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The number of chiral carbon atoms present in sucrose is

1. 7
2. 8
3. 9
4. 12

Correct answer: 9

Solution

Sucrose structure: alpha-D-glucopyranose linked at C1 to beta-D-fructofuranose at C2 via a 1,2-glycosidic bond. In the glucose part: C1, C2, C3, C4, C5 are all chiral (5 centres). In the fructose part: C2, C3, C4, C5 are chiral, C1 and C6 are -CH2OH (not chiral) — 4 centres. Total = 5 + 4 = 9 chiral carbons.

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