¹H NMR Spectrum Helper
Paste or enter your ¹H NMR peaks (δ, multiplicity, integration, optional J), and get a simulated spectrum, signal table, n+1 splitting hints, integration scaling to an expected total H, and a functional-group heatmap bar.
Background
In ¹H NMR, each signal tells you (1) where the protons sit (chemical shift δ), (2) how many are there (integration), and (3) who they couple with (splitting pattern).
How to use this helper
- Pick solvent so residual peaks get flagged.
- Paste peaks (optional) and click Parse — or type directly into the table.
- Enter an integration target (optional) to scale integrations to an expected total H.
- Click Analyze to get a simulated spectrum + heatmap bar + n+1 hints + pattern callouts.
How this helper works
- It parses each signal into δ (ppm), multiplicity, integration, and optional J (Hz).
- It flags common residual solvent and water peaks based on your selected solvent (so students don’t over-assign them).
- It generates an exam-friendly simulated spectrum (10 → 0 ppm) and a functional-group heatmap to show where signals cluster.
- It provides n+1 splitting hints for s/d/t/q/quint/sext/sept and warns when m / br makes n+1 unreliable.
- Optional: if you enter a target total H, it scales integrations and suggests the closest integer assignments that sum to that total.
Formula & Equation Used
Splitting (simple n+1 rule):
Where
Integration scaling (optional “sum to N H”):
Then we suggest integer H counts that sum to the target (helpful when signals overlap).
Example Problems & Step-by-Step Solutions
Example 1 — Classic ethyl group (–CH₂CH₃)
You see a triplet near 1.25 ppm integrating to ~3H and a quartet near 4.10 ppm integrating to ~2H, both with similar J ≈ 7 Hz.
This matches an ethyl pattern: CH₃ (t, 3H) coupled to CH₂ (q, 2H).
Example 2 — Aromatic + methoxy (anisole-ish)
A multiplet from 7.10–7.40 ppm integrates to ~5H (aromatic), plus a singlet at 3.78 ppm integrates to ~3H.
That combination often suggests an aromatic ring plus an O–CH₃ group.
Example 3 — Using “sum to N H” scaling
Suppose your non-exchangeable proton total should be 12 H, but the raw integrations sum to 11.4.
The scale factor is 12 / 11.4 ≈ 1.053, so each integration is multiplied by ~1.053 and the helper suggests the closest integer H counts that sum to 12.
Frequently Asked Questions
Q: Why are some peaks flagged as “solvent” or “water”?
Deuterated solvents still contain a little residual ¹H, and water often shows up too. We flag common ones so students don’t over-assign them.
Q: Is n+1 always reliable?
It’s a great starting point for simple s/d/t/q patterns, but multiplets, overlap, and exchangeable OH/NH can mislead.
Q: Why might “sum to N H” be off?
Overlapping peaks, missing integrations, impurities, and broad/exchangeable protons can shift totals. Treat it as a sanity check, not absolute truth.
