For each pair of conformations shown, choose which is most stable. [If both conformations have the same number of gauche interactions, choose the one where the interactions are between smaller groups.]
(e)

검증된 단계별 안내

Step 1: Understand the concept of conformational stability. Stability in conformations is influenced by steric hindrance and gauche interactions. Gauche interactions occur when two substituents are separated by a dihedral angle of approximately 60°, leading to increased steric strain.

Step 2: Analyze the conformations provided in the problem. Identify the substituents attached to the molecule and their relative positions in each conformation. Look for any gauche interactions between substituents.

Step 3: Count the number of gauche interactions in each conformation. If one conformation has fewer gauche interactions, it is more stable. Use the formula for dihedral angles to identify gauche interactions:

60°

Step 4: If both conformations have the same number of gauche interactions, compare the size of the groups involved in the interactions. Smaller groups cause less steric strain, making the conformation with smaller interacting groups more stable.

Step 5: Choose the most stable conformation based on the analysis above. Ensure that you consider both the number of gauche interactions and the size of the groups involved in those interactions.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Conformational Analysis

Conformational analysis involves studying the different spatial arrangements of a molecule that can be interconverted by rotation around single bonds. These conformations can significantly influence the stability and reactivity of the molecule. Understanding the energy associated with each conformation helps predict which arrangement is more stable under given conditions.

Gauche Interactions

Gauche interactions occur when two substituents on adjacent carbon atoms are positioned 60 degrees apart in a staggered conformation. These interactions can introduce steric strain, making certain conformations less stable. In evaluating stability, conformations with fewer or less significant gauche interactions are generally preferred, especially when comparing larger groups.

Steric Hindrance

Steric hindrance refers to the repulsion between atoms that occurs when they are brought close together, often due to their size. In conformational analysis, larger substituents can create more steric hindrance, leading to increased energy and decreased stability of a conformation. Thus, when comparing conformations, those with smaller groups experiencing less steric hindrance are typically more stable.

For each pair of conformations shown, choose which is most stable. [If both conformations have the same number of gauche interactions, choose the one where the interactions are between smaller groups.] (e)