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Total Strain of Cyclopropane versus Cyclobutane

Posted: Thu Mar 16, 2017 4:33 pm
by Atishay_Mathur_3L
In lecture we discussed that the total strain for cyclopropane is approximately 28 kcal/mole, and that of cyclobutane is approximately 26 kcal/mole, which are very similar numbers. I understand that the butterfly conformation only relieves some of the torsional strain, not all, but I was wondering why there wasn't a larger difference in between the strain energies for these two structures given that the bond angles are pretty different from 60 degrees to about 88 degrees?

Re: Total Strain of Cyclopropane versus Cyclobutane

Posted: Fri Mar 17, 2017 12:34 am
by Karan Ishii 3E
Because even the bonds between the carbon atoms are still bent (banana bonds). The arrangement is slightly staggered but there's still high energy.