Identify ‘ A ’ and ‘ B ’ in the following conversion. CH 3 - I → KCN A → Na / C 2 H 5 OH B

Methyl iodide can be converted into ethyl amine in two stage reaction sequence as shown below: The starting compound methyl iodide contains one carbon atom while the product ethylamine contains two carbon atoms. A reaction in which the number of carbon atoms increases involve a step-up reaction. The overall conversion of methyl iodide into ethyl amine is a step-up conversion.

Identify ‘ A ’ and ‘ B ’ in the following conversion. CH 3 - Br → AgNO 2 A → Sn / HCl B

Methyl bromide can be converted into nitromethane by reacting with AgNO 2 . Aliphatic and aromatic nitro-compounds can be reduced to primary amines using a metal-acid mixture like Sn / HCl or catalytic hydrogenation. The chemical reaction is as follows:

Identify ‘ A ’ and ‘ B ’ in the following conversion. C 2 H 5 - I → AgCN A → Na / C 2 H 5 OH B

AgCN is predominantly covalent as there is an equal sharing of electrons between two atoms which is homolytic fission. The fission is as follows: AgCN → Ag ∙ + CN ∙ The nucleophilic attack takes place from the nitrogen side instead of carbon because carbon is covalently bonded to silver due to very less electronegativity difference and nitrogen is free to donate its electron pair. So, the main product formed is alkyl isocyanide. The reaction of AgCN with R - X is as follows:

Explain carbylamine reaction with an example.

Carbylamine reaction mechanism includes the addition of amine to the intermediate created from the dehydrohalogenation of chloroform. This intermediate is called dichlorocarbene. The carbylamine reaction is also known as Hofmann isocyanide synthesis. It is the reaction of a primary amine, chloroform and a base to synthesize isocyanides. The dichlorocarbene intermediate is very important for this conversion. The carbylamine reaction cannot be used to synthesize isocyanides from secondary or tertiary amines. In general, the carbylamine reaction can be written as follows, R - NH 2 + CHCl 3 + 3 KOH → RNC ( Carbylamine ) + 3 KCl + 3 H 2 O .

Write short notes on Coupling reaction.

The azo products obtained have an extended conjugate system having both the aromatic rings joined through the – N = N – bond. These compounds are often coloured and are used as dyes. Benzene diazonium chloride reacts with phenol in which the phenol molecule at its para position is coupled with the diazonium salt to form p - hydroxyazobenzene. This type of reaction is known as coupling reaction.