1. Chapter 3 Adel M. Awadallah Islamic University of Gaza
Organic chemistry for medicine and biology students
Chem 2311
Chapter 3
By Prof. Dr.
Adel M. Awadallah
Islamic University of Gaza

2. Hydrocarbons (contain only carbon and hydrogen)
Alkenes and Alkynes
Hydrocarbons (contain only carbon and hydrogen)
Saturated: (Contain only single bonds)
Alkanes (CnH2N + 2 )
Cycloalkanes (CnH2N )
b) Unsaturated: contain
Alkenes: double bonds (,,,CnH2N)
Alkynes: triple bonds ((CnH2N - 2)
Aromatic: benzene like compounds

3. Facts about double and triple bonds Bond order is the number of chemical bonds between a pair of atoms. 

4. Nomenclature of alkenes and Alkynes
The ending ene is used for alkenes and yne for alkynes
Select the longest chain that includes both carbons of the multiple bond
Number the chain from the end nearest to the multiple bond
Indicate the position of the multiple.
Examples

5. Isomers and common names of simple alkenes

6. Compounds containing more than one double bond

7. Cis-Trans (Z-E) Isomerism in Alkenes
If each end of the double bond is attached to two different groups, then the compound exists in two different forms called (Diastereomers; These are non mirror image stereoisomers).
If the two groups are identical we distinguish the two isomers by adding the prefix cis (same side) or trans (opposite sides)
Example

8. If the groups attached to the double bond are different, we distinguish the two isomers by adding the prefix Z (same side) or E (opposite sides) depending on the atomic number of the atoms attached to each end of the double bond

10. Hydrogen is a symmetric reagent

13. Bromine is a symmetric reagent

15. Water is unsymmetric reagent

18. Addition of HBr (Unsymmetric reagent):

27. Free Radical Polymerization of Ethylene

33. Reduction of alkynes With hydrogen in presence of ordinary nickel, platinum or palladium gives alkanes Hydrogentaion of alkynes with Lindlar’s catalyst gives a cis alkene

34. Lindlar’s Catalyst