Constitutional isomer introduction
Consitutional isomers are compounds that have the same molecular formula but a different atom-to-atom bonding sequence. As shown by the examples of consitutional isomers of C6H12O, they have may have
The number of different constitutional isomers possible for a specified molecular formula
(a) the number of different possible arrangements of that number of carbons
(b) the number of different possible positions for a functional group on each of the carbon skeletons
For a six-carbon linear chain, there are only two ketones having the formula C6H12O.
These are shown above.
This is because of the symmetry of the chain shown in the image.
For the five-carbon chain with a one methyl branch, there is only one C6H12O ketone.
The structure for this is shown above.
This is because the C=O must be in the middle of the chain and two H on a carbon.
For a six-carbon linear chain there is only one possible C6H12O aldehyde.
This is because -CHO must be at the end of the chain.
For the five-carbon chain with one branch, there are two possible C6H12O aldehydes.
This is because because the pink carbon is not equivalent to the two red carbons because they are bonded to different groups.
different carbon skeletons
different positions of functional group
different functional groups
different positions of functional group
different functional groups
The number of different constitutional isomers possible for a specified molecular formula
(a) the number of different possible arrangements of that number of carbons
(b) the number of different possible positions for a functional group on each of the carbon skeletons
For a six-carbon linear chain, there are only two ketones having the formula C6H12O.
These are shown above.
This is because of the symmetry of the chain shown in the image.
For the five-carbon chain with a one methyl branch, there is only one C6H12O ketone.
The structure for this is shown above.
This is because the C=O must be in the middle of the chain and two H on a carbon.
For a six-carbon linear chain there is only one possible C6H12O aldehyde.
This is because -CHO must be at the end of the chain.
For the five-carbon chain with one branch, there are two possible C6H12O aldehydes.
This is because because the pink carbon is not equivalent to the two red carbons because they are bonded to different groups.