1. IUPAC Nomenclature of Hydrocarbons
I nternational
U nion of
P ure and
A pplied
C hemistry

2. Models Used to Represent Structures
Example
Empirical molecular formula
C7H16
Expanded molecular formula
CH3(CH2)5CH3
Structural formula
Condensed structural formula
CH3-CH2-CH2-CH2-CH2-CH2-CH3
Line structural formula

3. Naming Alkanes
The IUPAC name of any organic compound has three basic parts
Root- denotes number of carbon atoms in the longest continuous chain of carbon atoms
Prefix- gives positions and names of any branches
Suffix- indicates series to which the molecule belongs (e.g. alkane, alkene alkyne)

4. Root and Side Group Names of Alkanes
Number of Carbon Atoms
Root Name
Prefix (Side Group) 1
meth-
methyl- 2
eth-
ethyl- 3
prop-
propyl- 4
but-
butyl- 5
pent-
pentyl- 6
hex-
hexyl- 7
hept-
heptyl- 8
oct- 9
non- 10
dec-

5. The alkanes (CnH2n+2)

6. Steps for Naming Alkanes
Longest chain has 6 carbon atoms
Root name is hex-
Compound is alkane
Suffix is -ane
1. Identify the root
Identify the longest continuous chain
Find the root name for the number of carbons in the chain
2. Identify the suffix

7. Identify the prefix (name the branches)
Identify the number of carbon atoms in each branch
Determine the name of each branch
Number the C atoms on the longest chain to produce the lowest number combinations (or sum) for the branches
Two branches have one carbon atom and 3rd branch has 2 carbon atoms
Methyl- and ethyl-

8. Separate numbers using commas Separate numbers and words using hyphens
Precede the name of each branch with the number of the carbon atom to which it is attached on the main chain.
For more than one of the same branch use a prefix: di = 2 ,tri = 3, tetra = 4, penta = 5
Separate numbers using commas
Separate numbers and words using hyphens
3-ethyl
2,4-dimethyl

9. Arrange branches alphabetically (ignore prefixes di, tri, etc…)
4. Name the compound
Combine prefix, root, and suffix to name the compound
Prefix: 3-ethyl-2,4- dimethyl
Root: hex-
Suffix: -ane
Name: 3-ethyl-2,4- dimethylhexane

10. Finding the longest continuous chain
of carbon atoms is not always simple
all possibilites
must be examined
C-C
C-C-C-C-C-C-C-C-C
it won’t always be
the horizontal one
as shown here C 9
try these also ……..
C-C
C-C
C-C-C-
C-C-C-C-C-C C-
C-C-C
-C-C-C-C-C C C 6 8

11. Name this alkane
2-methylbutane

12. Find the longest continuous carbon chain
3-methylpentane

13. Name the Following Compound
4-ethylheptane

14. Number from the end nearest the first substituent
4-ethyl-3-methylheptane

15. Number from the end nearest the first substituent
3-ethyl-5-methyloctane

16. Use “di-” with two substituents
2,3-dimethylbutane

17. Every substituent must get a number
3,3-dimethylhexane

18. You need numbers, even though it appears on the same carbon!
2,2,4-trimethylpentane

19. Name the following compound
3,4,8-trimethyldecane

20. 6-ethyl-3,4-dimethyloctane
Name the following compound Dimethyl alphabetized as methyl, not dimethyl
6-ethyl-3,4-dimethyloctane

21. Drawing Alkanes e.g. draw Identify the root 3-ethyl-3-methylpentane
root: pent-
suffix: -ane
C-C-C-C-C
Identify the root
Gives the number of carbon atoms in the main chain
Identify the suffix
Indicates the type of bond between carbon atoms
3. Draw and number main chain

22. Identify the prefix and draw the side groups
Complete the condensed structural formula
Prefix: 3-ethyl-3- methyl-
(ethyl and methyl group on carbon 3)

23. Draw the structural diagram of 2-methylheptane

24. Boiling point range(oC)
Physical Properties of Alkanes
Since alkanes are non-polar, they are not soluble in water
Number of carbon atoms
Boiling point range(oC)
Uses
1 to 4
Below 30
(gases) Fuels to heat homes and cook
5 to 16
30 to 275
(liquids) automotive, diesel and jet engine fuels
16 to 22
Over 250
(heavy liquid) furnace oil
Over 18
Over 400
(Semi-solid) paraffin waxes to make candles
Over 26
Over 500
(Solid residues) asphalts and tars in paving

25. Naming Alkenes 1. Identify the root
Identify longest chain with a double bond.
Assign root name based on number of carbons
Identify the suffix
Number the main chain by starting at the end of the chain nearest the double bond.
Root: pent-
Suffix: -2-ene
(indicate the number of the carbon atom that precedes the double bond, only if alkene has 4 or more carbons)

26. Root: pent-
Prefix: 2,3-dimethyl-
Suffix: -2-ene
Name:
2,3-dimethylpent-2-ene
Identify the prefix
Name the side groups on alkenes as you would for alkanes
Name the compound.
Combine the prefix, root and suffix.

27. ethene
propene
but-1-ene
but-2-ene

28. 2-methylbut-2-ene

29. 6-methylhept-2-ene

30. trans-6-methyl-3-propyloct-2-ene

31. Drawing Alkenes draw a structural formula for 2-methylbut-1-ene
Identify the root
Identify the suffix
Draw and number the main carbon chain
Identify the prefix and draw the branches
Complete the structural formula by adding hydrogens
Root: but- (4 carbons)
Suffix: double bond between c-1 and c-2
Prefix: methyl group on c-2

32. Naming Alkynes 1. Identify the root
Identify longest chain with a triple bond.
Assign root name based on number of carbons
Identify the suffix
Number the main chain by starting at the end of the chain nearest the triple bond.
Root: pent-
Suffix: -1-yne
(indicate the number of the carbon atom that precedes the triple bond, only if alkyne has 4 or more carbons)

33. Root: pent-
Prefix: 3-methyl-
Suffix: -1-yne
Name:3-methylpent-1- yne
Identify the prefix
Name the side groups on alkynes as you would for alkanes
Name the compound.
Combine the prefix, root and suffix.

34. Drawing Alkynes draw a structural formula for 3-ethyhex-1-yne
Identify the root
Identify the suffix
Draw and number the main chain
Identify the prefix and draw any side groups
Add enough hydrogen atoms to give each carbon atom four bonds.
Root: hex- (6 carbons)
Suffix: -1-yne (triple bond between c1and c2
Prefix: ethyl group on c3

35. ethyne
propyne
“acetylene”
but-1-yne
but-2-yne

36. ALKYNES ( -YNE ) Hex-2-yne 4-methylpent-2-yne
The functional group has precedence in numbering.
Hex-2-yne
functional
group
The suffix has
precedence
over any
branches
4-methylpent-2-yne

37. nomenclature of halides and nitro compounds

38. 4-chloro-4-methylpent-2-yne
5-bromo-2-methylhept-3-yne

39. ene vs. yne: which one wins?
Number from the end closest to either the double bond
or the triple bond, whichever is closest to the end.
Compounds are named: en-yne.
CH3-CH2-C C-CH2-CH=CH-CH3
oct-2-en-5-yne

40. cycloalkanes
The names of the cycloalkanes always contain the prefix cyclo
Cycloalkanes have the general formula
CnH2n

41. Cyclic molecules

42. Naming Cyclic Hydrocarbons
1. Identify the root
Determine number of carbon atoms in the ring. Assign root name
2. Identify the suffix
Not necessary to indicate location of double or triple bonds, always between c1-c2
Root: pent-
Suffix: -1-yne
(indicate the number of the carbon atom that precedes the triple bond, only if alkyne has 4 or more carbons)

43. Naming Cyclic Hydrocarbons
3. Identify the prefix.
If there is only one substituent, do not use the “1”.
If there is more than one substituent, you must use all numbers, including “1”!
If there are two or more side groups, the numbering must start with a side group and then proceed in the direction that gives the lowest possible numbers to all the side groups.
If numbers are the same for two or more side groups, the side group that comes first alphabetically is assigned as c- 1.

44. Naming Cyclic Hydrocarbons
If the molecule is a cyclic alkene or cyclic alkyne, the multiple bond takes highest priority. The carbon atom on one side of the multiple bonds is c-1 and one the other side is c-2. If there are side groups, the numbering starts in the position that will make the number of the carbon atoms bonded to the side groups as small as possible.
4. Name the compound
Combine the prefix, root, and suffix to name the compound.

45. Naming Cyclic Hydrocarbons
Root: cyclopent
Suffix:-ene
Prefix:3,4-dimethyl
Name:
3,4-dimethylcyclopentene

46. 1,1-dimethylcyclohexane

47. 4-ethyl-1,1-dimethylcyclohexane

48. = Some cycloalkanes C H C H C H C H 1,3-dimethylcyclopentane
Drawn
differently
but same
name. C H 3 1 2 1 = 2 3 3 C H 3 2 C H 3 2 4 3 1 2 2 1 3
3-ethyl-1,1-dimethylcyclobutane
1-ethyl-4-methylcyclohexane
The more substituted carbon
takes precedence even
though E comes before M.
E before M

49. Numbering starts at the most highly-substituted carbon2 1 3 7 4 6 5
2-chloro-1,1,6-trimethylcycloheptane

50. cycloalkyl groups

51. 3-cyclobutyl-3-methylpentane

52. Another name of a group

53. 3-methyl-2-phenylpentane