1. Organic Reactions Kinds of Reactions Mechanisms (polar, non-polar) Bond Dissociation Energy Reaction Profiles

2. Types of Reactions Addition Reactions Elimination Reactions

3. Types of Reactions Substitution: –Polar –Non-polar

4. Rearrangement

6. Definitions Mechanism: Complete step-by-step of exactly which bonds break and which bonds form and in what order. Thermodynamics: The study of the energy changes that occur in chemical transformations. This allows for comparison of stability of reactants and products. Kinetics: The study of reaction rates, determining which products are formed most rapidly. One can predict how the rate will change with changing conditions.

7. Reaction Profile (Exothermic)

8. 2 nd Order Reaction

9. 1 st Order Reaction

10. Bond Breaking: Non-polar and Polar

11. Bond Forming: Non-polar and Polar

12. Non-polar Reaction Involves Free Radicals

13. Free Radicals are Neutral, but Electron-Deficient

14. Free Radical Chlorination

15. Experimental Evidence Helps to Determine Mechanism Chlorination does not occur at room temperature in the dark. The most effective wavelength of light is blue that is strongly absorbed by Cl 2 gas. The light-initiated reaction has a high quantum yield (many molecules of product are formed from each photon of light).

16. Free Radical Species are Constantly Generated Throughout the Reaction Propagation

17. Termination: Reaction of any 2 Radicals

19. Enthalpy of Reaction (  H o ) Measures Difference in Strength of Bonds Broken and Bonds Formed Bond Dissociation Energy

21.  H o =  bonds broken-  bonds formed

22.  H rxn = -105 kJ/mol

24. Why Not This Mechanism?

26. Chlorination of Propane

27. H’s are not abstracted at the same rate.

30. Chlorination of Methylpropane

31. Tertiary H’s removed 5.5 times more readily than primary H’s in chlorination reactions

32. 3 o Radicals are Easiest to Form

33. Stability of Free Radicals

35. Bromination is Very Selective

37. RDS in Bromination is highly endothermic

38. Consider the free radical monochlorination of 2,2,5-trimethylhexane. Draw all of the unique products (ignore stereoisomers; use zig-zag structures please) and predict the ratio or percent composition of the products. The relative reactivity of H abstraction in a chlorination reaction: 1 o : 2 o : 3 o = 1: 4.5: 5.5

39. Chlorofluorocarbons and the Depletion of Ozone

40. Polar Reactions: Nucleophiles & Electrophiles

42. Nucleophiles are Bases Electrophiles are Acids

43. Addition of HBr to Ethylene

44. Reactions Often Go Through Intermediates

45. Transition State

47. Addition Reaction is a Two- Step Mechanism

49. How Many Mechanistic Steps? How Many Intermediates? How Many Transition States? Which Step is Rate-Determining?