Question

Draw condensed structural formulas for the two carboxylic acids with the molecuJar formula \(\mathrm{CHO} \mathrm{O}\)

Short answer

Answer: The condensed structural formulas for the two carboxylic acids are: - Butanoic acid: \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{COOH}\) - 2-Methylpropanoic acid: \(\mathrm{CH}_{3}\mathrm{CH}\left(\mathrm{CH}_{3}\right)\mathrm{COOH}\)

Step-by-step solution

(Step 1: Understand carboxylic acids general structure)

A carboxylic acid is an organic compound that contains a carboxyl group (\(-\mathrm{COOH}\)) and has the general formula \(\mathrm{R-COOH}\), where R is an alkyl or aryl group. In this exercise, we have the molecular formula \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\) which means we have a total of 4 carbon atoms, 8 hydrogen atoms, and 2 oxygen atoms.

(Step 2: Find the possible structures for the carboxylic acids)

Using the general formula of carboxylic acids (\(\mathrm{R-COOH}\)) and the given molecular formula, we need to find the possible structures that fulfill the molecular formula \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\). Structure 1: \(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{COOH}\) (Butanoic acid) In this structure, we have a total of 4 carbon atoms, 8 hydrogen atoms, and 2 oxygen atoms as required. Structure 2: \(\mathrm{CH}_{3}-\mathrm{CH}\left(\mathrm{CH}_{3}\right)-\mathrm{COOH}\) (2-Methylpropanoic acid) In this structure, we also have a total of 4 carbon atoms, 8 hydrogen atoms, and 2 oxygen atoms as required.

(Step 3: Draw the condensed structural formulas)

Now that we have found the two possible structures for the carboxylic acids with the molecular formula \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\), we can draw the condensed structural formulas for them: - Butanoic acid: \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{COOH}\) - 2-Methylpropanoic acid: \(\mathrm{CH}_{3}\mathrm{CH}\left(\mathrm{CH}_{3}\right)\mathrm{COOH}\) These are the condensed structural formulas for the two carboxylic acids with the molecular formula \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\).

Key concepts

Condensed Structural Formulas

Condensed structural formulas provide a way to represent the molecular structure of a compound in a simplified manner without drawing out all the individual bonds. They are particularly useful for organic compounds, which can have complex and lengthy structures. A condensed structure shows the arrangement of atoms and the sequence of bonded atoms in a molecule but omits the bonds themselves for simplicity.

For example, the condensed structural formula for ethanoic acid (acetic acid) is written as CH₃COOH, denoting that a methyl group (CH₃-) is attached to the carboxyl group (-COOH) directly. This notation is valuable because it gives a clear and concise overview of the molecule's connectivity, which helps in understanding its properties and reactivity.

General Structure of Carboxylic Acids

Carboxylic acids are a class of organic compounds characterized by the presence of a carboxyl group ((-COOH)). This functional group consists of a carbon atom double-bonded to an oxygen atom and also bonded to a hydroxyl group (OH). The general formula for a carboxylic acid is R-COOH, where 'R' represents the rest of the molecule, which can be a hydrogen atom or any hydrocarbon chain, whether straight or branched.

Carboxylic acids play vital roles in various biochemical processes and are widely found in nature, for instance, in amino acids and fatty acids. Their chemistry is dominated by the presence of the carboxyl group, which is polar and can act as an acid by donating a proton due to the resonance stabilization of the remaining carboxylate ion.

Butanoic Acid

Butanoic acid, also known as butyric acid, has the molecular formula C₄H₈O₂ and is a four-carbon straight-chain carboxylic acid. Its structure can be represented as CH₃CH₂CH₂COOH. This acid is found in butter and has a distinctively unpleasant smell similar to rancid butter.

Butanoic acid is an important substance in the food and perfume industry and is also used in the manufacture of various esters for artificial flavorings and fragrances. It exemplifies the properties of carboxylic acids, having a higher boiling point and being more water-soluble than hydrocarbons of similar molecular weight due to hydrogen bonding influenced by the carboxyl group.

2-Methylpropanoic Acid

2-Methylpropanoic acid is a carboxylic acid with a molecular formula of C₄H₈O₂, similar to butanoic acid. However, instead of a straight chain, it contains a branched chain with the structural formula CH₃CH(CH₃)COOH, where a methyl group (CH₃) is attached to the second carbon of the propionic acid backbone.

The '2-' in its name indicates that the methyl substitution is on the second carbon of the three-carbon chain. This structural difference affects the compound's physical and chemical properties, such as boiling point and solubility. 2-Methylpropanoic acid is used in organic synthesis and is also found in some natural products.