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Gerome B. Vallejos*, Ellis Mika C. Trino, Jahn Camille B. Valdez, Ariza Yamashita Department of Biological Sciences, College of Science
Corresponding author: firstname.lastname@example.org
The purpose of this experiment was to synthesize isopentyl acetate via Fischer esterification reaction between acetic anhydride and isoamyl alcohol, using concentrated sulfuric acid as a catalyst. This reaction is characterized by the combining of an alcohol and an acid (with an acid catalyst) to yield and ester plus water. In order to accomplish this reaction, the reactants were refluxed for 30 minutes at 80 degrees Celsius ,to yield a mixture, the mixture was then mixed with sodium hydrogen carbonate and dried with anhydrous sodium sulfate. The product obtained from this reaction was then weighed and yielded 3.5753g, the total percent yield of isopentyl acetate obtained was 60 %. The advantages of using this particular esterification process, is that is fairly simple to set up and recreate, as long as the proper acidic conditions are present. Keywords: Esterification, Reflux, Extraction, Esters, Isopentyl acetate
Esters have the general formula of R’COOR, in which R’ can be H, an alkyl or an aromatic hydrocarbon group and R is an alkyl or an aromatic hydrocarbon group (Bettelheim et al., 2007). The volatile compounds in natural fruits and flowers are usually complex mixtures of compounds, where esters frequently predominate. Many artificial flavorings contain esters or mixtures of esters. Esters are a group of naturally occurring compound that generally possess distinctive odor. Many of the processed foods that you buy today come with an ingredient label that lists "artificial flavors" as one of the key ingredients. Artificial flavors are simply chemical mixtures that mimic a natural flavor in some way. Most organic fragrances and fruit flavours belong to this class of compounds. Anything that we smell has to contain some sort of volatile chemical -- a chemical that evaporates and enters a person's nose. In the case of taste, a chemical has to activate the taste buds. Taste is a fairly crude sense -- there are only four values that your tongue can sense such as sweet, salty, sour, and bitter -- while the nose can sense thousands of different odors. Carboxylic acid esters of low molecular weight are colourless, volatile liquids with pleasant odours, slightly soluble in water. Many esters are responsible for the fragrance and flavour of flowers and fruits; for example, isopentyl acetate is present in bananas, methyl salicylate in wintergreen, and ethyl butyrate in pineapples. These and other volatile esters with characteristic odors are used in synthetic flavours, perfumes, and cosmetics. Certain volatile esters are also used as solvents for lacquers, paints, and varnishes; for this purpose, large quantities of ethyl acetate and butyl acetate are commercially produced. Waxes secreted by animals and plants are esters formed from long-chain carboxylic acids and long-chain alcohols. Fats and oils are esters of long-chain carboxylic acids and glycerol. Therefore most artificial flavors have both taste and smell components. Any natural flavor is normally quite complex, with dozens or hundreds of chemicals interacting to create the taste/smell. But it turns out that many flavors -- particularly fruit flavors – have just one or a few dominant chemical components that carry the bulk of the taste/smell signal. Many of these chemicals are called esters. The primary objective of this experiment is to prepare the assigned ester via Fischer reaction and calculate its percent yield. Fischer reaction for the synthesis of esters is an acid catalyzed reaction of an alcohol and a carboxylic acid.
Scheme 1.0 Example of a Fischer Esterification
An example of this reaction is seen in Scheme 1.0, the acid and alcohol reactants are in equilibrium...