10 - Oxidation Of Alcohols And Aldehydes

Question 0

What are primary alcohols oxidised to?

Answer 0

Primary alcohols are oxidised to aldehydes. They can then further be oxidised.

Question 1

What’s a suitable oxidising agent for oxidising primary and secondary alcohols?

Answer 1

A solution containing acidified dichromate ions is a suitable oxidising agent. This is H+/Cr2O7-. This can be prepared by reacting potassium dichromate K2Cr2O7 and sulphuric acid together (H2SO4). K2Cr2O7 + H2SO4 -> H+/Cr2O72-.

Question 2

What are secondary alcohols oxidised to?

Answer 2

Secondary alcohols can be oxidised to ketones. They do not oxidise further.

Question 3

What needs to happen when you oxidised a primary alcohol?

Answer 3

The aldehyde needs to be distilled off to prevent further oxidation to a carboxylic acid.

Question 4

What conditions do you need to oxidised an aldehyde to a carboxylic acid?

Answer 4

To oxidised an aldehyde (from a primary alcohol) to a carboxylic acid you need to reflux it, and then distill of the carboxylic acid.

Question 5

What colour change occurs in the oxidation reactions? Why?

Answer 5

In oxidation reactions the colour changes from orange to green as the potassium dichromate changes from orange to green.