An Updated Simple SN2 Reaction for the Undergraduate Organic Laboratory

SN2 reactions are of fundamental importance in introductory organic chemistry courses, and a number of experiments suitable for the first-semester undergraduate organic lab have been previously reported. Most of these experiments have used alkyl halides as electrophiles, but alkyl halides are often less than ideal for reasons of toxicity/volatility and difficulty in TLC visualization. We report an updated methodology utilizing an alkyl tosylate, rather than a halide, as the electrophile. The SN2 reaction of 2-naphthol/sodium hydroxide with butyl p-toluenesulfonate is performed in a single 3 or 4 h lab period and affords a solid product in good yield. The tosylate electrophile gives students experience with a commonly encountered leaving group, is easily visualized on TLC, and has an improved safety profile.