Select the correct IUPAC name, including the $\left(R\right)$ or $\left(S\right)$ configuration, for the following compound: ${\mathrm{CH}}_3-\mathrm{CH}\left({\mathrm{Br}}_1\right)-\mathrm{CH}\left({\mathrm{OH}}_1\right)-{\mathrm{CH}}_3$ where the configuration at the carbon bearing the $\mathrm{Br}$ is $\left(R\right)$.

• A. $\left(R\right)$-3-bromo-2-hydroxybutane
• B. $\left(R\right)$-2-bromo-3-hydroxybutane
• C. $\left(S\right)$-3-bromo-2-hydroxybutane
• D. $\left(S\right)$-2-bromo-3-hydroxybutane

Answer: (B)

Verified step by step guidance

1. Identify the longest carbon chain in the molecule and number it to give the substituents the lowest possible numbers. Here, the chain is butane (4 carbons).
2. Locate the substituents: a bromo (Br) group and a hydroxy (OH) group attached to the chain. Determine their positions based on the numbering that gives the lowest numbers to substituents.
3. Assign the correct locants to each substituent. For example, if the bromo is on carbon 2 and the hydroxy on carbon 3, the name will reflect that order: 2-bromo-3-hydroxybutane.
4. Determine the stereochemistry (R or S) at the chiral center bearing the bromo substituent. Since the problem states the configuration at the carbon bearing Br is (R), include this in the name as (R)-2-bromo-3-hydroxybutane.
5. Combine all parts to write the full IUPAC name: start with the stereochemical descriptor (R) or (S), followed by the locants and names of substituents in alphabetical order, and finally the parent chain name.