Question

Mimosine is a natural product found in large quantities in the seeds and foliage of some legume plants and has been shown to cause inhibition of hair growth and hair loss in mice. a. What functional groups are present in mimosine? b. Give the hybridization of the eight carbon atoms in mimosine. c. How many \(\sigma\) and \(\pi\) bonds are found in mimosine?

Short answer

a. Mimosine contains an amide group (NHCO), a carboxylic acid group (COOH), and a pyridine ring (aromatic heterocyclic ring containing one nitrogen atom). b. The hybridization of the eight carbon atoms in mimosine are as follows: C1, C2, C3, C4, C6, C7 - sp² hybridized; C5, C8 - sp³ hybridized. c. There are 27 \(\sigma\) bonds and 7 \(\pi\) bonds found in the mimosine molecule.

Step-by-step solution

Identify Functional Groups

By analyzing the structure, we can see the following functional groups in mimosine: 1. An amide group (NHCO) 2. A carboxylic acid group (COOH) 3. A pyridine ring (aromatic heterocyclic ring containing one nitrogen atom)

Determine Carbon Atom Hybridization

Next, let's determine the hybridization of the eight carbon atoms of mimosine. We will label the carbon atoms as C1 to C8, starting from the left side of the molecule in the image. 1. C1: sp² hybridized - part of the aromatic ring 2. C2: sp² hybridized - part of the aromatic ring 3. C3: sp² hybridized - part of the aromatic ring 4. C4: sp² hybridized - part of the aromatic ring and connected to the amide group 5. C5: sp³ hybridized - connected to the hydroxyl group (OH) and amide group 6. C6: sp² hybridized - part of the aromatic ring 7. C7: sp² hybridized - part of the aromatic ring 8. C8: sp³ hybridized - connected to the carboxylic acid group (COOH) and aromatic ring

Calculate Number of σ and π Bonds

Lastly, let's calculate the number of \(\sigma\) and \(\pi\) bonds in mimosine. To do this, we need to account for all the single, double, and triple bonds present in the molecule. Single bonds: 20 (each single bond contains one \(\sigma\) bond) Double bonds: 7 (each double bond contains one \(\sigma\) bond and one \(\pi\) bond) Total number of \(\sigma\) bonds = 20 (from single bonds) + 7 (from double bonds) = 27 Total number of \(\pi\) bonds = 7 (from double bonds) There are 27 \(\sigma\) bonds and 7 \(\pi\) bonds found in the mimosine molecule.

Key concepts

Functional groups in Mimosine

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. In mimosine, we can identify several functional groups:

- **Amide group (NHCO):** This group is a combination of a carbonyl group (C=O) and an amine group (NH2), connected by a nitrogen atom. It is known for its role in forming peptide bonds in proteins.
- **Carboxylic acid group (COOH):** Characterized by a carbon double-bonded to an oxygen and also bonded to a hydroxyl group (OH), this group is known for its acidic properties.
- **Pyridine ring:** This is a six-membered aromatic ring structure similar to benzene but with one nitrogen atom replacing one carbon. It is important in many chemical reactions and as a structural feature in some drugs.

These functional groups contribute to the chemical properties and biological activities of mimosine.

Carbon atom hybridization in Mimosine

Carbon atom hybridization is a concept that explains the arrangement of atoms around a central atom by mixing its atomic orbitals. In mimosine, the carbon atoms can be hybridized in different forms depending on their bonding.

- **sp² Hybridized Carbons:**
- C1, C2, C3, C4, C6, C7: These carbons are part of the aromatic pyridine ring and one of them (C4) is also connected to an amide group. sp² hybridization involves one s orbital and two p orbitals mixing to form three equivalent sp² orbitals, allowing for a planar trigonal structure.

- **sp³ Hybridized Carbons:**
- C5: Connected to the hydroxyl (OH) and amide group, this carbon adopts a tetrahedral geometry typical of sp³ hybridized atoms.
- C8: Connected to the carboxylic acid group and the aromatic ring, also sp³ hybridized, allowing for more flexibility and 3D structure in this part of the molecule.

Understanding these hybridizations helps in visualizing the 3D structure of the molecule and predicting its reactivity.

Understanding Sigma and Pi Bonds

Sigma (\(\sigma\)) and pi (\(\pi\)) bonds are types of covalent bonds that occur due to the overlap of atomic orbitals. They play a crucial role in determining the stability and geometry of molecules.

- **Sigma Bonds (\(\sigma\)):** These are the strongest type of covalent bonds, formed by the head-on overlap of orbitals. Every single bond in a molecule consists of one \(\sigma\) bond. In mimosine, there are 20 \(\sigma\) bonds from single bonds and an additional 7 from double bonds, making a total of 27 \(\sigma\) bonds.

- **Pi Bonds (\(\pi\)):** These bonds result from the side-to-side overlap of p orbitals and are found in double and triple bonds. In mimosine, each of the 7 double bonds contains one \(\pi\) bond, for a total of 7 \(\pi\) bonds. Pi bonds add to the complexity of the molecule, influencing its chemical reactivity and properties by preventing free rotation around the bond.

The distribution of \(\sigma\) and \(\pi\) bonds determines much of the molecule's stability and reactivity.