Which of the following compounds is a constitutional (structural) isomer of glucose ($C_6{H}_{12}{O}_6$)?

• A. Maltose ($C_{12}{H}_{22}{O}_{11}$)
• B. Fructose ($C_6{H}_{12}{O}_6$)
• C. Sucrose ($C_{12}{H}_{22}{O}_{11}$)
• D. Galactose ($C_6{H}_{12}{O}_6$)

Answer: (B)

Verified step by step guidance

1. Identify the molecular formula of glucose, which is \(C_6H_{12}O_6\). This formula will be key to determining which compounds are isomers.
2. Recall that constitutional (structural) isomers have the same molecular formula but different connectivity of atoms. Therefore, any compound with a different molecular formula cannot be a constitutional isomer.
3. Examine the molecular formulas of the given compounds: Maltose (\(C_{12}H_{22}O_{11}\)), Fructose (\(C_6H_{12}O_6\)), Sucrose (\(C_{12}H_{22}O_{11}\)), and Galactose (\(C_6H_{12}O_6\)).
4. Eliminate compounds with molecular formulas different from glucose (\(C_6H_{12}O_6\)), which are Maltose and Sucrose, since they have \(C_{12}H_{22}O_{11}\) and thus cannot be isomers of glucose.
5. Focus on Fructose and Galactose, both having the same molecular formula as glucose. Determine which of these is a constitutional isomer by analyzing their structural differences: Fructose is a ketose sugar, while glucose is an aldose sugar, meaning they differ in the position of the carbonyl group, making them constitutional isomers.