Force field for the atomistic simulation of the properties of hydrazine, organic hydrazine derivatives, and energetic hydrazinium ionic liquids

Gutowski, Keith E.; Gurkan, Burcu; Maginn, Edward J.

doi:10.1351/PAC-CON-08-09-24

Pure Appl. Chem., 2009, Vol. 81, No. 10, pp. 1799-1828

http://dx.doi.org/10.1351/PAC-CON-08-09-24

Published online 2009-10-05

Force field for the atomistic simulation of the properties of hydrazine, organic hydrazine derivatives, and energetic hydrazinium ionic liquids

Keith E. Gutowski, Burcu Gurkan and Edward J. Maginn*

Department of Chemical and Biomolecular Engineering, University of Notre Dame, 182 Fitzpatrick Hall, Notre Dame, IN 46556-5637, USA

Abstract: A force field (FF) is reported for hydrazine (N₂H₄) and organic hydrazine derivatives, including monomethylhydrazine, 1,1-dimethylhydrazine, monoethylhydrazine, and 2-hydroxyethylhydrazine. The FF successfully reproduces a range of equilibrium properties, including vapor–liquid coexistence densities, vapor pressures, enthalpies of vaporization, and critical properties. Several dynamic properties, including self-diffusion coefficients and rotational time constants, are reported and found to be qualitatively consistent with experimental viscosities. Using this as a basis, a FF is also developed for the protonated forms of these species, i.e., hydrazinium-based cations. Properties of 1:1 energetic salts formed by pairing these cations with the nitrate anion are computed and compared with a limited amount of experimental data. The simulations indicate that the ionic liquid (IL) 2-hydroxyethylhydrazinum nitrate (2-HEHN) has significantly slower dynamics than the other hydrazinium ILs.