Naming organic compounds

Naming alkanes

1.pick the longest Carbon chain – it doesnt matter if it is not necessarily in one straight line.

2.Number from the end, so the sum of the substituent group is smallest – for exmple,


In 2-methylbutane, you could count from left to right because it will make the number smallest.

3. Substituents should be arranged alohabetically – here is another example –


This is 3-ethyl-2,3,2-trimethylheptane. There are ethyl and methyl, and because it should be arranged alphabetically, ethyl goes first and trimethyl follows.

Naming alkenes
Alkene is an unsaturated hydrocarbon with at least one carbon-carbon double bond, therefore has another level od isomerism as the double bond cannot rotate.

Alkenes are named in very similar way as alkanes are named, but the main differences are –
* The suffix is -ene.
* The position of the double bond has to be stated, and again, the sum of the numbers has to be as small as possible.
* The type of isomers has to be stated – either E isomer or Z isomer.




– There are four carbons in the longest chain, so but-.
– There is a double bond between carbons 1- and 2.
– The compounds is an alkene, so the suffix is -ene.
– The isomer is E (opposite).
– Therefore the name of this compound is e-but-1-ene.


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