1. C2.7 Alcohols & Carboxylic Acids
Reactions of alcohols
C2.7 Alcohols & Carboxylic Acids

2. Making alcohols Recap
The hydration of ethane: CH2=CH2(g) + H2O(g) ⇄ CH3CH2OH(g) Conditions: 300oC, atmospheres, phosphoric acid catalyst. Fermentation (e.g. glucose): C6H12O6  2C2H5OH + 2CO2 Conditions: 35oC, yeast, no oxygen

3. Dehydration reactions
Dehydration reaction: This type of reaction is an elimination reaction in which water is formed as a product. For alcohols the dehydration results in the formation of an alkene.
The acid catalysts normally used are either concentrated sulphuric acid (H2SO4) or concentrated phosphoric acid (H3PO4).
One alternative, non-acidic, catalyst could be aluminium oxide (Al2O3)
Usually some heat is also required. Around 180oC
CH3CH2CH2OH
CH3CH=CH2+ H2O
Al2O3
180°C

4. KNOWLEDGE CHECK
Write an equation for the dehydration of ethanol to give ethene.
Write an equation for the dehydration of cyclohexanol to give cyclohexene
Predict the three possible isomers formed in the dehydration of butan-2-ol (Hint: E/Z isomers)
State the necessary conditions for each reaction.

5. Alcohol Oxidation reactions
Oxidising agents are used to oxidise alcohols
In reactions the oxidising agent is given the symbol [O].
The most common oxidising agent is acidified potassium dichromate (K2Cr2O7 and H2SO4)
The oxidation also requires heat.

6. Alcohol Oxidation reactions
Primary alcohol + [O]  Aldehyde + [O]  Carboxylic acid ORANGE GREEN GREEN Secondary alcohol + [O]  Ketone ORANGE GREEN Tertiary alcohol + [O]  NO REACTION ORANGE ORANGE

7. Aldehydes
In aldehydes, the C=O group will appear at the end of the carbon chain.
RCHO
They have the suffix ‘-al’.
No numbering is needed as it will always be on the first carbon atom.

8. Ketones
In ketones, the C=O group will appear in the middle of the carbon chain.
Ketones have the suffix ‘-one’
RCOR
If there are 5 or more carbon atoms in the chain you will always have to say where the carbonyl group is in the chain.

9. Knowledge Check
Complete the worksheet on the reactions of alcohols.