Presentation on theme: "Oxidation of alcohols. Acidified potassium permanganate (H + /KMnO 4 ), and acidified potassium dichromate (H + /K 2 Cr 2 O 7 ) are important oxidising."— Presentation transcript:
Oxidation of alcohols
Acidified potassium permanganate (H + /KMnO 4 ), and acidified potassium dichromate (H + /K 2 Cr 2 O 7 ) are important oxidising agents. They will not react unless acid is present. Purple H + /MnO 4 - turns colourless when it has reacted. Orange H + /Cr 2 O 7 2- turns blue/green when it has reacted.
Primary alcohol with acidified dichromate; secondary alcohol with acidified permanganate, tertiary alcohol with acidified dichromate. The reactions are very slow unless heated in a water bath.
The primary alcohol has turned the dichromate blue/green. The secondary alcohol has decolourised the permanganate. The tertiary alcohol has not reacted with the dichromate.
Primary alcohols are oxidised by acidified dichromate or acidified permanganate. They form an aldehyde, and then a carboxylic acid. Secondary alcohols are also oxidised by these oxidising agents. They form ketones. Tertiary alcohols do not react with oxidising agents such as permanganate and dichromate.