Naming of hydrocarbon
No. of Carbons
1
Methane
2
Ethane
3
Propane
4
Butane
5
Pentane
6
Hexane
7
Heptane
8
Octane
9
Nonane
10
Decane
Formula Name
CH4
C2H6
C3H8
C4H10
C5H12
C6H14
C7H16
C8H18
C9H20
C10H22
(CnH2n+2)
Types of Alkyl group
•
•
•
a carbon at the end of a chain (primary alkyl group)
a carbon in the middle of a chain (secondary alkyl group)
a carbon with three carbons attached to it (tertiary alkyl group)
If the hydrocarbon is a substituent (a chain appended on a longer hydrocarbon chain),
these extra structures are named as alkyl group. The name will be similar to how we
name alkanes, change -ane to -yl.
Here are some examples:
propyl
isobutyl
butyl
pentyl
sec-pentyl
methyl
ethyl
isopropyl
sec-butyl
tert-butyl
neopentyl
isopentyl
In naming a hydrocarbon:
• Compounds are given systematic names by a process that uses
• Prefix-Parent-Suffix
Prefix tells you the substituents appended to the parent chain, Parent is the longest
chain, suffix represents the functional group (in our case, alkane)
• Naming follows the IUPAC rules
1. Named as longest possible chain (one in red, 8 carbon, octane)
2. Carbons in that chain are numbered in sequence (this is consecutively)
3. substituents are numbered at their point of attachment (lowest possible number)start numbering on the end where the substituents will get the lowest number (3
methyl, not 6 methyl.
1 2 3 4 5 6 7 8
3-methyl octane
4. Di, tri, tetra, sec, tert are ignored in alphabetizing, iso, neo, cyclo are not ignored
1 2 3 4 5 6 7 8
3-ethyl-4,5-dimethyl octane
5. When both direction leads to the same lowest number for one of the substituents, the
direction is chosen that gives the lowest possible number to one of the remaining
substituents (2,2,4-trimethylpentane, not 2,4,4)