10C 2. Oxidation Reactions of Alcohol (p. 272-273) Flashcards
What is the best way to consider oxidation of alcohols?
To consider it as the loss of hydrogen from an alcohol molecule
How many carbon atoms of an alcohol does oxidation affect?
Only one carbon atom
Which hydrogen atoms are removed from an alcohol molecule during oxidation?
a) The hydrogen of the OH group
b) a hydrogen atom from the carbon atom joined to the OH group
What does the organic product of an oxidation of an alcohol contain and how is it called?
- It contains a C=O group
- It is called a carbonyl group
Which alcohols can be oxidised in this way and which not?
- Primary and secondary alcohols can be oxidised in this way
- Tertiary alcohols cannot be oxidised in this way
Why can primary and secondary alcohols be oxidised in this way, but not tertiary alcohols?
- Only primary and secondary structures have a hydrogen atom on the C of the C-OH group - the tertiary structure has not
- Have a look at the diagram on page 272
What is the organic product of the oxidation of a secondary alcohol called?
It is called a ketone
What is a simplified formula for a ketone?
It is RCOR
What is the organic product of the oxidation of a primary alcohol called?
It is an aldehyde
What is a simplified formula for an aldehyde?
It is RCHO (not RCOH, which would imply that the molecule contains an OH group)
What is a special feature regarding the oxidation of aldehydes compared to the oxidation of alcohols?
They are more easily oxidised
What happens when an aldehyde is oxidised?
- It involves a gain of an oxygen atom, not the loss of a hydrogen atom
What is the organic product of the oxidation of an aldehyde called?
It is called a carboxylic acid
What is a simplified formula for a carboxylic acid?
It is RCOOH
Which are the usual reagents for the oxidations of alcohols?
- a mixture of potassium dichromate (VI)
- dilute sulphuric acid
How do we represent the oxidising agent for oxidation of alcohols?
We use [O], which represents an oxygen atom provided by the oxidising agent
Which technique do we use if we want to obtain a ketone or a carboxylic acid (complete oxidation)?
We use heating under reflux
Which technique do we use if we want to obtain an aldehyde (incomplete oxidation)?
We use distillation with addition
What is heating under reflux?
It is the heating of a reaction mixture with a condenser fitted vertically
What is distillation with addition?
It is heating a reaction mixture, but adding another liquid and distilling off the product as it forms
