Draw Mechanism Arrows
Common Questions
What are curved arrows in organic chemistry?
Curved arrows show the movement of electron pairs during a reaction mechanism. The arrow starts where the electrons are (a lone pair or bond) and points to where they are going (forming a new bond or becoming a lone pair).
What is the difference between a full arrow and a half arrow?
A full (double-headed) curved arrow represents the movement of two electrons (an electron pair). A half (single-headed, fishhook) arrow represents the movement of one electron, used in radical mechanisms.
How many arrows do you need for each mechanism step?
Each step needs enough arrows to account for all bond-breaking and bond-forming events. Typically 1-3 arrows per step. Every arrow must start from an electron source (lone pair or bond) and end at an electron sink.
What are common electron sources and sinks?
Electron sources (nucleophiles): lone pairs, pi bonds, sigma bonds. Electron sinks (electrophiles): atoms with positive charge or partial positive charge, pi antibonding orbitals, atoms that can leave as stable anions (leaving groups).