Addition Reactions Synthesis Alkenes Addition Reactions Synthesis

Addition of HBr or HCl Markovnikov Addition

HBr Addition with RO-OR Anti-Markovnikov

Free-Radical Mechanism

Addition of Br2

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.

Bromonium Ion Intermediate

Halohydrins

Bromohydrin Formation Addition of Br – OH Stereospecific & Regiospecific

Unsymmetrical Bromonium ion H2O opens ring at more hindered site

Br and OH are trans in anti addition

Catalytic Hydrogenation syn addition

Mechanism – Syn Addition

Syn Addition of H2

Hydrogenation all alkene p bonds are reduced

Hydrogenated Vegetable Oil

Hydration Addition of H2O

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

BH3 adds to Alkene

Hydroboration

Regiochemistry is Anti-Markovnikov

Syn Addition of H2O

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

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?

Problem A symmetrical unknown compound A, C8H16, reacts with H2 on a 1% Pt/C catalyst to form B (C8H18). Treatment of A with O3 followed by Zn/HOAc affords butanone only. Identify A and B.