Detection and confirmation test for functional group

1. Lab Report
Qualitative analysis of inorganic compound.
Course Title: Chemistry for biologist I
Course code: CHE 108


Prepared by:
Md. Shabab Mehebub


Department of
Genetic engineering and Biotechnology
East West University, Dhaka

2. Title: Detection and confirmation test for functional group.
Principal: Carbon and hydrogen are invariably present in the organic compounds it is not
necessary to test for these elements. In fact, if the test for other elements e,g. nitrogen, sulpher
and halogens are negative it is assumed that the compound belongs to this category. Nevertheless
the presence of carbon and hydrogen may be ascertained tests described under detection of
elements. For detection of oxygen there is no direct test but if the substance is readily soluble in
water then the presence of oxygen in the compound is almost certain. The tests for various
functional group should be performed in the following order only if the compound responds
positively to these tests, then the presence of that group is certain.
Materials:
Equipment:
1. Test tube
2. Test tube holder
3. Wash bottle
4. Dropper
5. Spatula
Reagent:
1. Tollene A
2. Tollene B
3. Fehling solution 1
4. Fehling solution 2
5. Sodium bicarbonate
6. Litmus paper
7. HCl
8. NaNo2
9. Dilute HCl
10. Sodium bicarbonate SoL
n

11. Ferric chloride SoL
n

12. 2, 4-dinitrophenyl hydrazine
Supplied Compound:
1. Benzoic Acid
2. Salicylic Acid
3. Benzofenon
4. Lactose
5. 4-amino acetophenon

3. Procedure:
(A)Test for carboxylic acid group, -COOH:
(i) Bicarbonate Test: At first, I had taken saturated solution of bicarbonate in a test tube.
Then warmed it and added a pinch of the Benzoic acid.
C6H5COOH + NaHCO3 = C6H5COONa + CO2 + H2O
(ii) Litmus paper test: Took a dilute aqueous solution of the organic compound and added
litmus paper.
(B) Test for Phenolic group:
Ferric Chloride test: 0.05 gm the compound had been dissolved. Added 5 ml of water. Then
1drop of ferric chloride solution had added. Appearance of blue, green, red or violet
coloration will indicate the presence of phenolic group.
6C6H5OH + FeCl3 = [(C6H3O)6Fe]
-3
+ 3HCL +3H
+
(C) Test for Aldehydes:
Fehling’s test: In a test tube, I had mixed 1 ml each of Fehling A and Fehling B solutions
when a deep blue color appeared. I added 0.1 gm of lactose substance. Then boiled 5
minutes.



(D) Test for Ketones: At first, I had taken 0.5 gm Benzophenon’s substance. Added 5
ml dilute HCL acid. Then added 2 ml of solution of 2,4-dinitrophenylhydrazine. Then cooled
in a ice pot and allow to stand for 2 minutes. When yellow, orange or red colored crystalline
will precipitate indicated the presence of ketonic group.
(E) Test for –NH2 Group:
Azo-dye Test: Dissolved 5 drops of the 4-Amino Acetophenon in a test tube. Added a slight
excess of dil. HCL then cooled in ice water. Added sodium nitrate drop by drop till there was
a slight excess of the nitrate. 1 cc of a strong solution of beta-naphthol in Sodium hydroxide
had added.

4. Observation:
(A)Test for carboxylic acid group, -COOH:
(i) Bicarbonate Test: An effervescence was occurred and indicated the present of a –COOH
group.
(ii) Litmus paper test: litmus paper turned red, so the organic compound might be a
carboxylic acid.
(B) Test for Phenolic group: Violet color formed in the solution.
(C) Test for Aldehydes: The blue color of Fehling’s solution slowly faded away and a
reddish brown precipitate of Cu2O is obtained.
(D) Test for Ketones: Orange colored crystalline precipitate had obtained.
(E) Test for –NH2 Group: A red precipitate had formed, the compound is primary
aromatic amine.
Result:
(A)Test for carboxylic acid group, -COOH: -COOH group had presented in that
compound.
(B) Test for Phenolic group: Phenolic group had presented in that group.
(C) Test for Aldehydes: -CHO group had presented.
.
(D) Test for Ketones: -CO group had presented.
(E) Test for –NH2 Group: Primary Aromatic Amine had presented.
Discussion:
(A)Test for carboxylic acid group, -COOH: The effervescence rate was increased by
excess warmed of saturated solution of bicarbonate in a test tube. Normally, properly warmed of
saturated solution of bicarbonate in a test tube given good effervescence. Blue litmus paper was
turned in Red.
(B) Test for Phenolic group: A dark Violet color formed in the solution.

5. (C) Test for Aldehydes: Mixed of Fehling A and Fehling B solutions gives deep blue color
and when substance added a reddish brown precipitate obtained and that was Aldehyde.
(D) Test for Ketones: -CO group had given Orange colored crystalline precipitate.
(E) Test for –NH2 Group: If a red or orange precipitateof azo-dye formed, the
compound was a primary aromatic amine. So a red precipitate had formed, the compound
had been primary aromatic amine.
Precaution:
1. I had worn Lab coat.
2. Volume had carefully measured.
3. The observation had recorded.
4. All apparatus had handled carefully.
5. Test tubes were cleaned by water during the experiment time.