Stereoisomerism

Question

Is the statement, "Methylcyclopropane and Methylcyclobutane, do not show stereoisomerism", correct? But cyclobutane can show conformational isomerism right ( for example, its puckered form) and conformational isomerism is a form of stereoisomerism right?

Answer 1

Yes. Stereoisomer is a generic term representing any kind of isomer that isn't just a molecular rotation about a bond. Only single bonds can rotate.

Stereo = 3 dimensional

Isomer = same parts

Something that has the same parts but is arranged differently in space (excluding rotations about bonds) is a stereoisomer...A conformational isomer is a kind of stereoisomer even though it is formed by just rotation about bonds. The statement that MCP and MCB do not show stereoisomers is correct. There is no way to make another unique molecule by substitution. The puckered form of MCB can flip into the other form, but they are not unique molecules.