Alkene Reagents

alkyl bromides

Alkenes react with H-Br to make:

They are weak and easy to break

How does a pi bond attract electrophiles

Hyperconjugation

delocalization of electrons by the overlap of a pi bond and an empty orbital

Regioselectivity

preferential formation of one constitutional isomer over another

The electrophile adds preferentially to the sp2 carbon that is bonded to the greater number of hydrogens (this is called the Markovnikov addition product)

Markovnikov’s rule:

H2SO4. requires an acid catalyst to produce an ether

fill in the yellow blank

1-2 Hydride shift

The movement of a hydride ion from one carbon to an adjacent carbon

1-2 methyl shift

The movement of a methyl group with its bonding electrons from one carbon to an adjacent carbon

hydrides before alkyl

Which shifts first: hydrides or alkyl

H2SO4 on top, H2O on bottom.

what goes on the line

Concerted reaction

All bonds break and form in the same step (no intermediate)

1. BH3/THF

2. HO-, H2O2, H2O

label 1 and 2

1. More space (sterics)

2. More stable transition state

Two reasons for selectivity

Vicinal carbons

Two groups of adjacent carbons