QSAR STUDY OF THE TOXICITY OF NITROBENZENES TO TETRAHYMENA-PYRIFORMIS

A QSAR analysis has been carried out of the toxicity of 47 monosubstit uted nitrobenzenes to the aquatic ciliate Tetrahymena pyriformis. The single most important parameter was the logarithm of the apparent part ition coefficient (log D) at pH 7.35. 2- and 3-derivatives yielded an excellent correlation of toxicity with log D, Swain-Lupton field param eter and modulus of change of charge on the nitro group oxygen upon su bstitution. This is consistent with their behaving as pro-electrophile s. 4-derivatives, however, clearly had a different mode of action, wit h the best correlation being found with log D, molar refractivity and the Shannon index.