The critical anomeric effect and specific optical rotation in cyclic carbohydrates are closely gover — Biomolecules Chemistry Question
Question
The critical anomeric effect and specific optical rotation in cyclic carbohydrates are closely governed strictly by the stereochemistry precisely at C-1. Which exact relative configuration perfectly characterizes $\alpha$ -D-glucopyranose in a standard correctly drawn Haworth projection?
💡 Solution & Explanation
In standard correctly oriented Haworth projections of D-sugars, the large $-CH_2OH$ group located at $C-5$ consistently points up. By strict definition, the $\alpha$ -anomer places the highly reactive anomeric $-OH$ group down at $C-1$ (trans relationship), whereas the $\beta$ -anomer strictly places it up (cis relationship).