Acetylsalicylic Acid - Preparation, Structure, Properties & Uses, FAQs

Q: What is another name for acetylsalicylic acid?

Another name for acetylsalicylic acid is aspirin .

Acetylsalicylic Acid - Preparation, Structure, Properties & Uses, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:24 PM IST

Acetylsalicylic acid is a small fragrant acid with its chemical name monohydroxy benzoic acid. It is naturally lipophilic and was first taken from the bark of the Willow Tree. It derives its common name from various related sources with the same name, e.g. It is available as a product of salicin (β-glycoside alcohol found in plants) and is an active metabolite produced from acetylsalicylic acid (aspirin). Naturally, they form like clear and colourless crystals of organic acid. The salt content and ester of this substance are also widely used in living chemicals and are known as salicylates.

This Story also Contains

Preparation of Aspirin or Acetylsalicylic acid
Physical Properties of Acetylsalicylic acid
Chemical Properties of Acetylsalicylic acid (Acetylsalicylic acid Reaction) / What is aspirin?
Methods of Preparation Acetylsalicylic acid

Acetylsalicylic acid

Preparation of Aspirin or Acetylsalicylic acid

IUPAC name of aspirin C₆H₄ (OH) COOH, which can also be written as C₇H₆O₃ in a concise manner. Its IUPAC name is 2-hydroxybenzoic acid. It consists of a hydroxyl group (-OH group) attached to the orthro in relation to the carboxylic acid group (-COOH group) present in the benzene ring.

The given molecular weight (or molar mass) of Acetylsalicylic acid is given as 138.12 g / mol.

NCERT Chemistry Notes :

Physical Properties of Acetylsalicylic acid

• Acetylsalicylic acid exists as glossy white or colourless and doorless crystals at room temperature

• The tongue taste of Acetylsalicylic acid is acrid

• The salting and melting point of Acetylsalicylic acid is 211 ° C and 315 ° C, respectively

• The brightest point of Acetylsalicylic acid is 157 ° C

• The concentration of Acetylsalicylic acid is 1.44 to 20 ° C

• Its vapor pressure is 8.2 x 10^-5 mm Hg at 25 ° C

• Its LogP is 2.26

• It is the practice of color-correction when exposed to direct sunlight due to its photochemical degradation

• When damaged, it emits irritating fumes and smells that are nutritious

• Its fire temperature is 3.026mj / mol at 25 ° C

• The pH of the complete solution of Acetylsalicylic acid is2.4

• Its pKa (dissociation constant) is 2.97

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Chemical Properties of Acetylsalicylic acid (Acetylsalicylic acid Reaction) / What is aspirin?

Formulation of aspirin structure: In the field of medicine, the most important response associated with use of acetylsalicylic acid is the production of aspirin is also known as acetylsalicylic acid, one of most widely used analgesic and thinning agents. Here, in this given reaction, acetylsalicylic acid is reacted with acetic anhydride in a given acidic environment that even leads to acetylation of the hydroxyl group that is present in acetylsalicylic acid, and it thereby leads to the production of acetylsalicylic acid (aspirin) the mass production of aspirin and must be removed from the resulting product by several refining processes. Aspirin chemical name or aspirin is known as acetylsalicylic acid

Esterification Reaction: Since acetylsalicylic acid is an organic acid, it can be converted by natural alcohol groups to produce a new class of natural chemicals, ester names. When acetylsalicylic acid is reacted with methanol in an acidic environment (possibly sulfuric acid) in the presence of heat, the end-of-life reaction occurs with water loss (OH-ion lost in the active carboxylic acid group present in the acetylsalicylic acid molecule and H⁺ ion is lost in the destruction of the methanol molecule), leading to the formation of methyl salicylate (ester).

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Methods of Preparation Acetylsalicylic acid

It is important to know how to prepare aspirin (acetylsalicylic acid). There are two widely used methods of preparing acetylsalicylic acid. These are the ways discussed below:

From Phenol: When phenol is taken with sodium hydroxide, it forms a sodium phenoxide that is allowed to absorb beverages and weight loss.

The Carboxylation reactions are often followed by carbon dioxide, which also leads to the formation of sodium salicylate (acetylsalicylic acid salt). This form of salt is also reacted with an acid (or hydronium ion or any other proton-expressing form) to obtain acetylsalicylic acid.

From methyl salicylate: Methyl salicylate (wintergreen oil) is also a well-known analgesic in the pharmaceutical industry. It can be used to prepare acetylsalicylic acid. In this reaction, methyl salicylate reacts with sodium hydroxide leading to the formation of a acetylsalicylic acid salt, called disodium salicylate, which, in turn, reacts with sulfuric acid, leading to the formation of acetylsalicylic acid.

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Acetylsalicylic acid uses

• Acetylsalicylic acid has many applications, especially in the pharmaceutical industry. The most common and popular use of acetylsalicylic acid is the preparation of an analgesic, called aspirin, which is an acetylated ingredient of acetylsalicylic acid.

• Acetylsalicylic acid is also used to treat acne and psoriasis. The way acetylsalicylic acid is used in the treatment of these conditions is that it releases the keratin content of the skin by breaking the bonds between molecules between two keratin molecules.

• Acetylsalicylic acid is used to treat warts. The way it treats warts infection is almost identical to its keratolytic action. It removes water from the body of skin cells affected by warts when applied to it and thus leads to its breakdown in the body.

• Acetylsalicylic acid is one of the substances used in anti-dan ramp shampoos. This is because acetylsalicylic acid prevents the accumulation of sebum in the pores of the skin and on the surrounding hair follicles.

• Acetylsalicylic acid also shows little antiseptic effect because it is a known bacteriostatic substance. It does not kill existing germs (so it is not an antibacterial agent) but it prevents the growth of germs when used.

• Acetylsalicylic acid also helps to remove blackheads. This is done with acetylsalicylic acid in the same ways as for acne prevention. It does not allow the skin pores to close and those that are already closed can be opened with the use of acetylsalicylic acid in that area.

• Acetylsalicylic acid is also used to treat infections of the worms and the wet form of infection with the tinea pedis (also known as athlete's foot). Acetylsalicylic acid is also used to treat a very rare skin disease, called Ichthyosis, in which the skin becomes dry, scaly, and thick.

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Frequently Asked Questions (FAQs)

1. What is the use of acetylsalicylic acid?

Acetylsalicylic acid, commonly known as aspirin, is used to relieve pain, reduce inflammation, and lower fever; it is also used in low doses to reduce the risk of heart attacks and strokes.

2. Is Ecosprin and acetylsalicylic acid same?

Yes, Ecosprin is a brand name for acetylsalicylic acid (aspirin), commonly used in low doses for cardiovascular protection and to reduce blood clotting.

3. Is acetylsalicylic acid a blood thinner?

Yes, acetylsalicylic acid (aspirin) is considered a blood thinner because it inhibits platelet aggregation, reducing the risk of blood clots.

4. What is another name for acetylsalicylic acid?

Another name for acetylsalicylic acid is aspirin.

5. Acetylsalicylic acid Formula?

The chemical formula for acetylsalicylic acid is C₉H₈O₄.

6. Aspirin is chemically named as?

Aspirin is chemically named as Acetylsalicylic acid.

7. Why is acetylsalicylic acid classified as a carboxylic acid?

Acetylsalicylic acid is classified as a carboxylic acid because it contains a carboxyl group (-COOH). This functional group is characteristic of carboxylic acids and is responsible for many of the compound's chemical properties, including its acidity.

8. How does the structure of acetylsalicylic acid relate to its function as a pain reliever?

The structure of acetylsalicylic acid allows it to inhibit the enzyme cyclooxygenase (COX), which is responsible for producing prostaglandins that cause pain and inflammation. The acetyl group in aspirin can transfer to and modify the COX enzyme, thereby reducing pain and inflammation.

9. How does acetylsalicylic acid behave in water?

Acetylsalicylic acid is slightly soluble in water. When dissolved, it partially dissociates into its ions, releasing hydrogen ions (H+) and making the solution acidic. This behavior is typical of weak organic acids.

10. What is the significance of the acetyl group in acetylsalicylic acid?

The acetyl group in acetylsalicylic acid is crucial for its function as a pain reliever and anti-inflammatory agent. It allows the molecule to acetylate (add an acetyl group to) the cyclooxygenase enzyme, inhibiting its activity and reducing the production of pain-causing prostaglandins.

11. What is acetylsalicylic acid, and why is it important?

Acetylsalicylic acid, commonly known as aspirin, is a synthetic organic compound with the formula C9H8O4. It's important because it's a widely used medication for pain relief, fever reduction, and anti-inflammatory purposes. Its discovery revolutionized medicine and it continues to be one of the most commonly used drugs worldwide.

12. How is acetylsalicylic acid prepared?

Acetylsalicylic acid is prepared by reacting salicylic acid with acetic anhydride in the presence of a catalytic amount of phosphoric acid. This reaction is an esterification process, where the hydroxyl group of salicylic acid reacts with acetic anhydride to form an ester bond.

13. What is the importance of purity in the synthesis of acetylsalicylic acid?

Purity is crucial in the synthesis of acetylsalicylic acid because impurities can affect its efficacy and safety as a medication. Common impurities like salicylic acid or acetic acid can cause stomach irritation. High purity is essential for consistent dosing and minimizing side effects.

14. What is the difference between salicylic acid and acetylsalicylic acid?

Salicylic acid and acetylsalicylic acid differ in their chemical structure. Salicylic acid has a hydroxyl group (-OH) directly attached to the benzene ring, while acetylsalicylic acid has this hydroxyl group replaced by an acetyl group (-OCOCH3). This structural difference gives acetylsalicylic acid additional anti-inflammatory properties not present in salicylic acid.

15. What is the significance of acetylsalicylic acid's ability to form esters?

Acetylsalicylic acid's ability to form esters is significant for its synthesis and its mechanism of action. The ester linkage in aspirin (between the acetyl group and salicylic acid) is key to its function. In the body, this ester can transfer its acetyl group to enzymes, which is the basis of its anti-inflammatory and antiplatelet effects.

16. How does the presence of the acetyl group affect the solubility of acetylsalicylic acid compared to salicylic acid?

The acetyl group in acetylsalicylic acid makes it less soluble in water compared to salicylic acid. This is because the acetyl group is less polar than the hydroxyl group it replaces, reducing the molecule's overall polarity and its ability to form hydrogen bonds with water molecules.

17. What is the structural formula of acetylsalicylic acid?

The structural formula of acetylsalicylic acid is:

18. What role does resonance play in the structure and properties of acetylsalicylic acid?

Resonance in acetylsalicylic acid occurs primarily in the carboxyl group and the benzene ring. This electron delocalization contributes to the stability of the molecule and influences its reactivity. The resonance in the carboxyl group also contributes to its acidity by stabilizing the conjugate base.

19. How does the pH of a solution affect the stability of acetylsalicylic acid?

Acetylsalicylic acid is most stable in acidic conditions. In neutral or alkaline solutions, it tends to hydrolyze (break down in the presence of water) into salicylic acid and acetic acid. This is why aspirin tablets often contain a small amount of acid to enhance stability.

20. What are the main uses of acetylsalicylic acid?

The main uses of acetylsalicylic acid include:

21. What is the significance of acetylsalicylic acid's ability to cross the blood-brain barrier?

Acetylsalicylic acid's ability to cross the blood-brain barrier is crucial for its fever-reducing and pain-relieving effects. This allows it to reach the hypothalamus (the body's thermostat) to reduce fever and affect pain perception in the central nervous system.

22. What is the role of catalysts in the synthesis of acetylsalicylic acid?

Catalysts, such as phosphoric acid or sulfuric acid, are used in the synthesis of acetylsalicylic acid to increase the rate of the esterification reaction between salicylic acid and acetic anhydride. The catalyst lowers the activation energy of the reaction, allowing it to proceed more quickly and efficiently without being consumed in the process.

23. What is the environmental impact of acetylsalicylic acid production and disposal?

The production of acetylsalicylic acid involves organic solvents and generates waste products that need proper disposal. When released into the environment, it can affect aquatic organisms. However, it generally degrades relatively quickly in the environment. Proper disposal of unused medications is important to minimize environmental impact.

24. What is the significance of acetylsalicylic acid's ability to form salts?

Acetylsalicylic acid's ability to form salts is important for its formulation in certain medications. Salts like calcium aspirin or sodium aspirin can have different solubility properties and can be less irritating to the stomach than the free acid form. This allows for the development of various aspirin formulations for different uses.

25. What is the role of acetylsalicylic acid in the pharmaceutical industry beyond its use as a medication?

Beyond its direct use as a medication, acetylsalicylic acid serves as a starting material or intermediate in the synthesis of other pharmaceuticals. Its relatively simple structure and well-understood chemistry make it a valuable building block in organic synthesis for more complex drug molecules.

26. How does the presence of electron-withdrawing groups affect the reactivity of acetylsalicylic acid?

The electron-withdrawing groups in acetylsalicylic acid, particularly the carboxyl and acetyl groups, increase the electrophilicity of the carbonyl carbons. This makes these carbons more susceptible to nucleophilic attack, influencing reactions like hydrolysis and the compound's interactions with enzymes.

27. How does acetylsalicylic acid differ from other pain relievers like ibuprofen or acetaminophen?

While all three are pain relievers, they work differently. Acetylsalicylic acid (aspirin) irreversibly inhibits both COX-1 and COX-2 enzymes. Ibuprofen reversibly inhibits both COX enzymes. Acetaminophen (paracetamol) primarily affects the central nervous system and has little anti-inflammatory effect. Aspirin also has antiplatelet effects, which the others don't have.

28. What is the mechanism of acetylsalicylic acid's antiplatelet action?

Acetylsalicylic acid irreversibly inhibits the enzyme cyclooxygenase-1 (COX-1) in platelets. This prevents the formation of thromboxane A2, a compound that promotes platelet aggregation and blood clotting. As platelets cannot synthesize new enzymes, this effect lasts for the lifetime of the platelet (about 7-10 days).

29. How does the body metabolize acetylsalicylic acid?

Acetylsalicylic acid is rapidly hydrolyzed in the body to salicylic acid, which is the active metabolite. This occurs primarily in the liver but also in the blood and other tissues. Salicylic acid is then further metabolized and excreted in the urine.

30. How does the structure of acetylsalicylic acid contribute to its acidity?

The carboxylic acid group (-COOH) in acetylsalicylic acid is responsible for its acidity. The carbonyl group (C=O) within the carboxylic acid withdraws electrons, making the hydrogen more easily dissociable and thus increasing the acidity of the molecule.

31. How does the melting point of acetylsalicylic acid compare to that of salicylic acid, and why?

Acetylsalicylic acid has a lower melting point (135°C) compared to salicylic acid (159°C). This is because the acetyl group in acetylsalicylic acid disrupts the hydrogen bonding between molecules, reducing the intermolecular forces and thus lowering the melting point.

32. How does temperature affect the rate of hydrolysis of acetylsalicylic acid?

Increasing temperature accelerates the rate of hydrolysis of acetylsalicylic acid. This is because higher temperatures provide more energy for molecules to overcome the activation energy barrier for the hydrolysis reaction. This is why aspirin tablets should be stored in a cool, dry place to maintain their stability.

33. How does the structure of acetylsalicylic acid contribute to its ability to inhibit prostaglandin synthesis?

The structure of acetylsalicylic acid, particularly its acetyl group, allows it to fit into the active site of the cyclooxygenase (COX) enzyme. The acetyl group can then be transferred to a specific serine residue in the enzyme, modifying it and preventing the conversion of arachidonic acid to prostaglandins.

34. What is the significance of acetylsalicylic acid's ability to form hydrogen bonds?

Acetylsalicylic acid's ability to form hydrogen bonds is important for its interactions with water (affecting solubility) and with biological molecules (influencing its pharmacological effects). The carboxyl group can act as both a hydrogen bond donor and acceptor, while the carbonyl oxygen of the acetyl group can act as a hydrogen bond acceptor.

35. How does the pKa of acetylsalicylic acid compare to other carboxylic acids, and why?

The pKa of acetylsalicylic acid is about 3.5, which is lower (more acidic) than many simple carboxylic acids. This increased acidity is due to the electron-withdrawing effect of the acetyl group and the stabilization of the conjugate base through resonance with the aromatic ring.

36. What is the importance of stereochemistry in acetylsalicylic acid?

Acetylsalicylic acid does not exhibit stereoisomerism as it doesn't have a chiral center. However, the planar structure of its aromatic ring and the specific orientation of its functional groups are crucial for its ability to interact with and inhibit the COX enzymes.

37. How does acetylsalicylic acid interact with other medications?

Acetylsalicylic acid can interact with various medications. It can enhance the effects of anticoagulants, increasing bleeding risk. It can also reduce the effectiveness of some blood pressure medications. When combined with other NSAIDs, it can increase the risk of gastrointestinal side effects. These interactions are due to its effects on prostaglandin synthesis and platelet function.

38. How does the structure of acetylsalicylic acid relate to its ability to cross cell membranes?

The structure of acetylsalicylic acid allows it to cross cell membranes relatively easily. Its carboxylic acid group can exist in both ionized and non-ionized forms. The non-ionized form is lipophilic, allowing it to pass through the lipid bilayer of cell membranes. Once inside the cell, it can ionize again, contributing to its pharmacological effects.

39. How does the structure of acetylsalicylic acid contribute to its stability in solid form?

In solid form, acetylsalicylic acid molecules form a crystal lattice stabilized by intermolecular forces, including hydrogen bonding between the carboxyl groups of adjacent molecules. The planar structure of the benzene ring allows for efficient packing. These factors contribute to its stability in solid form, although it can still slowly degrade over time, especially in the presence of moisture.

40. What is the significance of acetylsalicylic acid's ability to form coordination compounds with metals?

Acetylsalicylic acid can form coordination compounds with certain metals, particularly copper and iron. This property is important in understanding its interactions in biological systems and potential side effects. For example, its ability to chelate iron can contribute to iron deficiency in some individuals who take large doses regularly.

41. How does the structure of acetylsalicylic acid relate to its bitter taste?

The bitter taste of acetylsalicylic acid is related to its ability to interact with taste receptors on the tongue. The carboxyl group and the overall structure of the molecule allow it to bind to bitter taste receptors. This bitter taste is one reason why aspirin tablets are often coated or formulated with taste-masking agents.

42. What is the importance of acetylsalicylic acid's lipophilicity?

The lipophilicity of acetylsalicylic acid is crucial for its pharmacokinetics. It allows the molecule to cross cell membranes and the blood-brain barrier, contributing to its wide distribution in the body. This property also influences its absorption in the gastrointestinal tract and its ability to interact with target enzymes within cells.

43. How does the structure of acetylsalicylic acid contribute to its ability to form polymorphs?

Acetylsalicylic acid can form different crystal structures or polymorphs due to the various ways its molecules can pack together in the solid state. This is influenced by the planar aromatic ring and the flexible carboxylic acid and acetyl groups. Different polymorphs can have slightly different physical properties, which can be important in pharmaceutical formulations.

44. What is the significance of acetylsalicylic acid's ability to undergo hydrolysis in different pH environments?

The rate of hydrolysis of acetylsalicylic acid varies with pH, which is significant for its stability and pharmacokinetics. In acidic environments (like the stomach), hydrolysis is slower, helping the drug remain intact for absorption. In more alkaline environments (like the small intestine or bloodstream), hydrolysis occurs more rapidly, releasing the active salicylate.

45. How does the structure of acetylsalicylic acid relate to its ability to inhibit different isoforms of cyclooxygenase?

Acetylsalicylic acid's structure allows it to inhibit both COX-1 and COX-2 enzymes, but it has a stronger effect on COX-1. The acetyl group can fit into the active site of both enzymes, but the slight differences in the structure of the active sites result in different binding affinities and inhibition potencies for each isoform.

46. What is the importance of acetylsalicylic acid's ability to form hydrogen bonds with water?

Acetylsalicylic acid's ability to form hydrogen bonds with water is crucial for its dissolution in aqueous environments like the gastrointestinal tract and bloodstream. This property influences its solubility, which in turn