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Esters. R – C – O – R´ O. Session 39. Esters. They derive from the carboxylic acids, its functional group called ester is the following: - C - O - O
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Esters R – C – O – R´ O Session 39
Esters They derive from the carboxylic acids, its functional group called ester is the following: - C - O - O Esters are recognized for their nice scent and the constitute the source of the scents of flowers and taste of fruits.
Nomenclature IUPAC System Esters are named as salts of carboxylic acids. We first pronounce the anion name of the acid followed by the name of the alkyl group of the alcohol. The name of the acid part of the ester is obtained substituting the end “ol” for “yl”, the two words are by the word de. For Example: CH3CH2CH2- C - OCH2CH3 O Ethyl Butyrate
Preparation Esters are produced with the reaction of an alcohol with a carboxylic acid in presence of an catalyzing acid. This reaction is know by Esterification. R – C = O + R´- OH R – C – O – R´ + H2O OH O (in presence of an acid)
Physical Properties Esters with low molecular weight are colorless liquids, frequently with nice odor. The are insoluble in water. They are a good dissolvent for many organic compounds.
Chemical Properties Acid Hydrolysis R – COO – R´ + H2O R- COOH + R´- OH (in acid environment) Basic Hydrolysis. Saponification R – COO – R´ + NaOH R- COONa + R´- OH
Saponification of fats Creating soaps O CH2 – O – C – R CH2 – OH O ∆ CH – O – C – R + 3Na OH CH – OH + 3R - COONa Soap O CH2 – O – C – R CH2 – OH Fat glycerol
Importance and Applications Importance and Application of Esters Flavorings and Scents (rum, banana, orange, apricot, pineapple, etc). Essences in perfumes, candies y ointments. Acetylsalicylic acid active ingredient in aspirin. Used in the production of soaps and detergents. Production of synthetic fibers (polyesters like dacron)