Formation of ester molecule. Animation showing the reaction between an alcohol and a carboxylic acid to form an ester molecule. The atoms are colour-coded spheres: carbon (grey), hydrogen (white) and oxygen (red). Here, the two molecules shown at the start of the clip are butanol (C4.H9.OH, left) and ethanoic acid (CH3.COOH, right). This esterification reaction, also a condensation and dehydration reaction, results in the elimination of a water molecule (H2O). The resulting ester in this case is butyl acetate (C6.H12.O2), also known as butyl ethanoate. It is found in many fruits and is also used as a synthetic fruit flavouring.