Proton NMR

The ¹H nuclei are what?

Shielded by the magnetic field produced by the surrounding electrons

The higher the electron density around the nucleus, the higher the magnetic field required to cause resonance

What does the integration mean?

How many hydrogens of each type

What can be identified using proton NMR that can’t be using carbon NMR?

The relative numbers of each type of proton

The number of non-equivalent protons adjacent to a given proton

What is spin-spin coupling?

When the spin states on the proton (how the proton is aligned with the magnetic field) is affected by neighbouring protons

Protons can interact with the spin states of adjacent protons which causes the peak to split

The number of peaks in the splitting pattern means what?

The number of protons on the adjacent carbon atom + 1

/When are you likely to see a heptet?

(CH₃)CH(CH₃)

When are you likely to see a multiplex?

R-CH₂-R

Aromatic compounds

What are deuterated solvents?

Solvents that contain the hydrogen isotope Deuterium-D (²H atom)

Why can Deuterium be used?

It produces no signal in the frequency range so no peaks are present

What is the issue with -OH and -NH protons?

Peaks can appear over a wife range of different chemical shift values

Signals are often broad

Usually no splitting pattern

What is proton exchange?

A proton NMR spectrum is run using CDCl₃ : a broad peak s identified

Then add a small sample of D₂O and shake so all contents have dissolved

Run a second proton NMR and if OH or NH id present, the broad peak should disappear?

What is the equation for proton exchange?

CH₃OH + D₂O ⇌ CH₃OD + HOD

What id D₂O used for?

to identify OH / NH protons

What are the uses of the deuterated solvents?

CDCl₃ is used as a solvent

D₂O is used to identify OH or NH protons