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)

1 H – NMR C 2 H 4 O Doublet Quartet 1 3 Integral

9.8 ppm Ethanal 2.2 ppm

Quartet 1 H – NMR C 3 H 8 O Singlet Integral Septet (7) 1 1 6

2-propanol 4.0 ppm 2.2ppm 1.2ppm

Singlet 1 H – NMR C 4 H 8 O 2 Integral Quartet 2 3 3 Triplet

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

Sketch the 1 H NMR spectrum of compound

X

(see right) and label the relative peak areas. Label any peaks that would be H lost from the spectrum on shaking with D 2 O.

OH C H C O OH energy absorbed 12 11 10 9 8 7 6 5 chemical shift /  4 3 2 1 0 [4]

H OH C H C O OH 2 proton peak at δ = 3.3-4.3 – singlet (-CH2-) 1 proton peak at δ = 3.5-5.5 – singlet (-OH) 1 proton peak at δ = 11.0-11.7 – singlet (-COOH) (ranges of chemical shift (δ) values taken from data sheet) • • penalise each error once only ignore peak areas/heights unless incorrectly labelled 1 1 1 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