If we have a ketone with FOUR carbon atoms, where can the carbonyl group be placed?

1 Answer
Oct 25, 2016

Clearly, the carbonyl group is at C2 in butanone.

Explanation:

For a four carbon chain to be a ketone, the only position for the carbonyl is an C2, i.e. to give H3CC(=O)CH2CH3. Substitution at C1 gives the aldehyde, H(O=)CCH2CH2CH3.

Of course, for cyclohexanone, or cyclobutanone, the oxo group could be at C1, but these are special circumstances.