Acetaminophen Preparation - Organic Chemistry

Acetaminophen Prep

This lab focuses on preparing acetaminophen from p-aminophenol and an acetic anhydride. I will isolate the crude acetaminophen and allow it to crystallize. After this step I will decolorize the product and proceed with a crystallization in a Craig tube. The sample will be collected and viewed with a MelTemp to determine the melting point.

Chemical name

Structure

Molecular Weight (g/mole)

Physical properties

Amount used

Safety

p-aminophenol * 109.1 MP-188–190 °C

BP- 284 °C 0.150 g irritant, toxic

acetic anhydride * 102.09 MP- -73.1 C

BP- 139.8 C 0.165 mL corrosive

sodium dithionite * 174.107 anhydrous

210.146 dihydrate MP- 52 °C

BP- decomposes 0.2 g harmful

acetaminophen * 151.17 MP- 169 °C acquired

methanol * 32.04 MP- -97 °C

BP- 64.7 °C as needed in 50/50 h2o mixture flammable, toxic

Water 18.02 MP- 0 C

BP- 100 C 1.95 mL

Add 0.150 p-aminophenol to 5mL conical vial -> Mix 0.450 mL of h2o and 0.165 mL of acetic anhydride into vial -> Heat mixture on aluminum block -> solid dissolves, wait 20 additional minutes -> Let vial cool to room temperature to begin crystallization -> collect crystals in Hirsch funnel -> allow crystals to air dry -> weigh crude product and set small amount aside.

Dissolve 0.2 g of sodium dithiolate in 1.5mL of h2o -> Add rest of crude product -> heat mixture for 15 mins at 100 C -> cool in ice bath -> collect crystals with Hirsch funnel -> air dry and weigh purified product.

Place purified product in Craig tube -> crystallize with 50/50 water/methanol mixture -> Slowly add hot solvent to tube to dissolve solid via pg. 657 -> Cool mixture with plug inserted -> place in ice bath to induce crystal forming, will take around 10 minutes -> place setup in centrifuge tube and spin for several minutes -> collect crystals to air dry

Insert small sample into capillary tube and place into MelTemp -> watch and record first drop of liquid temperature-> record complete liquid temperature

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