Question

The two protons on the middle carbon of propane are interchangeable by rotational symmetry and are therefore said to be:

O homotopic
O enantiotopic
O Diastereotopic

Answer 1

The two protons on the middle carbon of propane are interchangeable and identical, therefore they are considered homotopic. These do not render the molecule chiral or lead to the creation of different compounds upon their exchange. O homotopic

Step-by-step explanation:

The two protons on the middle carbon of propane are indeed interchangeable by rotational symmetry. This means that the protons do not create sites of chirality and neither does the molecule change its properties when these protons are switched. Therefore, these protons are said to be homotopic. Homotopic atoms or groups in a molecule are identical in their chemical environment and their exchange does not lead to the formation of different compounds. In contrast, enantiotopic atoms or groups occur in species that are chiral (nonsuperposable on their mirror images) and can be interconverted by reflection in a mirror.

Diastereotopic atoms or groups are found in diastereomers- molecules that are non-superposable and not mirror images of each other, similar to the relationship seen in cis-trans isomers or in compounds like trans-1,2-dimethylcyclopropane.