⋯Br, O—H⋯Br and N—H⋯O hydrogen bonds.

Crystal Structure and Solid–Solid Phase Transition of 1-Dodecylamine Hydrobromide

Abstract 1-dodecylamine hydrobromide was synthesized. The crystal structure of the compound was determined by X-ray crystallography. Low-temperature heat capacities of the title compound were measured by an adiabatic calorimeter over the temperature range from 78 to 390 K. Three solid–solid phase transitions were observed at the peak temperatures of (329.278±0.234), (337.805±0.326), and (347.371±0.154) K. The molar enthalpies and entropies of the three phase transitions of the substance were calculated based on the analysis of heat capacity curves. Experimental values of heat capacities for the title compound were fitted to two polynomial equations. Three solid–solid phase transitions and a melting process of 1-dodecylamine hydrobromide were verified by DSC technique. In addition, the reversibility and repeatability of the three phase transitions were discussed.

n-Tridecyl-amine chloride monohydrate.

In the title compound, C13H30N+·Cl−·H2O, the C13H27 alkyl chain is in an all-trans conformation. In the crystal, intermolecular N—H⋯Cl, N—H⋯O and O—H⋯Cl hydrogen bonds connect the components into layers parallel to (010), with the alkyl chains oriented approximately perpendicular to these layers.

Penta­decyl­ammonium methyl sulfate

In the crystal of the title compound, C15H34N+·CH3SO4 −, the cations and anions are joined together via strong N—H⋯O hydrogen bonds into layers parallel to (001).

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-C12H25NH3Br)(s) has been synthesized using the liquid phase reaction method. The lattice potential energy of the compound 1-C12H25NH3Br 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-C12H25NH3Br(s) is measured to be ΔcUmo(1-C12H25NH3Br, s) = −(7369.03±3.28) kJmol−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 ΔcHmo(1-C12H25NH3Br, s) = −(7384.52±3.28) kJmol−1 from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound is calculated to be ΔfHmo(1-C12H25NH3Br, s)=−(1317.86±3.67) kJmol−1 from the standard molar enthalpy of combustion of the title compound and other auxiliary thermodynamic quantities through a thermochemical cycle.