Calculation of Some Thermodynamic Properties and Detonation Parameters of 1‐Ethyl‐3‐Methyl‐H‐Imidazolium Perchlorate, [Emim][ClO₄], on the Basis of CBS‐4M and CHEETAH Computations Supplemented by VBT Estimates

Abstract

Abstract This paper estimates some thermochemical (in kcal mol –1 ) and detonation parameters for the ionic liquid, [emim][ClO 4 ] and its associated solid in view of its investigation as an energetic material. The thermochemical values estimated, employing CBS‐4M computational methodology and volume‐based thermodynamics (VBT) include: lattice energy, U POT ([emim][ClO 4 ]) ≈︁ 123 ± 16 kcal · mol –1 ; enthalpy of formation of the gaseous cation, Δ f H °([emim] + , g) = 144.2 kcal · mol –1 and anion, Δ f H °([ClO 4 ] – , g) = –66.1 kcal · mol –1 ; the enthalpy of formation of the solid salt, Δ f H °([emim][ClO 4 ],s) ≈︁ –55 ± 16 kcal · mol –1 and for the associated ionic liquid, Δ f H o ([emim][ClO 4 ],l) = –52 ± 16 kcal · mol –1 as well as the corresponding Gibbs energy terms: Δ f G °([emim][ClO 4 ],s) ≈︁ +29 ± 16 kcal · mol –1 and Δ f G o ([emim][ClO 4 ],l) = +24 ± 16 kcal · mol –1 and the associated standard absolute entropies, of the solid [emim][ClO 4 ], S ° 298 ([emim][ClO 4 ],s) = 83 ± 4 cal · K –1 · mol –1 . The following combustion and detonation parameters are assigned to [emim][ClO 4 ] in its (ionic) liquid form: specific impulse ( I sp ) = 228 s (monopropellant), detonation velocity ( V oD ) = 5466 m · s –1 , detonation pressure ( p C–J ) = 99 kbar, explosion temperature ( T ex ) = 2842 K.