Types of Substitution and Elimination Reactions

leaving groups

- departs with a pair of electrons during a reaction

- good LG are conjugate bases of SA

- mostly sulfonate esters and halides

Tosylate

Mesylate

Substitution reaction

A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms.

Elimination reaction

The removal of a molecule from a saturated molecule to make an unsaturated molecule

Types of substitution reactions

Sn1 and Sn2

Types of elimination reactions

E1 and E2

SN2 mechanism

SN1 mechanism

E1 mechanism

E2 mechanism

Unimolecular SN1 reactions produce a ...

Racemized tetrahedral stereocenter due to the sp2 planar intermediate subject to attack from either side

bimolecular SN2 reactions produce a....

an inverted stereo center due to the nucleophilic attack on the C-X σ* antibonding orbital

E2 reactions produce (E/Z) geometric isomers

based on the alignment of the H and LG in an anti-coplanar arrangement

E1 reactions produce mostly E isomers

due to the steric hindrance of the side chains in the cationic intermediate