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.