The meaning of alpha carbon is as follows:
Definition: Alpha carbon is the closest carbon position on the main chain of an organic compound that is directly connected to the parent functional group. In other words, it is a carbon atom directly connected to the functional group. Functional groups are atoms or atomic groups that determine the chemical properties of organic compounds, such as hydroxyl and carboxyl groups.
2. Example: Taking propionic acid as an example, the carbon in the methylene group is the alpha carbon because it is directly connected to the carboxyl functional group.
3. Extension: The second carbon position connected to the parent functional group is called the beta carbon position. This naming convention helps to more accurately describe and locate carbon atoms in molecules and their connection relationships with other atoms in organic chemistry.