C2 – Alcohol

There are three different types of Alcohol molecules –
1. Primary Alcohol; is when the -OH is at the end of the chain.

2. Secondary Alcohol; is when the -OH group is attached to a carbon atom bonded to two alkyl groups.

3. Tertiary Alcohol; is when the -OH group is attached to a carbon atom bonded to three alkyl groups.

pstalcohols

Combustion and Oxidation of alcohols

In a good supply of oxygen, alcohols burn completely to form carbon dioxide and water –
C2H5OH(l) + 3O2 – 2CO2(g) + 3H2O(l)

Oxidation of alcohols

  • Primary alcohol 

1oxidation

 

Figure 1 shows how alcohol forms aldehyde under distillation*.

Figure 2 shows how alcohol froms carboxylic acid under reflux**.

**Reflux is the continual boiling and condensing of a reaction mixture to ensure that the reaction takes place without the contents of the flask boiling dry.

*Distillation apparatus

image001

 

**Reflux apparatus

200px-Reflux_labled.svg

 

  • Secondary alcohol

reaction_fig11

 

Secondary alcohols are oxidised by acidified dichromate ions to produce ketones.

  • Tertiary alcohol 

Tertiary alcohols are resistant to oxidation as the carbon atom is already bonded to three other alkyl groups.

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