Educational NMR Structure Builder – ¹H and ¹³C Spectra
Build an organic structure from fragments and generate educational NMR spectra: 1H with integration and simple splitting, plus a simplified proton-decoupled 13C{1H} estimate.
NMR structure builder
Click a fragment to select it.
What do the blocks represent?
The blocks are not a complete chemical drawing editor. They retain the information required by the educational model. CH₃, CH₂ and CH allow integration and simple vicinal coupling; COOR distinguishes its acyl and O-alkyl sides; the Ph block keeps six substitution positions. Connection-point order does not encode stereochemistry.
Simulated 1H NMR spectrum
Positions are simulated values inside educational correlation ranges. Splitting line spacing uses J in Hz and the selected spectrometer frequency.
1H NMR assignments
| Assignment | δ range [ppm] | Simulated δ [ppm] | Integration | Multiplicity | Source |
|---|
Simplified 13C{1H} spectrum
A proton-decoupled 13C spectrum is represented: each carbon environment is a singlet. Peak heights must not be interpreted quantitatively.
13C NMR assignments
| Environment | δ range [ppm] | Simulated δ [ppm] | Equivalent carbons / note | Source |
|---|
What is the model calculating?
Chemical shift is expressed relative to a reference, normally TMS:
\[\delta=\frac{\nu-\nu_{ref}}{\nu_0}\,10^6\]
In a first-order model, a proton set coupled to n equivalent vicinal protons gives approximately n+1 lines. An ethyl group is the classic triplet/quartet example.
\[\text{multiplicity}\approx n+1\]
J is measured in Hz, so line separation in ppm depends on field strength:
\[\Delta\delta=\frac{J}{\nu_0}\]
Chemically equivalent fragments are grouped using graph symmetry. This is useful for simple cases such as acetone, propane, 2-propanol and ethyl groups, but it is not a substitute for a full molecular-symmetry analysis.
How to use it for study
A useful sequence is: number of signals → integration → chemical shift → multiplicity. Build a simple molecule, predict these four items yourself, then generate the spectrum. Clicking an assignment highlights the corresponding fragment.
Do not memorize the simulated δ as an exact number. The important information is the region and why the signal moves there: oxygen, a carbonyl, aromaticity, halogens, and so on.