Laboratory Report on Preparation of Aspirin

Laboratory Report on Preparation of Aspirin
By(Name)
Institutional Affiliation

Introduction
Aspirin is a common name to 2-acetoxybenzoic acid. It is a white crystalline substance
that is characterized by pain-relieving properties1 . Acetylsalicylic acid is a derivative of salicylic
acid. It is a prodrug that initiates active metabolism of salicylic acid. Aspirin is an ester of
salicylic acid. It is also an analgestics.
The primary active gradient in aspirin is acetylsalicylic that is manufactured from the
principles of esterification. Esterification process in this case involves the use of acetic anhydride
and salicylic acid as the primary reagents. This procedure encompasses a chemical reaction
between acetic anhydride and carboxylate ester. This acid (salicylic acid) is a weak acid with
alkanol as the functional group it is attached to2. The reaction produces both acetylsalicylic acid
and acetic acid as the products.
The general mechanism for the reaction for aspirin preparation in this case is an
esterification. This reaction happens when an alkanoic acid and an alkanol reacts to produce an
ester. The water molecule split off to form and an alkanoic acid and alkanol forms an ester
instead. In this reaction, a phenoxide ion which is just a hydroxide ion attached to a ring
stabilizes by the electron that withdraws a carbonyl group on the salicyclic acid hence forming a
stable nucleophile. This property makes these reagents an excellent electrophile since the leaving
group undergoes stabilization because of the acidic media.
Industrial manufacturer of Aspirin
Industrially, aspirin is manufactured by reacting acetic anhydride with salicylic acid in
approximate or the same stoichiometric ratios, ZnO and CaO3. The reaction yields a mixture of
acetyl salicylic acid, zinc or calcium acetate. A maximum of 2% free salicylic acid is produced in
the process4. This process is an exothermic reaction and does not require recrystallization. The
aspirin produced is dense and is easily mixed with the excipients of acetyl salicylic acid which is
immediately compressed into the desired tabled once it is synthesized.
1 Paul Knochel, Viet A. Vu, and Ilan Marek, "Stereoselective Preparationof Functionalized Unsaturated Lactones and
Esters via FunctionalizedMagnesium Carbenoids," Synthesis, no. 12 (2013): 1799
2 Frederick A. Bettelheim and Joseph M. Landesberg, Laboratory Experiments for Introduction to General, Organic
and Biochemistry (Boston: Cengage Learning, 2012), 9
3 Knochel, Vu, and Marek, "Preparationof Functionalized Unsaturated Lactones and Esters" 1775.
4 Rachel M. Stevens, Gale Researcher Guide for: Natural Resources and Industrial Production (Gale, Cengage
Learning, 2018), 21

Industrial testing of aspirin.
Prior to packaging, the compressed tablets are tested for hardness in Schleunier machine.
Friability which is conducted to verify whether aspirin can withstand rigors of shipping and
packaging is also conducted. Disintegration test is also conducted to verify desirable solubility is
also conducted 5.
Comparison between industrial and Laboratory manufacture and testing of aspirin.
Industrial manufacture involves a reaction between salicylic acid and acetic anhydride lined in a
glass vessel. The produced liquid is pumped into crystalized where the liquid cooled to
commence crystallization process. The produced aspirin is then filtered to eliminate acetic acid
which are then recycled. The produced crystals are then washed and filtered. The produced
crystals are then subjected to sifting, granulation and tableting after dying.
Schematic diagram showing industrial manufacture of aspirin.
5 Stevens, Natural Resources and Industrial Production, 21