Question

Maleic acid and fumaric acid are the \(c i s\) - and trans- isomers, respectively, of \(\mathrm{C}_{2} \mathrm{H}_{2}(\mathrm{COOH})_{2}\), a dicarboxylic acid. Draw and label their structures.

Short answer

Question: Draw and label the structures of maleic acid and fumaric acid, which are the cis- and trans- isomers of C2H2(COOH)2. Answer: Maleic acid (cis-isomer): O || O=C-C=O | OH Fumaric acid (trans-isomer): O || O=C-C=O | OH

Step-by-step solution

Understanding isomers

Isomers are molecules that have the same chemical formula but a different atomic arrangement. In the case of maleic and fumaric acids, they are both C2H2(COOH)2, but they differ in their spatial arrangement. Cis-isomers have the similar groups on the same side of the double bond, while trans-isomers have similar groups on opposite sides of the double bond.

Draw the structure of maleic acid

Maleic acid is the cis-isomer of C2H2(COOH)2. To draw its structure, start with a carbon-carbon double bond (C=C). Place one carboxylic acid group (COOH) at the end of each carbon atom in the double bond. Since it is a cis-isomer, the groups will be on the same side of the double bond. Here's the structure: O || O=C-C=O | OH

Draw the structure of fumaric acid

Fumaric acid is the trans-isomer of C2H2(COOH)2. To draw its structure, start similarly with a carbon-carbon double bond (C=C). Place one carboxylic acid group (COOH) at the end of each carbon atom in the double bond. Since it is a trans-isomer, the groups will be on opposite sides of the double bond. Here's the structure: O || O=C-C=O | OH The structures of maleic acid (cis-isomer) and fumaric acid (trans-isomer) are now drawn and labeled correctly.

Key concepts

Cis-Trans Isomerism

Cis-trans isomerism is an interesting topic in organic chemistry, directly related to the spatial arrangement of atoms in a molecule. It occurs in molecules that contain a double bond or a ring structure, which restricts the movement of the atoms,

The Core Idea

Cis-trans isomers are types of stereoisomers. They not only have the same connectivity between the atoms, but also the same types of chemical bonds. However, their atoms are oriented differently in 3D space, much like having the same set of building blocks but arranging them differently.

• **Cis isomer**: In the cis configuration, similar or identical groups are on the same side of the double bond or ring structure. For example, in maleic acid, the two carboxyl groups are on the same side of the carbon-carbon double bond.
• **Trans isomer**: In the trans configuration, similar groups are on opposite sides. In fumaric acid, this means the two carboxyl groups are located across from each other.

Understanding this concept is essential for chemistry students as it directly impacts the physical and chemical properties of the compounds involved.

Dicarboxylic Acids

Dicarboxylic acids are organic compounds containing two carboxylic acid functional groups (-COOH) in their structure, making them unique and reactive.

Properties of Dicarboxylic Acids

The presence of two carboxyl groups results in certain characteristic features:

• **Acidic Nature**: Both carboxyl groups can donate protons (H⁺) to become negatively charged. This makes them actively react in different chemical scenarios.
• **Versatility**: They participate in a variety of chemical reactions due to their dual functional groups, acting as both an acid and as a point of reactivity.
• **Structural Significance**: The positioning of the carboxyl groups in either cis or trans formations, as seen with maleic and fumaric acids, influences properties like solubility, boiling and melting points.

Learning about dicarboxylic acids is fundamental for understanding many biological and chemical processes, including metabolism and industrial applications.

Chemical Structure Drawing

Chemical structure drawing is a valuable tool for chemists and students. It allows them to visualize complex molecules and understand their spatial arrangement.

Steps in Drawing Structures

To start drawing the structure of any organic molecule like maleic and fumaric acids, follow these steps:

• **Identify the Core Backbone**: Begin with mapping out the major structural elements, such as carbon-carbon bonds. For maleic and fumaric acid, this involves setting up the carbon double bond.
• **Add Functional Groups**: Next, attach groups like the carboxyl groups at the appropriate positions. With the cis and trans designations, place them on the same or opposite sides.
• **Confirm Geometry**: Ensure that all atoms conform to their typical geometric arrangements (tetrahedral for single-bonded carbons, planar for double-bonded carbons).

Once practiced, chemical structure drawing becomes an intuitive process, aiding comprehension and communication of complex organic molecules.