# How to read a nmr chart

This follows on from Example 2, and also involves an isomer of C 4 H 10 O but which isn't an alcohol.

## Deciphering 1H NMR Spectra

Before we go on to look at the other peaks, notice the heights of these two peaks we've been talking about. The 13 C- 13 C spin-spin splitting rarely exit between adjacent carbons because 13 C is naturally lower abundant 1. Relative configuration is predicted by coupling constant 3 J. The decoupling 13 C spectra shows only one peak singlet for each unique carbon in the molecule Fig 10. Fig 12.

Valence angle is related with ring size.

Note that sometimes integrations are simply given as absolute numbers, and you must find the common factor to deduce how many hydrogen atoms are represented by each integration value.

Its electronegativity is pulling electrons away from the methyl groups - and this tends to increase the chemical shift slightly.

But you would be wrong! The Vicinal coupling is the most useful information of dihedral angle, leading to stereochemistry and conformation of molecules.

The one closer to the carbon-oxygen double bond has the larger value.

Molecular formula is determined by chemical analysis such as elementary analysis Double-bond equivalent also known as Degree of Unsaturation is calculated by a simple equation to estimate the number of the multiple bonds and rings.

If you were working from the simplified table in an exam, your examiners would have to allow any valid alternatives. The different pulses depend on the number of protons attached to a carbon atom. One final important thing to notice.

Don't get me wrong, you still have to put in the time, but using this method to learn the reactions is just amazing. When nuclei from hydrogen atoms Z and Y split the signal for hydrogen X with very different coupling constants notice how the coupling constant J for the red Z hydrogen nuclei is larger than J for the blue Y hydrogen nuclei , all twelve peaks are spread out and identifiable.

The carbon in the CH 3 group is attached to 3 hydrogens and a carbon. If it was an acid, you would already have used up both oxygens in the structure in the -COOH group.

## NMR: Interpretation

Notice that protons in red neighboring or attached to electronegative elements N,O,S,Cl,Br,I have a large chemical shift d. This handout relates the basic theory of NMR described on the theory web handout with spectra of real molecules and how to deduce structure from the spectra. Consider a hydrogen X adjacent three bonds away to another hydrogen Y in a molecule.

Spin Multiplicity plays a role in determining the number of neighboring protons. Fig 13. These characteristic chemical shifts are collected in tables such as Fgure 13.

We've had all the information necessary.