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Test-tube Preparations of Esters

Prepare:
1. Methyl salicylate
2. Pentyl ethanoate (amyl acetate)

Method:
1. Introduce into a clean, dry test-tube:
- 1 ml of the alcohol
- 0.5 g (pea-size) or 0.5 ml (10-15 drops) of the organic acid
- 2 drops of concentrated [tex][tex]$H_2SO_4$[/tex][/tex]
2. Heat carefully for a few minutes.
3. Neutralize the mixture with dilute NaOH solution.
4. Compare the odour with that of the authentic ester.

Results:
[tex]\[
\begin{array}{|c|c|c|}
\hline
\text{Alcohol} & \text{Acid} & \text{Ester} \\
\hline
\text{ } & \text{Salicylic acid} & \text{Methyl salicylate} \\
\hline
\text{1-pentanol} & \text{ } & \text{ } \\
\hline
\end{array}
\][/tex]



Answer :

GinnyAnswer
To prepare the esters as specified in the question, here’s the detailed, step-by-step method and the results:

### Preparation of Esters:

#### 1. Methyl Salicylate
- Alcohol: Methanol
- Acid: Salicylic acid
- Ester: Methyl salicylate

Method:
1. Take a clean, dry test-tube.
2. Add 1 ml of methanol to the test-tube.
3. Introduce 0.5 g (pea-size) of salicylic acid into the same test-tube.
4. Add 2 drops of concentrated sulfuric acid ([tex]\( \text{H}_2\text{SO}_4 \)[/tex]) as a catalyst.
5. Heat the mixture carefully for a few minutes to promote esterification.
6. Neutralize the resulting mixture with a dilute sodium hydroxide ([tex]\( \text{NaOH} \)[/tex]) solution.
7. Compare the odour of the product with that of authentic methyl salicylate.

#### 2. Pentyl Ethanoate (Amyl Acetate)
- Alcohol: 1-pentanol
- Acid: Ethanoic acid
- Ester: Pentyl ethanoate (amyl acetate)

Method:
1. Take a clean, dry test-tube.
2. Add 1 ml of 1-pentanol to the test-tube.
3. Introduce 0.5 ml (10-15 drops) of ethanoic acid into the same test-tube.
4. Add 2 drops of concentrated sulfuric acid ([tex]\( \text{H}_2\text{SO}_4 \)[/tex]) as a catalyst.
5. Heat the mixture carefully for a few minutes to promote the esterification reaction.
6. Neutralize the resulting mixture with a dilute sodium hydroxide ([tex]\( \text{NaOH} \)[/tex]) solution.
7. Compare the odour of the product with that of authentic pentyl ethanoate (amyl acetate).

### Results:

Based on the procedures outlined:

[tex]\[ \begin{array}{|c|c|c|} \hline \text{Alcohol} & \text{Acid} & \text{Ester} \\ \hline \text{Methanol} & \text{Salicylic acid} & \text{Methyl salicylate} \\ \hline \text{1-pentanol} & \text{Ethanoic acid} & \text{Pentyl ethanoate (amyl acetate)} \\ \hline \end{array} \][/tex]

The resulting esters, methyl salicylate and pentyl ethanoate (amyl acetate), should have characteristic odours which can be compared to their authentic standards to verify successful preparation.

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