Question

Write a condensed structural formula for each of the following: \((\mathbf{a})\) an amide with the formula \(\mathrm{C}_{4} \mathrm{H}_{9} \mathrm{NO},(\mathbf{b})\) a cyclic ether with the formula \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O},(\mathbf{c})\) a diketone compound with the formula \(\mathrm{C}_{5} \mathrm{H}_{8} \mathrm{O}_{2}\), (d) a phenyl carboxylic acid with the formula \(\mathrm{C}_{7} \mathrm{H}_{6} \mathrm{O}_{2}\)

Short answer

The condensed structural formulas for the given compounds are: a) Amide with the formula C₄H₉NO: CH₃CH₂CONH₂ b) Cyclic ether with the formula C₄H₈O: CH₂OCH₂CH₂CH₂ (with the O atom forming the ring) c) Diketone compound with the formula C₅H₈O₂: CH₃COCH₂COCH₃ d) Phenyl carboxylic acid with the formula C₇H₆O₂: C₆H₅COOH (with the COOH group attached to the phenyl ring)

Step-by-step solution

Determine functional groups

Identify the functional groups associated with each type of compound: a) Amide: -CONR₂ b) Cyclic ether: C-O-C in a ring structure c) Diketone: Two carbonyl groups (C=O) within the same molecule d) Phenyl carboxylic acid: -COOH group connected to a phenyl ring

Write condensed structural formulas

a) Amide with the formula C₄H₉NO: Since we have 4 carbon atoms, the longest carbon chain will have 3 carbons, with the amide functional group (-CONH₂) located at one end of the chain. The condensed structural formula for the amide will be: CH₃CH₂CONH₂ b) Cyclic ether with the formula C₄H₈O: A cyclic ether will have oxygen bridging two carbon atoms in a ring structure. For a 4-carbon molecule, the structure will be a tetrahydrofuran ring. The condensed structural formula for the cyclic ether will be: CH₂OCH₂CH₂CH₂ (with the O atom forming the ring) c) Diketone compound with the formula C₅H₈O₂: Since there are two carbonyl groups, we can't have them at the ends of the molecule. The diketone structure would have a carbonyl group on the second and fourth carbon atoms. The condensed structural formula for the diketone compound will be: CH₃COCH₂COCH₃ d) Phenyl carboxylic acid with the formula C₇H₆O₂: A phenyl carboxylic acid will have a carboxylic acid (-COOH) group attached to a phenyl ring. Since there are 6 carbon atoms in a phenyl ring, the carboxylic acid group is attached to one of those carbon atoms. The condensed structural formula for the phenyl carboxylic acid will be: C₆H₅COOH (with the COOH group attached to the phenyl ring)

Key concepts

Amide Functional Group

An amide functional group is a common feature in organic chemistry. It is represented by the formula "-CONH₂". This group consists of a carbonyl group (C=O) that is bonded to a nitrogen atom. These structures are key components of proteins and peptides in biology.
The nitrogen in the amide group can form hydrogen bonds, which are important for the structure and function of biological molecules. Amides are typically formed through a reaction between a carboxylic acid and an amine.

• The carbonyl group provides the carbon, while the nitrogen comes from the amine.
• Amides can appear at the end of a carbon chain or within a larger compound.

Understanding amides is crucial for students exploring molecular structure and the reactivity of organic compounds, as they are present in many synthetic and natural materials.

Cyclic Ether

Cyclic ethers are a fascinating type of compound where an oxygen atom is incorporated within the ring structure. The presence of the oxygen atom within the ring imparts unique properties to cyclic ethers.
A common example of a cyclic ether is tetrahydrofuran, which has a four-carbon ring with one oxygen atom. Such compounds can serve as solvents in chemical reactions due to their good dissolving capabilities.

• Cyclic ethers can be easily identified by the presence of "C-O-C" within a ring.
• This configuration affects their chemical behavior, making them excellent solvents but sometimes challenging to synthesize.

Ethers generally have lower boiling points compared to alcohols of similar molecular weight, due to the absence of hydrogen bonding.

Diketone

A diketone contains two carbonyl (C=O) groups within its structure. These groups are typically found in separate locations along the carbon chain, impacting both the physical properties and reactivity of the compound.
The carbonyl groups in diketones are polar, influencing the molecule’s ability to interact with other chemical species. In fact, their reactivity can lead to important applications in organic synthesis, especially in the formation of enolates.

• Having two such reactive sites allows for a range of chemical transformations.
• Diketones can participate in unique reactions compared to compounds with a single carbonyl group.

These compounds are often used in the synthesis of more complex molecules, owing to the versatility provided by their dual carbonyl groups.

Phenyl Carboxylic Acid

A phenyl carboxylic acid is an aromatic compound characterized by the presence of a phosphophoric acid group (-COOH) attached to a phenyl ring. The phenyl ring is a stable, planar, six-carbon hydrogenated benzene ring, known for adding aromatic properties to compounds.
The carboxylic acid group is a highly functional group that can influence the compound's acidity and solubility. Its presence on the phenyl ring affects the compound’s chemical properties, making it more reactive than simple carboxylic acids.

• The combination of an aromatic ring and a carboxylic acid group makes these compounds interesting from both a structural and reactive standpoint.
• They are widely encountered in both natural substances and synthetic materials.

Understanding phenyl carboxylic acids is important for recognizing the varied reactivity in aromatic compounds, providing insights into their general properties and potential applications.