6.42 - Oxidation reactions of alcohols Flashcards
In this section, what is an oxidation reaction?
The loss of hydrogen from an alcohol molecule
Does oxidation affect one carbon atom, or multiple carbon atoms?
Only one carbon atom is affected
What hydrogen atoms are removed from an alcohol?
The hydorgen in the OH group, and the hydrogen attached to the carbon attached to the OH group
What does this result in being formed?
A C=O group, known as a carbonyl group
What types of alcohol can be oxidised?
Primary and secondary alcohols
Why can’t tertiary alcohols be oxidised?
Because the carbon attached to the OH group does not have another hydrogen attached to it
What is the product formed when a secondary alcohol is oxidised?
A ketone
What are ketones?
A homologous series with alkyl groups on either side of a C=O group
What is the product formed when a primary alcohol is partialy oxidised?
An aldehyde
What is a simplified formula for aldehydes?
RCHO - This must not be written as RCOH, as this would imply that there is an OH group
What is the main complication with aldehydes?
That they are more easily oxidised than alcohols, which means that the can be oxidised further
What happens when an aldehyde is oxidised (or an alcohol is fully oxidised)?
A carboxylic acid is formed
What is the usual reagent for oxidation reactions of alcohols?
Potassium Dichromate (VI)
How is the oxidising agent represented in equations? Why?
As [O], because it would otherwise make the equation too complicated
What is the colour change when potassium dichromate (VI) is used?
Orange -> Green -> Blue
Cr6+ -> Cr3+ -> Cr2+
