Question

Oxidation of one mole of glycerol with periodic acid gives (a) 1 mole each of methanol, methanal and methanoic acid. (b) 1 mole of methanal and 2 moles of methanoic acid. (c) 1 mole of methanoic acid and 2 moles of methanal. (d) three moles of methanal.

Short answer

Answer: The products formed by the oxidation of glycerol with periodic acid are 1 mole of methanal and 2 moles of methanoic acid.

Step-by-step solution

Determine the structure of glycerol

Glycerol is a polyol with the molecular formula C3H8O3. Its structure consists of a three-carbon chain with each carbon atom bonded to a hydroxyl group (-OH). The IUPAC name for glycerol is 1,2,3-propanetriol.

Understand the oxidation reaction with periodic acid

Periodic acid (HIO4) is a strong oxidizing agent, which is capable of cleaving carbon-carbon bonds adjacent to alcohol groups in molecules like glycerol. Periodic acid essentially oxidizes the carbon atoms that are bonded to hydroxyl groups, leading to the formation of various oxidation products such as aldehydes (R-CHO), ketones (R-CO-R'), and carboxylic acids (R-COOH).

Find the products of the oxidation reaction

Given the structure of glycerol and the oxidation effect of periodic acid, let's analyze the possible products: 1. Oxidizing the hydroxyl group on C1 (first carbon) would lead to the formation of an aldehyde (methanal). 2. Oxidizing the hydroxyl group on C2 (middle carbon) would lead to the formation of both an aldehyde (from C1) and a carboxylic acid (from C3). 3. Oxidizing the hydroxyl group on C3 (last carbon) would lead to the formation of a carboxylic acid (methanoic acid).

Match the products with the given options

With the information gathered in Step 3, we can now identify the correct option from the given choices: (a) 1 mole each of methanol, methanal, and methanoic acid. This option is incorrect, as methanol isn't a product of the reaction. (b) 1 mole of methanal and 2 moles of methanoic acid. This option is correct, as the oxidation of glycerol leads to the formation of one mole of methanal and two moles of methanoic acid. (c) 1 mole of methanoic acid and 2 moles of methanal. This option is incorrect, as there is only one mole of methanal formed in the reaction. (d) three moles of methanal. This option is incorrect, as only one mole of methanal is formed in the reaction. Thus, the correct answer is option (b) 1 mole of methanal and 2 moles of methanoic acid.

Key concepts

Periodic Acid

Periodic acid, with the chemical formula HIO4, is a prevalent oxidizing agent in organic chemistry. Its distinct ability lies in cleaving carbon-carbon bonds that are adjacent to alcohol groups. This makes it extremely useful for the oxidation of vicinal diols (alcohols with neighboring hydroxyl groups).

• It works by oxidizing the carbon atoms to which these hydroxyl groups are attached.
• This process eventually produces smaller molecules, such as aldehydes and carboxylic acids.

The type of products formed depends on the number and position of hydroxyl groups in the substrate. In the presence of glycerol, periodic acid cleaves the carbon-carbon bonds leading to a very specific set of smaller molecules. As discussed in the context of glycerol, the role of periodic acid is fundamental in transforming complex alcohols into more manageable substances, making it instrumental in many organic syntheses.

Glycerol Oxidation

Glycerol is a simple polyol compound and is often used in a variety of industrial applications. The molecular structure of glycerol is represented as C3H8O3, which corresponds to a three-carbon chain where each carbon is bonded to a hydroxyl group (-OH).

• The task of oxidizing glycerol involves the transformation of these hydroxyls using an oxidizing agent like periodic acid.
• During this reaction, it's important to note that the process involves the specific breaking of carbon-carbon bonds adjacent to the hydroxyl groups.

When glycerol undergoes oxidation by periodic acid, the result is a mixture of smaller molecules. Crucially, for glycerol, the outcome includes one mole of methanal and two moles of methanoic acid. This highlights how the structure of glycerol determines the very specific nature of its oxidation products. Understanding the exact structural pathways allows chemists to predict and manipulate the products of such reactions effectively.

Organic Chemistry Oxidation

Oxidation reactions in organic chemistry involve the increase of the oxidation state of a molecule. Typically, this means the addition of oxygen or the removal of hydrogen from the molecule. These reactions are crucial as they help transform molecules into more reactive or functional forms. Through oxidation, less reactive compounds can be converted into aldehydes, ketones, acids, or other essential organic compounds.

• The oxidation of organic molecules often involves the use of reagents like dichromate, permanganate, or acids like periodic acid.
• Such reagents facilitate the conversion of alcohols, which are relatively saturated, into more reactive carbonyl or carboxyl compounds.

In the case of glycerol oxidation by periodic acid, the additional complexity arises from the presence of multiple hydroxyl groups. The instruction of the oxidizing agent, therefore, becomes a detailed orchestration leading to specific oxidation products. This type of thorough understanding is indispensable as it forms the foundation of many synthetic pathways in organic chemistry.