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Which reagent should be used for the acetylation of salicylic acid?

Author

Carter Sullivan

Updated on February 20, 2026

Which reagent should be used for the acetylation of salicylic acid?

Aspirin, acetylsalicylic acid (3.2. 2), is synthesized by the acetylation of salicylic acid (3.2. 1) using acetic anhydride or acetyl chloride [60–63].

Furthermore, which reagent is used for acetylation?

Silica sulfuric acid as a mild and efficient reagent for the acetylation of alcohols in solution and under solvent-free conditions.

Beside above, what reagent is added to salicylic acid to obtain aspirin? To prepare aspirin, salicylic acid is reacted with an excess of acetic anhydride. A small amount of a strong acid is used as a catalyst which speeds up the reaction. In this experiment, phosphoric acid will be used as the catalyst.

Furthermore, why pyridine is used in acetylation of salicylic acid?

Acetyl chloride reacts with Salicylic acid vigorously in the presence of pyridine to form acetylsalicylic acid or the aspirin . Pyridine is used in the reaction because the nitrogen in the pyridine is a nucleophilic catalyst. Aspirin can also be formed by the reaction of salicylic acid and acetic anhydride.

What are the reagents used to prepare aspirin?

Aspirin is prepared by chemical synthesis from salicylic acid, through acetylation with acetic anhydride. The molecular weight of aspirin is 180.16g/mol. It is odourless, colourless to white crystals or crystalline powder.

What is acetylation example?

When the hydrogen of an alcohol is replaced with an acetyl group via an acetylation reaction, the final product formed is an ester. One of the most common examples of an acetylation reaction is the acetylation of salicylic acid with acetic anhydride to afford acetic acid and acetylsalicylic acid as the products.

What is acetylation give example?

When the hydrogen of an alcohol is replaced with an acetyl group via an acetylation reaction, the final product formed is an ester. One of the most common examples of an acetylation reaction is the acetylation of salicylic acid with acetic anhydride to afford acetic acid and acetylsalicylic acid as the products.

What do u mean by acetylation?

A chemical reaction in which a small molecule called an acetyl group is added to other molecules. Acetylation of proteins may affect how they act in the body.

What happens when salicylic acid is acetylated?

Acetylation of salicylic acid forms aspirin in acidic medium. Acetylation of salicylic acid is electrophilic reaction. This reaction occurs in the presence of Ac2O .

Does acetylation increase gene expression?

Thus, acetylation of histones is known to increase the expression of genes through transcription activation. By deacetylating the histone tails, the DNA becomes more tightly wrapped around the histone cores, making it harder for transcription factors to bind to the DNA.

What is the function of acetylation?

Acetylation neutralizes the positive charge of lysine and thus affects diverse aspects of protein function, such as stability, enzymatic activity, subcellular localization and interaction with other macromolecules in the cell.

What is the formula of salicylic acid?

C7H6O3

Is pyridine basic or acidic?

Pyridine is a weak base (pKa of the pyridinium ion is about 5.5) and can be dissolved in aqueous acid.

What is pyridine reagent?

Pyridine is a reasonable nucleophile for carbonyl groups and is often used as a catalyst in acylation reactions. The nitrogen atom in pyridine is nucleophilic because the lone pair of electrons on nitrogen cannot be delocalised around the ring.

Is pyridine toxic?

Pyridine is a toxic, flammable liquid with a strong and unpleasant fishy odour.

How is aspirin made from salicylic acid?

Aspirin can be made by reacting salicylic acid with acetic acid in the presence of an acid catalyst. The phenol group on the salicylic acid forms an ester with the carboxyl group on the acetic acid. However, this reaction is slow and has a relatively low yield.

What is the other name of salicylic acid?

The name is from Latin salix for willow tree. It is an ingredient in some anti-acne products. Salts and esters of salicylic acid are known as salicylates.

Salicylic acid.

Names
Preferred IUPAC name 2-Hydroxybenzoic acid
Identifiers
CAS Number69-72-7
3D model (JSmol)Interactive image

Why is pyridine used in organic chemistry?

Pyridine is a reasonable nucleophile for carbonyl groups and is often used as a catalyst in acylation reactions. The nitrogen atom in pyridine is nucleophilic because the lone pair of electrons on nitrogen cannot be delocalised around the ring.

What type of reaction is synthesis of aspirin?

The synthesis of aspirin is known in organic chemistry as an esterification reaction. This is a substitution reaction in which an alcohol (the –OH group in salicylic acid) reacts with acetic anhydride to form an ester, aspirin.

What is in salicylic acid?

Salicylic acid is a monohydroxybenzoic acid that is benzoic acid with a hydroxy group at the ortho position. It is obtained from the bark of the white willow and wintergreen leaves. It has a role as an antiinfective agent, an antifungal agent, a keratolytic drug, an EC 1.11.

Why is aspirin recrystallized?

Once the aspirin is synthesized, it can be collected by suction filtration while the more water soluble unreacted starting materials are washed away in the aqueous solvent. At this point the product is already isolated. To purify the product further, there is a need to recrystallise the crude aspirin.

What qualitative test would you use to determine if any of the salicylic acid remained in your product?

You want to perform a ferric chloride test on aspirin to see if any salicylic acid remains in the solution.

Why is salicylic acid not used in place of aspirin?

The anti-inflammatory activity of aspirin is due to its major metabolite, salicylic acid,22 yet salicylic acid is inactive against COX in either broken cells or purified enzyme preparations. It was, however, found to be a weak inhibitor of both COX isoforms in intact cells.

Why did the salicylic acid have to be dry before esterification?

Salicylic Acid needs to dry before esterification because the solvent will interfere with the melting point. Complete reaction of salicylic acid with acetic anhydride substitutes an ester for the phenolic group. The mixture is heated to form the acetylsalicylic acid (C9H8O4) and acetic acid (C2H4O2).

Why is sulfuric acid used in aspirin synthesis?

Making aspirin
In this case just a few drops of sulphuric acid added to the mixture means that there are some free positive hydrogen ions in the solution which can bind to the ethanoic anhydride. This makes it more active and speeds up the reaction. To ensure the reaction goes as quickly as possible we have to heat it.

Why is salicylic acid the limiting reagent in the synthesis of aspirin?

The limiting reagent of this experiment was salicylic acid. This is used as the limiting reagent because it is cheaper than acetic anhydride. However, the reduced amount of acetic anhydride makes it the limiting reagent—one that greatly reduces the theoretical yield of aspirin.

How do you find the mass of salicylic acid in aspirin sample?

4. Answers will vary. For the sample data, the mass of synthesized aspirin is 1.96 g. Corrected for purity, is: (1.96 × 0.75) = 1.47 g. The percent yield is: (1.47 g ÷ 2.63 g) × 100 = 55.9%.

Part I Synthesis of Aspirin.

Mass of salicylic acid used (g)2.01
Mass of aspirin synthesized (g)1.96

How do you convert salicylic acid to asprin give its complete reaction?

Complete answer:
For the preparation of aspirin, salicylic acid is reacted with an excess of acetic anhydride. Small amount of strong acid is used as a catalyst in these reactions which enhances the speed of reaction acid used is phosphoric acid. Excess acetic acid will be extinguished with the addition of water.

Which situation causes a greater than 100% yield?

Typically, percent yields are understandably less than 100% because of the reasons indicated earlier. However, percent yields greater than 100% are possible if the measured product of the reaction contains impurities that cause its mass to be greater than it actually would be if the product was pure.

Why is aspirin important?

Aspirin has been shown to be helpful when used daily to lower the risk of heart attack, clot-related strokes and other blood flow problems in patients who have cardiovascular disease or who have already had a heart attack or stroke. Many medical professionals prescribe aspirin for these uses.

How does aspirin work in the body?

Aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and indomethacin work by inhibiting an enzyme that produces prostaglandins--hormone-like messenger molecules that trigger many processes in the body, including inflammation.

Why is the aspirin washed with cold water?

Because aspirin is less soluble in cold water. In fact, aspirin is not very soluble in water at all, which is why you are supposed to take it with lots of water. You are not "chilling the aspirin", you are preventing it from dissolving too much so that you have a better yield of your product.

Is aspirin soluble in water?

Aspirin is only slightly soluble in water so if you add it to the reaction mixture the product would rather clump together than be in the water phase. This causes the solid to begin to form or 'precipitate'.

How do you calculate aspirin yield?

Example: Start with 0.027moles of aspirin (limiting reagent) going to 0.027moles of salicylic acid. 3. Divide the number of grams of product obtained experimentally, by the number of grams obtained in the theoretical yield calculations and multiply by 100 to calculate the percent yield.

What set of conditions could cause a less than 100% yield?

Usually, percent yield is lower than 100% because the actual yield is often less than the theoretical value. Reasons for this can include incomplete or competing reactions and loss of sample during recovery.

What is the melting point of aspirin?

135 °C

What affects purity of aspirin?

Weighing, mixing, heating, cooling, filtration, washing and drying are processes that can affect the yield and the purity of aspirin. In the chemical reaction, most of the time the aspirin produced might be impure. Therefore, aspirin must go through another process known as recrystallization.

How can you increase the yield of aspirin synthesis?

How to Improve Your Yield
  1. Add reagents dropwise if necessary.
  2. Continuously stir thoroughly.
  3. Carefully keep temperature of reaction and liquid reagents at the correct level during addition and reaction.
  4. Monitor your reaction carefully throughout the experiment.

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