Combustion and oxidation of alcohols

What are some uses of alcohols

• Fuels

• Solvent

• Disinfectants

• Feedstock

What is the equation for the combustions of an alcohol

Using ethanol as an example:

C₂H₆O + 3O₂ ⟶ 2CO₂ + 3H₂O

What can the OH groups within alcohols be oxidised by (oxidising agent)

It can be oxidised by strong oxidising agents, mainly use acidified potassium dichromate (VI)

What forms when you partially oxidise a primary alcohol

An aldehyde will form (HO)

What forms when you fully oxidise a primary alcohol

A carboxylic acid will form ( COOH)

What forms when you oxidise a secondary alcohol

A ketone will form (double bond O to carbon)

Why can’t a tertiary alcohol be oxidised

Carbon in which the -OH group is attached to has no hydrogen which is required to form a carbonyl group

What are the conditions needed to form carboxylic acid in primary alcohol, and why are they needed

Needs to be heated under reflux and excess oxidising agent. As reflux prevents loss of reactants as once it is vapour it will condense and go back into product. Without it, product will evaporate fully. You use excess oxidising agent, as when aldehyde condenses again it will undergo further oxidisation to form the carboxylic acid.

What are the conditions needed to form aldehyde in a primary alcohol and why

Alcohol oxidised with limited oxidising agent and then distilled immediately. Aldehyde will vaporise and is collected, preventing further oxidisation to a carboxylic acid.

What is the colour change when dilute sulfuric acid is added to potassium dichromate

Cr_2,O₇^2-(orange) → Cr³⁺(green)

Reflux diagram

Distil diagram

Bent bit called still head