This document discusses the naming of aromatic compounds. It defines aromatic compounds as those containing a benzene ring with delocalized pi bonds. It outlines three steps for naming aromatic compounds: 1) those with a single substituent, where the substituent name is used as a prefix, 2) those with two substituents, where ortho, meta, or para prefixes indicate carbon placement, and 3) those with multiple substituents, where the substituents are numbered to give the lowest sum and listed alphabetically. Examples are provided to illustrate each naming convention.

1. CONSUMER
CHEMISTRY
Aromatic Compounds

2. Aliphatic compounds
◦ Organic compounds that are usually straight chain hydrocarbons.
◦ They are non-aromatic compounds.
◦ Alkanes, alkenes, and alkynes are examples of aliphatic compounds.
 Alkanes are single-bonded hydrocarbons, alkenes are double-bonded and lastly,
alkynes are triple-bonded hydrocarbons.
◦ They differ on the type of bond that exist between carbon and hydrogen
atoms.

3. • Acetylene torch is used by a
welder to cut and weld steel.
• It uses acetylene as fuel.
HC CH
1. What kind of aliphatic
compound is acetylene?
2. What is the IUPAC name of
acetylene?
3. What were the steps you
follow in giving the IUPAC
name of acetylene?

4. Direction: For each number, draw inside the box what the direction in the talk balloon instructs
you to do.
1.
Draw a hexagon.
2.
For the first aromatic structure, repeat direction Number 1 and
draw a circle at the center.
3.
For the second aromatic structure, repeat direction Number 1
and inside the hexagon, draw three alternating lines opposite to
the original structure.

5. Questions:
1. In how many ways can you show the structure of aromatic compounds?
2. Describe the first structure for aromatic compounds. How about the second
structure?
3. What do you call the structure of aromatic compounds?
EEBZNEN GIRN
HINT: Rearrange the jumbled letters. It is a two word.

6. Aromatic compounds
◦ compounds that contain a benzene ring and have a distinctive aroma or odor.
◦ The molecular formula of benzene is C6H6.
◦ Six carbon atoms are attached cyclically with three alternating pi bonds or the presence of double bonds.
◦ Only one hydrogen atom is attached to each carbon atom.
Structures of Aromatic Compounds

7. ◦ Aromatic compounds are hydrocarbons
◦ only carbon and hydrogen are attached to form a compound.
◦ Aromatic hydrocarbons are named as derivatives of benzene to distinguish one
from another.
1. Comma (,) is used to separate numbers.
Example: 1,2
2. Hyphen/ dash (-) is used to separate numbers from names.
Example: 2-bromobenzene

8. Steps in Naming Aromatic Compounds
1. Aromatic Compounds with Single Substituent
◦ a. When the substituent on the benzene ring is an alkane that has six or less than six carbons, the
name of the substituent is added as a prefix to benzene. Alkanes become an alkyl group because they
lose one hydrogen atom, their names end with –yl except for methane (an alkane with one carbon). A
Example:
CH2CH3
ethylbenzene

9. ◦ b. When the substituent on the benzene ring is a halogen Br (bromine), F (fluorine), Cl (chlorine), I
(iodine); the name of the halogen is added as a prefix to benzene but the ine is changed to o. When the
substituent is NO2, it is nitro.
Example:
F NO2
fluorobenzene nitrobenzene

10. ◦ c. When common names are added as a substituent to the benzene ring, common name becomes the
parent molecule and will no longer be benzene. (NOTE: You have to memorize this portion in order not to
be confused.
Example:

11. 2. Aromatic Compounds with Two Substituents
◦ Ortho, meta, and para are used as prefixes to lessen the numbering of the substituents. Ortho (o-) for 1-
2 carbon placement, meta (m-) for 1-3 carbon placement, and para (p-) for 1-4 carbon placement. Add
the word di after prefix ortho (o-), meta (m-) or para (p-) plus the name of the substituent if the
substituent appears twice; if the substituents are not the same arrange them in alphabetical order.
Example:

12. 3. Aromatic Compounds with Multiple Substituents
◦ a. The location of each substituent is very important. Start numbering the carbon atom to which the
substituent is attached and count toward the carbon atom that has the other substituent making sure
that the sum of the locations gives the smallest possible number. Arrange the substituents in alphabetical
order.
Example 1 Example 2

13. ◦ b. If one of the substituents is a common name as stated in Rule No.1 letter c, the common name is used
as the parent molecule and assigned as carbon number 1. Arrange the substituents alphabetically. The
direction of the numbering for the rest of the substituents must give the sum of the lowest possible
number.
Example

14. ◦ c. If the same substituent occurs not just twice , use prefix such as tri for three or tetra for four. Do not
include these prefixes in arranging the substituents alphabetically.
Example