Qualitative Analysis for the Identification of the functional group in the Organic Sample Phenol

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AIM: Qualitative analysis for the identification of the phenolic functional group in the organic sample.

SAMPLE: Phenol (C₆H₅OH)

(A) PRELIMINARY TEST:

Color – Colourless
Physical State – Liquid
Odor – Carboxylic Odour
Ignition Test –
Experiment	Observation	Inference
A clean glass rod is taken and dipped in the given sample. The glass rod is then held at the mouth of the Bunsen flame.	Black sooty flame is obtained.	The sample is aromatic in nature.

(B) CONFIRMATORY TEST FOR THE IDENTIFICATION OF THE PHENOLIC FUNCTIONAL GROUP:

TEST NO. 1
LITMUS TEST
Experiment	Observation	Inference
A drop of the sample is taken on moist litmus paper.	Moist blue litmus paper turns red.	The sample is acidic in nature.

                              

                                                                                                     

TEST NO. 2
Sodium Carbonate (Na2CO3) or Sodium Bicarbonate (NaHCO3)
Experiment	Observation	Inference
A pinch of sodium carbonate/bicarbonate is added to a small amount of the sample taken in the test tube.	No effervescence is evolved.	The sample is a weak acid, may be a phenol.

  

TEST NO. 3
Neutral Ferric Chloride (FeCl3) Test
Experiment	Observation	Inference
To 0.5ml of the sample, 2-3 drops of neutral ferric chloride solution is added.	A violet coloured complex is obtained.	Presence of phenol in the sample is confirmed.

Preparation of Neutral Ferric Chloride (FeCl₃) solution –

To 1ml of the ferric chloride solution taken in a test tube with dilute NH₄OH is added dropwise until a reddish brown precipitate is formed. Then, the FeCl₃ solution is once again added dropwise till the precipitate dissolves. This solution is called neutral ferric chloride

TEST NO. 4
Liebermann's Test
Experiment	Observation	Inference
A pinch of NaNO2 is added in a test tube along with 0.2ml of the sample the test tube is heated gently until the NaNO2 melts. To the above solution concentrated H2SO4 is added dropwise. To the above solution, water is added dropwise. This is followed by an excess of NaOH.	Deep blue colour is obtained. The solution turns red or reddish brown.  The solution turns deep green.	Presence of phenolic group in the sample is confirmed.

TEST NO. 5
Azo-Dye Test
Experiment	Observation	Inference
In a test tube, marked as ONE, a pinch of NaNO2 is taken and distilled water is added to it. In the second test tube, marked as TWO, a solution of aniline in dilute HCl is prepared. In the third test tube, marked as THIRD, a solution of sample in dilute NaOH is taken and all three test tubes are immersed in an ice bath for at least 5 minutes. The NaNO2 solution is then added to the aniline solution with cooling immediately followed by the sample solution.	A bright orange saffron colour precipitate is observed.	Presence of phenolic group in the sample is confirmed.

REPORT: The presence of phenolic functional group present in the sample is confirmed.

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Know more about stuff related to this practical experiment (Important for Boards):-

• Qualitative Analysis for the identification of the Phenolic functional group in the organic sample
• Qualitative analysis for the identification of the functional group in the organic sample Acetic Acid (Example 1)
• Qualitative analysis for the identification of the functional group in the organic sample Benzoic Acid (Example 2)
• Qualitative Analysis for the identification of the Carboxylic functional group in the Organic Sample
• To find the molarity and strength of the given KMnO4 solution using M/20 standard Mohr salt solution
• How to find out the mass of salt required to achieve the required concentration of a solution
• Viva Questions related to Qualitative Analysis.
• Viva Questions related to Phenolic Functional Group.

Reference:-

• Verma, Dr. N.K.. Comprehensive Practical Chemistry, Class XII.
• NCERT. Chemistry Part I and II, Class XII.

For latest syllabus, both theory and practical papers for class XII, check out the CBSE’s official site http://cbseacademic.in/ for more info.

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