Aspirin synthesis, acetic anhydride

Essentially, all methods of synthesis are variations of the reaction of acetylchloride, acetic anhydride or ketene11 with salicylic acid using a variety of catalysts such as pyridine12 or sulfuric acid13 and reaction conditions (c.f. 14). The preparation of aspirin labeled with a i4c iaj-,eie(j acetyl group has also been reported.15 Efforts to improve the commercial processes continue to the present day. 

Bose et alm have demonstrated the synthesis of aspirin from salicylic acid and acetic anhydride using commercial microwave reactors (Scheme 9.6). Without optimising the conditions, high purity aspirin was obtained in greater than 80% yield (500-800 g scale). 

The synthesis of acetylsalicylic acid (aspirin) from the reaction of salicylic acid with acetic anhydride... 

Acetic Anhydride Acetic anhydride is the most important carboxylic acid anhydride. It is produced at the rate of about 4 billion pounds per year, primarily for synthesis of plastics, fibers, and drags. (See the synthesis of aspirin on p. 1009.) Acetic anhydride consists of two molecules of acetic acid, minus a molecule of water. The most common industrial synthesis begins by dehydrating acetic acid to give ketene. 

A singlet at 8 2.15 is H on carbon next to carbonyl, the only type of proton in the compound. The IR spectrum shows no OH, and shows two carbonyl absorptions at high frequency, characteristic of an anhydride. Mass of the molecular ion at 102 proves that the anhydride must be acetic anhydride, a reagent commonly used in aspirin synthesis. q q... 

Reactions 5.14 and 5.15 illustrate two specific examples. In another example, the laboratory synthesis of aspirin (Reaction 5.16), using acetic anhydride, gives excellent yields of the ester. 

The next example taken from the synthesis database is a reaction network for various routes to aspirin [57,58], Figures 9.22 through 9.24 show reaction networks for phenol, acetic anhydride, and aspirin, respectively. The digraph in Figure 9.25 shows the combination of two subnetworks for phenol and acetic anhydride that converge to produce the final target product. 

If you used 250 mg of salicylic add and excess acetic anhydride in the preceding synthesis of aspirin, what would be the theoretical yield of acetylsalicylic acid in moles In milligrams ... 

In this way, aspirin functions as an acetylating agent, much the way acetic anhydride functions as an acetylating agent in the preparation of aspirin. The same acetyl group that came from acetic anhydride (in the synthesis of aspirin) is ultimately... 

In a certain aspirin synthesis, 104.8 g of salicylic acid and 110.9 g of acetic anhydride are combined. Calculate the percent yield of the reaction if 105.6 g of aspirin are produced. 

The first step in the industrial synthesis of aspirin is known as the Kolbe-Schmitt carboxylation reaction. In this step, the phenolate ion reacts with carbon dioxide under pressure to form salicylic acid. Reaction of salicylic acid with acetic anhydride forms acetylsalicylic acid (aspirin). 

In a laboratory synthesis, a student begins with 3.00 mL of acetic anhydride (density = 1.08 g/mL) and 1.25 g of salicylic acid. Once the reaction is complete, the smdent collects 1.22 g of aspirin. Determine the limiting reactant, theoretical yield of aspirin, and percent yield for the reaction. 

Figure 14 4 Acetylation of salicylic acid to produce aspirin. The synthesis of aspirin is classified as an esterification reaction. Salicylic acid is treated with acetic anhydride, an acid derivative, causing a chemical reaction that turns salicylic acid s phenol group into an acetyl group, (R-OH R-OCOCH3). This process yields aspirin and acetic acid, which is considered a byproduct of this reaction. Small amounts of sulphuric acid (and occasionally phosphoric acid) are almost always used as a catalyst.

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