Ionic compounds environmental fate

Physical and Chemical Properties. As reported in Section 3.2, the relevant physical and chemical properties of cyanide compounds are known. Certain physical parameters such as octanol/water partition coefficient and soil partition coefficient that are used generally for covalently bound organic compounds to predict environmental fate and transport are neither available nor useful for most of the ionic cyanide compounds. 

Physical and Chemical Properties. More experimental and estimated data on the physical and chemical properties for 2,4-DNP are available than for other dinitrophenols (see Table 3-2). Even in the case of 2,4-DNP, reliable experimental or estimated values are not available for vapor pressure, Henry s law constant, and log K°<=. This is not surprising since dinitrophenols exist predominantly in the ionic forms at pH >6 with very low vapor pressure. If available, the physical constants are important in predicting the environmental transport of dinitrophenols. Therefore, it would be helpful to develop more reliable data on certain physical properties important in predicting the environmental fate of these compounds. 

Historically, organic environmental pollutants were hydrophobic, often persistent, neutral compounds. As a consequence, these substances were readily sorbed by particles and soluble in lipids. In modern times, efforts have been made to make xenobiotics more hydrophilic - often by including ionisable substituents. Presumably, these functional groups would render the compound less bioaccumulative. In particular, many pesticides and pharmaceuticals contain acidic or basic functions. However, studies on the fate and effect of organic environmental pollutants focus mainly on the neutral species [1], In the past, uptake into cells and sorption to biological membranes were often assumed to be only dependent on the neutral species. More recent studies that are reviewed in this chapter show that the ionic organic species play a role both for toxic effects and sorption of compounds to membranes. 

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