Aspirin Experiment
Synthesis of Aspirin and Oil of Wintergreen
INTRODUCTION: Synthesis and use of organic compounds is an extremely important area of modern chemistry. Approximately half of all chemists work with organic chemicals. In everyday life, many if not most of the chemicals you come in contact with are organic chemicals. Examples include drugs, synthetic fabrics, paints, plastics, etc. Synthesis of Aspirin and Methyl Salicylate. The two compounds we will be preparing, aspirin (acetylsalicylic acid) and oil of wintergreen (methyl salicylate), are both organic esters. An ester is a compound that is formed when an acid (containing the COOH group) reacts with an alcohol (a compound containing an -OH group).
O C R1 O H O
+
H
O C R2 R1 O R2
+
H
O H
acid
alcohol
ester
water
Here R1 and R 2 represent groups such as CH3 - or CH3 CH2 -. The reaction type shown above may be called a condensation reaction because the small molecule H 2 O is eliminated from the reactants while the remaining bits of the reactant condense together to give the main product. This reaction may also be called an esterification, since the product of the reaction is an ester, a compound containing the CO2 R group (see chapter 11 for definitions of acids, esters, and alcohols). Esters usually have pleasant, fruit-like odors and are the chemicals responsible for the odors and flavors of many fruits (oranges, bananas, pineapples) and flowers. In most cases, such natural products get their properties from a mixture of organic compounds. In this experiment you will prepare two esters of o-hydroxybenzoic acid, more commonly known as salicylic acid. One of the esters, acetylsalicylic acid, is aspirin, the common analgesic. We will synthesize aspirin by mixing salicylic acid with acetic anhydride. The second ester product is oil of wintergreen, or methyl salicylate, which we prepare by allowing salicylic acid to react with methyl alcohol. This compound, which has a familiar odor is used as
INTRODUCTION: Synthesis and use of organic compounds is an extremely important area of modern chemistry. Approximately half of all chemists work with organic chemicals. In everyday life, many if not most of the chemicals you come in contact with are organic chemicals. Examples include drugs, synthetic fabrics, paints, plastics, etc. Synthesis of Aspirin and Methyl Salicylate. The two compounds we will be preparing, aspirin (acetylsalicylic acid) and oil of wintergreen (methyl salicylate), are both organic esters. An ester is a compound that is formed when an acid (containing the COOH group) reacts with an alcohol (a compound containing an -OH group).
O C R1 O H O
+
H
O C R2 R1 O R2
+
H
O H
acid
alcohol
ester
water
Here R1 and R 2 represent groups such as CH3 - or CH3 CH2 -. The reaction type shown above may be called a condensation reaction because the small molecule H 2 O is eliminated from the reactants while the remaining bits of the reactant condense together to give the main product. This reaction may also be called an esterification, since the product of the reaction is an ester, a compound containing the CO2 R group (see chapter 11 for definitions of acids, esters, and alcohols). Esters usually have pleasant, fruit-like odors and are the chemicals responsible for the odors and flavors of many fruits (oranges, bananas, pineapples) and flowers. In most cases, such natural products get their properties from a mixture of organic compounds. In this experiment you will prepare two esters of o-hydroxybenzoic acid, more commonly known as salicylic acid. One of the esters, acetylsalicylic acid, is aspirin, the common analgesic. We will synthesize aspirin by mixing salicylic acid with acetic anhydride. The second ester product is oil of wintergreen, or methyl salicylate, which we prepare by allowing salicylic acid to react with methyl alcohol. This compound, which has a familiar odor is used as