oxidation of a primary alcohol

Question 1

What do we make when we oxidize a primary alcohol?

Answer 1

We make an aldehyde + water

Question 2

What catalyst do we use in the oxidation of a primary alcohol?

Answer 2

Acidified potassium dichromate K2Cr2O7/H+

Question 3

During the reaction, what does the oxidizing agent do?

Answer 3

Oxidizing agent is reduced from the dichromate (VI) ion which is orange to the chromium (III) ion which is green

Question 4

What can aldehydes be further oxidized into?

Answer 4

Carboxylic acid

Question 5

Why do aldehydes have extremely low boiling points?

Answer 5

They cannot form hydrogen bonds so we can easily remove the aldehyde by distillation

Question 6

How do we favour the production of an aldehyde?

Answer 6

Making sure that the starting alcohol is in excess and the oxidizing agent is limiting

Question 7

What is the pathway of oxidizing a primary alcohol?

Answer 7

primary alcohol -> aldehyde (+water) -> carboxylic acid

Question 8

How do we ensure that all of the aldehyde produced is then oxidized into a carboxylic acid?

Answer 8

We need an excess of the oxidizing agent

Question 9

Why do we heat the reaction under reflux?

Answer 9

Any volatile products are condensed and return to the reaction mix. By heating under reflux, we can heat the chemicals until the reaction completes and we can make our carboxylic acid

Question 10

What do we have at the end of reflux?

Answer 10

Our reaction contains a mixture of chemicals, including carboxylic acid and any unreached alcohol, aldehyde and oxidizing agent

Question 11

How do we separate the carboxylic acid from the mixture at the end of a reflux?

Answer 11

As carboxylic acid can form hydrogen bonds, it has a higher melting point so we can use distillation to separate out our carboxylic acid from reaction mixture