Choose the more stable alkene in each of the following pairs. Explain your reasoning.
1-Methylcyclohexene or 3-methylcyclohexene

Answer

To determine which alkene is more stable between 1-methylcyclohexene and 3-methylcyclohexene, we will analyze the number of alpha-hydrogens present in each structure, as the stability of alkenes is influenced by hyperconjugation, which is dependent on the number of alpha-hydrogens.

### Step-by-Step Solution:

1. **Draw the Structures**:
- **1-Methylcyclohexene**: Start with a cyclohexene ring. The double bond is between two carbons in the ring. Place a methyl group (−CH₃) at the first carbon (C1) of the ring.
- **3-Methylcyclohexene**: Again, start with a cyclohexene ring with a double bond. This time, place the methyl group at the third carbon (C3) of the ring.

2. **Identify Alpha Carbons**:
- The alpha carbons are the carbons adjacent to the double bond. For both structures, we will identify these carbons.
- In **1-methylcyclohexene**, the carbons adjacent to the double bond are C2 and C6.
- In **3-methylcyclohexene**, the adjacent carbons to the double bond are C2 and C4.

3. **Count Alpha Hydrogens**:
- **1-Methylcyclohexene**:
- C2 (alpha carbon) has 2 hydrogens.
- C6 (alpha carbon) has 2 hydrogens.
- Total alpha hydrogens = 2 (C2) + 2 (C6) = 4 alpha hydrogens.
- **3-Methylcyclohexene**:
- C2 (alpha carbon) has 2 hydrogens.
- C4 (alpha carbon) has 3 hydrogens (as it has a methyl group at C3).
- Total alpha hydrogens = 2 (C2) + 3 (C4) = 5 alpha hydrogens.

4. **Compare Stability**:
- The stability of alkenes increases with the number of alpha hydrogens due to hyperconjugation.
- **1-Methylcyclohexene** has 4 alpha hydrogens, while **3-Methylcyclohexene** has 5 alpha hydrogens.
- Since 3-Methylcyclohexene has more alpha hydrogens, it will be more stable due to increased hyperconjugation.

5. **Conclusion**:
- Therefore, **3-methylcyclohexene** is the more stable alkene compared to **1-methylcyclohexene**.