Intermediate Topic 794 of 1102 Organic Chemistry
Oxidation of Alcohols
Primary alcohols oxidize to aldehydes and acids, secondary to ketones, tertiary resist.
In-depth explanation of Oxidation of Alcohols
Oxidation of alcohols removes hydrogen from the carbon bearing the OH group and from the OH itself, and the product depends on the class of the alcohol. Primary alcohols are oxidized first to aldehydes, which can be collected by distillation if using pyridinium chlorochromate, or further oxidized to carboxylic acids with excess dichromate. Secondary alcohols give ketones, which resist further oxidation. Tertiary alcohols resist oxidation because they lack a hydrogen on the carbinol carbon. With acidified dichromate the solution changes colour from orange to green as chromium(VI) is reduced to chromium(III).
Going deeper: Oxidation of Alcohols
Key ideas: Primary alcohol goes to aldehyde (with PCC in CH2Cl2, or by distilling it out as formed) and then carboxylic acid (K2Cr2O7 in H2SO4 under reflux, or KMnO4). Secondary goes to ketone; tertiary resists oxidation without C-C cleavage. Dichromate turns orange to green on oxidation, used in breath testers. Dehydrogenation over copper at 573 K gives the same products.
Common mistakes and connections: Students expect to stop at aldehyde with aqueous chromic acid, but water hydrates the aldehyde and it oxidises further. Another error is oxidising tertiary alcohols to ketones. Count alpha hydrogens: primary has two, secondary one, tertiary none. Links to the Lucas test, Tollens test and oxidation numbers of carbon.
Visualization of Oxidation of Alcohols
Ethanol is oxidized first to ethanal and then to ethanoic acid when the carbon bearing OH loses hydrogen and gains oxygen. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Ethanol is oxidized to ethanal, which is further oxidized to ethanoic acid, CH3CH2OH giving CH3CHO giving CH3COOH.
Frequently asked questions about Oxidation of Alcohols
What is Oxidation of Alcohols?
Primary alcohols oxidize to aldehydes and acids, secondary to ketones, tertiary resist.
Is Oxidation of Alcohols a beginner, intermediate or advanced topic?
Oxidation of Alcohols is a intermediate topic in Organic Chemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Oxidation of Alcohols?
Study these earlier topics in Organic Chemistry first: Zaitsev's Rule, Alcohols, Properties of Alcohols.
What comes after Oxidation of Alcohols?
The next topics in Organic Chemistry are Lucas Test and Ethanol Production.
Can I practise Oxidation of Alcohols with quizzes?
Yes. The interactive lesson includes a self-check question on Oxidation of Alcohols, and the Organic Chemistry quiz draws on every topic in this area.
Where Oxidation of Alcohols fits in Organic Chemistry
Oxidation of Alcohols is topic 66 of 148 in Organic Chemistry.