Predicting temperature-dependent solid vapor pressures of explosives and related compounds using a quantum mechanical...

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Environmental Science

Background:

• Accurate prediction of vapor pressures for solid explosives and their byproducts is crucial for environmental and safety assessments.
• Existing models like COSMO-RS require corrections for solid-state properties, which are difficult to obtain experimentally for explosives.

Purpose of the Study:

• To improve the accuracy of vapor pressure predictions for solid explosives using a modified COSMO-RS approach.
• To develop a method for estimating necessary correction factors from standard quantum chemistry calculations.
• To predict vapor pressures for explosives and degradation products lacking experimental data.

Main Methods:

• Modified conductor-like screening model for real solvents (COSMO-RS) incorporating free energy of fusion and van der Waals interactions.
• Development of a quantitative structure-property relationship (QSPR) to estimate correction factors.
• Utilizing standard quantum chemistry calculations to provide input for the QSPR model.

Main Results:

• Improved COSMO-RS predictions for ambient vapor pressure of nitrogen-rich explosives by over an order of magnitude.
• Achieved accuracy of 0.32 log units for temperature-dependent vapor pressure calculations.
• Demonstrated good agreement between predicted and experimental temperature dependencies.

Conclusions:

• The enhanced COSMO-RS model provides accurate vapor pressure predictions for explosives, crucial for environmental fate and transport modeling.
• The QSPR approach effectively estimates correction factors, reducing reliance on limited experimental data.
• The method enables predictions for a wider range of explosives and their degradation products.