Question

The incorrect statement regarding the given structure is

• A. Can be oxidized to a dicarboxylic acid with Br2 water
• B. despite the presence of – CHO does not give Schiff's test
• C. has 4-asymmetric carbon atom
• D. will coexist in equilibrium with 2 other cyclic structure

Answer 1

The Correct Option is A

To analyze the given options and determine which statement is incorrect regarding the structure depicted, we need to understand the chemistry of the functional groups and the molecular structure shown.

1. Can be oxidized to a dicarboxylic acid with Br₂ water:
   • Aldehydes can generally be oxidized to carboxylic acids. However, oxidation directly to a dicarboxylic acid would require both the aldehyde and the primary alcohol group to get oxidized in the presence of Br₂ in water. Bromine water typically does not fully oxidize such molecules to dicarboxylic acids but stops at monocarboxylic acids.
2. Despite the presence of –CHO does not give Schiff's test:
   • Schiff's test is specific for aldehydes. While the presence of an aldehyde group (–CHO) typically gives a positive result, the configuration or conjugation in the cyclic form might hinder this reaction, making it a plausible statement.
3. Has 4-asymmetric carbon atom:
   • The structure depicted, assuming it is a typical sugar molecule like glucose, does indeed have multiple chiral centers (asymmetric carbon atoms). Therefore, this statement is likely correct.
4. Will coexist in equilibrium with 2 other cyclic structures:
   • Sugars like glucose can exist in equilibrium with their cyclic forms in solution (alpha and beta anomers of the pyranose form), supporting this statement's correctness. Additionally, a furanose form could also exist.

Conclusion: The incorrect statement is that the structure can be oxidized to a dicarboxylic acid with Br₂ water. This method does not typically lead to full oxidation to a dicarboxylic acid.

Answer 2

The compound shown is a monosaccharide with an aldehyde group (-CHO) and multiple hydroxyl (-OH) groups. When treated with Br$_2$ water, it is not oxidized to a dicarboxylic acid but rather forms a monocarboxylic acid, making option (1) incorrect.
Statement (2) is correct: Despite having a –CHO group, certain sugars like glucose do not respond to Schiff’s test.
Statement (3) is correct: There are 4 chiral (asymmetric) carbon atoms present in the structure.
Statement (4) is correct: The compound can exist in equilibrium with two other cyclic forms, $\alpha$-D-glucose and $\beta$-D-glucose.