Which pair of alkenes are stereoisomers that can both be hydrated to produce $3_{\mathrm{hexanol}}$ as the major product?

• A. $3_{\mathrm{hexene}}$ and $1_{\mathrm{hexene}}$
• B. $\mathrm{trans}-2_{\mathrm{hexene}}$ and $\mathrm{cis}-2_{\mathrm{hexene}}$
• C. $1_{\mathrm{hexene}}$ and $2_{\mathrm{methylpentene}}$
• D. ${\mathrm{cis}}_3-\mathrm{hexene}$ and ${\mathrm{trans}}_3-\mathrm{hexene}$

Answer: (B)

Verified step by step guidance

1. Identify the structure of 3-hexanol, which has the hydroxyl group (-OH) on the third carbon of a six-carbon chain.
2. Recall that hydration of alkenes typically follows Markovnikov's rule, where the -OH group adds to the more substituted carbon of the double bond.
3. Determine which alkenes, when hydrated, place the -OH group on carbon 3. This means the double bond must be between carbons 2 and 3 or carbons 3 and 4, so that Markovnikov addition leads to 3-hexanol.
4. Understand that stereoisomers are compounds with the same connectivity but different spatial arrangements. Cis- and trans- isomers of 2-hexene differ in the relative positions of substituents around the double bond but share the same carbon skeleton and double bond location.
5. Conclude that the cis- and trans- isomers of 2-hexene are stereoisomers that both hydrate to give 3-hexanol as the major product, because the double bond is between carbons 2 and 3, allowing Markovnikov addition to place the -OH on carbon 3.