Optically pure $(R)$ -octan-2-ol is converted by $TsCl$ /pyridine into its tosylate (no bond to the stereocentre is broken). The tosylate is then heated with $LiBr$ in DMF, and the bromide obtained is treated with $NaI$ in acetone for a short time, so that only one substitution per molecule has occurred. Each substitution is a clean SN2 reaction. The final product is

A $(S)$ -2-bromooctane
B $(S)$ -2-iodooctane
C $(R)$ -2-iodooctane
Dracemic 2-iodooctane

Answer: C

Tosylation proceeds with retention:

(R)

-tosylate (priorities OTs, hexyl, methyl, H). LiBr displaces the tosylate with inversion to give

(S)

-2-bromooctane (priorities Br, hexyl, methyl, H, same order). NaI then displaces bromide with a second inversion to give

(R)

-2-iodooctane (I, hexyl, methyl, H). Two inversions after a retention step give net retention overall, so the product has the same descriptor as the starting alcohol.

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Answer: C

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