Plan a synthesis in reverse: disconnect the target molecule one valid step at a time until you arrive at something you already have on the shelf.
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How to play
You hold the target molecule and work backward. Each retro step is a disconnection that must be chemically valid, sometimes needing the right mechanism partner. Keep peeling until the molecule you're holding is a starting material on the shelf.
Pick a retro-disconnection from the offered options to break a bond or transform a group.
Supply the correct mechanism partner when a step prompts for one.
Each valid step appends to your route; an invalid one is rejected.
Land on a shelf starting material to complete the synthesis, scored on steps against par.
Controls
Desktop: click an option to take a retro step, click a partner when prompted, and use Hint if stuck; choose Daily/Practice and a difficulty.
Phone & tablet: tap options and partners, fully touch-friendly.
Tips & strategy
Look for the bond that most simplifies the skeleton; the best disconnection usually splits the molecule near the middle.
Match each functional group to the role it plays before choosing its mechanism partner.
Fewer steps beats par, avoid disconnections that lead away from anything on the shelf.
What you'll learn
Retrosynth captures the backward-planning logic of retrosynthetic analysis, the organic chemist's craft.
For parents & teachers: retrosynthesis, the organic chemist's logic.
About Retrosynth
Retrosynth captures the backward-planning logic that organic chemists call retrosynthetic analysis, turning it into a tidy step-count puzzle. It's an original, free browser game with three difficulties and daily plus practice modes.
A free, original browser game on PlayPendium. No download, no install.
