Question

A compound having molecular formula \(\mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}_{3} .\) It may have functional group (A) Ester (B) Ketone (C) Acid anhydride (D) Carboxylic acid

Short answer

The compound with the molecular formula C5H10O3 belongs to the functional group Ester (Option A), as it fits the general formula R-COO-R' and has 3 oxygen atoms in the structure, unlike the other options.

Step-by-step solution

Option (A) Ester

Estergroup has the general formula: R-COO-R'. We know that it has one oxygen atom in the double bond and another in single bond connections. For the given molecule C5H10O3, since there are 3 oxygen atoms, it can represent an ester. It could be something like: CH3COOCH2CH2CH3.

Option (B) Ketone

Ketone has the general formula: R-CO-R'. Ketones have one oxygen atom in a double bond. The compound C5H10O3 has 3 oxygen atoms, so it cannot be a ketone because it has more than one oxygen atom. Hence, it doesn't fit the given molecular formula.

Option (C) Acid Anhydride

Acid anhydrides have the general formula: (R-CO)2O. They have two CO groups and an extra oxygen atom between them. This structure requires a minimum of 6 carbon atoms and 4 oxygen atoms for the simplest form. Since the given formula has only 5 carbons and 3 oxygen atoms, it cannot be an acid anhydride.

Option (D) Carboxylic Acid

Carboxylic acid has the general formula: R-COOH. They have one oxygen atom in a double bond and another in single bond connection with Hydrogen. Such a structure requires at least 2 oxygen atoms for each COOH group. Since the given formula has 3 oxygen atoms, it is not possible to have two carboxylic acid groups in the compound. So, it's not a carboxylic acid. On analyzing the given options, we can conclude that the compound with the molecular formula C5H10O3 belongs to the functional group given in option: (A) Ester

Key concepts

Ester

Esters are fascinating components in organic chemistry. They contain the functional group characterized by the \(-COO-\) linkage. This linkage consists of a carbonyl group \(C=O\) adjacent to an ether linkage \(O-C\). Esters are commonly found in natural flavors and fragrances, imparting fruity aromas.
In the context of a compound with the molecular formula \(C_5H_{10}O_3\), esters are a reasonable group to consider. This is because their structure can easily incorporate three oxygen atoms. For instance, one simple structure could be \(CH_3COOCH_2CH_2CH_3\), where the ester linkage is evident. Such arrangements allow esters to adopt formulas like \(C_5H_{10}O_3\) while still maintaining their characteristic functional group.

Molecular Formula Analysis

When faced with understanding molecular formulas, it's important to analyze the number of each type of atom present. This analysis helps deduce what possible organic functional groups might fit. Consider the molecular formula \(C_5H_{10}O_3\):

• It contains 5 carbon atoms.
• There are 10 hydrogen atoms.
• It has 3 oxygen atoms.

This information can narrowly define which functional groups can be considered. By knowing the general formulas of different groups, you can swiftly identify which ones are viable. In this exercise, we see that while a ketone is eliminated due to excess oxygen, an ester is feasible. Analyzing each element systematically can guide in identifying the correct functional group more accurately.

Acid Anhydride

Acid anhydrides are another class of functional groups known for their \(R-CO)_{2}O\) structure, consisting of two acyl groups connected by an oxygen atom. These compounds typically arise from the dehydration of carboxylic acids and are characterized by their need for four oxygen atoms to maintain balance.
In the molecular formula \(C_5H_{10}O_3\), the number of oxygen atoms is insufficient to form an acid anhydride, which requires at least four to satisfy the \(R-CO)_{2}O\) structural demands. Thus, despite being a viable chemical structure, it does not satisfy the given molecular formula's constraints. Understanding why certain molecules cannot be one thing but not another helps students make better deductions.

Carboxylic Acid

Carboxylic acids are identified by the \(R-COOH\) group, featuring a carbon atom double-bonded to oxygen and single-bonded to a hydroxyl group. These are pivotal in organic and biochemical processes, often contributing to acidic behavior in compounds.
The compound \(C_5H_{10}O_3\) with only three oxygen atoms cannot support multiple carboxylic acid groups, as each requires at least two oxygens. If the molecule contained six oxygen atoms, it might suggest the presence of multiple carboxylic groups. However, in this case, the molecular formula indicates another option fits better. Understanding oxygen demands for carboxylic acids assists greatly in functional group identification.