Nomenclature of Hydrocarbons
Selin Maden 12B
ring hydrocarbons with one single one double bond
Aromatic Hydrocarbons
Alkanes
Examples
- smallest unit of an aromatic hydrocarbon is called benzene and it's radical is called phenyl
- derivatives of benzene get the the name of the substituent as a prefix and some have special names such as;
hydrocarbons with at least one triple bond
Chain
Cycloaklane
- use the prefix cyclo and the parent name that corresponds with it.
- name each substituent, number the C atoms so that the smallest numer corresponds to the substituent that comes first alphabetically
- if there is only one there is no need to give it a number
- when there are two substituents they are named according to their position to each other. The prefixes for these are ortho-(o-) if they are on first and second, meta-(m-) if they are on first and third and para-(p-) if they are on first and fourth carbon
- the name of the radical corresponding to toluene is benzyl
Use the prefix corresponding to the number of C atoms and add -ane suffix
- find the longest continuous chain and name it as the parent chain
- number the C atoms on the chain, begining with the nearest branching
- write each substituent with the number of C atoms which it is connected to and a name, separate these with a hyphen
- if the same substituent is used more than once write the number of the C atoms and then add the prefix di, tri, tetra, penta etc. accordingly
- if there is more than one substituent list them alphabetically and number the C atoms to have the smallest group of numbers.
hydrocarbons with at least one double bond
Examples
1-bromo-2-ethyl-3-methyl-cyclopentane
Alkynes
- find the longest chain that contains the triple bond and name it accordingly
- number the C atoms giving the triple bond the lowest number
- if there is a double bond present as well it gets priority while numbering when it is at the end, closer to the end or they are both at the end, this compound is referred to as "enyne"
Examples
2-cyclopropyl-1-hexen-5-yne
Alkenes
Chain
- choose the longest chain that contains the double and name it with the suffix -ene
- number the C atoms so that the double bond has the lowest number.
- indicate double bond by the number of the first C atom on it
- if double bond has the same number from each side number it so that the substituent gets the lower number
- if ther is more than one double bond indicate their position with the number of the C atoms they are on and use the suffix -diene, -triene, -tetraene etc. accordingly
Examples
5,5-dichloro-2-methyl-2-hexene
Cycloaklene
- number the cycloalkene so that the double bond gets numbers 1 & 2 and the first substituent has the lowest number possible
- if there is a substituent on the double bond it gets number 1
Cis-Trans
- in alkenes as a result from geometric restrictions there occurs two geometric isomers.
- the isomers differ on which side of the double bond the groups are located
- if similar groups are located on the same side they have the prefix cis and if they are on opposite sides they get the prefix trans