c. The ketone functional group appears in the structure of many complex
drugs, such as steroid compounds and vitamins. Simple ketones, with the exception
of acetone, are seldom used. Acetone is used as a solvent and cleaning fluid.
Esters, as previously mentioned, are formed from the reaction of a carboxylic
acid with an alcohol and have the general structural formula RCOOR' or O where R
and R' can be the same or different hydrocarbon groups.
a. Properties of Esters. The simplest esters are liquids and have fragrant
odors. An example is ethyl acetate, CH3-CH2-OOC-CH3, which has the odor of
pineapple. Esters cannot form hydrogen bonds between themselves; consequently,
they have boiling points similar to alkanes of similar molecular weight. They can form
hydrogen bonds with water. Therefore, esters that contain less than five carbon atoms
b. Reactions of Esters. Esters are neutral in pH and undergo two important
chemical reactions, hydrolysis, and reduction. Hydrolysis is the splitting of an ester
with the incorporation of water to form a carboxylic acid and an alcohol.
R-C-O-R ---> R-C-OH + R'-OH
After hydrolysis, the acid product can undergo reduction to form a second alcohol as
c. Uses of Esters. The ester functional group is found in many complex
molecules which you will be studying in the pharmacology subcourses if you take
Acetylsalicylic Acid (Aspirin)--an analgesic