To work out the structure of the ester formed when an alcohol reacts with a carboxylic acid, it is easiest to first draw the structures of alcohol and acid and then remove the H₂O to see what is left when the molecules join.
For example, propan-1-ol and ethanoic acid react together to form propyl ethanoate and water.
propan-1-ol + ethanoic acid → propyl ethanoate + water
CH₃CH₂CH₂OH (l) + CH₃COOH (l) → CH₃COOCH₂CH₂CH₃ (l) + H₂O (l)
The displayed formula for esters is typically written to show the part which came from the carboxylic acid on the left:
This is still called propyl ethanoate: the alcohol bit of the name (propyl) comes first and then the carboxylic acid bit (ethanoate), even though the displayed formula is typically written the other way around. Notice that the structural formulae for esters is also typically written with the carboxylic acid bit first, so propyl ethanoate is CH₃COOCH₂CH₂CH₃.
Ili kujua muundo wa ester iliyoundwa wakati pombe inapoingiliana na asidi ya carboxylic, ni rahisi kwanza kuchora muundo wa pombe na asidi na kisha kuondoa H2O ili kuona kile kinachobaki wakati molekuli zinajiunga. Kwa mfano, propan-1-ol na asidi ya etanoic huingiliana ili kutokeza propyl ethanoate na maji. Chini ya chombo cha ethanol, ethanol ya propyl (CH3CH2CH2OH) na ethanol ya ethanol (CH3CH2CH2OH) ni chombo cha ethanol, na chombo cha ethanol (CH3CH2CH2OH) ni chombo cha ethanol, na chombo cha ethanol (CH3CH2CH2OH) ni chombo cha ethanol. Kwa mfano, katika muundo wa esters, ethanate ya propyl inaitwa CH3COCH2CH2CH3.