JEE Advanced levelOne or more correct optionsDifficulty 3 of 3bm042
Which statements about alpha-D-glucopyranose are correct?
AIt has four stereocentres.
BIts C-1 hydroxyl group and C-6 CH2OH group lie on opposite faces of the ring.
CC-1 is a hemiacetal carbon.
DThe ring contains five carbon atoms and one oxygen atom.
Answer: B, C, D
The pyranose ring has C-1 to C-5 and the ring O, and C-1 (bearing OH and ring O) is the hemiacetal carbon. There are five stereocentres, C-1 to C-5, so the first statement is false. In the alpha anomer the C-1 OH is trans to CH2OH.