Question

The anomers of fructofuranose are called:
a.) $\alpha -anomers$
b.) $\beta -anomers$
c.) Both A and B
d.) None of these

Answer 1

Hint: To solve this question, we must note that anomers are cyclic monosaccharides or glycosides. They differ from each other in the configuration of C-1 if they are aldoses or in the configuration at C-2 if they are ketoses.

Complete step by step solution: The anomers of fructofuranose differ in the position of -OH group on the first chiral carbon atoms.

The cycle is planar and should be imagined to be perpendicular to the screen with the bolded line being the closest to the observer. After the formation of the cycle the carbon in position 1 becomes asymmetric and the OH group can be below the plane of the ring (alpha-form) or above the plane of the ring (beta-form). The carbon in position 1 is named anomeric and alpha and beta forms are said anomers. In the case of fructose the forms alpha and beta refers to the position of the hydroxyl attached to anomeric carbon at position 2.
These anomers are called $\alpha -anomers$ and $\beta -anomers$. They are both dextrorotatory.
We can better understand this from the illustrations given below:

Hence, the correct answer is Option(C).

Additional information:
The anomers undergo a phenomenon, known as mutarotation, due to the interconversion of the different forms until equilibrium is reached which corresponds to 64% of beta anomer and 36% of the alpha anomer.

Note: Anomers are special cases — they are epimers that differ in configuration only at the anomeric carbon.
In solutions, the open and cyclic structures readily interconvert but the anomers take much longer.