Ester

In organic chemistry and biochemistry, a functional group resulting from the condensation? of an acid and an alcohol. The process is called exterification?:

  O                      O 
 RCOH   +   HOR'  <-->  RCOR'   +   H2O
 acid     alcohol      ester       water

Naming of esters:

              O
              ||
              C - CH3
             /
  CH3 - CH2-O

    ethyl      acetate/ethanoate 
  (comes from    (comes from
  the alcohol)      the acid)

Physical properties:

Esters can participate in hydrogen bonds as hydrogen bond acceptors, but cannot act as hydrogen bond donors, unlike their parent alcohols. This ability to participate in hydrogen bonds leads them to be more water soluble than their parent hydrocarbons. But the limitations on their hydrogen bonding also make them more hydrophobic than either their parent alcohols or parent acids. Their lack of hydrogen-bond donating ability means that they can't form hydrogen bonds between ester molecules, which makes them generally more volatile than an acid or ester of similar molecular weight.

Many esters have distinctive odors, which leads to their widespread use as artificial flavorings and fragrances.

Esters also participate in [ester hydrolysis]? - the breakdown of an ester by water.