Question

Maleic acid and fumaric acid are the cis- 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. Answer: Maleic acid (cis isomer) has the following structure: ``` O O || || H-C1=C2-OH H-C3=O || || O O ``` Fumaric acid (trans isomer) has this structure: ``` O O || || H-C1=C2-OH O=C3-H || || O O ```

Step-by-step solution

Understand the formula for the acids

The formula for both maleic acid and fumaric acid is \(\mathrm{C}_{2} \mathrm{H}_{2}(\mathrm{COOH})_{2}\). This tells us that there are two carbon atoms, two hydrogen atoms, and two carboxyl groups (COOH) in the compound.

Identify the type of isomerism

As stated in the exercise, maleic acid and fumaric acid are cis- and trans- isomers, respectively. Cis-trans isomerism is a type of stereoisomerism, where the arrangement of atoms in space is different but their connectivity is the same. In cis isomers, similar groups are positioned on the same side of the double bond, while in trans isomers, they are on opposite sides.

Draw the cis isomer (maleic acid)

Start by drawing the backbone of the molecule, consisting of two carbon atoms C1 and C2 with a double bond between them. Then, draw the two carboxyl groups (COOH) connected to the carbon atoms. For the cis isomer (maleic acid), the carboxyl groups should be on the same side of the double bond, and connect the two hydrogen atoms (H) to the carbon atoms as well. The structure for maleic acid will look like this: ``` O O || || H-C1=C2-OH H-C3=O || || O O ```

Draw the trans isomer (fumaric acid)

Draw the backbone of the molecule, consisting of two carbon atoms C1 and C2 with a double bond between them. Then, draw the two carboxyl groups (COOH) connected to the carbon atoms. For the trans isomer (fumaric acid), the carboxyl groups should be on opposite sides of the double bond, and connect the two hydrogen atoms (H) to the carbon atoms as well. The structure for fumaric acid will look like this: ``` O O || || H-C1=C2-OH O=C3-H || || O O ``` Now, the structures of maleic acid (cis isomer) and fumaric acid (trans isomer) have been drawn and labeled.