Orgo Exam 3 Memorizations

SN1 Reaction (1 pi bond to 2 sigma bond)

unimolecular substitution, 2 steps, retention AND inversion, 1 intermediate

SN2 Reaction (1 pi bond to 2 sigma bond)

bimolecular substitution, 1 step, inversion, no intermediate

E1 Reaction (2 sigma bonds to 1 pi bond)

unimolecular elimination, 2 steps, E OR Z, 1 intermediate

E2 Reaction (2 sigma bonds to 1 pi bond)

bimolecular elimination, 1 step, beta-hydrogen and leaving group are anti

Good E Donor Nucleophiles

Anions, uncharged N,P,S, and big bulky bases

Poor E Donor Nucleophiles

H2O, alcohols, uncharged carboxylic acids

Electrophile Hinderance (Primary to Tertiary)

Less hindered = substitution, More hindered = elimination

SN2/E2 Rate 

Single step = RDS

SN1/E1 Rate

2nd step is RDS

5 Rate and Reactivity Influences

Nucleophilicity, Leaving Group Ability, Crowding at Electrophile, Solvent Effects, and Hinderance of Nucleophile

Rate: Nucleophilicity

OH- is a better donor than OH2

Rate: Leaving Group Ability

Sulfonate esters = fastest LG’s:

Triflate > tosylate = mesylate

Halogens are slower:

I- > Br- > Cl -

Rate: Crowding

More crowded at electrophile = slower

Less crowded at electrophile = faster

Rate: Solvent Effects

Aprotic solvents = faster

Hydrogen bonds = slower (solvent cage)

Rate: Nucleophile Hinderance

Less hindered = faster

Hydroboration Oxidation

Reagents: 1. BH3 or BH2 2. H2OH and NaOH

Products: Addition of H/OH

Anti-Markovnikov, Syn

Hydroboration Oxidation Steps

1. Boron reagent is added to less hindered carbon

2. H2O is eventually added

3. Syn addition

Halogenation

Reagents: Halogen source + extra nucleophile

Products: Addition of halogen/nucleophile

Markovnikov, Anti

Halogenation Steps

1. 2 arrows connect to halogen simultaneously to avoid carbocation intermediate

2. Triangle ring forms

3. Nucleophile comes in and connects to other carbon

4. Anti addition

EpOxidation

Reagents: Some sort of peroxyacid + alkene

Products: Syn addition of an “O”, creates pair of diastereomers

Epoxidation Steps

1. 5 total arrows

2. Epoxidation occurs at most substituted alkene

3. Syn addition of oxygen to form triangle ring

Dihydroxylation Oxidation

Reagents: KMnO4 or OSO4 (ionic compounds)

Products: Syn addition of 2 OH’s

Workup step, don’t need to know

Dihydroxylation Steps

1. 3 total arrows

2. Syn addition of OH/OH

Ozonolysis Oxidation

Reagents: O3, and Zn if reductive and H2O2 if oxidative

Products: Double bond is cleaved in half and H is added if reductive and OH is added if oxidative 

Hydrogenation Reduction

Reagents: H2 with aid of metal catalyst (Pd/C)

Products: Alkene turns to alkane with addition of H/H

Syn addition of H/H

Alkyne will react until completely saturated

Hydrogenation Reduction with a Poisoned Catalyst

Reagents: Alkyne and H2 with some sort of metal (Pd) + solid support (CaCO3) + Poison (PbO or quiroline)

Products: Forms an alkene and tops after 1 addition of H/H

Syn, Z alkene only

Hydrogenation Reduction with a Dissolving Metal

Reagents: Li or Na metal + NH3 (l) as catalyst

Products: Alkyne converts to a E alkene

Anti only

Peroxyformic Acid

Peroxyacetic Acid

MCPBA