Structual Isomerism - Chemical Ideas 3.3
A structural isomer has the same molecular formula but can be drawn in more than one way. There are three types of structural isomerism which are;
·Different carbon chains
·Different positions for the functional group
·Different functional groups
Different carbon chains – The longest carbon chain length changes. This often occurs in alkanes. Both of the below share the molecular formula C4H10.
·Different carbon chains
·Different positions for the functional group
·Different functional groups
Different carbon chains – The longest carbon chain length changes. This often occurs in alkanes. Both of the below share the molecular formula C4H10.
Different positions for the functional group – The same functional group appears in different positions and is often seen in alcohols. Usually the number in the name changes to signify where the functional group is attached. Both of the below share the molecular formula C5H12O.
Different functional groups – The molecular formula remain the same but the functional groups change instead of changing position like above. Both of the below share the molecular formula C2H6O.
Isomerism at the oil refinery- When straight chained alkanes are heated in the presence of a platinum catalyst, they become branched alkanes. They then have a higher octane number and are less likely to auto-ignite.