1. Aromatic Hydrocarbons

2. Why aromatic hydrocarbons are called aromatic? AH are hydrocarbons containing BENZENE as part of their structure Molecular formula of benzene is C 6 H 6 What are the possible structures for molecular formula of C 6 H 6 ?

3. Structure of benzene 1865, a German chemist named August Kekule proposed following structure of benzene Electrons that are spread out and shared over the whole molecule are called delocalized electrons Thus, benzene has 6 identical bonds a hybrid between single and double bond

4. Compounds with this special electron arrangement are called aromatic This bond is much more stable than ordinary double bond and thus aromatic compounds are less reactive than double bond containing alkenes

5. TNT

6. Naming Aromatic Compounds If only one branch is attached to the benzene ring, you do not need to attach a position number. Methylbenzene (toluene) Ethenylbenzene (phenylethene, styrene, vinylbenzene) (1-methylethyl)benzene Isopropylbenzene Prop-2-ylbenzene

7. If two same branches are attached start numbering at the carbon with a branch of your choice and use multiplying prefix Common name IUPAC name ortho-dimethylbenzene o-dimethylbenzene meta-dimethylbenzene m-dimethylbenzene para-dimethylbenzene p-dimethylbenzene

8. If two different branches are attached start numbering at the carbon with the substituent closer to the beginning of the alphabet 1-methyl-4-propylbenzene (p-methylpropylbenzene) 1-bromo-3-methylbenzene m-bromomethylbenzene

9. If 3 or more branches are attached start numbering at the carbon that gives the lowest possible location numbers to all branches 1,2,4-trimethylbenzene 2-methyl-1,3,5-trinitrobenzene (2,4,6-trinitrotoluene) 2-ethyl-4-methyl-1-propylbenzene

10. Mystery compound 3-ethyl-4-methyl-2,5-diphenylheptane

11. Drawing Aromatic Compounds Draw a condensed structural diagram for following compound 2-ethyl-1,4-dimethylbenzene