Chemical Reaction Sequence: trans-3-Methylcyclopentanol to 3-methylcyclopentene

What is the final product of the reaction sequence involving trans-3-Methylcyclopentanol treated with CH₃SO₂Cl and then heated with KI in methanol? The final product of the reaction sequence involving trans-3-Methylcyclopentanol treated with CH₃SO₂Cl and then heated with KI in methanol is 3-methylcyclopentene, due to the stability preference in elimination reactions.

Reaction Mechanism:

Step 1: trans-3-Methylcyclopentanol is treated with CH₃SO₂Cl in the presence of a base. During this step, the hydroxyl group of the alcohol is replaced by a methanesulfonyl group, forming a mesylate ester.

Step 2: The mesylate ester is then heated with KI in methanol. In this step, a nucleophilic substitution reaction occurs, resulting in the replacement of the mesylate group by an iodide. This yields 3-methylcyclopentyl iodide as an intermediate product.

Step 3: When 3-methylcyclopentyl iodide is further heated in methanol, it undergoes an elimination reaction. In this reaction, the iodide group leaves, and a double bond forms within the cyclopentane ring, resulting in the formation of an alkene.

Final Product: The nature of elimination reactions favors the formation of more stable, highly substituted alkenes. As a result, the final product of the reaction sequence is 3-methylcyclopentene, which exhibits greater stability due to its alkene structure compared to other possible products like 1-methylcyclopentene.

Therefore, the multi-step reaction starting from trans-3-Methylcyclopentanol and involving treatment with CH₃SO₂Cl and subsequent heating with KI in methanol ultimately leads to the formation of 3-methylcyclopentene as the final product.

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