MolDraw › Templates › Stereochemistry › Assigning R and S
StereochemistryFree
Assigning R and S template
Free template. Download it, or open it in MolDraw to change it first.
(R)-Butan-2-ol and (S)-alanine worked through: CIP priorities 1–4 labelled, lowest priority on the hash, the curved 1 → 2 → 3 arrow and the R/S result.
What the template shows
- Rank the four groups (CIP rules), put the lowest away from you, then follow 1 → 2 → 3
- Two worked examples
- skeletal formula, H not drawn
- (S)-alanine (L-alanine)
- Rank the atoms attached to the stereocentre by atomic number: higher atomic number, higher priority (1). Ties are broken further out (see the CIP rules sheet).
- View with priority 4 pointing away (on the hash). 1 → 2 → 3 clockwise is R (rectus), anticlockwise is S (sinister).
- If priority 4 points toward you (on a wedge), read the turn and reverse it. Swapping any two groups turns R into S.
- R/S does not predict the sign of rotation: (R)-butan-2-ol is laevorotatory, (R)-(−). Nor does it follow D/L: most L-amino acids are (S), but L-cysteine is (R).
- Wedge = toward you, hash = away from you · every part of this figure is editable
Drawn with 11 atoms, 291 shapes – every one editable in MolDraw.
Sources
How to use this template
- Press Edit in MolDraw. The template opens on the canvas of the free MolDraw editor.
- Change anything: move structures, edit atoms and labels, recolour highlights or delete what you do not need.
- Add your own structures, arrows and text next to it, or combine several templates on one page.
- Export the drawing as PNG, SVG or PDF for slides, worksheets, theses and papers.
Frequently asked questions
Is the Assigning R and S template free?
Yes. The Assigning R and S template is one of the free MolDraw templates: open it in the editor or download it from this page as SVG or PNG and use it in your slides, worksheets and notes.
Can I edit the Assigning R and S template?
Yes. It opens as an ordinary MolDraw drawing, so every structure, arrow, label and colour can be changed, and you can add your own content around it.
Is the chemistry checked?
Every structure is checked with RDKit and every curly arrow passes MolDraw’s electron-flow audit. The sources used are listed on this page.
Are the R/S labels in the stereochemistry templates checked?
Yes. Every R/S and E/Z descriptor is computed with RDKit from the drawn structure, so the labels match the wedges and dashes.