Page 145 - Pharm.Org.Chem I 05-PC101 (1)

Exercise

Reaction Product/products Type of Type of solvent
Mechanism

n-propylchloride +
NaSH

Isobutyl iodide
+KOCH3

Tert.butyl bromide
+ H2O

Neopentyl
chloride + H2O

Allyl bromide +
H2O

Allyl bromide +
NaCN

Elimination reactions

Elimination reactions are competing with nucleophilic

substitution reactions when the nucleophile also
acts as a base.

α
β
Elimination or substitution? In general terms:
• strong bases favour elimination;
• large bases favour elimination;
• steric crowding in the alkyl halide favours elimination;
• high temperatures and aprotic polar solvents favour elimination.

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