See image — Hydrocarbons Chemistry Question

💡 Solution & Explanation

Concept: Oxymercuration with an alcohol solvent (solvomercuration) followed by reductive demercuration. Step 1 - Reagent Analysis: The first reagent is mercuric trifluoroacetate, (CF3CO2)2Hg, dissolved in ethanol (CH3CH2OH) as solvent. When oxymercuration is performed in an alcohol solvent instead of water, the nucleophile that attacks the mercurinium ion intermediate is the alcohol (ethanol) rather than water. This is called solvomercuration (or alkoxymercuration). Step 2 - Mechanism: Cyclohexene reacts with (CF3CO2)2Hg to form a bridged mercurinium ion. Ethanol (the solvent) acts as the nucleophile and attacks the more substituted carbon of the mercurinium ion in an anti fashion (Markovnikov selectivity). This gives an organomercury intermediate with an ethoxy group (-OCH2CH3) and a mercury substituent on the ring in a trans relationship. Step 3 - Reduction: Treatment with NaBH4 in base replaces the C-Hg bond with C-H, with retention of configuration at that carbon (the overall process proceeds with overall Markovnikov regioselectivity and anti addition is not always strictly maintained in the product after demercuration). The net result is Markovnikov addition of ethanol across the double bond: -OEt ends up on one carbon and -H on the other. Step 4 - Product: For cyclohexene (a symmetric alkene), both carbons of the double bond are equivalent, so Markovnikov selectivity gives the same carbon bearing the -OEt group as would anti-Markovnikov. The product is ethoxycyclohexane (cyclohexyl ethyl ether), a cyclohexane ring bearing a single -OCH2CH3 group. Why other options fail: - (a) Cyclohexanol would be the product if water were the solvent (standard oxymercuration-reduction). Here the solvent is ethanol, not water. - (c) Trans-1,2-cyclohexanediol would result from osmium tetroxide or similar dihydroxylation; not from this reaction. - (d) Two OEt groups on adjacent carbons is not produced; only one C-O bond forms per molecule of alkene in this reaction. Therefore, the correct answer is B.