Question

What is the major Hofmann elimination product formed from each amine?

a

b

c

Short answer

a

Major product of a.

b

Major product of b.

c

Major Pproduct of c.

Step-by-step solution

Hofmann elimination

It is the only possible way of converting $1^{°}$ amines into a better leaving group. The $1^{°}$ amine is converted into a quaternary ammonium salt before undergoing $\beta$-elimination.

Conditions for Hofmann elimination reaction

The reaction consists of 3 steps, all of which take place in one single step.

The reaction takes place via an anti-periplanar geometry, according to which the hydrogen atom and the amine group should be present on the opposite sides of the molecule.

Mechanism of the given reaction

The C-C bonds are rotated in the given molecules to obtain the anti geometry of the hydrogen atom and the amine group.

a

The given structure already has hydrogen and amine group anti to each other. Hence, the product of the reaction is given hereunder.

Product of a.

b

The C-C bond is rotated ${120}^{°}$ counterclockwise. The product of the reaction is given hereunder.

Product of b.

c

The C-C bond is rotated ${120}^{°}$counterclockwise. The product of the reaction is given hereunder.

Product of c.