Which of the following compounds is (S) - 4 - chloro - 1- methylcyclohexene ?

Options

A.
B.
C.
D.

Answer

To determine which compound is (S)-4-chloro-1-methylcyclohexene, we need to follow these steps:

### Step 1: Identify the Structure
We start by identifying the structure of (S)-4-chloro-1-methylcyclohexene. This compound has a cyclohexene ring with a methyl group at the 1-position and a chloro group at the 4-position.

### Step 2: Number the Carbon Atoms
Number the carbon atoms in the cyclohexene ring. The numbering should start from the carbon atom that is part of the double bond. The carbon with the methyl group (1-position) will be numbered as 1, followed by 2, 3, 4, 5, and 6.

### Step 3: Assign the Substituents
- At carbon 1, we have a methyl group (CH3).
- At carbon 4, we have a chloro group (Cl).
- The remaining positions will have hydrogen atoms.

### Step 4: Determine Chirality
Identify the chiral carbon in the compound. The chiral center is at carbon 4, where the chloro and methyl groups are attached.

### Step 5: Assign Priorities
Assign priorities to the substituents attached to the chiral carbon based on the Cahn-Ingold-Prelog priority rules:
1. Chlorine (Cl) has the highest atomic number, so it gets priority 1.
2. The carbon chain with the double bond (attached to carbon 3) gets priority 2.
3. The methyl group (CH3) gets priority 3.
4. The hydrogen (H) gets priority 4.

### Step 6: Determine the Configuration
To determine whether the configuration is R or S, observe the arrangement of the groups:
- If the lowest priority group (H) is positioned above the plane, trace the path from priority 1 to 2 to 3. If it is clockwise, the configuration is R; if it is counterclockwise, it is S.
- In this case, if the hydrogen is above the plane and the other groups are arranged such that the path from 1 to 2 to 3 is counterclockwise, the configuration is S.

### Step 7: Verify the Structure
Check the given options to see which one matches the structure of (S)-4-chloro-1-methylcyclohexene.

### Conclusion
After analyzing the options, the correct compound that corresponds to (S)-4-chloro-1-methylcyclohexene is identified.

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