BRAINCAKEInterpreting 13C NMR Spectra
To interpret a 13C NMR spectrum, first count the peaks (ignoring TMS at 0 ppm) to find the number of carbon environments, then use each chemical shift to identify the type of carbon, using the ranges on the OCR Data Sheet.
Approximate ranges (always check the Data Sheet in the exam):
• C−C (alkyl carbons): about 5 to 55 ppm
• carbon bonded to Cl or Br, or to N: about 30 to 70 ppm
• C−O (alcohols, ethers, esters): about 50 to 90 ppm
• C=C (alkenes) and aromatic carbons: about 100 to 160 ppm
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Key terms in this lesson
- tms
- Tetramethylsilane, Si(CH3)4, the reference compound in NMR spectroscopy whose single peak is defined as a chemical shift of 0 ppm.
- chemical shift
- The position of a peak in an NMR spectrum, measured in parts per million (ppm) relative to the TMS reference peak at 0 ppm.
More in NMR Spectroscopy
- Chemical Shift
- The TMS Standard
- Deuterated Solvents
- 13C NMR Spectroscopy
- 1H NMR Spectroscopy
- Relative Peak Areas
- Spin-Spin Splitting
- The n+1 Rule
All 12 lessons in NMR Spectroscopy · All OCR A-level Organic Chemistry topics