Experiment 150

Objective

To identify the presence of phenyl salicylate in an unknown organic sample through systematic analysis.

Introduction

This experiment includes a series of analyses, including physical observation, solubility testing, and functional group tests. The compound’s melting point is also compared against known values to confirm its identity.

Physical Characteristics of Sample:

●      Color: White

●      State: Solid

●      Odor: Sweet

●      Melting Point: 43°C

Solubility Test Results

Materials

Chemicals

●      Unknown organic sample (presumed phenyl salicylate)

●      Distilled water

●      5% HCl, 5% NaOH, 5% NaHCO₃

●      Ferrous sulfate, Nitric acid

●      Silver nitrate, Ferric chloride

●      10% NaNO₂, 2% bromine solution

Apparatus

●      Test tubes and holder

●      Bunsen burner

●      Thermometer

●      500 mL flask, test tube stand

●      Pipette

●      Fusion tube

●      Mortar and pestle

Preparation of Reagents

●      Prepare solutions of 5% HCl, 5% NaOH, 5% NaHCO₃, and 5% ferrous sulfate in a 500 mL flask.

●      Prepare a 10% NaNO₂ solution and a 20% NaOH solution for specific tests.

Procedure

1.    Elementary Analysis (Stock Solution Preparation)

●      Heat a piece of sodium in a fusion tube until molten.

●      Add a small amount of the sample, heat to a dull red, then drop the tube into a mortar with 3-5 mL of distilled water.

●      Crush the tube, filter the solution, and use it for further testing.

●      Test for Nitrogen: Add 1-2 mL of the stock solution to freshly prepared ferrous sulfate, boil, cool, and add a few drops of H₂SO₄.

●      Observation: No Prussian blue indicates nitrogen is absent.

●      Test for Halogens: Acidify 1 mL of boiling solution with nitric acid, boil, cool, and add silver nitrate.

●      Observation: No white, pale yellow, or yellow precipitate indicates no halogens (Cl, Br, I).

●      Test for Sulfur: Acidify 1 mL of solution with acetic acid and add lead acetate.

●      Observation: No black precipitate indicates sulfur is absent.

2.    Functional Group Tests

●      Test for Unsaturation: Dissolve 0.2 g of the sample in CCl₄, then add bromine solution.

●      Observation: No color discharge, indicating absence of unsaturation.

●      Carbonyl Group (=C=O): Dissolve in rectified spirit, add 2,4-DNPH.

●      Observation: No orange-red precipitate, indicating carbonyl group is absent.

●      Carboxylic Acid (-COOH): Add sample to NaHCO₃ solution.

●      Observation: Effervescence of CO₂, turning limewater milky, confirms -COOH.

●      Phenol Group (Ar-OH): Dissolve in rectified spirit, add 5% FeCl₃.

●      Observation: Intense coloration indicates phenol group is present.

●      Aromatic Hydrocarbon: Dissolve in absolute alcohol, add picric acid solution.

●      Observation: Orange-red needle-shaped crystals confirm aromatic hydrocarbon.

Observation

Identified Functional Groups:

●       Elements: None (N, X, S absent)

●       Functional Groups: Carboxylic acid (-COOH), Phenol (-OH)

Based on the melting point of 43°C and the presence of these functional groups, the sample is identified as phenyl salicylate (also known as salicylic acid derivative).

Questions

1.    What is phenyl salicylate?

2.    How is the -COOH group identified?

3.    How is the -OH group identified?

4.    What is the Liebermann test?

5.    How is phenyl salicylate identified?

6.    How is phenyl salicylate produced?