What a learner can do afterwards
- Reads a COSY map to trace a chain of coupled protons
- Uses a one-bond correlation experiment to attach each proton to its own carbon
- Uses a long-range correlation experiment to join fragments across a quaternary carbon
- Assembles the evidence from several spectra into one assigned structure and states the weakest link in the argument
1 · Read
You already know a one-dimensional spectrum shows where signals sit. A two-dimensional experiment shows which signals are connected. Each spot off the diagonal links two signals, so you read relations instead of guessing them.
A COSY map traces chains of coupled protons. Start at one proton, follow its cross-spot to the neighbour, then to the next. Walking the spots walks the chain, proton by proton, through the fragment.
A one-bond map attaches each proton to its own carbon. Every spot pairs one proton with the carbon holding it, so each chain from the COSY walk gains its carbon skeleton.
A long-range map joins fragments across carbons with no protons, such as quaternary centres. Its spots link a proton to carbons two or three bonds away, so they can reach past a carbon that has no proton of its own. Assemble all three maps into one structure, then name the weakest link: the connection that rests on the fewest supporting spots.
COSY walks the proton chains, the one-bond map adds carbons, and long-range spots bridge the silent centres.
2 · Watch
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Where it sits
Learn first
Optional connections
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.