1. Reactions of Alkenes and Alkynes
Chapter 5
Reactions of Alkenes and Alkynes
Dr. Sujatha Krishnaswamy
Chemistry Faculty
Chandler Gilbert Community College

2. Chapter 4 Problem 18

3. Chapter 4 Problem 17

4. Addition Reactions
The characteristic reaction of alkenes is addition—the  bond is broken and two new  bonds are formed.
Because alkenes are electron rich, simple alkenes do not react with nucleophiles or bases, reagents that are themselves electron rich. Alkenes react with electrophiles.

6. Hydrohalogenation - Addition of HX

7. Chapter 4 Problem 14

8. To draw the products of an addition reaction:

9. Addition of HX is regioselective
Markovnikov’s rule: in additions of HX, H adds to the carbon with the greater number of hydrogens

11. Stability of Carbocations

12. Chapter 5 Problem 3

14. Predict the major product in each reaction.

15. More reactions….. Chapter 5 Page 112 Problem 4 Page 116 Problem 10

17. Synthesis

18. Addition of H2O, Hydration
acid-catalyzed hydration of an alkene is regioselective; hydrogen adds preferentially to the sp2 carbon with less # of hydrogens.

20. What products are obtained upon hydration of the following alkenes?

21. Synthesis - How can you make these alcohols?

22. Addition of Cl2 and Br2

23. addition is stereoselective
stereoselective reaction: a reaction in which one stereoisomer is formed or destroyed in preference to all others that might be formed or destroyed
addition to a cycloalkene, for example, gives only a trans product

24. Reduction of Alkenes
Alkenes react with H2 in the presence of a transition metal catalyst to give alkanes
the most commonly used catalysts are Pd, Pt, and Ni

26. Predict the products of hydrogenation (reduction) of

27. Alkynes

28. Addition of HX to Alkynes

31. Addition of Halogens to Alkynes

33. Hydration of Internal Vs Terminal Alkynes
Keto-enol tautomers

34. Addition of Hydrogen to Alkynes

35. Reduction of an Alkyne to an Alkane
Alkane formation:

36. Addition of Hydrogen to Alkynes - Formation of cis Alkene

37. Conversion of Internal Alkynes to trans Alkenes

38. Summary of Alkyne Reductions