Thermophysical Properties of VX and RVX

Abstract

Selected thermophysical properties are reported for VX (O-ethyl-S-[2(diisopropylamino)ethyl] methylphosphonothiolate) and its isomer, RVX (O-isobutyl-S-[2(diethylamino)ethyl] methylphosphonothiolate). Several properties have been reported previously for both compounds; the focus of the current work has been the measurement of additional properties and expansion of the experimental ranges for the existing data. This report consolidates and compares physical property data measured in our laboratory for both compounds. It is important to know the physical properties of these supertoxic materials accurately to understand quantitatively the threat posed by them during military conflict, perform testing of defensive equipment, and determine the necessity to perform decontamination procedures. Knowledge of the properties of these toxic materials facilitates the selection of lower-toxicity candidates to simulate their behavior during testing where the use of the toxic agent is inappropriate. The current work has employed standard American Society for Testing and Materials (ASTM) international methods, intact and modified, to measure physical properties of VX and RVX. Properties investigated in the present work include liquid density, viscosity, surface tension, flash point, vapor pressure, heats of vaporization, and volatility. We also report correlations determined from previously available and new data, where appropriate.

Decontamination of VX from Silicone: Characterization of Multicomponent Diffusion Effects

“…Instead, the VX–silicone interaction parameter was computed from solubility parameters. The Hildebrand solubility parameter for VX was computed from its enthalpy of vaporization, Δ H vap, VX = 80.32 kJ/mol, and the following equation, …”

Vapor Pressure of Triethyl and Tri-n-Propyl Phosphates and Diethyl Malonate

“…Figure shows a comparison of the vapor pressures of TPPO, GF, and nerve agent VX ( O -ethyl- S -[2­(diisopropylamino)­ethyl] methylphosphonothiolate) . TPPO vapor pressure is about 1 order of magnitude lower than that of GF and nearly 1 order of magnitude higher than that of VX at T = (298.15) K.…”

“…A similar method in which quantitative analysis of the saturator effluent was performed using a trap-and-purge method, described elsewhere, was employed for TPPO. The carrier flow rate through the saturator was nominally 25.0 standard cubic centimeters per minute (sccm), referenced to 1 atm and T = (273.15) K, and saturation was confirmed by increasing the saturator flow rate to 50 sccm with no measurable change in TPPO vapor pressure.…”

“…Ambient temperature vapor pressure data were measured for TEPO using a modified ASTM International vapor saturation method 83 in which mass change was monitored after flowing dry nitrogen carrier gas through a specially designed vessel containing liquid TEPO using methodology described in detail elsewhere. 81 A similar method in which quantitative analysis of the saturator effluent was performed using a trap-and-purge method, described elsewhere, 79 was employed for TPPO. The carrier flow rate through the saturator was nominally 25.0 standard cubic centimeters per minute (sccm), referenced to 1 atm and T = (273.15) K, and saturation was confirmed by increasing the saturator flow rate to 50 sccm with no measurable change in TPPO vapor pressure.…”

“…This is the seventh report in a recent series from our laboratory describing determination of the vapor pressure of CW agents and their surrogates. − …”