Question

If you were to run this reaction on a 0.5 g acetaminophen, how much powdered potassium carbonate would you use ? Show your work

Alcohols and Ethers 185 14.3 THE WILLIAMSON ETHER SYNTHESIS: PREPARATION OF PHENACETIN FROM ACETAMINOPHEN One of the most common methods used to prepare ether Williamson ether synthesis. In this reaction, an alkoxide anion (RO) acts as a nucleophile in an S, 2 process, displacing a leaving group (X) from an electrophile (R-X). R-20 . RY ROR + xe an alkoxide anion (a nucleophile) an alkyl hallde an ether a leaving group The usual limitations on the S. 2 reaction apply: the alkoxide must not be too bulky: the electrophile is usually primary, secondary, or resonance stabilized (e.g., allylic or benzylic), but never tertiary: X must be a good Teaving groups and polar, aprotic solvents are preferred In this experiment, the Williamson ether synthesis will be demon- strated by converting one commonly used pharmaceutical product (aceta- minophen) into another (phenacetin). Both of these compounds are found in over-the-counter pain relievers-acetaminophen is the active ingredi- ent in Tylenol and many other non-asprin analgesics. Phenacetin was a very popular analgesic until recently. H H N CH, NCH ||| + CH CHI • KACO, + KI KHCO, l odoethane 2-butanone OH OCH,CH, acetaminophen potassium carbonate phenacetin (4-acetamidophenol) (4-acetamidoethoxybenzene) The overall reaction is shown in this diagram. Acetaminophen (formally known as 4-acetamidophenol) is a phenol, and thus is sufficiently acidic (pk, around 10) to be deprotonated by potassium carbonate. The resulting phenoxide anion serves as a nucleophile in the S2 displacement of lodide (a good leaving group) from lodoethane (a primary alkyl halide). The sol. vent. 2-butanone, Is polar and aprotic like acetone but has a higher boiling point. The side products will be removed with an aqueous wash, and the organic product, an ethyl ether, will be purified by recrystallization.

Answer 1

alled 1) The balanced equation shows Kelu Imol of acutaminophen reacts with Imol of K2 Mol. wt of acetaminophen = 151 g mor':. 0.5 g 0.5 moles a 0.0033 moles 151 i. Ky los required = 0.0033 moles Mol wat K2 coz = ( 78 +60 )gmort=138 og mot : weight required = 0.00 33 x 138 g = 0.457 g (Ans)