Select the Z - isomer from the following alkenes

Options

A.
B.
C.
D.

Answer

To determine the Z-isomer from the given alkenes, we need to follow a systematic approach to assign priorities to the substituents attached to the double bond. Here’s a step-by-step solution:

### Step 1: Identify the double bond
First, we need to identify the alkenes provided in the question. Alkenes have a carbon-carbon double bond (C=C), which is crucial for determining geometric isomerism.

### Step 2: Assign priorities to substituents
For each alkene, we will assign priorities to the groups attached to the carbon atoms of the double bond. The Cahn-Ingold-Prelog priority rules are used for this purpose:
- The atom with the higher atomic number gets higher priority.
- If the first atoms are the same, we look at the next atoms in the substituent until a difference is found.

### Step 3: Determine the configuration
Once we have assigned priorities, we can determine whether the configuration is Z or E:
- **Z (from the German "zusammen")**: If the highest priority groups on each carbon are on the same side of the double bond.
- **E (from the German "entgegen")**: If the highest priority groups are on opposite sides of the double bond.

### Step 4: Analyze each alkene
1. **Alkene 1**: Check if both substituents on one carbon are the same. If they are, we cannot determine Z or E.
2. **Alkene 2**: Assign priorities to the substituents. If the highest priority groups are on the same side, it is Z.
3. **Alkene 3**: Repeat the process. If the highest priority groups are on opposite sides, it is E.
4. **Alkene 4**: Assign priorities and check the configuration.

### Step 5: Select the Z-isomer
After analyzing all the alkenes, we find the one where the highest priority groups are on the same side. This will be our Z-isomer.

### Conclusion
Based on the analysis, the Z-isomer is found in **Option 3**.

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