Deep-Dive Guides · Carbohydrates
Carbohydrates — the complete deep dive
Carbohydrate chemistry is stereochemistry with a purpose.
Free extract — the opening section of the guide, in full.
0. How to use this guide — the sugar map
A carbohydrate is a polyhydroxy aldehyde or ketone (or something that hydrolyses to one). Classify along three axes and most of a problem is already answered:
| Axis | Options | What it tells you |
|---|---|---|
| Carbonyl type | aldose (–CHO) vs ketose (C=O) | aldoses are oxidised by Br₂/H₂O; ketoses are not — the standard distinguishing test |
| Chain length | triose, tetrose, pentose, hexose… | n stereocentres → 2ⁿ stereoisomers (aldohexose: n = 4 chiral C → 2⁴ = 16 stereoisomers = 8 D + 8 L) |
| Size class | mono-, di-, oligo-, polysaccharide | hydrolysis behaviour; reducing vs non-reducing |
The four questions to ask of any sugar problem: (1) Aldose or ketose? (2) D or L, and how many stereocentres? (3) Is there a free (hemiacetal) anomeric carbon — i.e. is it reducing and does it mutarotate? (4) What linkage/anomeric configuration joins the units (α/β, 1→4, 1→6, 1↔2)? Answer these and you can name the reactions, the tests, and the products.
Read the rest of this guide
The remaining 10 sections — Configuration & stereochemistry, Ring forms, mutarotation & conformation, Reactions of monosaccharides, Disaccharides and more — are part of ChemVidya Full Access, along with the other guides, the books, the study notes and 6,000+ practice questions with worked solutions.