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  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  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.