The predicted environmental distribution of substituted benzene derivatives

Abstract

The aim of this study is to calculate environmental equilibrium distributions of substituted benzenes and thus to indicate where each of them goes and what relative concentrations they adopt i n the environmental compartments. With the diversity of chemicals, reasons for predicting their environmental behaviour from their physicochemical properties such as vapor pressure, water solubility and n-octanol-water partition coefficient are obvious. In this study, Mackay's Level I Fugacity Model based on fugacity, a thermodynamic quantity related to chemical potential or activity that characterizes the escaping tendency from a phase, is used for calculations. The fugacity calculations are applied to an evaluative environment, " unit world" consisting of compartments of homogeneous air, soil, water, biota, suspended solids and sediment. Each compartment is assigned a reasonable volume and properties and I the equilibrium distributions of those chemicals are calculated using fugacity capacities that are calculated from physical and chemical data and partition coefficients. When the results are designed to yield priorities for each compartment, it is found that alkyl benzenes except butylbenzenexylenes, mono- and di -fluorobenzenes, mono- and di-bromobenzenes , mono-, di- tri-chlorobenzenes, iodobenzene for the air compartment, all phenols, all anilines , acetophenone, benzylcohol, butylbenzene, anisle, nitrobenzenes , diiodobenzenes , chlooiodobenzenes, bromoi odobenzenes, bromochl orobenzenes, iodobenzene, di bromobenzenes , tri bromobenzenes for the water compartment, diiodobenzenes, tribromobenzenes, hexachlorobenzene, bromoiodobenzenes, chloroiodobenzenes, tetrachlorobenzenes, pentachlorobenzene.for the biota, soil , sediment, and suspended solids compartments are priorities. During this work, good correlations between the mass partitioning of halobenzenes and total molecular surface area, molar volume and T hydrophobic substituent constant are obtained. The mass percentage values calculated by using the correlation equations obtained from this study are in agreement with those calculated through Mackay's Level I approach. Thus these correlations make it possible t o calculate the likely equilibrium distribution by using only one property.