Q48P - Chemistry (OpenStax)

Question

Explain why it is not possible to prepare a ketone that contains only two carbon atoms. 

Step-by-Step Solution

Answer

Ketones have an oxidation state of \({\rm{ + 2}}\) and do not oxidize further.

Because the oxidation state of aldehydes differs from that of ketones, only aldehydes are feasible with two carbon atoms.

Step 1: Ketone

The keto group has an oxidation state of \({\rm{ + 2}}\).

And it appears to be as follows: R-C(O)-R denotes alkyl chains including at least one carbon atom, and C(O) denotes a carbonyl group having a double bond between C and O.

Step 2: Explanation

Consider a molecule that has two carbon atoms and a carbonyl group.

Because it needs four bonds around, the carbon atom with the carbonyl group must also include one H atom.

As a result, the H atom reduces the oxidation state of the carbon atom by\({\rm{1}}\).

That's not a ketone but an aldehyde. Aldehydes can be oxidized further but ketones cannot.