Chlorinated phenols relationship

Most acid dissociation constants pKa exceed environmental pH values, the exceptions being the highly chlorinated phenols. As a result, these substances tend to have higher apparent solubilities in water because of dissociation. The structure-property relationships apply to the un-ionized or protonated species thus, experimental data should preferably be corrected to eliminate the effect of ionization, thus eliminating pH effects. 

Although many other phenolic derivatives have been chlorinated and examined as potential haloform precursors, few have shown any particular proclivity to react in this particular fashion. Possible exceptions are a few chlorinated phenols having chlorine atoms in a meta relationship to the OH group (28 Hirose et al., 1982). The mechanistic rationales for the formation of haloforms from these compounds have not become clear. Many phenols, particularly phenolic acids, do, however, undergo other interesting and unusual chlorination reactions vide supra). 

Tratnyek PG, Hoigne J. 1994. Kinetics of reactions of chlorine dioxide (OCIO) in water—II. Quantitative stmcture-activity relationships for phenolic compounds. Water Res 28(l) 57-66. 

Tratnyek, P. G., and Hoigne, J. (1994) Kinetics of Reactions of Chlorine Dioxide in Water—II Quantitative Stmcture-Activity Relationships for Phenolic Compounds. Water Res. 28, 57-66. 

With few exceptions (c.g., DES), a causal relationship between exposure to a specific environmental agent and an adverse effect on human health operating via an endocrine disruption mechanism has not been established. Short-term screening studies could be developed and validated in an effort to elucidate the mechanism. Through controlled dose-response studies, it appears that these compounds (e.g., alkyl phenol ethylates and their degradation products, chlorinated dibenzodioxins and difurans, and polychlorinated biphenyls) can induce irreversible induction of male sex characteristics on females (impo-sex), which can lead to sterility and reduced reproductive performance. 

Norwood D.L., Christman R.F. (1987), Structural characterisation of aquatic humic material. 2. Phenolic content and its relationship to chlorination mechanism in an isolated aquatic fulvic acid,... 

The simplest form of a Free Wilson analysis is presented in eq. 192 [22], which describes the antibacterial activities of phenol and isomeric chlorophenols (51, R = H, Cl one to five chlorine atoms) vs. Staphylococcus aureus at least the linearity of the structure-activity relationship can be derived from eq. 192 on the other hand, although most probably lipophilicity is responsible for the variance in the biological activities, no Hansch equation can be derived, because each other physicochemical property of the chlorine atom will give identical results. 

Similar structure-toxicity relationship trends are observed for the series of chlorophenols. For this series (compounds 13 to 21), the parent structure was assumed to be pentachlorophenol and the reported group contributions quantify the reduction in toxicity as chlorine atoms are dropped from a particular position. This is qualitatively equivalent to introduction of a chlorine atom at a given position in phenol. It can be seen that chlorination in para position to the -OH group makes the molecule most toxic. Chlorination of phenol at both the meta positions makes the compound more toxic, in contrast, chlorination at both ortho positions does not have much effect. 

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