Question

Formaldehyde is obtained as one of the product during reaction of \(\mathrm{HIO}_{4}\) and (A) Methyl \(\alpha\)-D-glucopyranoside (B) Methyl \(\alpha\)-D-glucofuranoside (C) 2,3 -Butanediol (D) 1-hydroxy-2-butanone

Short answer

The correct answer is (C) 2,3-Butanediol, as it is the only compound containing a 1,2-diol that can be cleaved by \(\mathrm{HIO}_{4}\) to produce formaldehyde.

Step-by-step solution

Option A: Methyl α-D-glucopyranoside

Methyl α-D-glucopyranoside is a carbohydrate-derived compound. It is an α-anomer of glucose in its pyranose form. It does not contain a 1,2-diol, so it cannot produce formaldehyde when reacted with \(\mathrm{HIO}_{4}\).

Option B: Methyl α-D-glucofuranoside

Methyl α-D-glucofuranoside is another carbohydrate-derived compound. It is an α-anomer of glucose in its furanose form. Similar to the previous option, it does not contain a 1,2-diol, so it cannot produce formaldehyde when reacted with \(\mathrm{HIO}_{4}\).

Option C: 2,3-Butanediol

2,3-Butanediol is an organic compound with the formula \(\mathrm{HOCH}_{2}\mathrm{CH}_{2}\mathrm{CH(OH)CH}_{3}\). As we can see, there is a presence of a 1,2-diol in its structure, which can be cleaved using \(\mathrm{HIO}_{4}\). The reaction will produce formaldehyde (\(\mathrm{CH}_{2}\mathrm{O}\)) and acetaldehyde (\(\mathrm{CH}_{3}\mathrm{CHO}\)).

Option D: 1-hydroxy-2-butanone

1-hydroxy-2-butanone is an organic compound with the formula \(\mathrm{CH}_{3}\mathrm{COR, R= CH}_{2}\mathrm{OH}\). It does not possess a 1,2-diol in its structure, so it won't produce formaldehyde when reacted with \(\mathrm{HIO}_{4}\). Considering the analysis of all the given options, we can conclude that:

Answer:

The correct answer is (C) 2,3-Butanediol, as it is the only compound containing a 1,2-diol that can be cleaved by \(\mathrm{HIO}_{4}\) to produce formaldehyde.

Key concepts

Formaldehyde Production

The production of formaldehyde is a significant chemical reaction, particularly in the context of organic chemistry. Formaldehyde, a simple aldehyde with the formula \( \mathrm{CH}_{2}\mathrm{O} \), is commonly produced by the oxidation of molecules that contain a 1,2-diol group. The species \( \mathrm{HIO}_{4} \)—periodic acid—is an oxidizing agent that can cleave these diol groups, converting them into two separate aldehyde molecules.

When \( \mathrm{HIO}_{4} \) encounters a 1,2-diol, it acts specifically on the carbon-carbon bond that connects the two alcohol (-OH) groups. By cleaving this bond and oxidizing the carbons, formaldehyde can be one of the products, if the original diol is part of a larger molecule like 2,3-Butanediol. In educational exercises, understanding the structural requirements for this reaction is crucial, emphasizing the need for a 1,2-diol group within the reactant molecule for formaldehyde production.

Carbohydrates Reactivity

Carbohydrates display varied reactivity based on their structural attributes, making their chemistry particularly interesting. In the context of their reaction with oxidizing agents like \( \mathrm{HIO}_{4} \), it's the presence - or lack - of a 1,2-diol group that defines their reactivity.

Take, for instance, Methyl \( \alpha \)-D-glucopyranoside and Methyl \( \alpha \)-D-glucofuranoside; both are derivatives of glucose, yet their structures preclude the formation of formaldehyde upon treatment with \( \mathrm{HIO}_{4} \) because they lack the essential 1,2-diol. This property is pivotal for students to grasp as they delve into carbohydrate chemistry. By understanding that only certain configurations and functional groups within a carbohydrate molecule will react with \( \mathrm{HIO}_{4} \) to yield specific products, learners can predict the outcomes of such reactions more accurately.

Organic Compound Cleavage

Cleavage of organic compounds, particularly the breaking of C-C bonds next to alcohol groups, is a fundamental transformation in organic synthesis and analytical chemistry. An excellent example of such cleavage involves the use of the powerful oxidant periodic acid \( \mathrm{HIO}_{4} \). This reaction specifically targets 1,2-diols, where the vicinal hydroxyl groups (adjacent -OH groups) are oxidatively cleaved to yield separate carbonyl compounds, which may include aldehydes like formaldehyde.

Engineering college-level exercises frequently test students' understanding of such cleavage reactions. Emphasizing the importance of the presence of a 1,2-diol group for \( \mathrm{HIO}_{4} \) to act upon, students need to identify potential cleavage points within molecular structures. Through practice, learners develop the ability to predict which bonds in a molecule \( \mathrm{HIO}_{4} \) will cleave and what products will emerge from the reaction.