NMR Spectroscopy – ¹H and ¹³C Spectra, Integration and n + 1 Splitting
ChemistryOrganic ChemistryAges 16–17
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Sign in to playChoose one of 23 small organic molecules and see its schematic ¹H NMR spectrum (chemical shift relative to TMS, integration trace, n + 1 splitting, expansion of each peak) and ¹³C NMR spectrum (number of carbon environments). Compare CDCl₃ with CHCl₃ as the solvent, do a D₂O shake to find O–H and N–H protons and change the spectrometer frequency, then identify unknown compounds from their spectra, including combined problems with IR and mass spectra.
Lesson: NMR spectroscopy and structure determination
What it shows
In a strong magnetic field, ¹H and ¹³C nuclei absorb radio waves at frequencies that depend on their chemical environment. The chemical shift δ, in ppm relative to TMS, shows what the atom is bonded to, so the number of peaks gives the number of environments. In a ¹H spectrum the area under each peak (integration) is proportional to the number of H, and a peak is split into n + 1 lines by n equivalent H on neighbouring carbons. Spectra here are schematic, built from typical data-book shifts, with simple first-order splitting.
How to use
On the ¹H NMR spectrum screen, choose a Molecule and tap a peak, or a table row, to expand it and read J. Change the Spectrometer, turn the Integration trace on or off, tick D₂O shake and switch the Solvent to CHCl₃. The ¹³C NMR spectrum screen counts carbon environments. On Identify the unknown and Combined problem, read the spectra, press a candidate and use Next unknown.
Parameters you can change
- Screen ¹H NMR spectrum, ¹³C NMR spectrum, Identify the unknown, Combined problem IR + MS + NMR
- Molecule ethanol, methoxymethane (dimethyl ether), ethanoic acid (acetic acid), methyl methanoate (methyl formate), propan-1-ol, propan-2-ol, methoxyethane, propanal, propanone (acetone), butanone, butanal, 2-methylpropanal, ethyl ethanoate (ethyl acetate), methyl propanoate, butanoic acid, 1-bromopropane, 2-bromopropane, propan-1-amine, propan-2-amine, N,N-dimethylmethanamine (trimethylamine), ethylbenzene, 1,4-dimethylbenzene (p-xylene), 1,2-dimethylbenzene (o-xylene)
- Spectrometer frequency 60 MHz, 100 MHz, 400 MHz
- Solvent CDCl₃ (deuterated), CHCl₃ (not deuterated)
- D₂O shake
- Show integration trace
Questions to explore
- Why is the CH₂ peak of ethanol a quartet while the CH₃ peak is a triplet?
- How can ¹³C NMR alone distinguish propan-1-ol from propan-2-ol?
- What happens to the ¹H spectrum of butanoic acid after a D₂O shake, and why?
