Question

Match list I (organic compounds oxidized by \(\left.\mathrm{HIO}_{4}\right)\) with list II (products of \(\mathrm{HIO}_{4}\) oxidation) and select the correct answer. List II (i) \(2 \mathrm{H}_{2} \mathrm{C}=\mathrm{O}+\mathrm{HCOOH}\) (ii) \(2 \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}=\mathrm{O}\) (iii) \(2 \mathrm{H}_{2} \mathrm{C}=\mathrm{O}\) (iv) \(\mathrm{PhCH}_{2} \mathrm{CH}=\mathrm{O}+\mathrm{CH}_{3} \mathrm{CH}=\mathrm{O}\) The correct matching is: 1 2 3 4 (a) (ii) (iv) (i) (iii) (b) (iv) (ii) (iii) (i) (c) (ii) (iii) (i) (iv) (d) (ii) (iv) (iii) (i)

Short answer

The correct match is option (d).

Step-by-step solution

Understanding Periodic Acid (HIO4) Oxidation

Periodic acid ( ext{HIO}_4) specifically cleaves vicinal diols (1,2-diols), resulting in aldehydes or ketones. We need to identify structures from List I that can be oxidized by  ext{HIO}_4 and match them to the corresponding products in List II.

Analyzing Products in List II

Looking at the options in List II, we note that: - (i) gives formaldehyde and formic acid, suggesting a vicinal diol broke into these products. - (ii) gives two molecules of acetaldehyde, indicating both cleavage from a longer carbon chain with vicinal diols. - (iii) gives only formaldehyde, likely splitting from a simpler symmetric diol. - (iv) gives benzaldehyde and acetaldehyde, implying one part was a benzyl alcohol and another an ethyl alcohol.

Matching with the Correct Answer

Given the products from List II, let's determine the matching from List I: - (2) relates to option (ii) in List II because it suggests a molecule like butane-2,3-diol splitting into two acetaldehyde. - (4) matches with (iv), benzaldehyde, and acetaldehyde come from a molecule like 1-phenylpropane-1,2-diol. - (1) matches with (i), which can derive from a glycol to produce formaldehyde and formic acid. - (3) connects to (iii), similar to a simpler diol producing two formaldehyde molecules.

Key concepts

Vicinal Diols

Vicinal diols, also known as 1,2-diols, are a type of glycol in which two hydroxyl (OH) groups are bound to adjacent carbon atoms in a carbon chain. This structural position is key to their reactivity and their subsequent transformations during oxidative processes. When periodic acid ("\( \text{HIO}_4 \)") is introduced, it has the ability to target these specific types of diols.

Periodic acid undergoes a cleavage reaction with vicinal diols.- This means it breaks the carbon-carbon bond holding the two alcohol groups together.- As a result of this reaction, the vicinal diol is split into two separate carbonyl compounds  either aldehydes or ketones.

This makes vicinal diols essential starting materials in many organic synthesis processes where specific aldehydes or ketones are the desired products. Understanding their structure and behavior during oxidation helps chemists achieve specific goals in building complex organic molecules.

Aldehydes Formation

The formation of aldehydes is a common outcome in the oxidation of vicinal diols using periodic acid. When periodic acid cleaves a vicinal diol, each of the newly formed molecules contains a carbonyl group, typically an aldehyde or, less frequently, a ketone.

This reaction is particularly useful because: - It allows for the generation of aldehydic functional groups from relatively stable alcohol frameworks. - Aldehydes themselves are highly valuable in synthetic chemistry due to their reactivity and ability to form further complex structures.

During the oxidation, an example reaction might involve the conversion of ethylene glycol, a simple vicinal diol, into formaldehyde, a basic aldehyde. This process of aldehyde formation is critical for converting simple molecules into more complex organic compounds useful in various applications, ranging from pharmaceuticals to polymers.

Organic Compounds Oxidation

Oxidation reactions are a fundamental component of organic chemistry, enabling significant transformations of molecular structures. Periodic acid (HIO_4) is a powerful oxidizing agent used primarily to oxidize organic compounds with vicinal diols.

When an oxidation process occurs, several changes take place: - The alcohol (OH) groups are converted into carbonyl (CO) groups. - There is a loss of hydrogen atoms, which is a hallmark of oxidation processes. - Cleavage of the bond between the carbons bearing the OH groups, forming individual molecules.

This type of oxidation has important applications: - It allows precise breaking of carbon skeletons at desired points, particularly useful in intricate synthetic pathways. - The specific formation of carbonyl groups enables further reactions and complexity in molecular design. - Known for its specificity, using periodic acid ensures that non-vicinal diol regions of the molecule are left intact, making it ideal for selective synthetic applications in organic chemistry.

The specificity and reliability of periodic acid oxidation make it an invaluable tool in organic synthesis, facilitating the conversion of simple diols into various valuable functional groups.