Question

which is more stable:
methyl cyclopropane
or cyclobutane

and why?

Answer 1

The -C-C-C- bond angles in cyclobutane are 144 degrees. In cyclopropane they are 60 degrees. The usual carbon to carbon bond angles in a tetrahedral structure is about 109 degrees. In which compound are the bond angles more strained? That is the LESS stable compound.