Ketone is next in the hydrocarbon-derivative family. As a group, the ketones are flammable and narcotic. They have moderate boiling and flash points, narrow flammable ranges, and high ignition temperatures. Ketones are polar, and fires should be fought with alcohol –or polar-solvent-type foams because water may be ineffective. They are made up of a carbon atom double-bonded to an oxygen atom, with a radical on each side. The general formula is R-C-O-R. Ketone is the first of several compounds that are part of the carbonyl family. Carbonyl compounds have a carbon double-bouded to oxygen. Carbonyls are polar. The degree of polarity is less than of the alcohols and organic acids. There are two radicals required in ketone compounds. The radicals may be the same, in which case the prefix “di” is used to indicate two, or the radicals may be different. When naming these compounds, the smallest is named first, then the second radical, ending in the word “ketone”. Some ketones have trade names by which they are some hints, such as with acetone, which is a three-carbon ketone, also called dimethyl ketone (Figure 5.58). The “one” ending indicates ketone, just as the “ol” ending indicates alcohol. The ending would be a tip-off that acetone may be a ketone. DMK is the trade name used for dimethyl ketone, which is also known as acetone. MEK is often used as a shortened name or trade name for methyl ethyl ketone (MEK). These are common ketones, and the more familiar you are with hazardous materials, the more familiar you will alternate names and trade names.