Question

Fumaric acid is a metabolic intermediate that has the systematic name trans-2-butenedioic acid. Draw its structure.

Short answer

The structure of fumaric acid has a four-carbon chain with a trans double bond between C2 and C3, and COOH groups at both ends.

Step-by-step solution

Understand the Systematic Name

The name "trans-2-butenedioic acid" gives us information about the molecule's structure. "Butene" indicates a four-carbon backbone with a double bond, and "dioic acid" signifies the presence of two carboxylic acid groups, one at each end of the carbon chain.

Identify the Double Bond Location and Geometry

The '2' in trans-2-butenedioic acid suggests the position of the double bond is between the second and third carbon atoms. The prefix 'trans' tells us that the substituents (in this case, the carboxylic acid groups) on the double-bonded carbons are on opposite sides.

Assemble the Carbon Backbone with the Double Bond

Draw the four-carbon chain, indicating the double bond between the second and third carbon atoms. Since it is trans, ensure the substituents on these carbons are staggered (opposite) to each other.

Add Carboxylic Acid Groups

Attach a carboxylic acid group (COOH) to each terminal carbon in the carbon skeleton. This placement aligns with the 'dioic acid' in the name.

Verify the Structure

Check the structure to ensure all components match the given name: a four-carbon chain, a double bond between carbons 2 and 3 with trans geometry, and carboxylic groups at both ends.

Key concepts

Systematic Naming in Chemistry

Systematic naming in chemistry aims to provide an unambiguous description of a compound's molecular structure using a standardized format. Let's break down the systematic name, "trans-2-butenedioic acid." Here’s what each part signifies:

• "Butene": This indicates the presence of a four-carbon chain in the molecule. "-ene" suggests there's a double bond in the carbon chain.
• "-2-": It specifies where the double bond is located—between the second and third carbon atoms.
• "Dioic acid": This means there are two carboxylic acid groups (COOH), one at each end of the four-carbon chain.
• "Trans": Refers to the geometric configuration of the molecule, indicating that similar groups, like the COOH in this case, are on opposite sides of the double bond.

Systematic names are valuable because they guide you on how to draw and understand the molecule's layout, ensuring clear communication in the scientific community.

Carboxylic Acids

Carboxylic acids are organic compounds characterized by the presence of at least one carboxyl group (COOH). This functional group consists of a carbon double-bonded to an oxygen and single-bonded to a hydroxyl group (OH). Here are some key features:

• Acidity: The COOH group can release a hydrogen ion (H+), which is why these compounds are acidic.
• Polarity: Carboxylic acids are polar due to the electronegativity of the oxygen atoms, allowing them to form hydrogen bonds.
• Solubility: Small carboxylic acids are soluble in water, but solubility decreases as the carbon chain length increases.
• Reactivity: They react readily with alcohols to form esters, and with bases to form salts.

In fumaric acid, having two carboxylic acid groups enhances its acidity and reactivity, making it an important biological compound in metabolic processes.

Organic Chemistry Structural Drawing

Drawing organic structures accurately is crucial for understanding chemical properties and reactions. The structure of fumaric acid involves visualizing and correctly placing each part of the systematic name. Here’s how you can approach it:

• Identify the Backbone: Start by sketching a four-carbon linear chain, as "butene" suggests.
• Add the Double Bonds: Place a double bond between the second and third carbon atoms, in accordance with "-2-" from the name.
• Incorporate Functional Groups: Attach carboxylic acid groups (COOH) to each end of the carbon chain. This is where "dioic acid" informs us of their position.
• Verify Geometry: Ensure the trans configuration by placing the COOH groups on opposite sides of the double bond.

This methodical construction ensures that the structure accurately represents the molecular formula and functional groups described by the name.

Trans Geometric Isomers

Geometric isomerism occurs due to restricted rotation around the double bond in alkenes, leading to different spatial arrangements of atoms or groups. These isomers have identical atoms, but differ in spatial geometry, impacting physical and chemical properties significantly.

• Definition of Trans Isomers: In "trans" isomers, identical or similar groups are positioned on opposite sides of a double bond.
• Contrast with Cis Isomers: "Cis" isomers would have these groups on the same side, differing in both geometry and properties.
• Properties: Trans isomers, like fumaric acid, tend to have higher melting points than their cis counterparts, due to tighter packing and stronger intermolecular forces.
• Biological Relevance: The specific geometry of trans isomers often plays a crucial role in biological systems, affecting how molecules interact and function.

Recognizing the trans configuration in fumaric acid is essential for anticipating its behavior in chemical reactions and biological pathways.