C C H H

H

H

H

H

C C O H

H

H

H

H

H

C

C

H

H

H

H

H

H

C

O

C C C

C C C

H OH H

H

H

H

H H

H

H

H OH

Which molecule has an odd number of peaks in its 13C NMR spectrum?

O

A D

O

O

O

C

MgCl

B

S

A structural isomer of C5H11OH has a significant peak in its mass spectrum with an m / z value of 31.

Its 13C NMR spectrum shows four different peaks.

What is the isomer?

A 3-methylbutan-1-ol B 3-methylbutan-2-ol

C pentan-1-ol D pentan-2-ol

The diagram shows the 13C NMR spectrum of an alcohol of formula C4H10O.

200 180 160 140 120 100 80 60 40 20 0

δ ppm

What is the alcohol?

A butan-1-ol B butan-2-ol

C 2-methylpropan-2-ol D 2-methylpropan-1-ol

Q1

Q2

Q3

Dioxins can be formed during the combustion of chlorine-containing compounds in waste incinerators.

Dioxins are very unreactive compounds and therefore remain in the environment and enter the food chain.

Many dioxins are polychlorinated compounds such as tetrachlorodibenzodioxin (TCDD) shown below.

Cl O

Cl

Cl

ClO

TCDD can also be analysed using 13C n.m.r.

Deduce the number of peaks in the 13C n.m.r. spectrum of TCDD.

C H

H

H

C H H

H

C H

H

H

H C H

H

Si

Si(CH3)4

[1]

Q4

C C H

H

H

O H

O

C C H

H

H

O H

O

C

H

H

C C H

H

H

O H

O

C

H

H

C

H

H

ethanoic acid propanoic acid butanoic acid

The 13C NMR spectrum of a compound with formula C4H8O2 shows peaks at 15 ppm, 20 ppm,

60 ppm and 175 ppm.

What is the structure of the compound?

HOCH2CHCHCH2OHA CH3COOCH2CH3C

H H

HO D C

H

C

C

H

OH

C H H

HCOOCH(CH3)2B

Q5

Shikimic acid, right, occurs naturally in star anise. HO

HO

OH

7

6

5 4 3

21

OH

O

Using the numbers on the diagram of shikimic acid’s structure,

indicate (by putting numbers in the boxes) which carbon atoms in

the molecule are responsible for each signal in its 13C NMR spectrum.

The precise order of carbons within the group of two and the group of three are not required.

200 180 160 140 120 100

δ / ppm

80 60 40 20 0

[3]

Q6

Atenolol is an example of the type of medicine called a beta blocker. These medicines

are used to lower blood pressure by slowing the heart rate. The structure of atenolol is shown below.

H2N CH2 CH2 CH2CH

OH

CH3CH

CH3H

C O N

O

The 13C n.m.r. spectrum of atenolol was recorded.

Use the structure of atenolol given to deduce the total number of peaks in the

13C n.m.r. spectrum of atenolol.

Part of the 13C n.m.r. spectrum of atenolol is shown on the right.

Use this spectrum to answer the questions which follow.

δ / ppm

100 80 60 40 20 0

Give the formula of the compound that is used as a standard and

produces the peak at δ = 0 ppm in the spectrum.

One of the peaks in the 13C n.m.r. spectrum is produced by

the CH3 group labelled q in the structure of atenolol.

Identify this peak in the spectrum by stating its δ value.

There are three CH2 groups in the structure of atenolol. One of these CH2 groups

produces the peak at δ = 71 in the 13C n.m.r. spectrum above.

Draw a circle around this CH2 group in the structure of atenolol shown below.

H2N CH2 CH2 CH2CH

OH

CH3CH

CH3H

C O N

O

p q

[1]

[1]

[1]

[1]

Q7

Q7 (a)

Q7 (b)

Q7 (c)

Q7 (d)

C C H H

H

H

H

H

C C O H

H

H

H

H

H

C C H H

H

H

H

H

C

O

Many aromatic nitro compounds are used as explosives. One of the most famous is

2-methyl-1,3,5-trinitrobenzene, originally called trinitrotoluene or TNT . shown below,

O2N NO2

CH3

NO2

Deduce the number of peaks in the 13C n.m.r. spectrum of TNT.

Deduce the number of peaks in the 1H n.m.r. spectrum of TNT.

Using the molecular formula (C7H5N3O6), write an equation for the decomposition

reaction that occurs on the detonation of TNT. In this reaction equal numbers of moles

of carbon and carbon monoxide are formed together with water and nitrogen.

Imipramine has been prescribed as an antidepressant.

The structure of imipramine is shown below.

N

CH2 H2C

H2C

CH2

H2C

N

H3C

CH3

Deduce the number of peaks in the 13C n.m.r. spectrum of imipramine .

Deduce the number of peaks in the 1H n.m.r. spectrum of imipramine .

[1]

[1]

[1]

[1]

[1]

Q8

Q8 (a)

Q8 (b)

Q8 (c)

Q9

Q9 (a)

Q9 (b)

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

absorptionof energy

/ ppmδ

3

2

1

C C O H

H

H

H

H

H

3

2

1

C C O H

H

H

H

H

H

C C H

H

H

H

H

C H

H

H

C C H

H

H

H

H

C C H

H

H

H

H

Atenolol is an example of the type of medicine called a beta blocker. These medicines

are used to lower blood pressure by slowing the heart rate. The structure of atenolol is shown below.

H2N CH2 CH2 CH2CH

OH

CH3CH

CH3H

C O N

O p q

The 1H n.m.r. spectrum of atenolol was recorded.

One of the peaks in the 1H n.m.r. spectrum is produced by the CH2 group labelled p in

the structure of atenolol.

Suggest a range of δ values for this peak. Name the splitting pattern of this peak.

Range of δ values

Name of splitting pattern

The 1H NMR spectrum of butanone is shown below.

Without considering chemical shift data, which peak is produced by

the red hydrogens;

the blue hydrogens;

the green hydrogens?

[1]

[1]

[1]

[2]

Q10

Q11

Q11 (a)

Q11 (b)

Q11 (c)

A

B

C

D

The 1H NMR spectrum of triethylamine is shown below.

Without considering chemical shift data, which peak is produced by

the red hydrogens;

the blue hydrogens?

[1]

[1]

Q12

Q12 (a)

Q12 (b)

A

B

C

Haloalkanes have been used as aerosol propellants and refrigerants but are now

largely banned due to the damage they cause to the ozone layer.

Halon 1211 was once commonly used in fire extinguishers (now only found in fighter

jets) and ‘Halothane’ is an inhalational general anaesthetic.

Further examples of haloalkanes are given in the table below.

Common name Structural Number of different

formula fluorine environments

A CFC-113 Cl2FC-CClF2B CFC-113a Cl3C-CF3C HFC-134a F3C-CH2F

D CFC-11 (Freon-11, R-11) CCl3F

E CFC-12 (Freon-12, R-12) CCl2F2F CFC-13 CClF3G Halon 1211 CBrClF2

NMR spectroscopy is a technique which reveals the number of different environments

of certain nuclei in a molecule. NMR active nuclei such as 1H, 13C and 19F are routinely studied.

Complete the table above indicating the number of different fluorine environments for

each of the compounds A–G .

The anaesthetic Halothane has the formula C2HBrClF3 and shows one signal in its 19F NMR spectrum. Draw the two possible three-dimensional structures for Halothane.

The intensity of a signal in a 1H or 19F NMR spectrum is proportional to the number

of nuclei in that particular environment.

For each compound with more than one signal in its 19F NMR spectrum, indicate in

the appropriate column of the table the expected intensity ratio.

Q13

Q13 (a)

Q13 (b)

Q13 (c)

[2]

[2]

[3]

NMR spectra are complicated by coupling between nuclei. If an NMR-active nucleus

is within three bonds of another similar nucleus which is in a different chemical

environment, its signal will be split into a number of peaks instead of appearing as a

single peak. If a nucleus couples to n NMR-active nuclei, its signal will split into a

total of (n + 1) peaks.

The 19F NMR spectrum of one of the haloalkanes from the table is shown below.

Draw the structure of the haloalkane and indicate with an arrow which fluorines give

rise the signals X and Y.

Q13 (d)

[2]

The 1H NMR spectrum for ibuprofen is shown below.

On the structure of ibuprofen below, mark the protons responsible for the peaks A, B,

C, D, E and F on the spectrum. The integrals and expansions for each peak are shown on the spectrum.

CH3 CH3

H3C

OH O

[6]

Q14

R C O

H

H

1H O

2H 2H

+ R C O

H

H

2H O

1H 2H

+ →

Below are the structures of a pair of isomers.

H

isomer 1

C

H

H O

H

H

H

OC

CC C

H

H

H

O

H

isomer 2

C

H

H

H

H

HC

CC

O CH

H

H

Give the molecular formula of these isomers.

What type of isomerism is shown by these two isomers?

Isomer 1 is named 2-phenylethyl propanoate. Give the name of isomer 2.

The 1H NMR spectrum of one of the isomers is shown in below.

10

5integration 2 22

3

5 0/ ppmδ

Explain which of the two isomers corresponds to the 1H NMR spectrum.

You should refer to the splitting patterns and integration values of all the peaks in your

answer. Note that the phenyl group protons appear as a single peak.

[1]

[1]

[1]

Q15

Q15 (a)

Q15 (b)

Q15 (c)

Q15 (d)

[6]

An unknown compound T consists of carbon, hydrogen and oxygen atoms only.

The 1H NMR spectrum of T and the 13C NMR spectrum of T are both shown below. T

Deduce the structural formula of the compound T and explain the form of the

spectra. This should include the identification of the atoms or groups of atoms

responsible for each signal.

11 10 9 8 7 6 51H NMR spectrum of T δ / ppm

4 3 2 1 0

200 180 160 140 120 100

13C NMR spectrum of T

80 60 40 20 0δ / ppm

Q16

[7]

A, B and C are three structural isomers of molecular formula C6H10O. They are all cyclic.

Isomers A and B have strong infra-red absorptions, A at 1720 cm–1 and B at 1780 cm–1;

C has an absorption at 1650 cm–1 and a broad absorption between 3230 and 3550 cm–1.

In the proton n.m.r. spectrum, A has three peaks (signals) with areas in the ratio

2:2:1 whereas B has two peaks in the ratio 3:2; C has 4 peaks with areas in the ratio 1:2:3:4.

C reacts readily with bromine water; A and B do not.

None of the three isomers can be oxidised by acidified potassium dichromate(VI).

Suggest structures for A, B and C, explaining your reasoning.

[10]

Q17