This is a type of reaction where an atom (such as Br) or a group of atoms (such as -OH) is replaced (substituted) by another atom or by another group of atoms.
It is important to note that substitution reactions occur for saturated compounds
Alkanes
Haloalkanes
Alcohols
ALKANES
Substitutions Reactions for Alkanes
Reaction condition:heat (Δ) or light (hf)
Notice that the H in the alkane is swopped with one Br from the Br2
Diagram 1
Notice the use of heat Δ .
The ALKANE (ethane) becomes the HALOALKANE (bromoethane).
The bromine Br2 changed into hydrogen bromide HBr.
HALOALKANES
Substitutions Reactions for Haloalkanes
Reaction condition for haloalkanes: NaOH (or (KOH) dissolved in ethanol and heat
Notice that the Br and the OH are swopped over.
Diagram 2
KOH (or NaOH) is dissolved in ethanol, then added to haloalkane
The entire mixture is warmed.
The KOH becomes KBr.
The haloalkane (bromoethane) becomes the alcohol (ethanol).
This is also possible
Diagram 3
ALCOHOLS
Substitutions Reactions for Primary and Secondary Alcohols
Reaction condition for primary and secondary alcohols: high temperature
Notice that the OH and the Br are swopped over.
Diagram 4
High temperature Δ was used
The HBr became water
The alcohol (ethanol) changed into the haloalkane (bromoethane)
Substitutions Reactions for Tertiary Alcohols
Reaction condition for tertiary alcohols: room temperature
Notice that the OH and the Br are swopped over.
Diagram 5
Room temperature is used
The HBr is changed into water.
The tertiary alcohol (2-methylbutan-2-ol ) is changed into the haloalkane (2-bromo-2-methylbutane)