The Monosaccharide Ribose, C₅H₁₀O₅ May Exist in Five Distinct Conformations

question 2

Multiple Choice

The monosaccharide ribose, C₅H₁₀O₅ may exist in five distinct conformations. Two of these conformations are six-membered rings and two are five-membered rings, with the remaining conformation being a straight chain. In a solution at 25 C, a sample of ribose was found to exist as 60% α-D-ribopyranose and 21% β-D-ribopyranose. Calculate the difference in molar energy between these two conformations, which differ only in the orientation of the anomeric hydroxyl group

• A) 0.22 kJ mol^-1
• B) 1.2 kJ mol^-1
• C) 2.6 kJ mol^-1
• D) 4.0 kJ mol^-1