# Logic Puzzle #17: What is the Coupling Pattern?

##### by Arvin Moser, Team Manager, Application Scientists, ACD/Labs

Spin-spin splitting or J-coupling is used to elucidate and verify a candidate structure. The observed coupling pattern (also referred to as splitting or multiplet pattern) serves as a guide in determining the neighbouring groups. Hence, the wrong coupling pattern can send an elucidator on a wild-goose chase.

The following 1H NMR spectrum below is for an unknown compound. Is the coupling pattern most consistent with a quartet (q) or a doublet of doublets (dd) or an AB spin system poised as two doublets (d)?

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## One Reply to “Logic Puzzle #17: What is the Coupling Pattern?”

1. Serge Lavoie says:

Clearly, it’s not a quartet since J isn’t uniform . So it must be a doublet of doublet (dd) or two AB doublet. The peak intensities for a dd should be 1:1:1:1, so I bet for two AB doublet!