triple bond is how many degrees unsaturation
Thus, a ring is said to introduce one degree of unsaturation, just like a pi bond. We can compute the total degree of unsaturation for a molecule by adding: (# of double bonds) + (2 x # of triple bonds) + (# of rings) Note that a triple bond counts for two degrees of unsaturation, because a triple bond contains two pi bonds. Quite often, a large number of isomeric compounds can be drawn from the same molecular formula.