Question

The products of oxidation of 2 -pentanone with concentrated nitric acid are (a) propanoic acid and ethanoic acid (b) butanoic acid and methanoic acid (c) propanoic acid and methanoic acid (d) 2 -methyl propanoic acid and methanoic acid

Short answer

Answer: The products of oxidation of 2-pentanone with concentrated nitric acid are propanoic acid and ethanoic acid.

Step-by-step solution

Write the structure of 2-pentanone

Firstly, write the structure of 2-pentanone. The structure is as follows: CH3 - CH2 - CO - CH2 - CH3

Oxidation of 2-pentanone with concentrated nitric acid

When 2-pentanone reacts with concentrated nitric acid, it undergoes an oxidation reaction by breaking carbon-carbon bonds adjacent to the carbonyl group. The carbonyl carbon (C=O) will oxidize to a carboxylic acid group (-COOH). For 2-pentanone, it will break the bond between the 2nd and 3rd carbon after oxidation. Now, we will have the following products: 1. A 2-carbon chain with a carboxylic acid group (-COOH) attached to the carbonyl carbon. 2. A 3-carbon chain with a carboxylic acid group (-COOH) attached to the carbonyl carbon.

Write the IUPAC names of the products

Write the IUPAC names for the obtained compounds in step 2: 1. The 2-carbon compound with a carboxylic acid group is called ethanoic acid (CH3-COOH). 2. The 3-carbon compound with a carboxylic acid group is called propanoic acid (CH3-CH2-COOH).

Match the obtained products with the given choices

Now, let's match our products with the given choices: (a) propanoic acid and ethanoic acid (b) butanoic acid and methanoic acid (c) propanoic acid and methanoic acid (d) 2 -methyl propanoic acid and methanoic acid Our products, propanoic acid and ethanoic acid, match with choice (a). Therefore, the correct answer is (a) propanoic acid and ethanoic acid.

Key concepts

2-pentanone

2-pentanone is a ketone, meaning it has a carbonyl group (C=O) bonded to two other carbons. In 2-pentanone, the carbonyl group is located on the second carbon of a five-carbon chain. This molecule can be represented as: CH3-CH2-CO-CH2-CH3. The numbers in the name "2-pentanone" come from the longest carbon chain ("pent" for five carbons) and the position of the ketone group ("2" indicating the carbon it's attached to). The ketone functional group is significant because it plays a crucial role in chemical reactions, such as oxidation processes.
When oxidized, the carbonyl group can facilitate the breaking of carbon-carbon bonds adjacent to itself, leading to the formation of other functional groups like carboxylic acids.

Nitric Acid

Nitric acid (HNO3) is a powerful oxidizing agent commonly used in organic chemistry to convert various functional groups into carboxylic acids. When it reacts with ketones like 2-pentanone, it can break carbon-carbon bonds adjacent to the carbonyl group. This results in two smaller carboxylic acids.
The effectiveness of nitric acid as an oxidizer comes from its ability to donate oxygen atoms, allowing for the formation of new bonds in the oxidized products. In the case of 2-pentanone, nitric acid will cleave the molecule into two smaller segments, each terminating with a carboxylic acid group.

Carboxylic Acids

Carboxylic acids are organic compounds characterized by the presence of a carboxyl group (-COOH). This functional group consists of a carbonyl and a hydroxyl group attached to the same carbon atom. They are commonly known for their acidic properties and distinct sour taste.
In oxidation reactions involving compounds like 2-pentanone, the formation of carboxylic acids is a common outcome. For example, after oxidizing 2-pentanone with nitric acid, one ends up with ethanoic acid and propanoic acid. These acids are classified based on the length of their carbon chain, meaning their names change depending on the number of carbons they contain. Ethanoic acid is a two-carbon carboxylic acid, while propanoic acid contains three carbons.

IUPAC Nomenclature

The International Union of Pure and Applied Chemistry (IUPAC) nomenclature is a standardized method for naming chemical compounds. The goal is to ensure that each compound's name gives you a clear idea about its structure and unique chemical properties.
When naming 2-pentanone oxidation products, we apply IUPAC rules to ensure accuracy. The reduction to carboxylic acids results in ethanoic acid and propanoic acid, named due to their carbon chain length. "Ethanoic acid" indicates a two-carbon acid, where the suffix “-oic acid” denotes the presence of the carboxyl group. Similarly, "propanoic acid" refers to a three-carbon chain acid. Understanding IUPAC nomenclature is crucial for all chemists to accurately communicate about and understand chemical structures and reactions.