ACS Organic Chemistry Practice Test 2026 - Free Organic Chemistry Practice Questions and Study Guide

Activating an alcohol with p-toluenesulfonyl chloride in base converts the alcohol into a tosylate ester. The base deprotonates the alcohol to form an alkoxide, which then attacks the sulfur of TsCl. This kicks out chloride and yields the tosylate ester, R–OTs. This product has a much better leaving group than the original hydroxyl, enabling SN2 or E2 reactions; the base’s role is to neutralize the HCl formed in the process, so the organic product remains the neutral tosylate ester. Thus the correct outcome is the tosylate ester of the alcohol, not the free alcohol, a tosylate salt, or an ether.