Halogen compounds, vapor pressure

N s are the numbers of atoms of carbon (C), sulfur (S), hydrogen (H), halogens (X), and oxygen (O) in the molecule. P is the total system pressure. is the vapor pressure of the compound at the flash point temperature. 

Results for vapor pressure as a function of temperature are presented for major organic chemical compounds. The coefficients are displayed in an easy-to-use table which is especially applicable for rapid engineering usage with the personal computer or hand calculator. The organic chemicals encompass hydrocarbon, oxygen, nitrogen, halogen, silicon, sulfur and other chemical type compounds. 

Solvatochromic Approach Solvatochromic relationships are multivariate correlations between a property, usually solubility or partitioning property (see Sections 11.4 and 13.3), and solvatochromic parameters, parameters that account for the solutes interaction with the solvent. In the case of vapor pressure, the solvatochromic parameters only have to account for intermolecular interaction such as selfassociation between the solute (i.e., pure compound) molecules themselves. The following model has been reported for liquid and solid compounds, including hydrocarbons, halogenated hydrocarbons, alkanols, dialkyl ethers, and compounds such as dimethyl formamide, dimethylacetamide, pyridine, and dimethyl sulfoxide... 

According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere, bromotrichloromethane, which has a measured vapor pressure of 39mmHg at 25°C, is expected to exist solely as a vapor in the ambient atmosphere. Based on bromotrichloromethane s structural similarity to bromotrifluoromethane, it is expected to slowly degrade in the atmosphere by reaction with photochemically produced hydroxyl radicals the half-life for bromotrichloromethane s reaction in air is estimated to be greater than 44 years. Photolysis may occur based on bromotrichloromethane s structural similarity to other halogenated methane compounds but not at an environmentally relevant rate. 

Ktihne et al. [105] used MP and 23 structural parameters to correlate the vapor pressure of 1838 hydrocarbons and halogenated hydrocarbons. The neural network model was built using 1200 compounds and provided a mean absolute error of 0.13 log units for the test set of 638 compounds. It should be noted that the authors predicted vapor pressure as a function of the temperature and total number of data points for model development was 8148. The MP and BP are also used in MPBPVP program developed by Syracuse Research Inc [101]. 

For these compounds there is a direct correlation between biological activity and certain physicochemical parameters such as partition coefficient, surface tension or vapor pressure. The accumulation of halogen atoms favors the passage of the biomembranes and the access to the CNS. Flansch has dehned a parameter, vr, representing the... 

Tabulated Data on Vapor Pressure of Halogen Containing Organic Compounds... 

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