Organic Chemistry 1- mechanisms and factoids

Alkene with hydrogen halide

What dictates the stability of a carbocation?

The amount of substituents attached

1,2-Hydride shift

The prefered carbocation rearrangement

1,2-methyl shift

Whenever a carbocation is formed, check to see if rearrangement occurs

Bromine to Alkene mechanism

Halohydrin formation

Hydration of a terminal alkyne

Hydroboration of an alkene

BH₃ adds to the least substituted carbon

Oxidation step hydroboration alkene

Hydroboration-oxidation product for an alkyne

Hydrogenation of an alkane

Hydrogenation of alkynes (Pd/c)

Hydrogenation of alkyne (lindlar catalyst)

Sn2 reaction

• Back attack

• Inversion

• Needs space

• Strong nucleophile needed

• Polar aprotic solvent

Sn1 reaction

• Carbocation intermediate formed

• Two step reaction

• Weak nucleophile needed

• Polar solvent needed

E2 reaction

• One step

E1 reaction

Sn1/Sn2/E2/E1 decision flowchart

Bromination

Nitration

Chlorination

Iodination

Sulfonation

Friedel-Crafts Acylation

Friedel-Crafts Alkylation

Alkylation of benzene by acylation reduction

Sandmeyer reactions

Synthesis of a diazonium salt

What is a electron withdrawing group and how does it effect benzene reactivity?

EWGs can withdraw electron density from the benzene ring via inductive or resonance effects. They deactivate benzene and are meta directors.
Examples: -NO2
- COO
-CN
-SO2R

What is a Electron Donating Group and how does it effect benzene reactivity?

EDGs donate electron density to the benzene ring via inductive or resonance effects. They activate benzene and are ortho/para directors.
Examples:
-OH
-NH2
-CH3

Which group is deactivating but ortho/para directors?

Halogens

What is the general rule to identify activating vs deactivating groups?

• Lone pairs = Activating EDGs

• Pi bond to electronegative atom = Deactivating EWGs