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

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

3. Facts about double and triple bonds 3

4. Nomenclature of alkenes and Alkynes 1)The ending ene is used for alkenes and yne for alkynes 2)Select the longest chain that includes both carbons of the multiple bond 3)Number the chain from the end nearest to the multiple bond 4)Indicate the position of the multiple. Examples 4

5. Isomers and common names of simple alkenes 5

6. Nomenclature of compounds containing more than one multiple bond 1)Number from the end nearest to the multiple bond. If a double and a triple bond are equidistant from he end, the double bond receives the lowest numbers Example 6

7. Compounds containing more than one double bond 7

8. 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

9. 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 9

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11. Hydrogen is a symmetric reagent 11

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14. Bromine is a symmetric reagent 14

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17. Water is unsymmetric reagent 17

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22. Addition of HBr (Unsymmetric reagent): 22

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42. Electrophilic addition of HBr to conjugated diens 42

43. The Diels –Alder Reaction 43

44. Free Radical Polymerization of Ethylene 44

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55. 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 55

56. Lindlar’s Catalyst 56

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