KETONE EC(50) VALUES IN THE MICROTOX TEST

The Microtox EC(50) values for the following ketones are reported in t he following homologous series: straight chain methyl ketones (acetone , 2-butanone, 2-pentanone, 2-heptanone, 2-octanone, 2-decanone, and 2- tridecanone); methyl ketones substituted at one alpha carbon (3-methyl -2-butanone; 3,3-dimethyl-2-butanone); methyl substituted at two alpha carbons (2,4-dimethyl-3-pentanone; 2,2,4,4-tetramethyl-3-pentanone); phenyl groups replacing methyl in acetone (acetophenone; benzophenone) ; methyl groups substituted at the alpha carbons of cyclohexanone; and 2,3- 2,4-, and 2,5-hexanediones, most for the first time. While there were linear relationships between log EC(50) and MW for the straight chain methyl ketones, and for methyl substitution at the ex carbon for methyl ketones, there were no other linear relationships. As molecula r weight increased, the EC(50) values of soluble ketones decreased; as distance between two carbonyl groups decreased so too did EC(50) valu es. Thus, for the ketones the geometry around the carbonyl group is an important determinant of toxicity as well as MW, water solubility, an d octanol/water coefficient. (C) 1995 Academic Press, Inc.