Question on alpha-terpinene and its Unsaturation

alpha-Terpinene is a natural oil isolated from turpentine as well as from oil of marjorum and other sources. Its formula is C₁₀H₁₆. It can be hydrogenated over a palladium catalyst and absorbs two molecules of hydrogen per molecule of alpha-Terpinene to yield a new hydrocarbon, C₁₀H₂₀.

How many degrees of unsaturation does alpha-Terpinene possess and out of them how many are double bonds and how many are rings?

Answer:

A saturated hydrocarbon has the molecular formula of C_nH_2n+2.

For a saturated hydrocarbon having 10 Carbon atoms, 22 Hydrogen atoms are required to make it saturated. The molecular formula of the compound is C₁₀H₁₆ which means it is unsaturated and the degree of unsaturation is equivalent to 3 molecules of Hydrogen.

The molecule absorbing two molecules of Hydrogen per molecule of it shows the presence of two double bonds, and so the other degree of unsaturation must be due to a ring.

Hence, alpha-terpinene has 3 degrees of unsaturation with 1 ring and 2 double bonds.