Synthesis of Acetophenetidin

Acetophenetidin

(4-ethoxyacetanilide) a synthetic comound that acts as an analgesic (pain reliever) and antipyretic (fever reducer)

used to be used with aspirin and caffeine in a popular over the counter tablet until found to be carcinogenic over time

What is the pathway for the synthesis of acteophenetidin?

forming an amide bond (amide synthesis)

Recrystalization

a purification technique for organic solids that allows organic molecules to self-assemble into a pure crystal lattice

The more pure the crystal . . .

the narrower and more precise the melting point range

Impure samples have a . . .

lower/broader melting point

Recrystallization solvent

- must dissolve in crude product when BOILING
-must NOT dissolve the desired compound at room/cold temperatures
-impurities must remain soluble after cooling

Water

solvent for the recrystallization of amide-synthesized acetophenetidin

Amide Synthesis (General)

-A crude sample is dissolved into a MINIMUM amount of solvent at its boiling point
-Remove colored decolorizing carbon via hot gravity filtration (physical impurity removal)
-Crystals are collected by vacuum filtration

Increase crystal yield by

1) initially scratch the inside of the flask with a glass stir rod to form a site of nucleation
2) use as little solvent as possible
3) use the "mother liquor" side product from when vaccum filtrating and brind it to a boil, evaporate it slightly, and cool it again/filtrate for a second crop of crystals
4) cool the hot solution really slowly and do NOT disturb the flask while in a 75% ice 25% water bath

Activated Carbon

aka “Decolorizing carbon" or “activated charcoal”; removes colored impurities.

Gravity Filtration

filtration w/ a stemless funnel (prevents crystallization) used to remove insoluble impurities from crude product

Recrystallization procedure

1) Boil near 40mL of DI water
2) In a 125mL flask, combine your product and MINIMUM amount water/solvent.
3) Stir with a wooden applicator stick.
4) After completely dissolved, remove flask and let cool to room temperature, then ice bath.
5) Perform vacuum filtration.

pure crystal lattices

- well ordered, tightly packed and have a narrow melting point range

impure crystal lattices

- lower melting point w/ wide range

percent yield

(actual yield)/(theoretical yield) x 100

Sodium acetate

is used as a buffer in amide synthesis to help neutralize HCl

percent recovery

(mass recovered from recrystallized product)/(mass of crude product) x 100

miscible

two liquids that are soluble in each other