Question

Write a condensed structural formula for each of the following: (a) an acid with the formula \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\), (b) a cyclic ketone with the formula \(\mathrm{C}_{3} \mathrm{H}_{3} \mathrm{O}_{3}\) (c) a dihydroxy compound with the formula \(\mathrm{C}_{3} \mathrm{H}_{5} \mathrm{O}_{2}\), (d) a cyclic ester with the formula \(\mathrm{C}_{5} \mathrm{H}_{8} \mathrm{O}_{2}\) -

Short answer

The condensed structural formulas for the given compounds are as follows: (a) Butanoic acid: CH_3CH_2CH_2COOH (b) Cyclopropanone (assuming the correct molecular formula is \(\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{O}\)): \(\mathrm{C(O)CH_2CH_2}\) (c) Propane-1,2-diol: CH_2(OH)CH(OH)CH_3 (d) γ-Butyrolactone: \(\mathrm{C_2H_5} - \mathrm{C(O)OCH_2}\)

Step-by-step solution

(a) Identify the functional group and draw the structure of the acid)

For the acid with formula \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\), we know the functional group is the carboxylic acid group (COOH). We can start by drawing the COOH group and then use the remaining carbon atoms to complete the structure. We have three carbon atoms left to build the structure which makes the acid butanoic acid. The condensed structural formula is CH_3CH_2CH_2COOH.

(b) Identify the functional group and draw the structure of the cyclic ketone)

For the cyclic ketone with the formula \(\mathrm{C}_{3} \mathrm{H}_{3} \mathrm{O}_{3}\), we know the functional group is a ketone group (C=O). Since it is a cyclic compound, we have to form a closed ring structure using the remaining carbon and oxygen atoms. However, there seems to be a mistake in the given molecular formula, as a 3-membered ring with a ketone functional group would have a molecular formula of \(\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{O}\). Assuming the correct molecular formula is \(\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{O}\), the structure of the cyclic ketone can be drawn as cyclopropanone with the condensed structural formula: \( \mathrm{C(O)CH_2CH_2} \).

(c) Identify the functional group and draw the structure of the dihydroxy compound)

For the dihydroxy compound with the formula \(\mathrm{C}_{3} \mathrm{H}_{5} \mathrm{O}_{2}\), we can infer that the compound has two hydroxyl groups (OH). We have three carbon atoms, which will form the base of the structure. Using the atomic formula we can deduce the structure as propane-1,2-diol with the following condensed structural formula: CH_2(OH)CH(OH)CH_3.

(d) Identify the functional group and draw the structure of the cyclic ester)

For the cyclic ester with the formula \(\mathrm{C}_{5} \mathrm{H}_{8} \mathrm{O}_{2}\), we know that the functional group is an ester group (COO). Since it is a cyclic compound, we should form a closed-ring structure with the ester group acting as a bridge between two carbon atoms. We have three remaining carbon atoms to complete the structure. This corresponds to a 5-membered ring structure which is γ-butyrolactone. Its condensed structural formula is \( \mathrm{C_2H_5} - \mathrm{C(O)OCH_2} \).

Key concepts

Carboxylic Acid

Carboxylic acids are organic compounds characterized by the presence of a carboxyl group \(\mathrm{COOH}\). The unique feature of carboxylic acids is their ability to donate a proton due to the carboxyl group. This group is responsible for the acidic nature of these compounds. To differentiate carboxylic acids in condensed structural formulas, look for the \(\mathrm{COOH}\) group at the end of the carbon chain.
For instance, butanoic acid with a formula of \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\) includes such a carboxyl group. In its condensed structural form, it appears as \(\mathrm{CH_3CH_2CH_2COOH}\).
Carboxylic acids are common in nature. They often have sharp odors and are used in various chemical processes, including the synthesis of polymers, pharmaceuticals, and even as food preservatives.

Cyclic Ketone

Cyclic ketones are a fascinating class of organic compounds where the ketone group \(\mathrm{C=O}\) is incorporated into a ring. This structure provides stability and unique reactivity to the compound.
You can recognize a cyclic ketone by the presence of a closed ring in its chemical structure alongside the ketone carbonyl group. For the example of cyclopropanone \(\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{O}\), the condensed formula could be written as \(\mathrm{C(O)CH_2CH_2}\). However, the formula provided in the original problem appears to contain an error, showing \(\mathrm{C}_{3} \mathrm{H}_{3} \mathrm{O}_{3}\), which doesn't accurately depict a typical cyclic ketone.

• Cyclic ketones are important in various industrial applications including perfumery and pharmaceuticals.
• They can participate in a range of chemical reactions, making them versatile building blocks in organic synthesis.

Dihydroxy Compound

A dihydroxy compound contains two hydroxyl groups \(\mathrm{OH}\). These groups can dramatically influence the physical and chemical properties of the molecule.
You will find dihydroxy compounds in both aliphatic and aromatic settings. In propane-1,2-diol, with the formula \(\mathrm{C}_{3} \mathrm{H}_{5} \mathrm{O}_{2}\), the structure is more clearly understood by its condensed formula: \(\mathrm{CH_2(OH)CH(OH)CH_3}\).
In practical terms, the hydroxyl groups make such molecules polar, allowing them to dissolve in water easily.

• These compounds are commonly used as intermediates in chemical synthesis.
• They are also used in the cosmetics and food industries due to their solvent properties.

Cyclic Ester

Cyclic esters, also known as lactones, have an ester group \(\mathrm{COO}\) bound within a ring structure. This arrangement imparts distinct reactivity and applications to the compound.
When identifying cyclic esters, note how the ester group connects two parts of the same molecule, forming a closed loop. In the given example of γ-butyrolactone, with the formula \(\mathrm{C}_{5} \mathrm{H}_{8} \mathrm{O}_{2}\), the functional group creates a five-membered ring, depicted in its condensed formula as \(\mathrm{C_2H_5C(O)OCH_2}\).

• Cyclic esters are valuable in synthesizing biodegradable polymers.
• They also serve as flavoring agents and solvents in various chemical processes.