Question

Which of the following alcohols forms a ketone when oxidized?
(A) $ 1 - propanol $
(B) $ Methanol $
(C) $ \;2 - Methyl - 2 - propanol $
(D) $ 2 - propanol $

Answer 1

Hint :The primary, secondary and tertiary alcohol when oxidized gives different products. Primary alcohols can be oxidized to form aldehydes and carboxylic acids. Secondary alcohols can be oxidized to give ketones. Tertiary alcohol cannot be oxidized without breaking the $ C - C $ bond.

Complete Step By Step Answer:
Primary alcohol- They are oxidised to either aldehydes or carboxylic acids depending upon the reaction condition. For the carboxylic acid formation, alcohol is first oxidised into an aldehyde which is then further oxidised into carboxylic acid.
Secondary alcohol- They are oxidised to ketones. For example the reaction of $ propan - 2 - ol $ with sodium yields $ propanone $ .
Tertiary alcohol- Tertiary alcohol does not undergo oxidation reaction therefore no product is yielded.
Now going through the options one by one we can see that the first option is $ 1 -$ propanol which is a primary alcohol. Therefore when it is oxidised it will give aldehyde as a product. The following oxidation reaction is mention of $ 1 - propanol $ :
 $ C{H_3} - C{H_2} - C{H_2}OH \to C{H_3}C{H_2}CHO $
Similarly let’s take a look at option b which is $ Methanol $ . It is also a primary alcohol therefore the product obtained from $ Methanol $ oxidation will be an aldehyde. The reaction is as follow:
 $ C{H_3}OH \to HCHO $
The next option c is $ 2 - Methyl - 2 - propanol $ . As we have already mentioned, tertiary alcohol doesn’t undergo oxidation unless in a drastic condition. Therefore $ 2 - Methyl - 2 -$ propanol which is a tertiary alcohol will not give the oxidation reaction under normal circumstances.
Now looking at our last option which is $ 2 - propanol $ is a type of secondary alcohol. Secondary alcohol on oxidation gives ketone. The following product is yielded when under $ 2 - propanol $ goes oxidation:
 $ C{H_3}CHOHC{H_3} \to C{H_3}COC{H_3} $ .

Note :
It’s only under the drastic condition that a tertiary alcohol will give oxidation reaction. Remember the oxidation product of the primary and secondary alcohol that is carboxylic acid and ketone respectively.