What is an $\alpha$-carbon, and how can I identify one?

The other questions because of which my questions has been termed as duplicated is asking about alpha carbons in alkyl halide , while my question addresses simply ,"what an alpha carbon is and not in any particular kind of carbon compound", I didn't even knew if alpha carbon is supposed to be connected to functional groups or halogens or double/triple bond, While the other post asks for alpha carbon in "alkyl halide".


1 Answer 1


It is a descriptor of the position of one group relative to another. The most common situation would be for a carbonyl group, where the α-carbon is the one immediately adjacent to the carbonyl itself: ketone position labels

It is for this reason that naturally occurring amino acids are often called α-amino acids - the amine is attached to the α-carbon.

  • $\begingroup$ so what you are trying to say is that $\alpha carbon$ is a carbon that's attached to the carbon that's attached to a functional group? $\endgroup$
    – Intensed
    Commented Jan 17 at 17:37
  • $\begingroup$ Not quite - I'd say the α-carbon is the one that's attached to the functional group. For example, the "ketone" functional group in the molecule above includes both the oxygen and the carbon. So the α-carbon is the first carbon attached to the ketone $\endgroup$
    – PCK
    Commented Jan 18 at 16:26

Not the answer you're looking for? Browse other questions tagged or ask your own question.