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
- 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 heatNotice that the Br and the OH are swopped over.
- 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).
ALCOHOLS
Substitutions Reactions for Primary and Secondary Alcohols
Reaction condition for primary and secondary alcohols: high temperatureNotice that the OH and the Br are swopped over.
- 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 temperatureNotice that the OH and the Br are swopped over.
- 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)