IB Chemistry Topic S3.2.10 Proton Nuclear Magnetic Resonance Spectroscopy Revision Notes (HL)

IB Chemistry Topic S3.2.10 Proton Nuclear Magnetic Resonance Spectroscopy Revision Notes (HL) | RevisionDojo

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Proton Nuclear Magnetic Resonance Spectroscopy (¹H NMR)

How Does ¹H NMR Work?

At the core of ¹H NMR is the interaction between hydrogen nuclei (protons) and a magnetic field.
When placed in a strong magnetic field, these protons align either with or against the field, creating two distinct energy states: a lower-energy state (aligned with the field) and a higher-energy state (opposite to the field).
When you apply radiofrequency radiation of the correct frequency, the protons absorb energy and transition from the lower-energy spin state to the higher-energy spin state.
This absorption occurs at specific frequencies depending on the chemical environment of each proton.
The resulting NMR spectrum displays these frequencies as signals, providing a fingerprint of the molecule’s structure.

Key Features of ¹H NMR Spectra

To decode the structure of a molecule, focus on three main features of the ¹H NMR spectrum: the number of signals, their chemical shifts, and the integration of each signal.

Number of Signals

The number of signals in a ¹H NMR spectrum corresponds to the number of unique hydrogen environments in the molecule.
Hydrogens in identical environments produce a single signal, while hydrogens in different environments produce separate signals.

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Proton Nuclear Magnetic Resonance Spectroscopy (¹H NMR)

How Does ¹H NMR Work?

At the core of ¹H NMR is the interaction between hydrogen nuclei (protons) and a magnetic field.
When placed in a strong magnetic field, these protons align either with or against the field, creating two distinct energy states: a lower-energy state (aligned with the field) and a higher-energy state (opposite to the field).
When you apply radiofrequency radiation of the correct frequency, the protons absorb energy and transition from the lower-energy spin state to the higher-energy spin state.
This absorption occurs at specific frequencies depending on the chemical environment of each proton.
The resulting NMR spectrum displays these frequencies as signals, providing a fingerprint of the molecule’s structure.

Key Features of ¹H NMR Spectra

To decode the structure of a molecule, focus on three main features of the ¹H NMR spectrum: the number of signals, their chemical shifts, and the integration of each signal.

Number of Signals

The number of signals in a ¹H NMR spectrum corresponds to the number of unique hydrogen environments in the molecule.
Hydrogens in identical environments produce a single signal, while hydrogens in different environments produce separate signals.

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Structure 1. Models of the particulate nature of matter5 subtopics

Structure 2. Models of bonding and structure4 subtopics

Structure 3. Classification of matter2 subtopics

Reactivity 1. What drives chemical reactions?4 subtopics

Reactivity 2. How much, how fast and how far?3 subtopics

Reactivity 3. What are the mechanisms of chemical change?4 subtopics

IB Chemistry S3.2.10 Proton Nuclear Magnetic Resonance Spectroscopy Notes

Proton Nuclear Magnetic Resonance Spectroscopy (¹H NMR)

How Does ¹H NMR Work?

Key Features of ¹H NMR Spectra

Number of Signals

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Proton Nuclear Magnetic Resonance Spectroscopy (¹H NMR)

How Does ¹H NMR Work?

Key Features of ¹H NMR Spectra

Number of Signals

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Structure 1. Models of the particulate nature of matter5 subtopics

Structure 2. Models of bonding and structure4 subtopics

Structure 3. Classification of matter2 subtopics

Reactivity 1. What drives chemical reactions?4 subtopics

Reactivity 2. How much, how fast and how far?3 subtopics

Reactivity 3. What are the mechanisms of chemical change?4 subtopics