Salicylic Acid Test. Methyl alcohol with salicylic acid and concentrated sulfuric acid will give methyl salicylate or oil of wintergreen, a compound with an odor of peppermint. In a test tube containing 0.2 gm of salicylic acid, add 1 ml. of concentrated sulfuric acid (CAUTION!). Introduce 1 ml. of methanol into the test tube. QUESTIONS: 1. What will be the result? 2. To make the odor more pronounced, pour the contents of the tube into a small beaker containing 20 ml. of water. What is the reaction called? 3.ÂÂ
Salicylic Acid Test. Methyl alcohol with salicylic acid and concentrated sulfuric acid will
give methyl salicylate or oil of wintergreen, a compound with an odor of peppermint.
In a test tube containing 0.2 gm of salicylic acid, add 1 ml. of concentrated sulfuric acid
(CAUTION!). Introduce 1 ml. of methanol into the test tube.
QUESTIONS:
- What will be the result?
- To make the odor more pronounced, pour the contents of the tube into a small
beaker containing 20 ml. of water. What is the reaction called?ÂÂ
The Correct Answer and Explanation is :
1. What will be the result?
The result of this reaction will be the formation of methyl salicylate (also known as oil of wintergreen), a compound with a characteristic minty or peppermint-like odor. The reaction is an example of an esterification reaction, where methanol (CH₃OH) reacts with salicylic acid (C₇H₆O₃) in the presence of concentrated sulfuric acid (H₂SO₄) to produce methyl salicylate (C₈H₈O₄) and water (H₂O).
2. To make the odor more pronounced, pour the contents of the tube into a small beaker containing 20 ml of water. What is the reaction called?
The reaction is called Fischer esterification. This is a specific type of esterification reaction where a carboxylic acid (salicylic acid) reacts with an alcohol (methanol) in the presence of a strong acid (concentrated sulfuric acid) to form an ester (methyl salicylate) and water.
The purpose of adding water is to help the ester dissolve and volatilize, which will intensify the odor of methyl salicylate. Water also aids in driving the equilibrium of the esterification reaction towards the product side. The ester, once formed, has a strong minty odor, and adding it to water helps release the vapors into the air, making the scent more noticeable.
Explanation:
The reaction between salicylic acid and methanol in the presence of sulfuric acid is a classic example of Fischer esterification, a reaction that involves the formation of an ester from a carboxylic acid and an alcohol. The sulfuric acid serves as a catalyst, helping to promote the reaction by protonating the carbonyl oxygen of the carboxylic acid, which increases its electrophilicity and facilitates nucleophilic attack by the alcohol.
The product, methyl salicylate, is an ester with a strong and characteristic odor of wintergreen or peppermint. This compound is often used in products such as topical analgesics and flavorings due to its pleasant, minty aroma.
By adding water to the reaction mixture, you dilute the sulfuric acid and help release the ester into the air, enhancing the scent of methyl salicylate. This is a common technique to increase the volatility of the ester and intensify its aromatic properties.