Ketones - organic compounds with the General formula R-CO-R (where R is a hydrocarbon radicals, such as CH3-, CH3 CH2and so on). Lowest ketones - liquid with a characteristic smell, such as acetone (CH3)2CO, high - solids, such as camphor. To the class of ketones are also steroid hormones (estrone, cortisone, and others), many of which are used in medicine.