1. Chemistry 250-02 Organic Chemistry I Fall, 2014 Day 14 10/3/14
Chemistry
Organic Chemistry I
Fall, 2014
Day 14
10/3/14
Chapter 6 Start to Read Chapter 7
Alkene Structure
Chem Activity 6C
An Overview of Organic Reactions
What Kind of Reactions Are There?
Why do Reactions Happen?
How do Reactions Happen?
What Factors Control Reactions?

2. Some Types of Organic Reactions
Addition
Elimination
Substitution
hydrolysis - reaction with H2O
condensation - formation of H2O
Rearrangement

3. Garoutte ChemAct 33 p

4. Garoutte ChemAct 33 p. 133-134 Oxidation Reduction Substitution
Hydrolysis
Elimination (reverse is Addition)
Acid-Base
Oxidation - 3 types add oxygen
lose hydrogen
loss of electrons
Substitution
Condensation
Addition (reverse is Elimination)

5. How do we classify these reactions
How do we classify these reactions? Addition, Elimination, Substitution, Rearrangement

6. How do we classify these reactions
How do we classify these reactions? Addition, Elimination, Substitution, Rearrangement
Substitution
Nucleophilic
Polar-Ionic H+
Elimination
Addition Δ
Substitution
Radical hν

7. Reaction Types

8. What Kinds of Organic Reactions Are There
What Kinds of Organic Reactions Are There ? How Can We Describe These Reactions ? Problem 6.1

9. What Kinds of Reactions Are These?

10. What Kinds of Reactions Are These?
Substitution
Substitution
Elimination

11. Polar Reactions Recall polarity
These reactions involve a nucleophile (e- - rich) and an electrophile (e- - poor)
What kind of reaction is this ?

12. Nucleophiles attack Electrophiles

13. Reaction Types

14. What kind of reaction is the transformation shown below?
an elimination reaction
a rearrangement reaction
a substitution reaction
an addition reaction
none of these

15. In the reaction shown below which is the electrophile?
propene
the H of HCl
the Cl of HCl
propane
none of these
all of these

16. In the reaction shown below which is the nucleophile?
propene
the H of HCl
the Cl of HCl
propane
none of these
all of these

17. Free Energy Diagrams What Does the TS (‡) Look Like ?

18. Which statement best describes the energetics of the reaction shown below? C2H4 + H2 → C2H6
exothermic with positive activation energy
exothermic with negative activation energy
endothermic with positive activation energy
endothermic with negative activation energy
cannot be determined without knowing BDE’s

19. On the reaction energy profile shown below which has the highest energy?II
III IV V

20. On the reaction energy profile shown below which is the highest energy intermediate?II
III IV V

21. On the reaction energy profile shown below which represents the slowest step?
I to II
II to III
III to IV
IV to V
All steps proceed at the same rate

22. On the reaction energy profile shown below which represents the energy of the reaction? The energy difference between:
I and II
I and III
II and III
III and IV
III and V
I and V

23. Organic Rxns and Biological Rxns

24. Reaction Types

25. Addition to Pi Bonds (C=C)

26. Alkene (C=C) Nomenclature
Name longest chain containing the double bond
Number the chain so that
1. Double bond gets lowest #, then
2. Substituents get lowest #s
Name as
“(stereochem) - # - substituents - # -prefixene”
Do ChemAct 6C Alkene Stereoisomers
Read Models and answer CTQ 31-36

27. Assign stereochemistry of bonds a, b, & c
E, Z, & E
Z, Z, & E
E, Z, & Z
E, E, & E
Neither, Z, & E
Neither, E, & Z

28. CA 6C Alkene Stereoisomers
Read Model 11 and answer CTQ

29. Assign stereochemistry to bonds a, b
Z, Z
E, E
E, Z
Z, E
Neither, E
Neither, Z

30. CA 6C Alkene Stereoisomers
Read Model 12 and answer CTQ 37.

31. What is the stereochemistry about bonds a, b?
E, Z
Z, E
E, E
Z, Z
Neither, Z
Neither, neither

32. CA 6C Alkene Stereoisomers
Read Model 13 and answer CTQ 38.
After naming, check with CTQ 37:
only conformers have the same name!
If the name differs only by E/Z, the molecules are configurational stereoisomers.

33. The more substituted the alkene the lower the energy (the more stable)

34. Alkene Stability (McMurry 7.6 )
Trans (E) more stable than cis (Z)
Substitution increases stability (decreases PE)

35. Alkene Stability (PE) from ΔHHydrogenation C=C + H2 -> H-C-C-H

36. The George Hammond Postulate (McMurry 7.10)
How does the stability of an intermediate (ΔG°) relate to the rate of the reaction (ΔG‡)?
Postulate: the TS for an endergonic reaction step structurally resembles the product of that step.
Thus: for an exergonic reaction, the TS resembles the reactant.

37. Which of the following represents a correctly drawn reaction mechanism?

38. Electrophilic Addition to Alkenes

39. Electrophilic Addition to Alkenes

40. Problems 5.6 and 5.7

42. Where are the electrophilic sites? Where are the nucleophilic sites?

43. Follow the arrows to the products

44. Two Reactions of Radicals
R-H →
R-H →

45. Radical Substitution The Mechanism

46. Radical Addition in Prostaglandin Synthesis

47. Polar Bonds and Polar Reactivity

48. Some Nucleophiles and Electrophiles

49. Nucleophiles and Electrophiles React !

50. C-H bond breaking in alkanes

51. How Can Bonds Be Broken and Made ?

52. Polar Reactions

53. Nucleophiles and Electrophiles

54. Problem 5.4 and 5.8