1
3-ethylhexane
2
3-methylbut-1-ene
3
2,2-dimethylhexane
3-ethylhexane
2
3-methylbut-1-ene
3
2,2-dimethylhexane
The longest carbon chain may not be on the same line on the page.
The name is based on the longest chain containing the functional group.
In the alkane 1 the longest chain has six carbon atoms. If you have difficulty seeing this, move your mouse over the image.
The name is based on the longest chain containing the functional group.
In the alkene 2 the longest chain containing the functional group has four carbon atoms. Move your mouse over the image to see that the alternate chain also has four carbons.
Any atom or group of atoms replacing H at a carbon is called a substituent.
The functional group in the compound determines the numbering of the chain.
The number is referred to as the locator in the name.
Substituents on the longest chain are included in the name as prefixes.
Common substituents and their names are shown below:
Compound 1 has an ethyl substituent.
Note that saturated hydrocarbon substituents have the same name as the parent alkane with the -ane at the end of the name substituted by -yl.
For compounds with two of the same substituents at either the same or different carbons in the chain, the prefix di- is used.
This is preceded by the numbers of the carbons on which the substituents are located separated by a comma.
See 2,2-dimethylhexane, a compound having the structure shown at the right.
Common substituents and their names are shown below:
| CH3– | methyl |
| CH3CH2– | ethyl |
Compound 1 has an ethyl substituent.
Note that saturated hydrocarbon substituents have the same name as the parent alkane with the -ane at the end of the name substituted by -yl.
For compounds with two of the same substituents at either the same or different carbons in the chain, the prefix di- is used.
This is preceded by the numbers of the carbons on which the substituents are located separated by a comma.
See 2,2-dimethylhexane, a compound having the structure shown at the right.
The functional group in the compound determines the numbering of the chain.
In an alkene, the two carbons of the double bond have the lowest possible number.
See compound 2.
For alkanes the alkyl substituent has the lowest possible number.
See compound 2.
For alkanes the alkyl substituent has the lowest possible number.
The number is referred to as the locator in the name.