ORGANIC CHEMISTRY Chapter 4 4.11 The Origin of Ring Strain in Cyclopropane and cyclobutane Angle Strain and Torsional Strain Department of Chemistry, Xiamen UniversityORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 4 4.11 The Origin of Ring Strain in Cyclopropane and Cyclobutane: Angle Strain and Torsional Strain