Undergraduate organic chemistry students typically show the greatest interest in laboratory experiments utilizing familiar substances or compounds with a definite and readily understood function, such as analgesics, sweeteners, or flavorings. Considering the common use of experiments involving the analgesic aspirin, it is surprising that there have been few synthetic procedures developed for the high school or undergraduate laboratory involving acetaminophen (I) (1-3). This is notable because numerous experiments, concepts, and techniques can be directly linked with acetaminophen and its derivatives and would facilitate integration of its use in a broader pedagogical strategy. 1 This report describes the conversion of the analgesic acetaminophen to the artificial sweetener dulcin (IV). The experimental sequence is suitable for both high school and undergraduate laboratories and can be performed on either a micro or macro scale. Phenacetin (II), also a physiologically active analgesic, is an intermediate isolated during the sequence (2, 4 ). Consequently, the procedures described can be adopted as a multistep synthesis of dulcin from acetaminophen or, alternatively as one-period conversions of either acetaminophen to phenacetin or phenacetin to dulcin. A Williamson-type synthesis of aromatic ethers is featured in the former transformation, while the latter demonstrates an amide hydrolysis followed by a nucleophilic addition reaction of an aryl amine with an isocyanate. 2 The procedure described offers numerous advantages over previously reported methods, making the experiment suitable for student laboratories. Yields are high and crude products are commonly isolated with sufficient purity that refinement before analysis or use in subsequent reactions is optional. Reaction conditions are optimized to provide adequate time for product purification and characterization within each 3-hour laboratory period. Finally, halogenated solvents are eliminated and the experiment can be run if desired on a single Tylenol tablet, thus significantly minimizing chemical use and wastes.
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