Synthesis andAnalysis of AspirinChemistry 1060 Laboratory
Analysis• Purity determination
• Thin Layer Chromatography (TLC)• Separation and identification• stationary phase – silica gel• mobile phase – organic solvent
• Relative attraction to the two phases
• Polarity
Analysis• Thin Layer Chromatography (TLC)
• Retention factor (Rf) values
3 cm
5 cm
Solvent front
Rf = 3/5 = 0.60
Origin
Analysis• Thin Layer Chromatography (TLC)• Salicylic acid (starting material)• Pure aspirin• Isolated product
• UV detection
• Results• Isolated product • Rf of pure aspirin• salicylic acid removed?
UV
Analysis• Structure confirmation
• 1H nuclear magnetic resonance (1H NMR) - or proton magnetic resonance (PMR)
Analysis• 1H NMR
Analysis• 1H NMR
radio-frequency region of the spectrum
Analysis• 1H NMR – Shielding
Analysis• 1H NMR – Chemical Shifts, Chemical Equivalency
CH3 Si
CH3
CH3
CH3
tetramethylsilane(TMS)
Analysis• 1H NMR – Chemical Shifts, Integration
3
1
Analysis• 1H NMR – Chemical Shifts, Complex Patterns
Analysis• 1H NMR – Characterizing starting material and product
salicylic acid
aspirin
OH
O
OH
H
H
H
H
OH
O
O
H
H
H
HO
CH3
Summary• Goals
Week 1:• To synthesize aspirin, from salicylic acid and acetic anhydride
• To purify the product using recrystallization
Week 2:• To verify the purity and identity of the product using thin layer
chromatography (TLC)
• To further confirm the identity of the product by nuclear magnetic resonance (NMR) spectroscopy
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