How do alkanes, alkenes and alkynes differ?

1 Answer
Jul 23, 2016

By their degree of unsaturation.


Alkanes are saturated; they contain the maximum number of (energy rich) #C-H# bonds. An alkane has general formula #C_nH_(2n+2)#. Each 2 hydrogens LESS than this formula corresponds to a double bond OR a ring junction.

Thus if we consider hexanes, #C_6H_14#, we would consider it to be saturated. Why?

On the other hand isomeric hexene, and cyclohexane have a formula of #C_6H_12#; 1 degree of unsaturation, as we could predict from the formula. How many degrees of unsaturation does acetylene, #HC-=CH#, have?