MolDraw › Chemistry tools › Haworth Projection Drawer
Haworth Projection Drawer
In short: Pick a monosaccharide, the ring size and α or β. You get the Haworth projection with every OH up or down, the Fischer projection of the open chain, the chair conformation for pyranoses, and the isomeric SMILES. Download the drawing as SVG or PNG.
OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O.Examples:
Haworth projection
Fischer projection ()
Chair conformation
Up and down groups
How to use the Haworth projection drawer
- Choose a sugar, for example D-glucose.
- Choose the ring size (pyranose or furanose) and the anomer (α or β).
- Read the Haworth projection, the Fischer projection of the open chain and, for pyranoses, the chair conformation. The table lists every group as up or down.
- Press Download SVG or Download PNG, or copy the isomeric SMILES.
From Fischer projection to Haworth projection
A Haworth projection draws the ring of a cyclic sugar as a flat hexagon (pyranose) or pentagon (furanose) seen from the side, with the near edge drawn thick. Each ring carbon has one group pointing up and one pointing down. By convention the ring oxygen sits at the back right and the anomeric carbon (C1 of an aldose, C2 of fructose) on the right, and the carbons are numbered clockwise.
- Right is down, left is up. A group on the right of the Fischer projection points down in the Haworth projection; a group on the left points up.
- The ring-closing carbon. Its OH becomes the ring O. To bring that O into the ring the carbon is rotated, so the rest of the chain (CH2OH, or CH3 in fucose and rhamnose) points up in D-sugars and down in L-sugars.
- The anomeric carbon. α: the anomeric OH is on the same side, in the Fischer projection, as the O on the configurational carbon (the highest-numbered stereocentre, C5 in hexoses, C4 in pentoses). β: opposite side. For D-sugars this means α = OH down, β = OH up.
How this tool makes sure up and down are right
The configuration of each sugar is stored as its Fischer projection. A 3D model of the ring is built from the rules above, and the isomeric SMILES (with @ and @@) is computed from that geometry. The drawing is then made from the SMILES again, by testing for each ring carbon which group must point up to give the @ or @@ in the SMILES. The test suite checks the SMILES against known structures, for example β-D-glucopyranose OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O, and checks the R/S labels of every open-chain sugar (D-glucose 2R,3S,4R,5R).
Chair conformations
For pyranoses the chair is drawn too. In the 4C1 chair (C4 up, C1 down) the axial bonds point down on C1, C3 and C5 and up on C2 and C4. A group that is up in the Haworth projection is therefore equatorial on C1, C3 and C5 and axial on C2 and C4. The tool shows the chair with fewer and smaller axial groups (4C1 for D-aldohexoses, 1C4 for L-fucose and L-rhamnose, 2C5 for β-D-fructopyranose). Press Flip chair to see the other one.
Worked examples
β-D-glucopyranose
Fischer: C2 OH right, C3 left, C4 right, C5 right (D).
C1 OH up, C2 down, C3 up, C4 down, CH2OH up; all equatorial in 4C1
α-D-galactopyranose
Galactose differs from glucose only at C4 (OH left in Fischer).
C1 OH down, C2 down, C3 up, C4 up, CH2OH up; OH-1 and OH-4 axial in 4C1
β-D-fructofuranose
Ring from O5 to C2; C1 and C6 are both CH2OH.
C2 OH up and CH2OH down, C3 OH up, C4 OH down, C6 CH2OH up
2-deoxy-β-D-ribofuranose
The sugar of DNA: C2 has two H atoms.
C1 OH up, C3 OH down, C5 CH2OH up; SMILES OC[C@H]1O[C@@H](O)C[C@@H]1O
Limitations
- Only the standard Haworth orientation is drawn (ring O at the back right). Flipped or rotated drawings, as used for sucrose or in some textbooks, are the same molecule turned over.
- Furanose forms are offered for fructose, ribose, 2-deoxyribose, xylose and arabinose. Aldohexose furanoses (for example glucofuranose, under 1 % in water) are not drawn because their side chain has its own stereocentre.
- The chair shown is chosen from the sizes of the axial groups, with the anomeric effect used only to break ties. It is a teaching estimate, not a computed conformer population.
- Glycosides, disaccharides and modified sugars (phosphates, uronic acids) are not built. Draw them in the MolDraw editor starting from the SMILES.
Building a disaccharide or a glycoside? Open the sugar in MolDraw, the free online chemical structure editor, and add the glycosidic bond.
Open MolDraw editorFrequently asked questions
How do you convert a Fischer projection to a Haworth projection?
Groups on the right of the Fischer projection point down in the Haworth projection, and groups on the left point up. The ring-closing carbon is the exception: for a D-sugar its CH2OH (C6) points up. The ring O sits at the back right and the anomeric carbon at the right.
How can I tell α from β in a Haworth projection?
Compare the anomeric OH with the CH2OH on the ring-closing carbon. For D-sugars in the standard orientation, α has the anomeric OH down (trans to CH2OH) and β has it up (cis). The formal rule: α means the anomeric OH is on the same side as the O of the configurational carbon in the Fischer projection.
What is the SMILES of β-D-glucopyranose?
OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O, which is (2R,3R,4S,5S,6R)-6-(hydroxymethyl)oxane-2,3,4,5-tetrol. α-D-glucopyranose differs only at the anomeric carbon: OC[C@H]1O[C@H](O)[C@H](O)[C@@H](O)[C@@H]1O.
Why is β-D-glucose the most stable aldohexose?
In its 4C1 chair every group other than hydrogen is equatorial: the OH groups on C1 to C4 and the CH2OH on C5. No other D-aldohexose can have all of them equatorial, which is why about 64 % of glucose in water is the β-pyranose.
How is fructose drawn as a furanose?
D-fructose closes a five-membered ring from the C5 oxygen to the C2 ketone carbon. In β-D-fructofuranose the C2 OH points up and the C1 CH2OH points down, C3 OH up, C4 OH down and the C6 CH2OH on C5 up. This is the fructose unit found in sucrose.
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