Chem2445 Aspirin
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Transcript of Chem2445 Aspirin
DR. EDDY
CHEM 2445 - Aspirin
Aspirin
Chapter 41, p 529Acylation of salicyclic acidMacroscale Procedure, p 533Using product for next experiment
SAVE THE ASPIRIN
History of Pain Relief
Salicin isolated from willow bark and poplar bark Used as analgesic
Salicyclic acid developed from Kolbe synthesis (1860) Attacks mucoid
membranesAspirin found to
minimize mucoid irritation (1869, 1874)
Annalen der Chemie und Pharmacie, 1860, 113, 125Chem. Rev., 1957, 57, 583
Rev. Med. Interne, 2000, 21, 8
Medicinal Effects of Aspirin
Analgesic, antipyretic (fever reducer), anti-inflammatory
Interacts with COX-2 Acylates terminal amine Covalent modification of protein, irreversible inhibition
Aspirin Resistance Can prolong bleeding time Associated with platelet thromboxane A2 and 12-
hydroxyeicosatetraenoic acid (12-HETE)Lowers risk of stroke, heart attack and vascular
death with low dose aspirinCan cause aspirin-induced asthma in adultsBMJ, 2008, 336, 195
Can. J. Cardio., 1995, 11, 221Lancet, 1999, 353, 2179Gastroenterology, 2003, 124, 47BMJ, 2004, 328, 434
Synthesis of Aspirin
Ester synthesisWithout a catalyst, reaction takes prolonged
timeFour catalysts
H2SO4
BF3•OEt2
Pyridine NaOAc
Ester Synthesis
H2SO4 and BF3•OEt2 Mechanism
Pyridine Mechanism
Sodium Acetate Mechanism
Procedure
Four test tubes 0.2 g NaOAc 5 drops pyridine 5 drops sulfuric acid 5 drops BF3•OEt2
Record time required for 4°C increaseHeat in hot water bath for 5 minutesPour all 4 tubes into flask containing 50 mL waterCool and induce crystallizationVacuum filterRecord mp and weightTest solubility in toluene and waterSAVE ALL ASPIRIN
IR of Aspirin
NMR of Aspirin
Pre-Lab Things
Include Table of chemicals Hazards Reactions Mechanisms
Make a note to save the aspirin
Post-Lab Things
Things to discuss Difference in mechanisms
Which is more effective, and why? What would happen if you didn’t destroy excess acetic
anhydride? Other acylating agents possible?
Getting out on time
Work in pairs One person do bases, one acids Have water bath heating while waiting
SAVE THE ASPIRIN