Oxidation of 2-butanol by PCC, KMnO4, K2Cr2O7, K2CrO4
2-butanol is a secondary alcohol compound and can be oxidized to 2-butanone by mild oxidizing agents such as PCC and strong oxidizing agents such as KMnO4, K2Cr2O7, K2CrO4. Because 2-butanol is a secondary alcohol, it can be oxidized to 2-butanone (a ketone compound).
In this tutorial, we will discuss followings.
- Oxidation of 2-butanol by PCC
- Oxidation of 2-butanol by strong oxidizing agents
- Combustion of 2-butanol with oxygen gas
Oxidation of 2-butanol by PCC
PCC is a mild oxidizing agent and secondary alcohols such as 2-butanol are oxidized to ketones. Reaction of 2-butanol and PCC gives 2-butanol as the product.
Oxidation of 2-butanol by strong oxidizing agents
As strong oxidizing agents, KMnO4, K2Cr2O7, K2CrO4 are used in organic chemistry. All of these solutions of strong oxidizing agents should be acidic.
2-butanol and acidic KMnO4 reaction
- 2-butanol is oxidized to 2-butanone.
- KMnO4 is reduced to Mn2+. Oxidation number of Manganese atom of KMnO4 is changed from +7 to +2 (in Mn2+) state.
- Due to the reduction process of KMnO4, purple colour of KMnO4 is changed to pale pink or colourless.
2-butanol and acidic K2Cr2O7 reaction
- 2-butanol is oxidized to 2-butanone.
- K2Cr2O7 is reduced to Cr3+. Oxidation number of Chromium atom in K2Cr2O7 is at +6 to and it is reduced to +3 state (in Cr3+).
- Due to the reduction process of K2Cr2O7, orange colour of K2Cr2O7 is changed to green.
2-butanol and acidic K2CrO4 reaction
- As with other strong oxidizing agents, 2-butanol is oxidized to 2-butanone.
- K2CrO4 is reduced to Cr3+. Oxidation number of Chromium atom in K2Cr2O7 is at +6 to and it is reduced to +3 state (in Cr3+).
- Due to the reduction process of K2CrO4, orange colour of K2CrO4 is changed to green.
Combustion of 2-butanol with oxygen gas
When 2-butanol is combusted with oxygen gas, carbon dioxide gas and water are given as products. Oxidation number of carbon atom in carbon dioxide molecule is +4. Therefore, all carbon atoms in 2-butanol molecule are oxidized to higher oxidation state.
Questions
What are the physical and chemical observations when 2-butanol is oxidized from acedic medium KMnO4 and acedic medium K2Cr2O7?
Both KMnO4 and K2Cr2O7 are strong oxidizing agenets and 2-butanol is converted to 2-butanone as the result in an acedic medium. When KMnO4 is reduced as the reduction half reaction, purple colour of solution is changed to colourless or pale pink colour. But, orange colour of K2Cr2O7 is converted to green colour when 2-butanol is oxidized.
As strong oxidizing agents, KMnO4, K2Cr2O7 and K2CrO4, will 2-butanol be oxidized to same product?
Yes, 2-butanol will be oxidized to 2-butone.