For inorganic and organic compounds, linear structure–
activity relationships can be proposed based on the electrondonor/
acceptor characteristics, structural analogy and from
the expected chlorination mechanisms. Considering the
known chlorine reactivity with the main functional groups,
an estimation of the order of magnitude of chlorination
reaction rate constants can be carried out. Such estimations
were shown to be in agreement with literature data for
numerous pharmaceuticals and endocrine disruptors. However,
due to more complex chemical structures, such estimations
are more difficult to be obtained in the case of certain
heterocycles or cyanotoxins.