Question

What is meant by the heat of hydrogenation?

Answer 1

The heat of hydrogenation is the measure of the stability of an alkene. Lower the heat of hydrogenation of alkene the more stable it is and vice versa. Alkyl substitution at unsaturated C lowers the heat of hydrogenation and therefore increases its stability. It is due to its hyperconjugative effect. More the number of hyperconjugative structures, lower the heat of hydrogenation hence more stability is incurred on it.