Estimations of vapor pressure and activity coefficients in water and octanol for selected aromatic chemicals at 25°C

Lee, Sum Chi; Hung, Hayley; Shiu, Wan Ying; Mackay, Donald

doi:10.1002/etc.5620191102

“…Ideal solution behavior (i.e., γ o within an order of magnitude of unity) was expected for the OC pesticides, because like octanol, these molecules are slightly polar. These estimates of γ o are consistent with experimental and calculated values reported for selected aromatic organic chemicals [22]. A good correlation between p

_{o}^{L}

and K oa is obtained with the resulting regression equation at 25°C: Log K oa = ‐0.982 log p

_{o}^{L}

+ 6.88 ( r 2 = 0.808).…”

Section: Resultssupporting

confidence: 87%

Using measured octanol‐air partition coefficients to explain environmental partitioning of organochlorine pesticides

Shoeib

¹

,

Harner

²

2002

Enviro Toxic and Chemistry

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Octanol-air partition coefficients (Koa) were measured directly for 19 organochlorine (OC) pesticides over the temperature range of 5 to 35 degrees C. Values of log Koa at 25 degrees C ranged over three orders of magnitude, from 7.4 for hexachlorobenzene to 10.1 for 1,1-dichloro-2,2-bis(p-chlorophenyl) ethane. Measured values were compared to values calculated as KowRT/H (where R is the ideal gas constant [8.314 J mol(-1) K(-1)], T is absolute temperature, and H is Henry's law constant) were, in general, larger. Discrepancies of up to three orders of magnitude were observed, highlighting the need for direct measurements of Koa. Plots of Koa versus inverse absolute temperature exhibited a log-linear correlation. Enthalpies of phase transition between octanol and air (deltaHoa) were determined from the temperature slopes and were in the range of 56 to 105 kJ mol(-1) K(-1). Activity coefficients in octanol (gamma(o)) were determined from Koa and reported supercooled liquid vapor pressures (pL(o)), and these were in the range of 0.3 to 12, indicating near-ideal solution behavior. Differences in Koa values for structural isomers of hexachlorocyclohexane were also explored. A Koa-based model was described for predicting the partitioning of OC pesticides to aerosols and used to calculate particulate fractions at 25 and -10 degrees C. The model also agreed well with experimental results for several OC pesticides that were equilibrated with urban aerosols in the laboratory. A log-log regression of the particle-gas partition coefficient versus Koa had a slope near unity, indicating that octanol is a good surrogate for the aerosol organic matter.

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“…Ideal solution behavior (i.e., ␥ o within an order of magnitude of unity) was expected for the OC pesticides, because like octanol, these molecules are slightly polar. These estimates of ␥ o are consistent with experimental and calculated values reported for selected aromatic organic chemicals[22]. A good correlation between and K oa is ob-o p L tained with the resulting regression equation at 25ЊC: Log K oa ϭ Ϫ0.982 log ϩ 6.88 (r 2 ϭ 0.808).…”

supporting

confidence: 87%

Using Measured Octanol-Air Partition Coefficients to Explain Environmental Partitioning of Organochlorine Pesticides

Shoeib¹,

Harner²

2002

Environ Toxicol Chem

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Octanol-air partition coefficients (Koa) were measured directly for 19 organochlorine (OC) pesticides over the temperature range of 5 to 35 degrees C. Values of log Koa at 25 degrees C ranged over three orders of magnitude, from 7.4 for hexachlorobenzene to 10.1 for 1,1-dichloro-2,2-bis(p-chlorophenyl) ethane. Measured values were compared to values calculated as KowRT/H (where R is the ideal gas constant [8.314 J mol(-1) K(-1)], T is absolute temperature, and H is Henry's law constant) were, in general, larger. Discrepancies of up to three orders of magnitude were observed, highlighting the need for direct measurements of Koa. Plots of Koa versus inverse absolute temperature exhibited a log-linear correlation. Enthalpies of phase transition between octanol and air (deltaHoa) were determined from the temperature slopes and were in the range of 56 to 105 kJ mol(-1) K(-1). Activity coefficients in octanol (gamma(o)) were determined from Koa and reported supercooled liquid vapor pressures (pL(o)), and these were in the range of 0.3 to 12, indicating near-ideal solution behavior. Differences in Koa values for structural isomers of hexachlorocyclohexane were also explored. A Koa-based model was described for predicting the partitioning of OC pesticides to aerosols and used to calculate particulate fractions at 25 and -10 degrees C. The model also agreed well with experimental results for several OC pesticides that were equilibrated with urban aerosols in the laboratory. A log-log regression of the particle-gas partition coefficient versus Koa had a slope near unity, indicating that octanol is a good surrogate for the aerosol organic matter.

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“…In that case, b 0 (T ) serves as a general fitting constant. Alternatively, the fitting can take place within a particular class of compounds, as in the study by Lee et al (2000) of substituted benzene compounds wherein for predicting p o L, i (298.15) the value of b 0 (298.15) was not obtained from the fitting process. Rather, it was defined that b 0 (298.15)= log 10 p o L, benzene (298.15).…”

Section: Nonoxygenated Alkanesmentioning

confidence: 99%

“…In a generalization (though first order) of the Lee et al (2000) approach, Capouet and Müller (2006) allowed that a range of parent structures would be of interest, and so existing p o L,i (T ) data for a range of compounds were fit to…”

Section: Nonoxygenated Alkanesmentioning

confidence: 99%

SIMPOL.1: A simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

Pankow¹,

Asher²

2007

Preprint

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Abstract. The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure pLo (atm) and enthalpy of vaporization ΔHvap (kJ mol-1) of organic compounds as functions of temperature (T). For each compound i, the method assumes log10pL,io(T)=Σkνk,ibk(T) where νk,i is the number of groups of type k, and bk(T) is the contribution to log10 pL,io(T) by each group of type k. A zeroeth group is included that uses b0(T) with ν0,i=1 for all i. A total of 30 structural groups are considered: molecular carbon, alkyl hydroxyl, aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde, ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary, secondary, and tertiary), aromatic amine, amide (primary, secondary, and tertiary), peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate, nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C–C=O in a non-aromatic ring, and carbon on the acid-side of an amide. The T dependence in each of the bk(T) is assumed to follow b(T)=B1/T+B2+B3T+B4lnT. Values of the B coefficients are fit using an initial basis set of 272 compounds for which experimentally based functions pL,io=fi(T) are available. The range of vapor pressure considered spans fourteen orders of magnitude. The ability of the initially fitted B coefficients to predict pLo values is examined using a test set of 161 compounds and a T range that is as wide as 273.15 to 393.15 K for some compounds. σFIT is defined as the average over all points of the absolute value of the difference between experimental and predicted values of log10pL,io(T). After consideration of σFIT for the test set, the initial basis set and test set compounds are combined, and the B coefficients re-optimized. For all compounds and temperatures, σFIT=0.34: on average, pL,io(T) values are predicted to within a factor of 2. Because d(log10pL,io(T))/d(1/T) is related to the enthalpy of vaporization ΔHvap,i, the fitted B provide predictions of ΔHvap,i based on structure.

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Estimations of vapor pressure and activity coefficients in water and octanol for selected aromatic chemicals at 25°C

Cited by 11 publications

References 54 publications

Using measured octanol‐air partition coefficients to explain environmental partitioning of organochlorine pesticides

Using measured octanol‐air partition coefficients to explain environmental partitioning of organochlorine pesticides

Using Measured Octanol-Air Partition Coefficients to Explain Environmental Partitioning of Organochlorine Pesticides

SIMPOL.1: A simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

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