Question

a. Explain why the following reaction leads to the products shown:

b. What product is obtained from the following reaction?

Short answer

a.

b.

Step-by-step solution

Formation of Eliminated and Substitution product

On reacting 2-methyl propane-1-amine with sodium nitrite and HCl forms, the alkyl diazonium (2,2-dimethylpropane-1-diazonium), which is a very unstable loss of the stable nitrogen molecule (N₂) and a 1,2-hydride shift forms a tert-butyl carbocation which on undergoing elimination form the prop-1-ene and on substitution forms 2-methyl propane-2-one shown as follows:

Formation of prop-1-ene and 2-methyl propane-2-one

Step 2: 

3-amino-2,3-dimethyl butane-2-olReact with sodium nitrite, and HCl forms the forms3-hydroxy-2,3-dimethyl butane-2-diazonium which is very unstable loss the stable nitrogen molecule (N₂) and forms a tert-butyl tertiary carbocation which on undergoing pinacol like rearrangementto form the 3,3-dimethyl butane-2-one product shown as follows:

Formation of 3,3-dimethyl butane-2-one