Why does the ketone start from propane, but not methane?

1 Answer
Mar 1, 2017

Because a ketone specifies an internal carbonyl group.

Explanation:

And thus neither "formaldehyde, " "H"_2"C=O", nor "acetaldehyde, " "H"_3"CC"("=O")"H" supports an internal carbonyl. Both functions are terminal, and thus these species are formally "aldehydes". Capisce?

On the other hand, "acetone", "H"_3"CC(=O)CH"_3, does support the internal carbonyl group, and can thus be classified as a "ketone".