교과서 질문
Which conformation in each of the following pairs has the least strain energy?
(b)
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4. Alkanes and Cycloalkanes
Ring Strain
객관식
Which of the following cycloalkanes has the most angle strain?
A
B
C
D
검증된 단계별 안내1
Recall that angle strain in cycloalkanes arises when the bond angles deviate from the ideal tetrahedral angle of 109.5° due to ring size constraints.
Identify the ideal bond angles for each cycloalkane based on their ring size: cyclopropane (3-membered), cyclobutane (4-membered), cyclopentane (5-membered), and cyclohexane (6-membered).
Understand that smaller rings have more angle strain because their internal bond angles are forced to be much smaller than 109.5°. For example, cyclopropane has bond angles of approximately 60°, which is far from ideal.
Compare the bond angles: cyclopropane (~60°), cyclobutane (~90°), cyclopentane (~108°), and cyclohexane (~109.5°). The closer the bond angle is to 109.5°, the less angle strain the molecule has.
Conclude that cyclopropane has the most angle strain because its bond angles deviate the most from the ideal tetrahedral angle, making it the most strained among the given options.
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