Identify A and B in the following reaction:

When the given compound reacts with KCN , nucleophilic substitution takes place and the chloride ion is replaced by - CN group, which undergoes reduction in the presence of H 2 / Pd to form primary amine as the product. A is 3 -( 2 -Oxocyclohexyl)propanenitrile and B is 2 -(Propylamine)cyclohexanone.

Give one reaction that can be used as a test for primary amines.

The carbylamine reaction, also known as Hoffman's isocyanide test is a chemical test for detection of primary amines. In this reaction, the analyte is heated with alcoholic potassium hydroxide and chloroform. If a primary amine is present, the isocyanide is formed which are foul smelling substances.

Out of ethylamine and ethyl alcohol, which has higher boiling point and why?

Ethyl alcohol has higher boiling point than ethyl amine because intermolecular hydrogen bonding is stronger in alcohol as compared to ethyl amine. This is due to a high electronegativity difference between O and H in ethyl alcohol as compared to N and H in ethyl amine.

Arrange the following substances in increasing order of their basic strength in water: C 6 H 5 NH 2 , ( C 2 H 5 ) 2 NH , ( C 2 H 5 ) 3 N , C 2 H 5 NH 2

There is a subtle interplay of the inductive effect, solvation effect and steric hindrance of the alkyl group which decides the basic strength of alkyl amines in the aqueous state. The order of basic strength in case of ethyl substituted amines in aqueous solution is as follows: ( C 2 H 5 ) 2 NH > ( C 2 H 5 ) 3 N > C 2 H 5 NH 2 Aniline ( C 6 H 5 NH 2 ) is the least basic because the lone pair of electrons on nitrogen gets delocalised as a result of resonance. Therefore, the increasing order of their basic strength in water is: C 6 H 5 NH 2 < C 2 H 5 NH 2 < ( C 2 H 5 ) 3 N < ( C 2 H 5 ) 2 NH

What do you mean by carbylamine reaction? What is its importance?

Carbylamine reaction: Aliphatic and aromatic primary amines on heating with chloroform and ethanolic solution of potassium hydroxide form isocyanides or carbylamines, which are foul smelling substances. Secondary and tertiary amines do not give this reaction. This reaction is used as a test for primary amines. R - NH 2 + CHCl 3 + 3 KOH → ∆ R - NC + 3 KCl + 3 H 2 O

Arrange the following in increasing order of basic strength :

Aniline is a Lewis base due to the presence of lone pair of electrons on nitrogen atom. The electron releasing group - OCH 3 increases the basic strength of aniline, while the electron withdrawing groups such as - Cl , NO 2 decreases the basic nature of aniline. Therefore, the increasing order of basic strength of the given compounds is as shown below:

Aniline does not undergo Friedel-Crafts reaction. Give reason.

Aniline does not undergo Friedel-Crafts reaction (alkylation and acetylation) due to salt formation with the Lewis acid, anhydrous aluminium chloride, which is used as a catalyst. Due to this, nitrogen atom of aniline molecule acquires positive charge hence acts as a strong deactivating group for further reaction.

Complete the following reaction: What will happen if aniline is treated with aqueous bromine?

The – NH 2 group of aniline is protected by acetylation reaction with acetic anhydride. The bromination reaction now will give p-bromo derivative as the major product, which on basic hydrolysis gives p-bromoaniline. Aniline reacts with aqueous bromine to form a white coloured precipitate called 2 , 4 , 6 -tribromoaniline.

E M B I B E

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter -1 - Amines>Meghalaya Board-2020>Q 13

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12th Meghalaya Board

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