Interpreting Hydrogen NMR. Interpreting NMR Spectra Calculate elements of unsaturation (1/2(2C+2-H), ignore O, halogens count as H’s Count number of signals.

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Presentation transcript:

Interpreting Hydrogen NMR

Interpreting NMR Spectra Calculate elements of unsaturation (1/2(2C+2-H), ignore O, halogens count as H’s Count number of signals (equals number of types of H) Check integration to determine ratio of types of H Check splitting to determine connectivity Use chemical shift table to identify types of H Work out fragments Assemble fragments, remembering rules of bonding Check result to make sure it matches formula and number of types of H.

Signal a, 4 Units Septet, 1.34 ppm Signal b, 12 units Triplet, 0.91 ppm C 3 H 8 EoU=0 2 signals, 2 types of H Ratio is 1:3 or 2:6 a is a septet, so 6 H’s adjacent b is a triplet, so 2 H’s adjacent a is at 1.3 ppm: CH 2 ? b is at 0.9 ppm: CH 3 ? Structure is CH 3 CH 2 CH 3

C 4 H 8 O 2, EoU=1 a, quartet 4 units b, singlet 6 units c, triplet 6 units 3 signals, 3 types of H Ratio is 4:6:6 (or 2:3:3) a is a quartet, adjacent to 3H b is a singlet, adjacent to 0H c is a triplet, adjacent to 2H a at 4.1 ppm, CH 2 O? b at 2.0 ppm, CH 3 C=O? c at 1.4 ppm, CH 3 ? Structure is CH 3 C(O)OCH 2 CH 3