Question

Draw the structure of acetylsalicylic acid, and circle the portion of the molecule that shows that it is an ester. From what acid and alcohol is acetylsalicylic acid synthesized?

Short answer

The structure of acetylsalicylic acid, also known as aspirin, is as follows: ``` O || -- C | \ HC--O--C --O--H | / HC--OH | HC - C - CH || O ``` The ester portion, represented by -COO-, can be found and circled in the structure: ``` O || -- C --(O) | \ (O)HC--O--C --O--H | / HC--OH | HC - C - CH || O ``` Acetylsalicylic acid is synthesized from salicylic acid (acting as the acid) and acetic anhydride (providing the alcohol portion) during an esterification reaction.

Step-by-step solution

Draw the structure of acetylsalicylic acid

Acetylsalicylic acid, also known as aspirin, has the molecular formula C9H8O4. Its structure is as follows: ``` O || -- C | \ HC--O--C --O--H | / HC--OH | HC - C - CH || O ```

Identify and circle the ester portion of the molecule

In esters, the functional group is -COO- (consisting of a carbonyl group attached to an oxygen atom). In the structure of acetylsalicylic acid, this ester part can be circled as follows: ``` O || -- C --(O) | \ (O)HC--O--C --O--H | / HC--OH | HC - C - CH || O ``` The ester portion is indicated by (O) brackets.

Identify the acid and alcohol from which acetylsalicylic acid is synthesized

Acetylsalicylic acid is synthesized from salicylic acid and acetic anhydride. Salicylic acid acts as the acid source, while acetic anhydride provides the alcohol portion during the esterification reaction. The reaction takes place as shown below: \[ Salicylic\, Acid + Acetic\, Anhydride \rightarrow Acetylsalicylic\, Acid + Acetic\, Acid \] The structures of the starting compounds are as follows: Salicylic Acid: ``` O || --C -OH | HC--OH | HC - C - CH || O ``` Acetic Anhydride: ``` O || C --O--C | || H || O ``` From these structures and the synthesis reaction, we can conclude that acetylsalicylic acid is synthesized from salicylic acid and acetic anhydride.

Key concepts

Esterification

Esterification is a chemical reaction where an acid reacts with an alcohol to form an ester and water. This reaction is a fundamental process in organic chemistry and is used in the synthesis of many compounds, including acetylsalicylic acid, commonly known as aspirin.
Esterification typically involves the reaction between a carboxylic acid and an alcohol in the presence of an acid catalyst, such as sulfuric acid. The product of this reaction, the ester, contains the functional group -COO-.

• For example, the synthesis of acetylsalicylic acid is an esterification reaction involving salicylic acid and acetic anhydride.
• The -OH group of the salicylic acid and the acyl group from the acetic anhydride combine to form the ester linkage.

This transformation highlights the role of functional groups in determining the properties and reactivity of organic molecules.

Salicylic Acid

Salicylic acid is an essential starting material in the synthesis of acetylsalicylic acid. It is a naturally occurring compound, often found in willow bark, that has been used for centuries for its medicinal properties.
In the context of synthesizing aspirin, salicylic acid acts as the acid component in the esterification reaction. Its chemical structure includes a benzene ring functionalized with both a hydroxyl group (-OH) and a carboxyl group (-COOH).

• The presence of these groups makes salicylic acid an active participant in forming the ester bond during the synthesis process.
• When it reacts with acetic anhydride, the hydroxyl group of salicylic acid is replaced with an acetyl group, forming acetylsalicylic acid.

Understanding its structure helps in visualizing how the ester functional group is created in the acetylsalicylic acid molecule.

Acetic Anhydride

Acetic anhydride is an acylation agent used in the esterification process to synthesize acetylsalicylic acid. It is a derivative of acetic acid and contains two acyl groups connected by an oxygen atom.
This makes it particularly effective in transferring one acetyl group to salicylic acid, resulting in the formation of acetylsalicylic acid.

• Acetic anhydride reacts by transferring its acetyl group to the hydroxyl group of salicylic acid. This reaction liberates a molecule of acetic acid as a by-product.
• This is a substitution reaction where the -OH group of the salicylic acid is replaced by an acetyl group, forming the ester linkage in aspirin.

Understanding the role of acetic anhydride is crucial for grasping how acetylsalicylic acid is synthesized through esterification.

Ester Functional Group

The ester functional group is central to the structure and properties of acetylsalicylic acid. It is characterized by the -COO- group, which results from the reaction between an acid and an alcohol.
This group imparts unique properties to esters, such as distinct odors and the ability to participate in various chemical reactions.

• In acetylsalicylic acid, the ester group connects the acetyl component from acetic anhydride to the salicylic acid molecule.
• This linkage is vital for its function as a medication because it can influence how the molecule interacts with biological systems.

Identifying the ester functional group in molecules helps chemists understand their reactivity and properties.

Organic Chemistry

Organic chemistry is the branch of chemistry that deals with the structure, properties, and reactions of organic compounds containing carbon. It is a vast field that encompasses the study of all carbon-containing molecules and their transformations.
Esterification, as seen in the synthesis of acetylsalicylic acid, is one of the numerous reactions studied in organic chemistry.

• This field provides the foundational knowledge needed to understand how molecules like acetylsalicylic acid are constructed and modified.
• Organic chemistry principles help in understanding molecular bonding, reactions, and the behavior of functional groups, which are critical in the development of pharmaceuticals and other chemicals.

Mastering organic chemistry concepts, such as functional groups and synthesis reactions, is essential for careers in chemical, pharmaceutical, and biological sciences.