What is H-NMR Spectroscopy?

Proton Nuclear Magnetic Resonance (¹H-NMR) is a powerful analytical technique used in organic chemistry to determine the structure of a molecule. It works by observing the behavior of hydrogen nuclei (protons) within a magnetic field. An H-NMR spectrum provides crucial information about the electronic environment of each proton, its neighboring protons, and the number of equivalent protons in a single signal.

How to Use This Tool

1. Enter a Compound: Type the name (e.g., "Ethanol") or the chemical structure (e.g., "CH3CH2OH") into the input box.
2. Select from Examples: Alternatively, use the dropdown menus to select a compound from our extensive, categorized library.
3. Analyze: Click the "Analyze" button to generate the predicted spectrum and data table.
4. Explore the Spectrum:
   • Zoom: Use your mouse wheel or the (+) and (-) buttons to zoom in and out.
   • Pan: After zooming, you can either click and drag the chart with your mouse or use the (<) and (>) buttons to move left and right.
5. View Details: Click "Show Analysis Steps" to see a detailed explanation of how each signal's properties were determined.

How Does the Tool Work? (The Principles)

The tool's predictions are based on a comprehensive, manually curated database derived from established NMR principles and reference data. Here’s what each column in the results table means:

Chemical Shift (δ)

This value (in ppm) indicates the electronic environment of the proton. Protons near electronegative atoms (like O, N, halogens) are "deshielded" and appear at a higher chemical shift (further downfield).

Integration

This number represents the relative count of protons that contribute to a single signal. For example, in ethanol (CH₃CH₂OH), the signal for the -CH₃ group has an integration of 3.

Splitting (Multiplicity)

This describes how a signal is split by its non-equivalent neighboring protons ('n'). The tool uses the fundamental n+1 rule. While complex spectra can show intricate patterns, here are the common multiplicities:

• n = 0 → Singlet (s): A single peak. No adjacent protons.
• n = 1 → Doublet (d): Two peaks of equal height (1:1 ratio).
• n = 2 → Triplet (t): Three peaks with a 1:2:1 intensity ratio.
• n = 3 → Quartet (q): Four peaks with a 1:3:3:1 intensity ratio.
• n = 4 → Quintet: Five peaks (1:4:6:4:1 ratio).
• n = 5 → Sextet: Six peaks.
• n = 6 → Septet: Seven peaks.
• n > 6 → Multiplet: For a large number of neighbors, the signal becomes a complex multiplet, and it's often not practical to count the individual peaks.