CHEM 162 LAB #6: SYNTHESIS OF ASPIRIN complete solution

General Chemistry 162
Laboratory #6: Synthesis Of
Aspirin

, INTRODUCTION – GOALS OF LAB
• Synthesize aspirin (acetylsalicylic acid) from
the starting material salicylic acid
• Evaluate the purity of the product via two
techniques
– Detecting leftover salicylic acid via absorbance
Spectroscopy (beer’s law)
– Comparing the melting point of the product mixture to
the melting point of pure aspirin

,INTRODUCTION – TECHNIQUES OF LAB

• Part i – synthesis of aspirin
– Use microscale glassware; conical vial with air
condenser for synthesis
– Vacuum filtration using a hirsch funnel
• Part ii – determination of % salicylic acid
– Absorbance spectrum of iron(iii)-salicylate complex
– Beer’s law: a = ɛ𝓁c
• Part iii – melting point determination
– Melting point apparatus

, REACTION BASICS




(aspirin)


The hydroxyl (-oh) group on the aromatic ring of
salicylic acid reacts with acetic anhydride under acidic
conditions (h+) to form an ester product.