Ring strain in cyclopropanes

The Origin of Ring Strain in Cyclopropane and Cyclobutane Angle Strain and torsional Strain... 

As an illustration, the ring strain in cyclopropane, cyclobutane and cyclohexane and cyclodecane has been calculated ... 

Problem 9.6 Account for the ring strain in cyclopropane in terms of geometry and orbital overlap. ... 

Because of the ring strain in cyclopropane (Problem 9.6), there is less orbital overlap (Fig. 9-1) and the sigma electrons are accessible to attack by electrophiles. 

C-C bond Fluonnation increases the bond strengths in cycloalkanes, including cyclobutanes [75, 94], but by contrast, it decreases C-C bond strengths and increases ring strain in cyclopropanes and other three-membered nng compounds [75 94, 95]... 

While angle strain accounts for most of the ring strain in cyclopropane, it does not account for it all. Because the ring is (of necessity) planar, the C — H bonds of the ring are all eclipsed (Figs. 4.9, c), and the molecule has torsional strain from repulsive dispersion forces as well. 

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