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Unit 3
Elements of Organic Chemistry

3-13. ESTERS

Esters, as previously mentioned, are formed from the reaction of a carboxylic acid with an alcohol and have the general structural formula RCOOR' or 803fig0323.jpg (2134 bytes) where R and R' can be the same or different hydrocarbon groups.

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 are soluble.

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.

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After hydrolysis, the acid product can undergo reduction to form a second alcohol as described previously.

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 them.

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Acetylsalicylic Acid (Aspirin)--an analgesic

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Nitroglycerin--a cardiac drug