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Solvation descriptors for pesticides from the solubility of solids: diuron as an example

Green, CE; Abraham, MH; Acree, WE; De Fina, KM; Sharp, TL; (2000) Solvation descriptors for pesticides from the solubility of solids: diuron as an example. Pest Management Science , 56 (12) 1043 - 1053.

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Abstract

Solubilities of diuron in 19 organic solvents are reported. These: are combined with the solubility in water and the vapour pressure of diuron to give 19 values of water-solvent partitions, P, and 19 values of gas-solvent partitions, L. Coefficients in the general solvation equations (i) and (ii) are known for all 38 of these systems. In equations (i) and (ii), the independent variables are solute descriptors as follows: R-2 is an excess molar refraction, pi (2)(H) is the dipolarity/polarizability, Sigma alpha (H)(2) and Sigma beta (H)(2) are the overall hydrogen-bond acidity and basicity, Vx is the McGowan characteristic volume, and log L-16 is a descriptor where L-16 is the solute L coefficient on hexadecane at 298 K. (i) log SP = c + rR(2) + s pi (H)(2) + a Sigma alpha (H)(2) + b Sigma beta (H)(2) + nu Vx (ii) log SP = c + rR(2) + s pi (H)(2) + a Sigma alpha (H)(2) + b Sigma beta (H)(2) + log L-16 We estimate R-2 as 1.28 and calculate Vx as 1.5992, and then solve the total set of 38 equations to yield pi (H)(2)=1.60, Sigma alpha (H)(2)=0.57, Sigma beta (H)(2)=0.70 and logL(16)=8.06 log units. These descriptors reproduce the 38 observed log P and log L values with a standard deviation of only 0.12 log units, and a test set of 13 independent log P and logL values with a standard deviation of 0.10 log units. Once the solvation descriptors for diuron are known, a range of physicochemical properties can be predicted; some examples are given. Similar analyses are reported for monuron and other substituted 3-ghenyl-1,1-dimethylureas. (C) 2000 Society of Chemical Industry

Type:Article
Title:Solvation descriptors for pesticides from the solubility of solids: diuron as an example
Additional information:Journal Article DEC 379UL Abraham MH Univ London Univ Coll, Dept Chem, 20 Gordon St, London WC1H 0AJ, England PEST MANAG SCI
Keywords:298 K, 3- phenyl-1;1-dimethylurea, ALPHA, As, beta, Brain, chemical, COEFFICIENTS, DESCRIPTORS, diuron, ENERGY RELATIONSHIP ANALYSIS, EQUATION, EQUATIONS, EXAMPLE, HYDROGEN-BOND, industry, LFER, LOG-P, MH, NU, Other, PARAMETER, PARTITION, partition coefficient, PENETRATION, pesticide, pesticides, PHASE LIQUID-CHROMATOGRAPHY, PREDICTION, Pressure, RANGE, S, SKIN PERMEABILITY, societies, SOLUBILITY, SOLUTE, SOLUTE DESCRIPTORS, SOLUTES, SOLVATION, solvation descriptors, solvation equations, Solvents, SYSTEM, SYSTEMS, VALUES, vapour pressure, variable, VARIABLES, volume, Water
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry

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