CHAP SEVEN/EIGHT OUTLINE: WADE
ALKENE SYNTHESIS AND REACTIONS
1) Structure and Properties
a) The pi bond and hindered C-C rotation
i) cis- / trans- nomenclature
ii) E/Z nomenclature
b) Molecular Orbital Energy Diagram of ethene
c) The E/Z Nomenclature System
d) Relative Stability via Heats of Hydrogenation
2) Formation of Alkenes
a) From Alkyl Halides via E2 with strong bases (Ch 6 Review; Zaitsev product
unless anti-coplanar transition state not possible)
Section 7-9
b) From Alcohols via E1 with strong acid catalysts (rearrangement likely)
Section 7-10
c) Skip 7-9D
d) Skip 7-11
3) Reactions of Alkenes
CHAPTER EIGHT
a) Alkenes as Nucleophile
i) Addition of HX in absence of peroxides to form Markovnikov Alkyl Halide
(both enantiomers)
 Mechanism
 Stereochemistry
 Reaction Energy Profile
 Regio-Selectivity: Markovnikov’s Rule
 Carbocation stability (review)
o Inductive effects
o Hyperconjugation
o Carbocation rearrangement
ii) Addition of HOH or HOR
(1) Via reaction with H2SO4 and water or alcohol to make Markovnikov
Alcohol or Ether (rearrangement likely) Mech 8-4
(2) Via reaction with Hg(OAc)2 and H2O or ROH followed by NaBH4 to
make Markovnikov Alcohol or Ether (no rearrangement) Mech 8-5
iii) Hydroboration-Oxidation: Addition of BH3•THF followed by H2O2, OH– to
form ANTI-Markovnikov Alcohol
Mech 8-6
iv) Addition of X2 to form vicinal dihalide Mech 8-7
v) Addition of Carbenes to Alkenes (Section 8-11)
(1) Diazomethane decomposition to methylene carbene
(2) Simmons-Smith Reaction: Addition of CH2I2, Zn(Cu)
ICH2ZnI decomposition to methylene carbene
(3) Haloform in KOH decomposition to dihalocarbene
b) Oxidation Reactions
i) Formation of Epoxides with Peroxyacids: Concerted Mechanism
ii) Formation of vicinal diols
(1) Anti dihydroxylation via epoxide ring opening
(2) Syn dihydroxylation via reaction with OsO4
(3) Syn dihydroxylation via KMnO4 under mild conditions
CHAP SEVEN/EIGHT OUTLINE: WADE
ALKENE SYNTHESIS AND REACTIONS
iii) Oxidative Cleavage
(1) With KMnO4 under basic conditions or higher temp to form
ketones/carboxylates
(2) Ozonolysis With O3 followed by (CH3)2S to form ketones/aldehydes
c) Free Radical Reactions
i) Addition of HX in presence of peroxides to form ANTI-Markovnikov Alkyl
halide (both enantiomers) Mech 8-3
ii) Addition of NBS in presence of peroxides to form allylic alkyl halide (Chap
6-6 review)
iii) Polymerization Section 8-16B
d) Oxidation-Reduction
i) Reduction to alkane via syn addition of H2 with metal catalyst (Pd, Pt, Ni,
Rh, Ru, etc) Section 8-10
ii) Oxidation to Epoxide via reaction with peroxyacid Section 8-12; Mech 8-9
iii) Syn-Dihydroxylation Section 8-14
(1) with OsO4 and H2O2
(2) with KMnO4, OH–
iv) Oxidative Cleavage Section 8-15
(1) with O3 followed by Zn or (CH3)2S to aldehydes and/or ketones
(2) with KMnO4 when concentrated in base or with heat or acidic solution
to carboxylic acids and/or ketones
v) Olefin Metathesis with Mo (Shrock) or Ru (Grubbs) catalyst Section 8-17;
Mech 8-11
LEARNING OUTCOMES:
 Identify electrophiles and nucleophiles according to their roles in well
characterized chemical reactions
 Understand the most common chemical reactions involving alkenes including
analysis of regio- and stereo- selectivity in product formation, step-wise
mechanisms and identification of intermediates, and advantages/ disadvantages
of similar reactions.
 Design a multiple-step synthesis of a target compound utilizing alkene
chemistry.
 Propose a mechanism for a molecular transformation by applying principles
learned from known reactions.
 Sketch a reaction Energy profile for a reaction from its known mechanism.
 Understand how chirality and optical activity depend on mechanism and the
stereochemistry of the starting materials.
 Name alkenes according to Cahn-Ingold-Prelog E/Z Nomenclature.
 Predict relative stability of alkenes from Heats of hydrogenation.
 Recognize structural features of a molecule that are key to its stability and
reactivity.
CHAP SEVEN/EIGHT OUTLINE: WADE
ALKENE SYNTHESIS AND REACTIONS
SAMPLE EXAM PROBLEMS:
1. Provide a mechanism for the following reaction. Use curved arrows and include
all lone electron pairs and formal charge.
2. Draw the following molecule: 4R-(Z)-2,4-dibromo-3,4-dimethyl-2-hexene:
3. Provide the missing reagents to complete the following chemical transformation:
4. Consider the reaction below and tell why it DOES NOT provide high yields of the
product shown. Draw alternative products, if any are formed