Ethanol has two carbon atom and propanol has three. Therefore we have to increase number of carbon atoms by one. Also note that both ethanol and propanol are alcohols.
There are several reactions to increase carbon atoms by one.
According to the question or given reagent you have to select one of the above reaction.
In this tutorial we are going to prepare propanol by following methods.
ethyl magnesium bromide - CH3CH2MgBr
ethyl bromide - CH3CH2Br
Steps of converting ethanol to propanol is explained below.
Ethanol reacts with PBr3 to give bromoethane. Then bromoethane reacts with Mg / dry ether to give grignard reagent.
Grignard reacts with carbon dioxide to give carboxylic acid ( propanoic acid).
Propanoic acid is the carboxylic acid we use in this reaction. Propanoic acid is reduced to propanol by LiAlH4 / ether.