SCH 4U Reactions of Functional Groups

Reactions of Functional Groups
Reactions of Alkanes
1. Combustion
2. Addition
Reactions of Alkenes
1. Addition – a reaction in which atoms are added to a carbon-carbon double bond.
Markovnikov’s rule – when a hydrogen halide or water molecule reacts with alkene the H-atom
will bond to carbon atom in the multiple bond that has the most hydrogen atoms already
bonded to it.
2. Hydrogenation
Reactions of ALCOHOLS
1. Substitution: Halogen acids like HCl, HBr or HI replace the OH group in the alcohol. The reverse
reaction can occur also, turning the alkyl halide back into an alcohol.
2. Elimination: When alcohols are heated in presence of H2SO4, a strong acid and dehydrating agent, the
OH group and one H leave the molecule, producing water and creating a double bond. This reaction is
also known as dehydration (loss of water).
3. Oxidation: Refers to a reaction in which there are more bonds to oxygen or less bonds to hydrogen. It
can also be referred to as dehydrogenation because it removes hydrogen from the molecule. An
oxidizing agent must be present such as KMnO4, K2Cr2O7 and O3. The symbol for an oxidizing agent is
Primary alcohol: Is oxidized to form an aldehyde; if oxidized further, becomes a carboxylic acid
Secondary alcohol: oxidized to form a ketone; cannot oxidize further
- Tertiary alcohol: cannot be oxidized. C-C bonds are too strong to be broken by an oxidizing reagent.
4. Creation of an ether: alcohol + alcohol  ether and water
Reactions of ALDEHYDES and KETONES
1. Oxidation: In the presence of an oxidizing agent, [O], Aldehydes oxidizes to form a carboxylic acid but
ketones do not undergo oxidation
2. Reduction: In the presence of a reducing agent such as LiAlH4 or hydrogen gas over a platinum catalyst
(H2/Pt), Aldehydes reduce to produce primary alcohols and Ketones reduce to produce secondary
alcohols. Reduction is also known as hydrogenation because it adds hydrogen to the molecules being
1. Condensation: Two smaller molecules come together to form a larger molecule, releasing water in the
process. Carboxylic acids react with alcohols to form esters.
2. Reduction: In the presence of a reducing agent, carboxylic acids can be reduced to form aldehydes
and then further reduced to form alcohols.
Reactions of ESTERS and AMIDES
Hydrolysis: One larger molecule is split into two smaller molecules by the addition of water. Hydrolysis usually
requires heat.
Hydrolysis of an ester produces a carboxylic acid and an alcohol