Animated Solution for Chemistry - Organic Chemistry: Ceric ammonium nitrate and ${\text{CHCl}}_3$ /alc. KOH are used for the identification of functional groups present in ......... and ......... respectively.

CAN and Carbylamine

Qualitative analysis is a fascinating branch of organic chemistry where we act like molecular detectives. By observing color changes, precipitates, or even distinct smells, we can deduce the exact functional groups hiding within an unknown compound. In this problem, we are tasked with identifying the functional groups that react with two very famous reagent mixtures: Ceric Ammonium Nitrate and a combination of Chloroform with alcoholic KOH.

Let's start with the first reagent: Ceric Ammonium Nitrate, often abbreviated as CAN. This reagent is the gold standard for identifying the presence of an alcoholic hydroxyl group ($-\text{OH}$).

When an aliphatic alcohol is treated with a few drops of CAN reagent, a rapid ligand exchange occurs. The alcohol molecules displace the nitrate ligands around the central Cerium(IV) ion. This coordination results in the formation of a highly characteristic red-colored complex.

The general reaction can be represented as:

If you see that vibrant red color appear in your test tube, you can confidently conclude that an alcohol is present!

Now, let's shift our focus to the second reagent mixture: Chloroform (${\text{CHCl}}_3$) and alcoholic KOH. This specific combination should immediately trigger alarm bells in your head—it's the legendary Carbylamine Test (also known as the Isocyanide test).

This test is highly specific and is used exclusively to detect primary amines (both aliphatic and aromatic). When a primary amine (${\text{R-NH}}_2$) is heated with chloroform and a strong base like alcoholic KOH, a fascinating reaction takes place. The base and chloroform first react to generate a highly reactive intermediate called dichlorocarbene ($:{\text{CCl}}_2$). This electrophilic carbene then attacks the nucleophilic nitrogen of the primary amine.

After a series of eliminations, the final product is an isocyanide (or carbylamine):

How do you know the reaction worked? You don't need to look; you will smell it. Isocyanides possess an incredibly distinct, foul and offensive odor. If your test tube starts smelling terrible, you have successfully identified a primary amine.

By analyzing the reagents, we have successfully cracked the code. Ceric Ammonium Nitrate is the signature test for alcohols, and Chloroform with alcoholic KOH is the signature test for primary amines. Therefore, the reagents identify alcohol and amine, respectively.