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

1 Answer
Mar 1, 2017

Answer:

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"#.