Oxidation of Alcohols

oxidation in organic

whenever a carbon forms a bond with a more electronegative element

e.g oxygen

Primary alcohols are oxidised to…

aldehydes, which can be further oxidised to carboxylic acids.

Secondary alcohols are oxidised to…

ketones

During the oxidation of alcohols, Cr₂O₇^2-​ is reduced to Cr³⁺

Write the half equation for this reaction.

Cr₂O₇^2-+14H⁺+6e^- —→2Cr³⁺+7H₂O

A chemist added acidified potassium dichromate to an alcohol. The solution remained orange. Which possible class of alcohol does the chemist have?

Tertiary

A chemist has a bottle of unknown liquid. She knows it either contains a primary or a tertiary alcohol. How could she find out which one it was?

The chemist should add acidified potassium dichromate to the unknown liquid and heat the reaction mixture.

If the solution remains orange, this means an oxidation reaction has not taken place, so the bottle contains a tertiary alcohol. If the solution turns green, this means an oxidation reaction has taken place, so the bottle contains a primary alcohol.

How do we represent the oxidising agent in equations for oxidation reactions?

[O]

boiling point of ketones with the same number of carbons compared to alcohols have?

a lower boiling point.

what happens during reflux? (2)

Vapour condenses back into the reaction mixture

The reaction mixture is heated

what happens during distillation?(2)

The reaction mixture is heated

The product is separated from the reaction mixture

To separate aldehydes from the reaction mixture, we should use…

distillation

What forces do aldehydes experience…

Van der Waals forces

induced dipole-dipole forces

What method should we use to prevent the aldehyde leaving the reaction system?

reflux

To produce aldehydes, we use…

distillation

To produce carboxylic acids and ketones, we use…

reflux

how to extract the ketone from the reaction mixture?

distillation

Butane-1,3-diol is oxidised using acidified potassium dichromate. Identify the structure of an organic product that could form when acidified potassium dichromate is not in excess.

Draw a diagram of the equipment required to convert propan-2-ol to a ketone.

Draw a diagram of the equipment required to produce ethanal from ethanol.

If we add acidified potassium dichromate to a tertiary alcohol, the colour of the solution will be…

orange

To test whether an alcohol is primary or secondary, we can use…

Tollens’ reagent

what are two other reagents we can use to identify whether we have an aldehyde or ketone

Benedict’s solution and Fehling’s solution

Result when either Benedict’s solution or Fehling’s solution are added to an aldehyde?

red

Result when either Benedict’s solution or Fehling’s solution are added to a ketone?

no observable change