Esters have a carbon atom double-bonded to one oxygen atom and a single bond with another oxygen atom. Esters are carbonyls and are polar. The degree of polarity is much less than organic acids and alcohols and is similar to ketones and aldehydes. Esters are miscible with water and require polar solvent foams when fighting fires. In this book, only three esters will be discussed because of their common commercial use. The general for mula for ester is R-C-O-O-R or R-C-O2-R. There are two radicals in the ester compounds.