Just to be pedantic: You can never smell the alcohol (ethanol) in any alcoholic drink. It's a tasteless and odourless chemical. What you taste or smell are the congeners, which are other organic molecules that are the byproducts of fermentation. In the case of whisky, you also have the additional flavour and odour chemicals leached from wood barrels.

You're basically smelling "charred wood extract" when smelling Whiskey.