Which reagent converts an alcohol to a tosylate, improving its leaving group for substitution?

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Multiple Choice

Which reagent converts an alcohol to a tosylate, improving its leaving group for substitution?

Converting an alcohol into a tosylate makes the leaving group much better for substitution. p-toluenesulfonyl chloride does this by transferring the tosyl group to the alcohol oxygen, giving an alkyl tosylate. In the presence of a base (often pyridine), the reaction also neutralizes the HCl that forms, driving the process forward. The resulting tosylate ester (OTs) leaves very readily in SN2 substitutions because the sulfonate group stabilizes the negative charge in the leaving state and is a superb leaving group. Hydrochloric acid would tend to replace the alcohol with chlorine instead of forming a tosylate. PCC oxidizes the alcohol to a carbonyl compound, not to a tosylate. Pyridine on its own doesn’t install the tosyl group; it acts as the base/solvent to facilitate the TsCl reaction, but the key reagent that actually creates the tosylate is p-toluenesulfonyl chloride.

Converting an alcohol into a tosylate makes the leaving group much better for substitution. p-toluenesulfonyl chloride does this by transferring the tosyl group to the alcohol oxygen, giving an alkyl tosylate. In the presence of a base (often pyridine), the reaction also neutralizes the HCl that forms, driving the process forward. The resulting tosylate ester (OTs) leaves very readily in SN2 substitutions because the sulfonate group stabilizes the negative charge in the leaving state and is a superb leaving group.

Hydrochloric acid would tend to replace the alcohol with chlorine instead of forming a tosylate. PCC oxidizes the alcohol to a carbonyl compound, not to a tosylate. Pyridine on its own doesn’t install the tosyl group; it acts as the base/solvent to facilitate the TsCl reaction, but the key reagent that actually creates the tosylate is p-toluenesulfonyl chloride.

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