1. Alkenes, Reactions

2. NR   some R-H R-X R-OH R-O-R Alkenes Acids Bases Metals Oxidation
Reduction
Halogens

3. Alkenes, reactions.
Addition
ionic
free radical
Reduction
Oxidation
Substitution

4. Reactions, alkenes:
Addition of hydrogen (reduction).
Addition of halogens.
Addition of hydrogen halides.
Addition of sulfuric acid.
Addition of water (hydration).
Addition of aqueous halogens (halohydrin formation).
7. Oxymercuration-demercuration.

5. 8. Hydroboration-oxidation.
9. Addition of free radicals.
10. Addition of carbenes.
11. Epoxidation.
12. Hydroxylation.
13. Allylic halogenation
14. Ozonolysis.
15. Vigorous oxidation.

6. Addition of hydrogen (reduction).
| | | |
— C = C — H Ni, Pt, or Pd  — C — C —
| |
H H
a) Requires catalyst.
#1 synthesis of alkanes
CH3CH=CHCH H2, Ni  CH3CH2CH2CH3
2-butene n-butane

7. Alkanes
Nomenclature
Syntheses
1. addition of hydrogen to an alkene
2. reduction of an alkyl halide
a) hydrolysis of a Grignard reagent
b) with an active metal and acid
3. Corey-House Synthesis
Reactions
1. halogenation
2. combustion (oxidation)
3. pyrolysis (cracking)

8. heat of hydrogenation:
CH3CH=CH H2, Pt  CH3CH2CH3 + ~ 30 Kcal/mole
ethylene 32.8
propylene 30.1
cis-2-butene 28.6
trans-2-butene 27.6
isobutylene 28.4

9. fats & oils: triglycerides
CH2—O—CCH2CH2CH2CH2CH2CH2CH2CH2CH3
| O
CH—O—CCH2CH2CH2CH2CH2CH2CH2CH2CH3
CH2—O—CCH2CH2CH2CH2CH2CH2CH3
“saturated” fat

10. O
CH2—O—CCH2CH2CH2CH2CH=CH2CH2CH2CH3
| O
CH—O—CCH2CH2CH2CH2CH=CH2CH2CH2CH3
CH2—O—CCH2CH2CH=CHCH2CH2CH3
Ω - 3 “unsaturated” oil

11. Saturated triglycerides are solids at room temperature and are called “fats”.
butter fat, lard, vegetable shortening, beef tallow, etc.
Unsaturated triglycerides have lower mp’s than saturated triglycerides. Those that are liquids at room temperature are called “oils”. (All double bonds are cis-.)
corn oil, peanut oil, Canola oil, cottonseed oil, etc.

12. polyunsaturated oils + H2, Ni  saturated fats
liquid at RT solid at RT
oleomargarine
butter substitute
(dyed yellow)
Trans-fatty acids formed in the synthesis of margarine have been implicated in the formation of “bad” cholesterol, hardening of the arteries and heart disease. 

13. 2. Addition of halogens.
| | | |
— C = C — X  — C — C —
| |
X X
X2 = Br2 or Cl2
test for unsaturation with Br2
CH3CH2CH=CH Br2/CCl4  CH3CH2CHCH2
Br Br
1-butene ,2-dibromobutane

14. Addition of hydrogen halides.
| | | |
— C = C — HX  — C — C —
| |
H X
HX = HI, HBr, HCl
Markovnikov orientation
CH3CH=CH HI  CH3CHCH3 I
CH3 CH3
CH2C=CH HBr  CH3CCH3 Br

15. Markovnikov’s Rule:
In the addition of an acid to an alkene the hydrogen will go to the vinyl carbon that already has the greater number of hydrogens.

16. CH3CH2CH=CH2 + HCl  CH3CH2CHCH3
CH3CH=CCH HBr  CH3CH2CCH3 Br
CH3CH=CHCH HI  CH3CH2CHCH3 I

17. An exception to Markovikov’s Rule:
CH3CH=CH HBr, peroxides  CH3CH2CH2Br
CH CH3
CH3C=CH HBr, peroxides  CH3CHCH2Br
“anti-Markovnikov” orientation
note: this is only for HBr.

18. Markovnikov doesn’t always correctly predict the product!
CH CH3
CH2=CHCHCH HI  CH3CH2CCH  I
Rearrangement!

21. why Markovinkov?
CH3CH=CH HBr  CH3CHCH o carbocation
|   H
or? CH3CHCH o carbocation
 | more stable
+ Br  CH3CHCH3 | Br

22. In ionic electrophilic addition to an alkene, the electrophile always adds to the carbon-carbon double bond so as to form the more stable carbocation.

23. Addition of sulfuric acid.
| | | |
— C = C — H2SO  — C — C —
| |
H OSO3H
alkyl hydrogen sulfate
Markovnikov orientation.
CH3CH=CH H2SO4  CH3CHCH3 O
O-S-O OH

24. Addition of water.
| | | |
— C = C — H2O, H  — C — C —
| |
H OH
a) requires acid
Markovnikov orientation
low yield 
CH3CH2CH=CH H2O, H+  CH3CH2CHCH3 OH

26. | | H | |
— C = C — H2O  — C — C —
| |
OH H
Mechanism for addition of water to an alkene to form an alcohol is the exact reverse of the mechanism (E1) for the dehydration of an alcohol to form an alkene.

29. How do we know that the mechanism isn’t this way?
One step, concerted, no carbocation

30. CH3CH=CH Br2 + H2O + NaCl 
CH3CHCH CH3CHCH CH3CHCH2
Br Br OH Br Cl Br

31. Some evidence suggests that the intermediate is not a normal carbocation but a “halonium” ion:
| |
— C — C —
Br 
The addition of X2 to an alkene is an anti-addition.

32. Addition of halogens + water (halohydrin formation):
| | | |
— C = C — X2, H2O  — C — C — HX
| |
OH X
X2 = Br2, Cl2
Br2 = electrophile
CH3CH=CH Br2(aq.)  CH3CHCH HBr
OH Br

34. 7. Oxymercuration-demercuration.
| | | |
— C = C — + H2O, Hg(OAc)2  — C — C — + acetic
| | acid
OH HgOAc
| | | |
— C — C — NaBH4  — C — C —
OH HgOAc OH H
alcohol

35. oxymercuration-demercuration:
#1 synthesis of alcohols.
Markovnikov orientation.
100% yields. 
no rearrangements 
CH3CH2CH=CH2 + H2O, Hg(OAc)2; then NaBH4 
CH3CH2CHCH3 OH

36. With alcohol instead of water:
alkoxymercuration-demercuration:
| | | |
— C =C — + ROH, Hg(TFA)2  — C — C —
| |
OR HgTFA
| | | |
— C — C — NaBH4  — C — C —
OR HgTFA OR H
ether

37. alkoxymercuration-demercuration: #2 synthesis of ethers.
Markovnikov orientation.
100% yields. 
no rearrangements 
CH3CH=CH2 + CH3CHCH3, Hg(TFA)2; then NaBH4  OH
CH3 CH3
CH3CH-O-CHCH3
diisopropyl ether
Avoids the elimination with 2o/3o RX in Williamson Synthesis.

38. Ethers
nomenclature
syntheses
1. Williamson Synthesis
2. alkoxymercuration-demercuration
reactions
1. acid cleavage

39. 8. Hydroboration-oxidation.
| | | |
— C = C — + (BH3)2  — C — C —
| |
diborane H B — |
| | | |
— C — C — + H2O2, NaOH  — C — C —
H B — H OH
alcohol

40. hydroboration-oxidation:
#2 synthesis of alcohols.
Anti-Markovnikov orientation. 
100% yields. 
no rearrangements 
CH3CH2CH=CH2 + (BH3)2; then H2O2, NaOH 
CH3CH2CH2CH2-OH

41. CH3
CH3C=CH H2O, Hg(OAc)2; then NaBH4 
Markovnikov CH3CCH3 OH
CH3C=CH (BH3)2; then H2O2, NaOH 
anti-Markovnikov CH3CHCH2

42. Alcohols:
nomenclature
syntheses
1. oxymercuration-demercuration
2. hydroboration-oxidation 3.
4. hydrolysis of a 1o / CH3 alcohol 5. 6. 8.

43. 9. Addition of free radicals.
| | | |
— C = C — HBr, peroxides  — C — C —
| |
H X
anti-Markovnikov orientation.
free radical addition
HI, HCl + Peroxides
CH3CH=CH HBr, peroxides  CH3CH2CH2-Br

44. Mechanism for free radical addition of HBr:
Initiating steps:
1) peroxide  2 radical•
2) radical• + HBr  radical:H + Br• (Br• electrophile)
Propagating steps:
3) Br• + CH3CH=CH2  CH3CHCH2-Br (2o free radical) •
4) CH3CHCH2-Br HBr  CH3CH2CH2-Br Br•
3), 4), 3), 4)…
Terminating steps:
Br• + Br•  Br2
Etc.

45. In a free radical addition to an alkene, the electrophilic free radical adds to the vinyl carbon with the greater number of hydrogens to form the more stable free radical.
In the case of HBr/peroxides, the electrophile is the bromine free radical (Br•).
CH3CH=CH HBr, peroxides  CH3CH2CH2-Br

46. 10. Addition of carbenes.
| | | |
— C = C — + CH2CO or CH2N2 , hν  — C — C —
 CH2
•CH2• “carbene” adds across the
double bond
| |
— C = C —
 
•CH2•

47. | | | |
— C = C — CHCl3, t-BuOK  — C— C —
CCl2
 -HCl
•CCl2• dichlorocarbene
| |
— C = C —
 
•CCl2•

49. 11. Epoxidation.
| | C6H5CO3H | |
— C = C — (peroxybenzoic acid)  — C— C — O
epoxide
Free radical addition of oxygen diradical.
| |
— C = C —
 
•O•

51. 12. Hydroxylation. (mild oxidation)
| | | |
— C = C — KMnO4  — C — C — syn
| |
OH OH OH
— C = C — HCO3H  — C — C — anti
peroxyformic acid | |
glycol

52. CH3CH=CHCH3 + KMnO4  CH3CH-CHCH3
OH OH
2,3-butanediol
test for unsaturation purple KMnO4  brown MnO2
CH2=CH KMnO4  CH2CH2
ethylene glycol
“anti-freeze”

53. 13. Allylic halogenation.
| | | | | |
— C = C — C — + X2, heat  — C = C — C — + HX
| |
H  allyl X
CH2=CHCH Br2, 350oC  CH2=CHCH2Br + HBr
a) X2 = Cl2 or Br2
b) or N-bromosuccinimide (NBS)

54. CH2=CHCH Br2  CH2CHCH3
Br Br
addition
CH2=CHCH3 + Br2, heat  CH2=CHCH2-Br + HBr
allylic substitution

55. 14. Ozonolysis.
| | | |
— C = C — O3; then Zn, H2O  — C = O + O = C —
used for identification of alkenes
CH3
CH3CH2CH=CCH O3; then Zn, H2O 
CH3CH2CH=O O=CCH3

56. 15. Vigorous oxidation.
=CH KMnO4, heat  CO2
=CHR KMnO4, heat  RCOOH carboxylic acid
=CR KMnO4, heat  O=CR ketone

57. CH3CH2CH2CH=CH2 + KMnO4, heat 
CH3CH2CH2COOH + CO2
CH CH3
CH3C=CHCH3 + KMnO4, heat  CH3C=O + HOOCCH3

58. CH3CH=CHCH3 + KMnO4  CH3CHCHCH3
OHOH
mild oxidation  glycol
CH3CH=CHCH hot KMnO4  2 CH3COOH
vigorous oxidation

59. Reactions, alkenes:
Addition of hydrogen
Addition of halogens
Addition of hydrogen halides
Addition of sulfuric acid
Addition of water/acid
Addition of halogens & water (halohydrin formation)
7. Oxymercuration-demercuration

60. 8. Hydroboration-oxidation
9. Addition of free radicals
10. Addition of carbenes
11. Epoxidation
12. Hydroxylation
13. Allylic halogenation
14. Ozonolysis
15. Vigorous oxidation

61. CH CH3
CH3C=CH H2, Pt  CH3CHCH3
isobutylene
CH3
“ Br2/CCl4  CH3C-CH2
Br Br
“ HBr  CH3CCH3 Br
“ H2SO4  CH3CCH3 O
SO3H

62. CH CH3
CH3C=CH H2O, H+  CH3CCH3
isobutylene OH
CH3
“ Br2(aq.)  CH3C-CH2Br OH
CH CH3
CH3C=CH2 + H2O,Hg(OAc)2; then NaBH4  CH3CCH3
“ (BH3)2; then H2O2, OH-  CH3CHCH2

63. CH CH3
CH3C=CH HBr, peroxides  CH3CHCH2
isobutylene Br
CH3
“ CH2CO, hv  CH3C–CH2
CH2
“ PBA  CH3C–CH2 O

64. CH CH3
CH3C=CH KMnO4  CH3C–CH2
isobutylene OH OH
CH3
“ Br2, heat  CH2C=CH HBr Br
“ O3; then Zn/H2O  CH3C=O + O=CH2
“ KMnO4, heat  CH3C=O + CO2