1. Alkene’s and Alkyne’s
Both Alkenes and Alkynes are unsaturated hydrocarbons
(* Alkanes are saturated)
Have a C-C double or triple bond in the molecule
They are also hydrocarbons
Alkenes can be produced by ‘cracking’ of alkanes (heating them to very high temperatures)
An example of a simple alkyne is acetylene (used for welding)

2. Alkene nomenclature Nomenclature patterns are similar to alkanes
1-pentene
3-hexene
                                                         
5-methyl-1-hexene
2,3,3-trimethyl-1-butene

3. Alkene nomenclature (contd)
2,3,3-trimethyl-1-butene
           
                
,             
2,3-dimethyl-1-pentene
Cyclohexene
3,4-dimethyl-2-pentene

4. Alkyne nomenclature
Alkynes are unsaturated hydrocarbons with triple bond between C-C
Follows same nomenclature pattern (yne ending)
2-chloro-2-butene
4-chloro-1-butene

5. Alkene and Alkyne properties
They are nonpolar, therefore soluble in nonpolar solvents
They float as a layer on water (i.e less dense)
Flammable, Nontoxic
Chemically reactive at the multiple bond
Displays cis-trans Isomerism*

6. Addition Reactions of Alkenes and Alkynes
Hydrogenation takes place in presence of a catalyst only, such as Pd, Ru etc..
alkyne
alkene

7. Addition Reactions (contd)
With excess H - X alkynes can be completely halogenated
Q: What is the standard reaction for alkene with HBr ?

8. Classes of Organic Reactions
Four important classes of reactions
Addition: occurs when two reactants add together to form a single molecule
Elimination: Generally occurs when a single reactant splits into two compounds
Substitution: When two reactants exchange parts to form two new products
Rearrangement: A reactant undergoes a reorganization of bonds and atoms to often yield an isomeric product

9. Addition Reaction: Markovnikov’s rule
When a compound HX is added to an unsymmetrical alkene,
the hydrogen gets attached to the carbon with the
most hydrogens attached to it already.
Which reaction gives the correct products?

10. Addition of water: Hydration
In the presence of an acid, an addition reaction takes place
between an alkene and water, producing an alcohol
* Also follows Markovnikov’s addition rule
The water molecule adds across the double bond producing an
alcohol
(presence of C-OH bond)