A chemist desires to synthetically isolate optically pure -chlorobutane starting explicitly from a p — Haloalkanes and Haloarenes Chemistry Question
Question
A chemist desires to synthetically isolate optically pure $(S)-2$ -chlorobutane starting explicitly from a pure sample of $(R)-2$ -butanol, demanding a reaction pathway with guaranteed 100% complete inversion of configuration. Which of the following specific reagent systems is most flawlessly appropriate?
💡 Solution & Explanation
The chemist requires complete inversion of configuration ($R \rightarrow S$). A) Pure $SOCl_2$ proceeds via $S_Ni$, resulting in total retention. C) Lucas reagent ($HCl/ZnCl_2$) relies heavily on carbocation character, leading to substantial racemisation. D) This mixture generates $HCl$, similar to C. B) The presence of pyridine forcefully directs the $SOCl_2$ reaction away from the internal $S_Ni$ collapse and into a classic intermolecular $S_N2$ displacement by free chloride ions. This rigorous backside attack guarantees the complete Walden inversion required by the chemist.