Question

Fructose on oxidation with conc. \(\mathrm{HNO}_{3}\) gives (a) Tartaric acid (b) Saccharic acid (c) Glycolic acid (d) Both (a) and (c)

Short answer

Fructose oxidized with conc. NO_3 ight gives saccharic acid, so the answer is (b).

Step-by-step solution

Understanding the Reaction

Fructose is a sugar molecule that can undergo oxidation. When oxidized using concentrated nitric acid (NO_3 ight), it typically forms an oxidized sugar acid.

Identifying Reaction Products

Upon oxidation of fructose with concentrated nitric acid, the main product that forms is generally a dicarboxylic acid, which is known as saccharic acid. This is because the reaction breaks down the fructose's sugar ring, leading to the formation of two carboxylic acid groups.

Reviewing Answer Options

Given the products of the reaction are dicarboxylic acids, look at the options. Saccharic acid matches the expected product of oxidizing fructose with concentrated nitric acid. Tartaric acid and glycolic acid are not expected products in this particular reaction.

Confirming the Correct Option

Verify that option (b) correctly identifies saccharic acid as the product formed from oxidizing fructose with concentrated nitric acid.

Key concepts

Concentrated Nitric Acid Oxidation

Concentrated nitric acid plays a crucial role in the oxidation of organic molecules, especially sugars like fructose. The process involves breaking down complex organic structures to form more stable compounds. Concentrated nitric acid ( (NO_3) ) is a strong oxidizing agent and reacts with fructose by attacking its carbon chain. This reaction typically begins with the addition of the nitric acid to the sugar molecule, leading to the formation of intermediate oxidation products. These intermediates are subsequently converted into fully oxidized end products.

• The primary reaction involves breaking down the sugar monosaccharide, which in the case of fructose leads to the oxidation of specific carbon atoms in the molecule.
• This eventually results in the conversion of fructose into acids, which in this context is saccharic acid due to its formation of two carboxylic acid groups.
• Nitric acid is particularly effective because it can bring about complete oxidation, converting alcohol groups to carboxylic acids.

Understand that the concentrated nature of nitric acid is vital as it ensures the reaction proceeds to completion, yielding the expected dicarboxylic acids.

Dicarboxylic Acids

In chemical reactions involving sugars, dicarboxylic acids are often the major outcome, especially with agents like concentrated nitric acid. A dicarboxylic acid is simply an organic compound containing two carboxylic acid groups ( (-COOH) ). In the oxidation of fructose, the formation of dicarboxylic acids is pivotal. It's important to note that when fructose is oxidized, the sugar molecule undergoes a transformation from a simple sugar to a more complex system of acids:

• Saccharic acid is the primary dicarboxylic acid formed from the oxidation of fructose.
• The reaction alters the sugar structure significantly by breaking down the ring and introducing carboxylic groups.
• This not only makes the molecule more acidic but also significantly increases its reactivity in biochemical processes.

Dicarboxylic acids, like saccharic acid, exhibit distinct properties compared to their parent sugars, offering diverse applications in biochemistry and industry.

Sugar Ring Oxidation

Sugar ring oxidation is a chemical process where the cyclic (ring) structure of a sugar molecule is broken down. This is essential for forming acids from sugar molecules like fructose. When nitric acid oxidizes fructose, it targets the carbon atoms involved in the sugar's ring structure. The oxidation process affects the ring as follows:

• The sugar ring opens up, allowing the carbon atoms to form new bonds with oxygen.
• This transformation is where the aldehydes or ketones present transform into carboxylic acids.
• In the specific case of fructose, the breakdown of its five-carbon ring facilitates the formation of dicarboxylic acids, particularly saccharic acid.

The disruption of the sugar ring shows how powerful chemical oxidizing agents, like concentrated nitric acid, can change the fundamental structure of a sugar molecule, leading to new and useful acid derivatives. This process is a classic example of sugar ring oxidation and its outcome.