Which of the following structures has the
configuration? I II III
The Correct Answer and Explanation is:
To determine which structure has the R configuration, we will follow the Cahn-Ingold-Prelog priority rules. These rules involve the assignment of priorities to the substituents attached to the chiral center based on atomic number and other criteria. After determining the priorities, we will arrange the substituents in the correct order and determine if the configuration is R or S.
Let’s analyze each structure one by one:
- Structure I:
- The chiral center is attached to a bromine (Br), a methyl group (CH3), an ethyl group (CH2CH3), and a hydrogen (H).
- The priorities are assigned based on atomic numbers. Bromine (Br) has the highest priority, followed by the ethyl group (CH2CH3), the methyl group (CH3), and hydrogen (H).
- After arranging the substituents in a clockwise manner with the lowest priority (H) directed away from the viewer, if the order is clockwise, the configuration is R; otherwise, it is S.
- Structure II:
- This chiral center is attached to a chlorine (Cl), a methyl group (CH3), a propyl group (CH2CH3), and a hydrogen (H).
- The priorities are assigned as follows: chlorine (Cl) has the highest priority, followed by the propyl group (CH2CH3), the methyl group (CH3), and hydrogen (H).
- The same method of assigning priorities and evaluating the configuration is used here.
- Structure III:
- This chiral center is attached to a hydroxyl group (OH), a methyl group (CH3), a propyl group (CH2CH3), and a hydrogen (H).
- The priorities are assigned as follows: the hydroxyl group (OH) has the highest priority, followed by the propyl group (CH2CH3), the methyl group (CH3), and hydrogen (H).
By analyzing the structures and applying the Cahn-Ingold-Prelog priority rules, the configuration of each molecule is determined.
