Dr. Shruti Ramteke

Steraic acid has various names like Octadecanoic acid, Stearophanic acid, n-Octadecanoic acid, etc.

Stearic acid comes under the category of long chain saturated fatty acid which consists of eighteen carbon atoms. The fat of various plants and animals contains stearic acid. Stearic acid is a useful kind of saturated fatty acid comes from plants and animals and it is waxy solid.

Stearic Acid Structure

Chevreul M.E. was the scientist who basically discovers formula of stearic acid. Stearic acid named from the Gracian word “stear’ that means fat (specially known for beef fat). The stearic acid has molecular formula C₁₈H₃₆O₂. Following is the stearic acid structure which consists of a long chain of carbon atoms containing total eighteen carbon atoms.

From all the carbon atoms sixteen carbons form a long chain of CH₂ groups attached in the middle of the structure. At the one end of the structure with one methyl (CH₃) group is attached and on the other end carboxylic (COOH) group is attached to it.

The IUPAC name of stearic acid is octadecanoic acid. The chemical formula for stearic acid is CH₃(CH₂)₁₆COOH. It is a sticky in nature and white or slight yellowish solid crystalline powder with a characteristic mild odour. Stearic acid boiling point is 383 degree Celsius and melting point is 68.8 degree Celsius.

Stearic acid is the main constituent of shea butter and cocoa butter. Stearic acid has a mild odour and solid in nature which is whitish in colour. Stearic acid gets floats on water if we try to dissolve it in water.

Stearic acid is not soluble in water as we see it floating on water. But it is quietly slight soluble in some organic solvents like benzene and ethanol. Stearic acid is completely soluble in organic solvents like chloroform, acetone and carbon disulphide. Stearic acid can consider stable under some recommended storing conditions.

Stearic acid when heated to high temperature to decomposition it gets decomposed on boiling point of 360 degree Celsius and it also emits some irritating fumes and acrid smoke. Stearic acid gets volatize slowly at the temperature of 90 to 100 degree Celsius. Esterification of stearic acid is known as stearates.

Sodium or potassium salts of saturated fatty acids are known as soaps which are prepared by saponification or alkaline hydrolysis of fats. Stearic acid in pure form is obtained by various complicated methods like vacuum distillation, from a crystallization mixture, or acids chromatography and other suitable derivatives. Carboxylic acids are a typical chemical reaction undergone by pure acids, which is a waxy solid, colourless and not soluble in water.

Stearic acid comes under saturated fats which is active in various diets as contrast with the other saturated fats and carbohydrates. Stearic acid is better known for the decrease of nasty cholesterol i.e. low density lipoproteins (LDL) cholesterol. In various studies, stearic acid is shown to be quite safe.

Principal source of stearic acid is animal fats, with some contribution of green fats i.e. vegetable or botanical or plants fats except palm kernel oil, coconut, shea butter etc. Likewise, there is no proof that ingesting Stearic Acid causes heart disease and does not affect a blood lipid profile of any person during consumption.

Stearic acid has a very high melting point as it comes under saturated fatty acids. Stearic acid occurs in nature in dilute levels still it gets utilised in various food items. If stearic acid treated with magnesium metal, there is the formation of an ester magnesium stearate. Magnesium stearate is toxic in nature and should cause various negative effects after getting ingest. This magnesium stearate molecule is also causing irritation to the respiratory organs and skin on combustion and heats up freely.

Stearic Acid production

Stearic acid is made by oils and shows the properties of fatty acids. Stearic acid is produced by triglycerides saponification by heating the solution at the temperature of 100 degree Celsius. Then the subsequent solution gets distilled. Octadecanoic acid which is generally available is a mix acid i.e. the mixture of stearic acid and palmitic acid.

In terms of oils and fats, stereophonic acid consists of more fat of animals than vegetable fats. Cocoa butter and Shea butter is the only outliers which contains at least 28 to 45 per cent of stearic acids which possess the fatty acids properties. With the help of fatty acid machinery stearic acid can be made from crabs biosynthetically.

Uses of stearic acid

Stearic acid used as a flavouring agents in the food category like frozen dairy, baked goods, gelatin and puddings, non-alcoholic beverages, cheese, soft candies, hard candies, etc.

Stearic acid is used for ointments, suppositories, coating bitter remedies and coating enteric pills.

Stearic acid is used in the manufacturing of esters i.e. stearates with metals like zinc, aluminium and other metals.

Stearin soap is used for phonograph records, insulators, opodeldoc, candels, plaster of paris impregnation, compounds modelling, and vanishing cream and in some various other cosmetics.

Stearic acid is used as food additive and lubricating agent.

It is used in detergent production and pharmaceuticals manufacturing.

Stearic acid is used in food packaging industry and also in preparation of shampoos, soaps and cosmetics.

Acetylsalicylic Acid Structure and IUPAC Name

Acetylsalicylic acid, commonly known as aspirin, is a synthesized derivative of salicylic acid. It is widely used as a medication to relieve pain, reduce inflammation, and lower fever. Understanding the chemical structure and IUPAC name of acetylsalicylic acid is essential for comprehending its properties and mechanisms of action.

Chemical Structure

Acetylsalicylic acid has a molecular formula of C9H8O4 and a molecular weight of 180.16 g/mol. Its chemical structure consists of a benzene ring with two functional groups attached to it: an acetyl group (-COCH3) and a carboxylic acid group (-COOH). The acetyl group is attached to the benzene ring at the ortho position, while the carboxylic acid group is attached at the meta position.

The acetyl group is introduced through a process called acetylation, which involves the esterification of salicylic acid. During this reaction, the hydroxyl group (-OH) of salicylic acid reacts with acetic anhydride, resulting in the formation of acetylsalicylic acid. This acetylation reaction is catalyzed by an acid catalyst, such as sulfuric acid.

The chemical structure of acetylsalicylic acid is responsible for its pharmacological properties. The acetyl group enhances the lipophilicity of the molecule, allowing it to cross cell membranes more easily. This property contributes to the rapid absorption and distribution of acetylsalicylic acid in the body.

IUPAC Name

The IUPAC name of acetylsalicylic acid is 2-Acetoxybenzoic acid. This name reflects the presence of the acetyl group (-COCH3) attached to the benzene ring, as well as the carboxylic acid group (-COOH) at the meta position.

The IUPAC nomenclature system is used to provide a standardized way of naming chemical compounds. It ensures clarity and consistency in the identification and communication of chemical structures. By using the IUPAC name, scientists and healthcare professionals can accurately refer to acetylsalicylic acid in their research and clinical practice.

Salicylic Acid Structure and IUPAC Name

Salicylic acid is a natural compound found in the bark of the Willow tree. It is a versatile chemical with various applications in medicine, skincare, and even food preservation. Understanding its chemical structure and IUPAC name can provide valuable insights into its properties and functions.

Chemical Structure

The chemical structure of salicylic acid consists of a benzene ring with a hydroxyl group (-OH) and a carboxyl group (-COOH) attached to it. This structure gives salicylic acid its characteristic properties and allows it to interact with other molecules in a specific way.

The molecular formula of salicylic acid is C₇H₆O₃, and its molecular weight is approximately 138.12 g/mol. The presence of the hydroxyl group makes salicylic acid a weak acid, which means it can donate a proton (H⁺) in a chemical reaction.

Salicylic acid is often referred to as a precursor to acetylsalicylic acid, commonly known as aspirin. This is because acetylsalicylic acid is synthesized from salicylic acid through a process called acetylation. During acetylation, an acetyl group (-COCH₃) is added to the hydroxyl group of salicylic acid, resulting in the formation of acetylsalicylic acid.

IUPAC Name

The IUPAC name of salicylic acid is 2-Hydroxybenzoic acid. This name accurately reflects the structure of the compound, with the hydroxyl group located at the 2-position of the benzene ring and the carboxyl group at the 1-position.

The IUPAC naming system is a standardized way of naming chemical compounds, ensuring clarity and consistency in scientific communication. By using the IUPAC name, researchers and chemists can easily identify and refer to specific compounds, regardless of their common names or synonyms.

Acetylsalicylic Acid Structure Functional Groups

Acetylsalicylic acid, commonly known as aspirin, is a medication that has been widely used for its analgesic, anti-inflammatory, and antipyretic properties. Understanding the structure of acetylsalicylic acid is crucial in comprehending its chemical properties and mode of action.

Acetyl Group: Attached to the hydroxyl group of salicylic acid

One of the key functional groups in acetylsalicylic acid is the acetyl group. This group is attached to the hydroxyl group (-OH) of salicylic acid through a process called acetylation. The acetyl group is composed of two carbon atoms, three hydrogen atoms, and one oxygen atom, forming the chemical formula CH3CO-. This acetylation reaction involves the replacement of the hydroxyl group with the acetyl group, resulting in the formation of acetylsalicylic acid.

The addition of the acetyl group to the salicylic acid molecule alters its chemical properties, leading to the development of aspirin. This modification enhances the stability and solubility of the compound, making it more suitable for medicinal use.

Carboxyl Group: Present in both salicylic acid and acetylsalicylic acid

Another important functional group found in both salicylic acid and acetylsalicylic acid is the carboxyl group. The carboxyl group is composed of one carbon atom, one oxygen atom, and one hydroxyl group (-OH), forming the chemical formula -COOH. This group is responsible for the acidic properties of these compounds.

In salicylic acid, the carboxyl group is directly attached to the benzene ring. However, during the acetylation process, the carboxyl group remains intact in the final structure of acetylsalicylic acid. This group plays a crucial role in the pharmacological activity of aspirin by facilitating its interaction with target molecules in the body.

Understanding the functional groups present in the structure of acetylsalicylic acid provides insights into its chemical properties and mode of action. The acetyl group, attached to the hydroxyl group of salicylic acid, enhances the stability and solubility of the compound. The carboxyl group, present in both salicylic acid and acetylsalicylic acid, contributes to the acidic properties and pharmacological activity of aspirin.

How Does Acetylsalicylic Acid Work?

Acetylsalicylic acid, commonly known as aspirin, is a widely used medication that belongs to the class of nonsteroidal anti-inflammatory drugs (NSAIDs). It is primarily used to relieve pain, reduce inflammation, and lower fever. But have you ever wondered how acetylsalicylic acid actually works in our bodies? In this section, we will explore the mechanism of action of acetylsalicylic acid and its antiplatelet activity.

Mechanism of Action: Inhibition of Prostaglandin Production

One of the key ways in which acetylsalicylic acid works is by inhibiting the production of prostaglandins. Prostaglandins are hormone-like substances that play a crucial role in the body’s inflammatory response and pain signaling. They are produced by an enzyme called cyclooxygenase (COX).

Acetylsalicylic acid acts by irreversibly inhibiting the COX enzyme, specifically COX-1 and COX-2. By doing so, it prevents the conversion of arachidonic acid into prostaglandins. This inhibition of prostaglandin synthesis leads to a reduction in pain, inflammation, and fever.

Antiplatelet Activity: Preventing Blood Clot Formation

In addition to its role as an analgesic and anti-inflammatory agent, acetylsalicylic acid also exhibits antiplatelet activity. Platelets are small cell fragments in the blood that play a crucial role in blood clotting. When blood vessels are damaged, platelets aggregate at the site of injury to form a clot, preventing excessive bleeding.

Acetylsalicylic acid works as an antiplatelet agent by inhibiting the production of thromboxane A2, a substance that promotes platelet aggregation and blood clot formation. By inhibiting thromboxane A2, acetylsalicylic acid helps to prevent the formation of unwanted blood clots, reducing the risk of heart attacks and strokes.

It is important to note that the antiplatelet activity of acetylsalicylic acid is long-lasting due to its irreversible inhibition of COX enzymes. This means that even a single dose of acetylsalicylic acid can have an effect on platelet function for several days.

Salicylic Acid Structure Melting Point

Salicylic acid, a commonly used compound in various industries, possesses a unique structure and characteristic melting point. Understanding the structure and melting point of salicylic acid is essential for its applications in pharmaceuticals, cosmetics, and organic synthesis.

Salicylic acid has a molecular formula of C7H6O3 and a molecular weight of 138.12 g/mol. It is a white crystalline solid that is sparingly soluble in water but dissolves readily in organic solvents such as ethanol and ether. The chemical structure of salicylic acid consists of a benzene ring substituted with a carboxylic acid (-COOH) group and a hydroxyl (-OH) group.

The melting point of salicylic acid is an important physical property that determines its solid-state behavior. The melting point of a substance is the temperature at which it changes from a solid to a liquid state. In the case of salicylic acid, it has a melting point range of approximately 159-161°C.

The melting point of salicylic acid can vary slightly depending on factors such as impurities and the rate of heating. Impurities in the sample can lower the melting point, while a slower heating rate can result in a higher melting point. Therefore, it is crucial to use pure salicylic acid and standardize the heating conditions when determining its melting point.

The melting point range of salicylic acid is relatively high compared to many other organic compounds. This is due to the presence of intermolecular hydrogen bonding between the hydroxyl and carboxylic acid groups. These hydrogen bonds create a network of interactions that stabilize the solid structure of salicylic acid.

The melting point of salicylic acid is often used as a quality control parameter in its production and purification processes. It serves as an indicator of the compound’s purity and can help identify any impurities present. Additionally, the melting point can be used to differentiate salicylic acid from other compounds with similar structures.

Acetylsalicylic Acid Structure Name

Acetylsalicylic acid, commonly known as aspirin, is a widely used medication that belongs to the class of nonsteroidal anti-inflammatory drugs (NSAIDs). It is primarily used to relieve pain, reduce inflammation, and lower fever. The structure of acetylsalicylic acid is composed of two main components: a benzene ring and a carboxylic acid group. Let’s explore the common and chemical names of this compound in more detail.

Common Name: Aspirin

Aspirin is the most well-known and widely used name for acetylsalicylic acid. It is a non-prescription drug that can be easily obtained over the counter. Aspirin is often used to alleviate minor aches and pains, such as headaches, toothaches, and muscle soreness. It is also commonly used as a blood thinner to reduce the risk of heart attacks and strokes.

Chemical Name: 2-Acetoxybenzoic Acid

The chemical name of acetylsalicylic acid is 2-acetoxybenzoic acid. This name provides a more precise description of the compound’s chemical structure. The “2” in the name indicates the position of the acetyl group on the benzene ring. The acetyl group is derived from acetic acid and is attached to the hydroxyl group of salicylic acid through an esterification reaction.

The presence of the acetyl group in acetylsalicylic acid is what distinguishes it from its precursor, salicylic acid. The acetylation of salicylic acid results in the formation of acetylsalicylic acid, which exhibits different properties and therapeutic effects.

To summarize, acetylsalicylic acid, also known as aspirin, has a chemical structure consisting of a benzene ring and a carboxylic acid group. Its common name, aspirin, is widely recognized and used in everyday language, while its chemical name, 2-acetoxybenzoic acid, provides a more detailed description of its structure. Understanding the structure of acetylsalicylic acid is essential for comprehending its properties and mechanisms of action.

Acetylsalicylic Acid Chemistry

Acetylsalicylic acid, commonly known as aspirin, is a widely used medication that belongs to the class of drugs known as nonsteroidal anti-inflammatory drugs (NSAIDs). It is primarily used to relieve pain, reduce inflammation, and lower fever. Understanding the chemistry of acetylsalicylic acid is crucial to comprehend its structure and properties.

Synthesis

The reaction can be represented as follows:

Salicylic acid + Acetic anhydride → Acetylsalicylic acid + Acetic acid

The acetylation reaction results in the formation of acetylsalicylic acid and acetic acid as a byproduct. The presence of the acetyl group in acetylsalicylic acid is responsible for its pharmacological properties.

Chemical Formula

The chemical formula of acetylsalicylic acid is C9H8O4. It consists of nine carbon atoms, eight hydrogen atoms, and four oxygen atoms. The molecular formula represents the actual number of atoms present in a molecule.

Molecular Structure

The molecular structure of acetylsalicylic acid is characterized by a benzene ring fused with a carboxylic acid group (-COOH) and an ester group (-COOCH3). The benzene ring provides stability to the molecule, while the carboxylic acid group and ester group contribute to its acidic and ester-like properties, respectively.

The acetyl group (-COCH3) is attached to the hydroxyl group (-OH) of salicylic acid, resulting in the formation of an ester linkage. This esterification process leads to the synthesis of acetylsalicylic acid.

Properties

Acetylsalicylic acid is a white crystalline powder that is sparingly soluble in water but readily soluble in organic solvents such as ethanol and acetone. It has a melting point of around 135-136°C.

One of the key properties of acetylsalicylic acid is its ability to inhibit the production of prostaglandins, which are responsible for pain, inflammation, and fever. This mechanism of action makes it an effective analgesic, anti-inflammatory, and antipyretic agent.

In addition to its therapeutic properties, acetylsalicylic acid also exhibits antiplatelet activity, which means it helps prevent the formation of blood clots. This property has led to its widespread use as a preventive medication for cardiovascular diseases.

Overall, the chemistry of acetylsalicylic acid plays a crucial role in understanding its structure, synthesis, and properties. This knowledge is essential for the development of new drugs and the optimization of existing medications for various therapeutic purposes.

How Was Acetylsalicylic Acid Discovered?

Acetylsalicylic acid, commonly known as aspirin, was first synthesized by chemist Felix Hoffmann at Bayer in 1897. The discovery of this compound marked a significant milestone in the field of medicine and revolutionized the treatment of pain, inflammation, and fever.

The Journey of Discovery

The story of acetylsalicylic acid begins with a compound called salicylic acid. Salicylic acid is derived from willow bark and has been used for centuries to alleviate pain and reduce fever. However, it had some drawbacks, including its strong acidity, which could irritate the stomach lining.

Felix Hoffmann, a young chemist working at Bayer, set out to find a way to modify salicylic acid to make it more tolerable and effective. His goal was to create a compound that retained the beneficial properties of salicylic acid while minimizing its side effects.

The Synthesis of Acetylsalicylic Acid

Hoffmann’s breakthrough came through a process known as acetylation. Acetylation involves adding an acetyl group to a molecule, in this case, salicylic acid. By doing so, Hoffmann was able to modify the chemical structure of salicylic acid and create a new compound: acetylsalicylic acid.

The acetylation reaction involved treating salicylic acid with acetic anhydride, a compound that provides the acetyl group necessary for the reaction. This process resulted in the formation of acetylsalicylic acid and acetic acid as a byproduct.

The Significance of Acetylsalicylic Acid

The discovery of acetylsalicylic acid had a profound impact on medicine. Unlike salicylic acid, acetylsalicylic acid was much less acidic, making it gentler on the stomach. This breakthrough allowed for the widespread use of acetylsalicylic acid as a pain reliever, anti-inflammatory agent, and fever reducer.

Furthermore, acetylsalicylic acid exhibited enhanced stability and a longer shelf life compared to salicylic acid. This made it easier to produce and distribute, further contributing to its popularity and widespread use.

The Legacy of Acetylsalicylic Acid

Since its discovery, acetylsalicylic acid has become one of the most widely used drugs in the world. Its effectiveness in relieving pain, reducing inflammation, and preventing blood clotting has made it a staple in medicine cabinets around the globe.

Beyond its medicinal uses, acetylsalicylic acid has also found applications in various industries. It is used in the production of dyes, fragrances, and polymers. Additionally, ongoing research suggests that acetylsalicylic acid may have potential benefits in the prevention and treatment of certain types of cancer.

Structure of Aspirin

Aspirin, also known as acetylsalicylic acid, is a widely used medication that belongs to the class of drugs known as nonsteroidal anti-inflammatory drugs (NSAIDs). It is commonly used to relieve pain, reduce inflammation, and lower fever. Understanding the chemical structure of aspirin is crucial in comprehending its mechanism of action and how it interacts with the body.

Chemical Structure

The chemical structure of aspirin consists of a benzene ring with an acetyl group (-COCH3) and a carboxyl group (-COOH) attached to it. This unique arrangement of atoms gives aspirin its distinct properties and therapeutic effects.

The acetyl group is derived from acetic acid, which is obtained through a process called acetylation. Acetylation involves the reaction of acetic acid with salicylic acid, resulting in the formation of acetylsalicylic acid, or aspirin. This process is essential in the synthesis of aspirin and is responsible for its analgesic and anti-inflammatory properties.

The carboxyl group, on the other hand, is responsible for the acidic nature of aspirin. It is this group that allows aspirin to undergo hydrolysis in the stomach, converting it into salicylic acid. Salicylic acid is the active form of aspirin that exerts its effects on the body.

To better understand the structure of aspirin, let’s take a closer look at its molecular formula and molecular structure.

Molecular Formula and Structure

The molecular formula of aspirin is C9H8O4, indicating that it consists of nine carbon atoms, eight hydrogen atoms, and four oxygen atoms. The molecular structure of aspirin can be represented as follows:

As shown in the image, the benzene ring forms the backbone of the molecule, with the acetyl group (-COCH3) attached to one side and the carboxyl group (-COOH) attached to the other side. This arrangement of atoms gives aspirin its characteristic shape and allows it to interact with specific receptors in the body.

Understanding the structure of aspirin is essential in comprehending its mechanism of action and how it interacts with the body. By targeting specific enzymes involved in the production of inflammatory mediators, aspirin effectively reduces pain and inflammation. Additionally, its ability to inhibit platelet aggregation makes it a valuable medication for preventing cardiovascular events.

Chemical Structure of Acetylsalicylic Acid

Acetylsalicylic acid, commonly known as aspirin, is a widely used medication that belongs to the class of drugs known as nonsteroidal anti-inflammatory drugs (NSAIDs). It is primarily used to relieve pain, reduce inflammation, and lower fever. Understanding the chemical structure of acetylsalicylic acid is crucial in comprehending its properties and mechanisms of action.

Molecular Formula: C9H8O4

The molecular formula of acetylsalicylic acid is C9H8O4, which represents the number and types of atoms present in a molecule. In this case, there are nine carbon atoms (C), eight hydrogen atoms (H), and four oxygen atoms (O). The molecular formula provides a basic understanding of the composition of acetylsalicylic acid, but it does not reveal the arrangement of atoms within the molecule.

To gain a deeper insight into the structure of acetylsalicylic acid, we need to examine its molecular structure.

Molecular Structure

The molecular structure of acetylsalicylic acid consists of a benzene ring attached to a carboxylic acid group (COOH) and an ester group (COOCH3). The benzene ring is a six-membered ring composed of alternating carbon and hydrogen atoms. The carboxylic acid group is represented by the COOH moiety, which consists of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (OH). The ester group, represented by COOCH3, is formed through the reaction of an alcohol group (-OH) with an acid group (-COOH), resulting in the formation of an ester bond (-COO-).

The presence of the acetyl group (CH3CO-) in acetylsalicylic acid is responsible for its name. The acetyl group is formed through a process called acetylation, which involves the addition of an acetyl group to a compound. In the case of acetylsalicylic acid, acetylation occurs through the esterification of salicylic acid with acetic anhydride.

Acetylsalicylic Acid Synthesis

The synthesis of acetylsalicylic acid involves the reaction between salicylic acid and acetic anhydride in the presence of a catalyst, such as sulfuric acid. During the reaction, the hydroxyl group (-OH) of salicylic acid reacts with the acetic anhydride, resulting in the formation of acetylsalicylic acid and acetic acid. The reaction can be represented as follows:

Salicylic acid + Acetic anhydride → Acetylsalicylic acid + Acetic acid

The synthesis of acetylsalicylic acid is an important process in the pharmaceutical industry, as it allows for the production of aspirin on a large scale.

Properties of Acetylsalicylic Acid

Acetylsalicylic acid exhibits several properties that contribute to its therapeutic effects. It is a white, crystalline powder that is sparingly soluble in water but soluble in organic solvents. It has a melting point of around 135 degrees Celsius.

One of the key properties of acetylsalicylic acid is its ability to inhibit the production of prostaglandins, which are responsible for mediating pain, inflammation, and fever. By inhibiting the enzyme cyclooxygenase (COX), acetylsalicylic acid reduces the synthesis of prostaglandins, thereby alleviating pain and inflammation.

Furthermore, acetylsalicylic acid has anticoagulant properties, meaning it can prevent the formation of blood clots. This property is particularly useful in reducing the risk of heart attacks and strokes.

Salicylic Acid Structure Name

Salicylic acid, also known as 2-hydroxybenzoic acid, is a common organic compound with a chemical formula C7H6O3. It is widely used in various industries, including pharmaceuticals, cosmetics, and agriculture, due to its diverse properties and applications.

Common Name: Salicylic acid

Salicylic acid is the common name for 2-hydroxybenzoic acid. It is derived from the Latin word “salix,” which means willow tree. The compound was first isolated from the bark of willow trees, which have been used for centuries to alleviate pain and reduce fever.

Salicylic acid is a white crystalline solid that is slightly soluble in water. It has a characteristic odor and a bitter taste. It is commonly used in skincare products, such as acne treatments and exfoliants, due to its ability to unclog pores and remove dead skin cells.

Chemical Name: 2-Hydroxybenzoic acid

The chemical name of salicylic acid is 2-hydroxybenzoic acid. This name reflects the compound’s molecular structure, which consists of a benzene ring with a hydroxyl group (-OH) and a carboxylic acid group (-COOH) attached to it.

The hydroxyl group is responsible for the compound’s acidity and its ability to act as a weak acid. The carboxylic acid group contributes to the compound’s solubility in organic solvents and its reactivity in various chemical reactions.

Salicylic acid is an important precursor for the synthesis of many pharmaceutical drugs, including acetylsalicylic acid, commonly known as aspirin. It is also used as a starting material for the production of other salicylates, such as methyl salicylate and ethyl salicylate, which are used in topical analgesics and fragrances.

Salicylic Acid Structure Class 12

Salicylic acid structure is often studied in chemistry classes at the 12th-grade level.

Salicylic acid, also known as 2-hydroxybenzoic acid, is a common organic compound that belongs to the class of aromatic compounds. It is derived from the metabolism of salicin, a natural compound found in plants such as willow bark and wintergreen leaves. Salicylic acid has a molecular formula of C7H6O3 and a molecular weight of 138.12 g/mol.

The structure of salicylic acid consists of a benzene ring with a hydroxyl group (-OH) attached to it at the ortho position (position 2). This hydroxyl group is responsible for the acid properties of salicylic acid. The carboxyl group (-COOH) is attached to the benzene ring at the para position (position 4). The presence of both the hydroxyl and carboxyl groups makes salicylic acid a carboxylic acid.

Here is a table summarizing the structural properties of salicylic acid:

Property	Description
Chemical Formula	C7H6O3
Molecular Weight	138.12 g/mol
Molecular Structure
Functional Groups	Hydroxyl group (-OH) and Carboxyl group (-COOH)
Aromaticity	Benzene ring

Salicylic acid is a precursor to many important compounds, including acetylsalicylic acid, commonly known as aspirin. The synthesis of acetylsalicylic acid involves the acetylation of the hydroxyl group of salicylic acid, where an acetyl group (-COCH3) is added. This reaction is typically carried out through esterification, resulting in the formation of acetylsalicylic acid and water.

Salicylic Acid Structure and Uses

Salicylic acid is a versatile compound that is widely used in the field of medicine and skincare. Its chemical structure plays a crucial role in its effectiveness and applications. Let’s explore the structure of salicylic acid and its various uses.

Structure of Salicylic Acid

Salicylic acid, also known as 2-hydroxybenzoic acid, has a simple yet important molecular structure. It consists of a benzene ring with a hydroxyl group (-OH) attached to it at the ortho position. This hydroxyl group is responsible for the acid properties of salicylic acid. The chemical formula of salicylic acid is C7H6O3.

The molecular structure of salicylic acid is characterized by its aromatic ring and the hydroxyl group, which gives it both acidic and phenolic properties. This unique structure allows salicylic acid to exhibit various beneficial effects on the skin and body.

Uses of Salicylic Acid

Salicylic acid is used in the treatment of various skin conditions, such as acne, psoriasis, and warts. Its keratolytic properties make it effective in exfoliating the skin and unclogging pores, which helps in treating acne. Salicylic acid also has anti-inflammatory properties that can reduce redness and swelling associated with skin conditions.

In addition to its skincare applications, salicylic acid is also used in the production of aspirin. Aspirin, also known as acetylsalicylic acid, is derived from salicylic acid through a process called acetylation. The acetyl group is added to the hydroxyl group of salicylic acid, resulting in the formation of aspirin.

Apart from its role in skincare and pharmaceuticals, salicylic acid is also used as a food preservative, flavoring agent, and in the production of dyes and fragrances. Its versatility and effectiveness make it a valuable compound in various industries.

Salicylic Acid Structure and Hydrogen Bonding

Salicylic acid is a compound that is widely known for its medicinal properties. It is a key ingredient in many over-the-counter skincare products and is also the precursor to acetylsalicylic acid, commonly known as aspirin. One important aspect of salicylic acid’s structure is its ability to form hydrogen bonds, which play a crucial role in its chemical properties and interactions.

Hydrogen Bonding in Salicylic Acid

Salicylic acid contains two functional groups that are capable of forming hydrogen bonds: the hydroxyl group (-OH) and the carboxyl group (-COOH). These groups contain highly electronegative oxygen atoms, which can attract hydrogen atoms from other molecules.

The hydroxyl group in salicylic acid consists of an oxygen atom bonded to a hydrogen atom. This oxygen atom has a partial negative charge due to its high electronegativity, while the hydrogen atom has a partial positive charge. This creates a dipole moment within the hydroxyl group, making it capable of forming hydrogen bonds with other molecules or functional groups.

Similarly, the carboxyl group in salicylic acid also contains an oxygen atom with a partial negative charge and a hydrogen atom with a partial positive charge. This allows the carboxyl group to engage in hydrogen bonding with other molecules or functional groups.

Importance of Hydrogen Bonding

Hydrogen bonding is a type of intermolecular force that plays a crucial role in the physical and chemical properties of many compounds, including salicylic acid. The presence of hydrogen bonding in salicylic acid contributes to its solubility in water and its ability to form complexes with other molecules.

When salicylic acid is dissolved in water, the hydroxyl and carboxyl groups can form hydrogen bonds with water molecules. This interaction allows salicylic acid to dissolve readily in water, making it easier for the compound to be absorbed by the body when ingested or applied topically.

Hydrogen bonding also influences the stability and structure of salicylic acid. The formation of hydrogen bonds between different salicylic acid molecules can lead to the formation of dimers or larger aggregates. These interactions contribute to the overall structure and physical properties of the compound.

Salicylic Acid Structure Functional Groups

Salicylic acid is a compound that plays a crucial role in the synthesis of acetylsalicylic acid, commonly known as aspirin. Understanding the functional groups present in salicylic acid is essential to comprehend its chemical properties and reactivity.

Salicylic acid contains two main functional groups: a hydroxyl group (-OH) and a carboxyl group (-COOH). These functional groups are responsible for the compound’s acidity and its ability to undergo various chemical reactions.

The hydroxyl group (-OH) is a characteristic feature of alcohols. In salicylic acid, this group is attached to a benzene ring, which gives the compound its aromatic nature. The presence of the hydroxyl group makes salicylic acid a weak acid, allowing it to donate a proton (H+) in solution.

The carboxyl group (-COOH) is a combination of a carbonyl group (-C=O) and a hydroxyl group (-OH). It is a characteristic feature of carboxylic acids. The carboxyl group in salicylic acid contributes to its acidity, making it more acidic than the hydroxyl group alone. This acidity is due to the ability of the carboxyl group to release a proton (H+) in solution.

The combination of these two functional groups in salicylic acid gives it unique chemical properties and reactivity. The hydroxyl group allows for hydrogen bonding and solubility in polar solvents, while the carboxyl group enhances its acidity and reactivity towards nucleophiles.

What Parts of Acetylsalicylic Acid Are Rigid

Acetylsalicylic acid, commonly known as aspirin, is a widely used medication with various therapeutic properties. Understanding its structure is crucial in comprehending its function and effects. In this section, we will explore the rigid parts of acetylsalicylic acid, namely the benzene ring and the acetyl group.

The Benzene Ring: A Rigid Structure

The benzene ring is a fundamental component of acetylsalicylic acid’s structure. It consists of six carbon atoms arranged in a hexagonal shape, with alternating single and double bonds. This unique arrangement gives the benzene ring its exceptional stability and rigidity.

The rigid nature of the benzene ring is due to the delocalization of electrons within the ring structure. This delocalization creates a resonance effect, where the electrons are shared among all the carbon atoms in the ring. As a result, the benzene ring remains stable and resistant to deformation.

The rigidity of the benzene ring is essential for the overall stability of acetylsalicylic acid. It ensures that the molecule maintains its structure and properties, allowing it to interact effectively with its target receptors in the body.

The Acetyl Group: Another Rigid Component

Another rigid part of acetylsalicylic acid is the acetyl group. The acetyl group consists of two carbon atoms bonded to each other, with one of the carbon atoms also bonded to three hydrogen atoms. This group is attached to the benzene ring through an ester linkage.

The acetyl group plays a crucial role in the pharmacological activity of acetylsalicylic acid. It is responsible for the acetylation reaction, where the acetyl group is transferred to specific proteins in the body. This acetylation process influences various cellular processes, including inflammation and pain perception.

Similar to the benzene ring, the acetyl group is relatively rigid due to the presence of multiple bonds. The double bond between the two carbon atoms and the polar nature of the ester linkage contribute to the stability of the acetyl group. This rigidity ensures that the acetyl group remains intact during interactions with target proteins, allowing for precise and controlled acetylation reactions.

What Does Acetylsalicylic Acid Look Like

Acetylsalicylic acid, commonly known as aspirin, is a white crystalline powder. Its physical appearance is that of fine, needle-like crystals. When observed under a microscope, these crystals appear as elongated structures with sharp edges.

The white color of acetylsalicylic acid is a result of its molecular structure. The compound is composed of carbon, hydrogen, and oxygen atoms arranged in a specific pattern. This arrangement gives rise to the characteristic white color of the powder.

The crystalline nature of acetylsalicylic acid is due to the way its molecules pack together. The molecules align themselves in an organized manner, forming a repeating pattern that extends throughout the crystal lattice. This arrangement contributes to the stability and solid nature of the compound.

It is important to note that acetylsalicylic acid is highly soluble in organic solvents, such as ethanol and acetone, but has limited solubility in water. This property further influences its physical appearance, as the compound tends to dissolve in certain liquids rather than remaining in its solid form.

Why Is Acetylsalicylic Acid in Aspirin

Acetylsalicylic acid, commonly known as aspirin, is a widely used medication that has been trusted for decades to relieve pain, reduce inflammation, and lower fever. But have you ever wondered why acetylsalicylic acid is the key ingredient in aspirin? In this section, we will explore the therapeutic effects of acetylsalicylic acid that make it an essential component of this popular medication.

Therapeutic Effects: Acetylsalicylic acid’s anti-inflammatory and analgesic properties make it a key ingredient in aspirin.

Acetylsalicylic acid is a derivative of salicylic acid, a compound found naturally in plants such as willow bark. It belongs to a class of drugs known as nonsteroidal anti-inflammatory drugs (NSAIDs). Aspirin, with acetylsalicylic acid as its active ingredient, is widely used for its therapeutic effects, primarily due to its anti-inflammatory and analgesic properties.

Anti-inflammatory Effects

Inflammation is a natural response of the body to injury or infection. While it is an essential part of the healing process, excessive inflammation can lead to pain and discomfort. Acetylsalicylic acid works by inhibiting the production of certain enzymes called cyclooxygenases (COX). These enzymes play a crucial role in the production of prostaglandins, which are responsible for inflammation. By blocking the COX enzymes, acetylsalicylic acid helps reduce inflammation, providing relief from conditions such as arthritis, muscle sprains, and joint pain.

Analgesic Effects

Pain is a common symptom experienced by individuals due to various reasons, ranging from headaches to chronic conditions. Acetylsalicylic acid acts as an analgesic, which means it helps alleviate pain. It does so by interfering with the transmission of pain signals in the body. By inhibiting the production of prostaglandins, acetylsalicylic acid reduces the sensitivity of pain receptors, resulting in pain relief.

Other Therapeutic Effects

Apart from its anti-inflammatory and analgesic effects, acetylsalicylic acid also possesses additional therapeutic properties. It acts as an antipyretic, which means it helps lower fever by reducing the production of prostaglandins in the brain. Additionally, acetylsalicylic acid has antiplatelet properties, meaning it inhibits the aggregation of platelets in the blood, which can help prevent blood clots and reduce the risk of heart attacks and strokes.

Acetylsalicylic Acid Crystal Structure

Acetylsalicylic acid, commonly known as aspirin, is a widely used medication known for its analgesic (pain-relieving), antipyretic (fever-reducing), and anti-inflammatory properties. But have you ever wondered what the crystal structure of acetylsalicylic acid looks like? In this section, we will explore the unique arrangement of molecules that form the crystal structure of acetylsalicylic acid.

Acetylsalicylic acid forms crystals with a specific arrangement of molecules. These crystals belong to the monoclinic crystal system, which is characterized by three unequal axes and one angle that is not a right angle. The crystal structure of acetylsalicylic acid is made up of individual molecules held together by intermolecular forces such as hydrogen bonding.

The acetylsalicylic acid molecule consists of a benzene ring attached to a carboxylic acid group and an acetyl group. The carboxylic acid group (-COOH) is responsible for the acidic properties of acetylsalicylic acid, while the acetyl group (-COCH3) is derived from the process of acetylation, where an acetyl group is added to a compound through esterification.

In the crystal structure of acetylsalicylic acid, the molecules are arranged in layers. Within each layer, the molecules are held together by intermolecular hydrogen bonds between the carboxylic acid groups of adjacent molecules. These hydrogen bonds play a crucial role in stabilizing the crystal structure and determining the physical properties of acetylsalicylic acid.

The layers of acetylsalicylic acid molecules are further stabilized by van der Waals forces, which are weak attractive forces between molecules. These forces help maintain the overall structure of the crystal and contribute to the solid-state properties of acetylsalicylic acid, such as its melting point and solubility.

It is worth noting that the crystal structure of acetylsalicylic acid can vary depending on factors such as temperature and pressure. Changes in these conditions can lead to different crystal forms, each with its own unique arrangement of molecules.

Acetylsalicylic Acid Structure Formula

Acetylsalicylic acid, commonly known as aspirin, is a widely used medication that belongs to the class of drugs known as nonsteroidal anti-inflammatory drugs (NSAIDs). It is primarily used to relieve pain, reduce inflammation, and lower fever. But have you ever wondered what the chemical structure of acetylsalicylic acid looks like? In this section, we will explore the molecular formula and structure of acetylsalicylic acid.

Chemical Formula: C9H8O4

The chemical formula of acetylsalicylic acid is C9H8O4. This formula provides us with valuable information about the composition of the molecule. Let’s break it down:

• C9: This indicates that acetylsalicylic acid contains 9 carbon atoms. Carbon is an essential element in organic compounds and forms the backbone of many molecules.

• H8: This tells us that there are 8 hydrogen atoms in acetylsalicylic acid. Hydrogen is the most abundant element in the universe and plays a crucial role in chemical reactions.

• O4: This signifies that acetylsalicylic acid consists of 4 oxygen atoms. Oxygen is a highly reactive element and is involved in various biological processes.

By analyzing the chemical formula, we can deduce that acetylsalicylic acid is composed of carbon, hydrogen, and oxygen atoms. However, the formula alone does not provide a complete picture of the molecule’s structure.

Molecular Structure

To understand the molecular structure of acetylsalicylic acid, we need to delve deeper into its chemical composition. Acetylsalicylic acid is derived from salicylic acid through a process called acetylation. During acetylation, an acetyl group (CH3CO-) is added to the hydroxyl group (-OH) of salicylic acid, resulting in the formation of acetylsalicylic acid.

The addition of the acetyl group modifies the properties of salicylic acid, making it more stable and less irritating to the stomach. This modification allows acetylsalicylic acid to be used as a medication without causing significant gastrointestinal side effects.

The molecular structure of acetylsalicylic acid can be represented as follows:

CH3COOH
|
HO-C6H4-CO2H
|
OH

In this structure, the acetyl group (CH3CO-) is attached to the hydroxyl group (-OH) of salicylic acid. The presence of the acetyl group alters the chemical properties of the molecule, giving rise to the unique characteristics of acetylsalicylic acid.

The chemical formula and molecular structure of acetylsalicylic acid provide insights into its composition and properties. Understanding the structure of this widely used medication can help us comprehend how it interacts with our bodies and exerts its therapeutic effects. In the next section, we will explore the synthesis and properties of acetylsalicylic acid in more detail. Stay tuned!

Acetylsalicylic Acid Structural Formula

The structural formula of acetylsalicylic acid shows the arrangement of atoms and bonds in the molecule.

Acetylsalicylic acid, also known as aspirin, is a widely used medication that belongs to the class of nonsteroidal anti-inflammatory drugs (NSAIDs). Its chemical formula is C9H8O4, and its molecular structure consists of a benzene ring attached to a carboxylic acid group (COOH) and an ester group (COOC2H3). The acetyl group (CH3CO) is attached to the hydroxyl group (OH) of the salicylic acid molecule through a process called acetylation.

The acetylation reaction involves the esterification of the hydroxyl group of salicylic acid with acetic anhydride, resulting in the formation of acetylsalicylic acid. This process is commonly used in the synthesis of aspirin. The acetyl group adds a functional group to the salicylic acid molecule, which enhances its pharmacological properties.

The structural formula of acetylsalicylic acid can be represented as:

H
|
H - C - O - C - CH3
|
C
|
H - C - O - OH
|
C
|
H

In this formula, the benzene ring is represented by a hexagon, and the bonds between the atoms are shown by lines. The carbon atoms are represented by the letter C, the hydrogen atoms by H, and the oxygen atoms by O. The acetyl group is represented by CH3CO, and the carboxylic acid group is represented by COOH.

The structural formula of acetylsalicylic acid provides valuable information about the arrangement of atoms and bonds in the molecule. It helps in understanding the chemical properties and interactions of the compound, which are crucial for its pharmacological effects.

Frequently Asked Questions

1. What is the structure and IUPAC name of acetylsalicylic acid?

The structure of acetylsalicylic acid, also known as aspirin, is represented as follows:

Its IUPAC name is 2-acetoxybenzoic acid.

2. What is the structure and IUPAC name of salicylic acid?

The structure of salicylic acid is represented as follows:

Its IUPAC name is 2-hydroxybenzoic acid.

3. What are the functional groups present in the structure of acetylsalicylic acid?

The functional groups present in the structure of acetylsalicylic acid are the carboxylic acid group (-COOH) and the acetyl group (-COCH3).

4. How does acetylsalicylic acid work?

Acetylsalicylic acid works by inhibiting the production of prostaglandins, which are responsible for pain, inflammation, and fever. It achieves this by irreversibly inhibiting the enzyme cyclooxygenase (COX), thereby reducing the production of prostaglandins.

5. What is the melting point of salicylic acid?

The melting point of salicylic acid is approximately 159 °C.

6. What is the name of the structure of acetylsalicylic acid?

The structure of acetylsalicylic acid is commonly referred to as the aspirin structure.

7. What is the chemistry of acetylsalicylic acid?

The chemistry of acetylsalicylic acid involves its synthesis through acetylation, where the acetyl group is added to salicylic acid. This process is known as esterification. Acetylsalicylic acid can undergo hydrolysis to form salicylic acid and acetic acid.

8. How was acetylsalicylic acid discovered?

Acetylsalicylic acid was first synthesized by a chemist named Felix Hoffmann in 1897 while working for the pharmaceutical company Bayer. It was developed as a derivative of salicylic acid to reduce its side effects.

9. What is the structure for aspirin?

The structure for aspirin is the same as the structure for acetylsalicylic acid, which is represented as follows:

10. What are the uses of salicylic acid?

Salicylic acid is commonly used in skincare products for its exfoliating and anti-inflammatory properties. It is also used in the treatment of acne, psoriasis, and other skin conditions. Additionally, salicylic acid is used in the production of dyes, fragrances, and rubber.

Succinic acid also named as amber acid, butanedioic acid and 1, 2-ethanedicarboxylic acid.

Basic succinic acid structure and its molecular formula is C₄H₆O₄, it is a dicarboxylic acid having molecular weight 118.09 g/mol. Butanedioic acid is its IUPAC name. Succinic acid was first formed as an Amber distillation product. Amber is notorious for its colour and beauty which is a fossilized tree resin.

Basic Succinic acid structures are as follows:

Georgius Agricola is a person who first refined succinic acid from amber. Traditionally succinic acid was produced by petrochemical technology. Succinic acid is a colourless water soluble crystalline solid. Succinic acid has a vital role in intermediary metabolism of all plants and animal tissues. Succinic acid name formed from the name of Amber whose Latin name is Succinum.

From the above structure the succinic acid structure is consists of two carboxylic groups attached with two carbon atoms. The first and basic method of synthesis of succinic acid is the catalytic hydrogenation of maleic acid or its anhydride, afterword’s various methods being investigated and used for the synthesis of succinic acid.

There are various techniques for the analysis and characterization of structure succinic acid or any other acid like Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Scanning electron spectroscopy, etc. which confirms the structure of any compound.

From the FTIR spectra, it confirms the presence of functional group i.e. CH₂ and COOH confirms by the presence of the FTIR peaks like 1720 peaks shows C=O stretch of COOH group, 1396 peak shows the symmetric stretch of COO^–, 1552 peak shows anti-symmetric stretch of COO^–, 1901, 1722 and 1728 peaks shows C=O stretching, 1564 and 1570 peaks shows anti-symmetric stretch of COO^– group, 2650 peak shows O-H stretching and 2932 peak shows C-H stretching. All this functional groups from FTIR spectra of succinic acid confirms the succinic acid structure.

Succinic acid is a good natural antibiotic due to its caustic or acidic nature but even its more concentration cause’s burns. Succinic acid plays a vital role in Krebs cycle i.e. citric acid cycle and works as an electron donor to produce FADH2 and fumaric acid.

Succinates can active the degradation of acetaldehyde which is a toxic alcoholic metabolism by-product into H₂O and CO₂ by aerobic metabolism and helps to reduce the hangover effect. Succinic acid also helps to encourage neural system recovery and encourage the immune system. It also claims that it can enhance cognizance, impulses and concentration.

Drug interaction capacities of succinic acid shows that, the excretion of succinic acid can be decreased when combine with acetyl salicylic acid, benzoic acid, bumetanide, aminohipporic acid, benzyl penicillin, baricitinib, acyclovir, etc.

Methods of synthesis of succinic acid

From Maleic acid (reduction)

Maleic acid when reduced in presence of nickel and heat succinic acid is formed.

Here, in this reaction the pi-double bond of maleic acid gets break as the reduction done and as the hydrogen atom gets attached to two carbon atoms of maleic acid, succinic acid gets formed with the single covalent bond between two carbon atoms of succinic acid.

From di-bromo ethane

In this method, 1, 2 di-bromo ethane is treated with two molecules of sodium cyanide, then two molecules of sodium bromide gets removed forming 1, 2-dicyano ethane. Then 1, 2-dicyano ethane on hydrolysis gives succinic acid with the release of two molecules of ammonia as a by-product.

From Tartaric acid (Reduction with H-I/ Red P/ 200⁰ C)

In the above method, tartaric acid reduced with hydrogen iodide in presence of red phosphorous with heating at 200⁰ C forms succinic acid.

Physical properties of succinic acid

1. Succinic acid is a colourless/ white or shiny crystalline solid.
2. It is odourless.
3. It is very acidic in taste.
4. It is soluble in water, ethanol, acetone, ethyl ether and methanol and slightly soluble in deuterated dimethyl formamide,
5. It is insoluble in benzene and toluene, practically insoluble in petroleum ether, carbon tetrachloride and carbon disulphide.

Chemical properties of succinic acid

Reaction with (NaHCO₃) sodium bi-carbonate

Succinic acid when treated with two molecules of sodium bi-carbonate, sodium succinate is obtained with two water molecules and two carbon di-oxide molecules as by-product.

Reaction with ethyl alcohol

Succinic acid when reacts with two molecules of ethyl alcohol, di-ethyl succinic acid is formed with the removal of two water molecules.

Reaction with PCl₅ (phosphorous pentachloride)

Succinic acid when heated with phosphorous penta-chloride, succinic chloride is formed with the release of phosphorous tri-chloride and two hydrochloride molecules.

Reaction with ammonia at low temperature

Succinic acid on treatment with ammonia, heating at low temperature forms succinic amines.

Reaction with ammonia at high temperature

Succinic acid on heating with ammonia at high temperature obtained succinic amide with the release of ammonia gas.

Reaction with sodalime (NaOH+CaO)

Succinic acid on heating with sodalime (NaOH + CaO) forms propionic acid with the evolution of carbon dioxide gas.

Other properties of succinic acid

• Boiling point of succinic acid is 235⁰ C
• Melting point of succinic acid is 188⁰ C
• Solubility of succinic acid is 5 to 10 mg/ml at 76⁰ F
• Density of succinic acid is 1.572
• It is non-hygroscopic in nature.
• Succinic acid on heating to decomposition emits acrid smoke and fumes.

Uses of succinic acid

Succinic acid has various uses in various fields like agriculture, manufacturing, drug compounds and food production. Also succinic acid has a budding platform as a chemical to yield various high value-added products such as surfactants, pharmaceutical products, plastics, detergents, and ingredients to stimulate the growth of plants and animal.

The reactions which involve oxidation and reduction are called Redox reactions. Redox reactions are also called electrons transfer reactions.

Oxidation reduction reaction is the chemical reactions involves transmission of electrons from one kind of atom to another kind. Molecular Equations: It is the molecular form of reactants and products called molecular equation. Ionic Equations: The reaction consists of reactant and products in ionic form called ionic equations.

Molecular equation as follows

2FeCl₃ + SnCl₂ → 2FeCl₂ + SnCl₄

Ionic equation as follows

2Fe³⁺ + Sn²⁺ → 2Fe²⁺ + Sn⁴⁺

4HCl + MnO₂ → MnCl₂ + Cl₂ + 2H₂O

In this redox reaction process, HCl has been oxidized to Cl₂ and MnO₂ has been reduced to MnCl_2.

• Example 1
• Example 2
• Example 3
• Example 4

Oxidation number:

Oxidation number is the charge on the atom of any element when it is in ionic or combined state. Oxidation number is also said oxidation state.

Rules for calculation of oxidation number for redox reaction process:

1. The oxidation number is zero when any atom in its elementary state.
2. Monoatomic ions oxidation number is equal to charge on it.
3. H is in +1 oxidation number when combined with non-metals and in -1oxidation numberwhen combined with active metals like calcium,sodium, etc. Ex: In hydrides like NaH, CaH₂.
4. Oxygen is in -2 oxidation number excluding in peroxides like Na₂O₂,H₂O₂, etc. where it is -1 and OF₂ where it is +2.
5. Alkali and alkaline earth metals oxidation numbers have +1 and +2 respectively.
6. Halogens have -1 oxidation number in metal halides.
7. In metals and non-metal compounds, metals are in positive oxidation number while non-metals are in negative oxidation number.
8. If the compounds having two various elements, the element which are more electronegative in nature has negative oxidation numbers although the other has positive oxidation number.
9. In neutral molecules summation of oxidation numbers of all particles is zero.
10. If the compounds containing complex ions, the summation of oxidation numbers of whole atoms is equivalent to the charge on the ion.

Example 1: Oxidation number of Cr in CrO₅

By conventional method:

CrO₅ i.e. Cr=x and O₅= 5 x (-2)

So, x + 5 x (-2) = 0

or x = +10 (wrong)

Oxidation number 10 for Cr is wrong, because it cannot be more than +6, according to maximum number of valence electrons, 3d⁵, 4s¹.

Oxidation number of Cr is calculated by chemical bonding method since CrO₅ contains peroxide linkage, other than Cr=O

By Chemical bonding method

Structure of CrO₅ is

Oxidation number of Cr in CrO5 is calculated as

For Cr = x

For Cr=O = 1 x (-2)

For O-O = 4 x (-1)

i.e. x + 1 x (-2) + 4 x (-1) = 0

x – 2 – 4 = 0 or x = -6

Some important terms for Redox reactions process:

Oxidation (De-electronation)–

Loss of electrons or increase in oxidation number of its atom is oxidation.

Oxidising agent –

It accepts electrons (electron acceptor) or oxidation number of atoms decreases.

Reduction (Electronation) –

Reduction is the gain of electrons or decrease in oxidation number of atoms.

Reducing agent –

It gives electron (electron donor) or oxidation number of atoms increases.

+6         +2       +3     +3

Cr₂O₇ + Fe → Cr + Fe

O.A       R.A

Here Oxidation number of Cr decreases by 3 as +6 to +3

And oxidation number of Fe increases by 1 as +2 to +3

Types of redox reaction process redox reaction steps:

1. Intermolecular redox reaction

In this reaction one substance is oxidized and other is reduced.

2Al + Fe₂O₃ → Al₂O₃ + 2Fe

Al is oxidised to Al₂O₃; Fe₂O₃ is reduced to Fe

• Intra-molecular redox reaction

Redox reaction consist of one element of a compound is oxidized and another is reduced.

2KClO₃ → 2KCl + 3O₂

Cl(+5) in KClO₃ is reduced to Cl(-1); O₂(-2) in KClO₃ is oxidised to O₂(0)

• Disproportionation reaction (Auto-redox)

One molecule of the same substance is reduced at the expense of other which is oxidized.

Balancing Redox Equation by Oxidation number method:

This method is based on the principle that any increase in oxidation number must be compensated by a decrease. This method consists of the following steps .

1. Note the elements which undergo change in oxidation numbers.
2. Select the suitable coefficients for the oxidising and reducing agents so that the total decrease in oxidation number of the oxidising agent becomes equal to the total increase in the oxidation number of the reducing agent.

Example 2: CuO + NH₃ → Cu + N₂ + H₂O

In the above equation oxidation number of Cu decreases from +2 (in CuO) to 0 (in Cu) while that of N increases from -3 (in NH₃) to 0 (in N₂) and hence:

In order to equalise the total increase in O.N (=3) to the total decrease in O.N. (=2), we should have three atoms of Cu for every two atoms of N and hence the equation should be written as:

3CuO + 2NH₃ → 3Cu + N₂ + H₂O

Now in order to balance O-atoms we should add 3H₂O molecule to the right hand side. Thus:

3CuO + 2NH₃ → 3Cu + N₂ + 3H₂O

Balancing Redox Equations by Ion-electron Method – By the use of Half-reactions

1. Divide the whole equation in two half reactions, in one-half reaction changesgo through reducing agent and the other-half changesgo through oxidising agent.
2. Balance the both half reaction equal to the number of atoms of each element in the reaction. For this purpose:
3. For each half-reaction balance the atoms other than H and O by using simple multiples.
4. H₂O and H⁺are added in neutral and acid solutionsfor balancing oxygen and hydrogen atoms. Oxygen atomgets first balanced andeveryextra oxygen atom on one side of the equation, add one H₂O molecule to the other side equation. Now use H⁺ to balance hydrogen atoms.
5. In alkaline solutions, OH^– may be used. For each additionalatom on one side, balance the equation by adding one H₂O to the same side and add 2H^– to the other side equation. If hydrogen is still unbalanced, balance the equation by adding one OH^– for each additional hydrogen atom on the same side and one H₂O to the other side of the equation.
6. Balance the charges on both sides of equation by additionof electrons to the side having inadequate negative charges.
7. With suitable number multiply one or both half-reactions,so that on adding the both equations, the electrongets balanced.
8. Both balanced half reactions are added and cancel any common termsif there to both sides. Also see that all electrons cancel.

Example 3: Fe²⁺ + MnO₄^– + H⁺ → Mn²⁺ + Fe³⁺ + H₂O

Above redox reaction takes place in acidic medium and can be broken into the following two half reactions showing redox reaction process redox reaction steps:

MnO₄^–    →    Mn²⁺ ……Reduction half reaction

(Mn=+7)        (Mn=+2)

And      Fe²⁺ →    Fe³⁺ …….Oxidation half reaction

        (Fe=+2)       (Fe=+3)

For reduction half reaction,

1. For balancing O-atom add 4H₂O to right hand side to get.

MnO₄^– → Mn²⁺ + 4H₂O

1. For balancing H-atoms add 8H⁺ to the left hand side to get.

MnO₄^– + 8H⁺→ Mn²⁺ + 4H₂O

1. For balancing the charges add 5e^– to the left hand side to get.

MnO₄^– + 8H⁺ +5e^– → Mn²⁺ + 4H₂O (i)

For oxidation half reaction,

Balance the charges on both sides by adding 1e- to the left hand side to get,

Fe²⁺ → Fe³⁺ + e^–

5Fe²⁺ → 5Fe³⁺ + 5e^–(ii) or

On adding equation (i) and (ii) we get:

MnO₄^– + 8H⁺ + 5Fe²⁺ → Mn²⁺ + 4H₂O + 5Fe³⁺

This is the balanced equation.

Electrochemical cell

The cell or device produce electric current from a chemical (redox) reaction is electrochemical cell, i.e. alteration of chemical energy to electrical energy.

This redox reaction involves two half reaction, one is oxidation half reaction and other is reduction half reaction.

Example 4: Zn + CuSO₄→ZnSO₄ + Cu

Zn + CuSO₄→ZnSO₄ + Cu

Or Zn + Cu²⁺ → Zn²⁺ + Cu

Two half reactions of this redox reactions are-

Zn → Zn²⁺ +2e^–(oxidation half reaction)

Cu²⁺ + 2e^–→ Cu (reduction half reaction)

Electrochemical cell based on this reaction is called Daniel cell.

Electrochemical cell has two half reactions using two half cells which are joined to each other by a salt bridge.

A U-shaped tube enclosing a concentrated solution of an inactive electrolyte like K₂SO₄, KCl, KNO₃, etc. is a Salt bridge.

Types of reactions in terms of directions and the reversible reaction examples as follows:

Reversible reaction- The reactions which proceed in both forward and reverse direction simultaneously are called reversible reactions. It is represented as ⇋

Reactants ⇋ Products

Explanation of reversible and irreversible reactions and reversible reaction example:

Irreversible reaction:

Here, if we see the graph of irreversible reaction, it is as follows. As the reaction proceeds reactants start being converted into products so the concentration of reactants in that reaction apparatus started decreasing  and it kept on decreasing until it was zero all the reactants were used up during the reaction. Similarly in the beginning concentration of products was zero but with the passage of time concentration of products kept on increasing and it reach to its maximum obtainable level.

Reversible reaction

The double arrows are two half arrows in opposite direction. One is facing to the forward direction and other is facing to the reverse direction. That means there are two reactions taking place in this reaction mixture. In one reaction, reactants being converted into products, this is a forward reaction. The bottom arrow represents the reverse reaction. In this reaction products are being converted into reactants. This is a reverse reaction.

As we see the graph for reversible reaction. The reactants in the beginning were in maximum concentrations and products were not there in the beginning because the reaction started with reactants, so the concentration of the products in the beginning as zero. As the reaction proceeded concentration of reactants kept on decreasing because they were being converted into products. Similarly products were being formed so the concentration of products kept on increasing but after some time the line of reactants concentration straightens up it does not goes to zero, similarly the line for the concentration of products also straighten up it does not reaches its maximum  possible value, these two line becomes parallel to each other after some time.

Equilibrium or Dynamic equilibrium

The rate of forward reaction has become equal to the rate of reverse reaction. So reactants are being converted into products and products are still being converted into reactants but both these processes are taking place in the same rate that is why the concentration of reactants and products is not changing anymore, now this condition is called equilibrium. These happen in reversible reaction only.

“It is the position when the forward reaction becomes equal to the rate of reverse reaction”.

Position = concentrations of reactants and products.

That means the position/concentration at which the rate of forward reaction is equal to the rate of reverse reaction.

If the position of equilibrium is shifting towards right (product) side, that means the concentration of products is increasing and the concentration of reactants is decreasing. That means forward reaction is dominating over the reverse reaction. So products are being formed at higher rate as compared to the formation of reactants. If the equilibrium position shifting to left, which means the concentration of reactants is increasing and the concentration of products is decreasing because the reverse reaction is not dominating over the forward reaction.

Factors affecting equilibrium position:-

When we are talking about factors affecting equilibrium position means we are talking about reversible reaction. Because in chemical reactions the equilibrium position is attained only in reversible reaction, there is no such concept for irreversible reaction.

Here we have to analyse which factors could affect the position of equilibrium, these are the same factors which actually affect the rate of reactions. So basically we have to analyse all those factors which affect the rate of reaction that do they effect the position of equilibrium or not.

So the factors affect the rate of reaction as follows.

Concentration

“If concentration of reactants is increased, equilibrium position shifts to the forward side and the yield of products increases”.

“If concentration of products is increased, equilibrium position shifts to the reverse side and the yield of products decreases”.

“If concentration of reactants is decreased, equilibrium position shifts towards the reverse side and the yield of products decreases”.

“If concentration of products is decreased, equilibrium position shifts to the forward side and the yield of products increased”.

Temperature

For all reversible reactions of forward reaction is exothermic. There reverse reaction is endothermic. But if the forward reaction is endothermic then the reverse reaction is exothermic.

Increase in temperature favors the endothermic side of the reaction and decrease in temperature favors the exothermic side of the reaction.

Pressure

Increase in pressure favors the side with less gaseous moles and decrease in pressure favors the side with more gaseous moles. Here are some reversible reaction examples showing effect of pressure.

Example: 1) 2SO_{2 (g)} + O_{2 (g}    ⇋   2SO_{3 (g)}    

Reactant side                 product side

We have to consider gases only during pressure applying no liquid or solid. Here during analysis the molar ratios of the variables should be consider as number of moles. So in above reaction, on the reactant side there are two moles of sulphur dioxide and two moles of oxygen, so there are 2 + 1 = 3 gaseous moles. In product moles there is only one product and it has two moles of sulphur trioxide present in the product side. So the product side has less gaseous moles as compared to reactant side. So we have more and more products to be formed, but we have to keep a high pressure.

In the above reaction, a high pressure will increase the yield of product because there are less gaseous moles on the product side and increase in pressure favours the side with less gaseous moles.

Example 2) N_{2 (g)} + 3H_{2 (g)} ⇋   3NH_{2 (g)}

In the above example, there are 1 + 3 = 4 gaseous moles on the reactant side and there are total 2 gaseous moles on the product side. So we want to increase the yield of the product so we want these side to be favoured which has less gaseous moles. So a high pressure will increase the yield of the product.

Example 3) H_{2 (g)} + I_{2 (g)} ⇋ 2HI _(g)

On the reactant side of example 3), there are 1 + 1 = 2 gaseous moles on the reactant side and two gaseous moles on the product side, so technically none of the side has a higher or lower number of gaseous moles. The number of gaseous moles on each side is exactly equal, that means the equilibrium position will not be affected by pressure.

Example 4) Ca _(s) + 2CH₂COOH _(aq) ⇋ (CH₃COO)₂Ca _(aq) + H_{2 (g)}

In the 4) example on reactant side there is a solid and an aqueous reactants, there is no gas on the reactant side. Here we do not have to evaluate only number of moles; we have to evaluate only number of gaseous moles. There are zero gaseous moles on reactant side, but there is one gaseous product on the product side and if we want to increase the yield of the products, we need to keep the pressure low, because low pressure favours the side with the greater number of gaseous moles.

• Presence of a catalyst

Rates of reactions increases in presence of a catalyst, catalyst is a substance which increases the rate of a reaction without itself being chemically changed. A catalyst does increase the rate of reaction but it increases the rate of both forward and reverse reaction equally. So the overall effect is cancel out, that means it does not favors any side, the presence or absence of a catalyst has no effect on equilibrium position or the yield of the products.

Some more reversible reaction examples:

Example 5) Bronsted-Lowry concept of acid and bases

Acid= Substance (molecule or ion) which donates proton (H⁺ ions)

HCl + H2O ⇋ H3O+ + Cl-

Base= Substance (molecule or ion) which accepts proton (H⁺ ions)

            NH₃ + H₂O ⇋ NH₄⁺ + OH^–

Read more on 10+ Acid-Base Reaction Example: Detailed Explanations

Example 6) Conjugate acid base pair

In an acid-base reaction pair of substance which differs by a proton and which can be formed from one another by the gain or loss by proton are called as conjugate acid-base pair.

                    HCN + H₂O ⇋ H₃O⁺ + CN^–

Example 7) Hydrolysis reaction

Salt of strong acid and weak base

NH₄Cl + H₂O ⇋ HCl + NH₄OH                

Salt of weak acid and strong base

CH₃COONa +H₂O ⇋ CH₃COOH + NaOH

Salt of weak acid and weak base

(NH₄)₂CO₃ +2H₂O ⇋ H₂CO₃ + 2NH₄OH

Example 8) Common ion effect

The phenomenon in which degree of dissociation of weak electrolytes supressed by adding small amount of strong electrolyte containing a common ion is called common ion effect.

CH₃COOH_(aq) ⇋ CH₃COO^–_(aq) + H⁺_(aq)

Example 9) Buffer solutions

Acidic buffer

CH₃COONa ⇋ CH₃COO^– + Na⁺

Basic buffer

NH₄OH ⇋ NH₄⁺ + OH^–