Lab
Dot = front carbon, circle = back carbon. Twist the slider to turn the back carbon.
Click an atom or a bond to interrogate it · switch to 3-D to turn it over
Open a molecule with a C=C to see what a reagent does to it, one curved-arrow step at a time.
Tour
Challenge
Press for a challenge. In bond-line it hides whatever it is asking about, then switches it on when you answer. In 3-D you manipulate the model and it grades the geometry.
What each view is for
- Bond-line — what the notation hides: implicit hydrogens, undrawn lone pairs, formal charge, R/S. Each is computed, so switching it on reveals the real answer.
- 3-D — what the drawing cannot show: dihedrals, torsional strain named interaction by interaction, axial vs equatorial, and the backside an SN2 nucleophile has to reach.
- Newman + energy — select a rotatable single bond, then choose View Newman. The dot is the near carbon and the circle is the far carbon; twist the slider to see the projection and its energy curve move together. Low valleys are populated most; eclipsed peaks are crossed rapidly.
- Ring flip is a real geometric operation, not a flipped template — it reports what the flip costs in kcal/mol.
- Curved arrows — draw them on the flat structure and the legality is checked against it: an arrow from an atom with no lone pair, or into an atom that already has an octet, is called out with the count that refutes it. Arrows are judged as a set, so the first arrow of a two-arrow step is kept and labelled provisional rather than refused.
- What the arrows produce — the step is worked through and every formal charge recounted, and the product can be adopted as the structure, so a mechanism is drawn one step at a time on its own intermediate.
- Proton-transfer bench — any acid in the pKa table against any base in it, with the acidic hydrogen drawn so it can be clicked, and ΔpKa, K and the favoured side reported once both arrows are there.
- Molecules marked ◆ carry a 3-D challenge. Paste any SMILES to interrogate a structure from a problem set.