using proton nmr

Using Proton NMR

How many Proton environments?

How many Proton environments?

How many Proton environments?

How many Proton environments?

Proton NMR Spectra

• Number of environments = number of peaks• Number of protons in environment = relative

peak area (integral)• Number of protons on neighbouring carbon =

splitting pattern (eg. doublet, triplet)• Type of proton environment = chemical shift

(compare with datasheet)

1H – NMR C2 H4 O

Quartet

Doublet

1 3 Integral

9.8 ppm

2.2 ppm

Ethanal

1H – NMR C3H8O Quartet

Septet (7)

Singlet

Integral 1 1 6

4.0 ppm

2.2ppm

1.2ppm

2-propanol

Integral 2 3 3

1H – NMR C4H8O2

Triplet

Quartet

Singlet

Ethyl ethanoate

4.1 ppm

2.0ppm

1.3ppm

Draw a Proton NMR to represent 1-Bromopropane – label with chemical shift, splitting pattern and relative integration

Draw a Proton NMR to represent 1-Bromopropane

Draw a Proton NMR to represent Butanoic acid – label with chemical shift, splitting pattern and relative integration

Draw a Proton NMR to represent Butanoic acid

O H

H C

H

O H

C

O

12

energyabsorbed

chem ical sh ift /

11 10 9 8 7 6 5 4 3 2 1 0

Sketch the 1H NMR spectrum of compound X (see right) and label the relative peak areas. Label any peaks that would be lost from the spectrum on shaking with D2O.

[4]

2 proton peak at δ = 3.3-4.3 – singlet (-CH2-) 11 proton peak at δ = 3.5-5.5 – singlet (-OH) 11 proton peak at δ = 11.0-11.7 – singlet (-COOH) 1

(ranges of chemical shift (δ) values taken from data sheet)• penalise each error once only• ignore peak areas/heights unless incorrectly labelled

Labelled diagram of the structure of G proposed by the student may be used to provide evidence for the positioning of peaks on the sketched spectrum.

Both OH and COOH protons disappear on shaking with D2O 1

O H

H C

H

O H

C

O