Identify Functional Group in Organic Compound: Guide

Contents: Click for quick access

Apparatus Required Chemical Required Theory Observation Result Conclusion Precaution More From Chemistry Practical | 1st Year | BSc |T.U.

In this blog, we’ll explore the process of identifying the functional group in a given organic compound. Think of understanding the functional group as unlocking the molecular signature of the compound. We’ll take a deep dive into the methods and important clues that guide us in identifying these chemical teams. Throughout our discussion, we’ll cover the basics, including the needed equipment, essential chemicals, the underlying theory, our observations, the results we obtain, and ultimately, we’ll draw conclusions from our exploration. If you’re eager for a thorough examination of each aspect, keep reading!

Apparatus Required

Test tube
Test Tube holder

Chemical Required

dil. NAOHCO3
alcohol
ether
KMNO4
Fecl3
fehling’s solution
organic compound

Theory

The functional group is like the active part of an organic compound, created by certain atoms. It’s what makes organic compounds act in specific ways. Things like double and triple bonds are examples of these active groups, and they’re the spots where the chemistry magic happens in a molecule. Detecting this functional group is super important for figuring out what kind of organic compound we’re dealing with. We start this detective work by looking at the compound’s physical traits, like its color, state, smell, and how stable it is. Organic compounds can be solid and crystal-like or more shapeless. They also come in different colors, like white, red, or orange. Each one has its own unique smell, ranging from bitter to pungent. How the compound behaves with different liquids tells us more about its nature, and if we light it up, we can find out if it’s aliphatic, aromatic, or has certain special groups inside.

Observation

Sample no: 01

Physical properties

State: crystalline solid

Color: white

Odor: characteristics smell.

Solubility test of organic compound (O1)

Cold H2O	Hot H2O	Dil. HCl	Dil. NaOH	Dil.NAHCO3	Alcohol	Ether
+	+	+	+	+	–	–

Preliminary test of organic compound (01)

S.N	Experiment	Observation	inference
1.	The solution of organic compound and water was treated with litmus paper	Neutral to litmus	May be aldehyde or ketone.
2.	Ignition test: A pinch of organic compound was taken in a spatula and brunt in a Bunsen burner.	Burnt with non sooty flame	May be aliphatic compound.
3.	Unsaturation test: The solution of organic compound was taken, added water / alcohol and was treated with Bayer’s reagent.	The pink color of KMNO4 got discharged.	May be unsaturated compound.
4.	Dil. NaOH test: The water was added in the sample and then was treated with dil, NaOH.	The substance was insoluble.	May be aldehyde group.
5.	Sodium bicarbonate test: The sample was treated with sodium bicarbonate NaHCO3.	No effervescence was obtained	Absence of carboxylic group(COOH)
6.	FeCl3 test: sample + water / alcohol was treated with 1 2 drops of FeCL3	The color was not changed	Absence of phenolic group
7.	Fehling’s solution test: Little organic compound was heated with fehling’s solution (A+ B) in a test tube.	Blood red precipitate was formed	.may be aldehyde group

Confirmatory test for functional group

S.N.	Experiment	observation	inference
1.	Sehiff’s reagent test: About 1 ml of aqueous or alcohol solution of given compound was shaken by adding 1 ml of Sehiff’s reagent.	Pink color was appeared.	Presence of aldehyde group.
2.	Fehling’s solution test: 2 ml of fehling’s solution A was added in fehling’s solution b until clear blue solution was obtained. 0.2 gm of given compound was added and warmed for few minutes.	A reddish ppt of Cu2O was formed	-CHO group was confirmed.
3.	Tolllen’s reagent test: 1 ml of AgNO3 solution was taken in clear test tube & NaOH was added drop wise. NH4OH was added till precipitated dissolved 0.5 g of given compound was added and warmed.	Silver mirror on the inner wall of test tube was formed	-CHO group was confirmed

Result

The functional group present in the given organic compound was aldehyde group.

Conclusion

Hence, the functional group present in given organic compound can identified by the help of physical properties, preliminary and confirmatory test.

Precaution

Chemical should be handled properly.
Physical properties should be noted carefully.
Test tube should be carried out carefully.
Test tube should be handled by test tube holder.

Explore related practical files by clicking the link below. The upcoming experiment also addresses the same concepts we’ve talked about earlier.

Identify Functional Group in Organic Compound: Step-by-Step