Alkenes Addition Reactions Synthesis Addition of HBr or
Alkenes Addition Reactions Synthesis
Addition of HBr or HCl Markovnikov Addition
HBr Addition with RO-OR Anti-Markovnikov
Free-Radical Mechanism
Addition of Br 2
A Similar Mechanism to the Addition of HBr?
Trans is formed exclusively (No cis is formed)
Carbocation can be Stabilized by Neighboring Br
Bromonium Ion is Opened Equally from Both Sides
Definitions • Stereospecific – only one stereoisomer is formed at the expense of the other (e. g. trans vs. cis) • Stereoselective – one stereoisomer is formed preferentially over the other.
Anti-Addition Stereospecific Reaction Anti-addition
Bromonium Ion Intermediate
Halohydrins
Bromohydrin Formation Addition of Br – OH Stereospecific & Regiospecific
Unsymmetrical Bromonium ion H 2 O opens ring at more hindered site
Br and OH are trans in anti addition
Catalytic Hydrogenation syn addition
Mechanism – Syn Addition
Syn Addition of H 2
Hydrogenation all alkene p bonds are reduced
Hydrogenated Vegetable Oil
Hydration Addition of H 2 O
Oxymercuration Hydration Markovnikov addition Regiospecific Reaction
Oxymercuration Mechanism
Predict the Oxymercuration Hydration Products
What Alkene would you use to Make These Alcohols?
Hydroboration Hydration Anti-Markovnikov Syn addition
BH 3 adds to Alkene
Hydroboration
Regiochemistry is Anti-Markovnikov
Syn Addition of H 2 O
Draw the Major Products
2 Complementary Hydration Reactions
Oxymercuration – the more highly substituted alcohol forms Hydroboration – the less highly substituted alcohol forms
Predict Both Oxymercuration and Hydroboration Products
Cyclopropanation
A Carbene is Similar to Geometry of a Carbocation
Dichlorocarbene Reactions
Simmons-Smith Reaction
In situ Preparation of Carbene
Two MCAD Inhibitors
Epoxide Preparation From Alkenes
Epoxide Preparation From Halohydrins
Mechanism
Epoxide groups are Common in Biologically Active Molecules
A New Class of Anti-tumor Agents
Ozonolysis Forms 2 Carbonyl Compounds
Ozonolysis Alkene Cleavage
Mechanism of Ozonolysis
What Alkene will Undergo Ozonolysis to Give the Products Shown?
Addition polymers
Air Pollution Reacts with Tires
O 3 reacts with all alkene p Bonds
Problem A symmetrical unknown compound A, C 8 H 16, reacts with H 2 on a 1% Pt/C catalyst to form B (C 8 H 18). Treatment of A with O 3 followed by Zn/HOAc affords butanone only. Identify A and B.
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