Question

The letter ‘D’ in D-carbohydrates represents

• A. dextrorotation
• B. direct synthesis
• C. configuration
• D. mutarotation
• E. optical activity

Hint:

D/L notation is about structure, not optical rotation (+/−).

Answer 1

The Correct Option is C

Concept:
The D/L system in carbohydrates refers to the configuration of the molecule relative to D- and L-glyceraldehyde. It does not indicate the direction of optical rotation.

Step 1: Basis of D/L notation

• If the -OH group on the chiral carbon (farthest from carbonyl) is on the right → D-form
• If on the left → L-form

Step 2: Important clarification

• D $\neq$ dextrorotatory (+)
• L $\neq$ levorotatory (−) They only indicate stereochemical configuration, not optical activity.

Step 3: Analysis of options

• (A) Dextrorotation → incorrect misconception
• (B) Direct synthesis → unrelated
• (C) Configuration → correct
• (D) Mutarotation → different concept
• (E) Optical activity → incorrect Final Conclusion:
‘D’ denotes stereochemical configuration: \[ \boxed{(C)} \]