Propene (propylene) may be prepared by heating propanol or isopropanol with sulphuric acid (mechanism as for ethylene from ethanol) :

CH3CH2CH2OH     -H2O   CH3CH=CH2

CH3CH(OH)CH3     -H2O    CH3CH=CH2

It may also be prepared by heating propyl iodide with ethanolic potassium hydroxide :

CH3CH2CH2I  +  KOH  ethanol  CH3CH=CH2 + KI + H2O

Propane is obtained commercially in huge quantities as a by-product in the cracking of petroleum. It is a colourless gas, b.p. -48oC, insoluble in water but fairly soluable in ethanol. It us used industrially for the preparation of isopropanol, glycerol, polypropylene (a plastic) etc.