[Maximum number: 6]

Menthol and menthone, the main constituents of oil of peppermint, can be made synthetically from thymol by the following route.

(a)

Suggest one test for each of the three compounds that would give a positive result with the stated compound but a negative result with both the other two compounds.
thymol
test
observation
menthol
test
observation
menthone
test
observation

[ 6 ]

[Maximum number: 2]

G belongs to a group of compounds called ethers.

Fig. 3.1

(a)

K has molecular formula $\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}$ .

When K is added to 2,4-dinitrophenylhydrazine, an orange precipitate forms. When K is warmed with Tollens' reagent, a silver mirror forms.

Draw the displayed formula of K.

[ 2 ]

[Maximum number: 1]

The formula of hydrocortisone acetate is shown.

hydrocortisone acetate

Which row is correct?

number of C atoms in one molecule

number of chiral atoms in one molecule

[Maximum number: 3]

Trihalomethanes are organic molecules in which three of the hydrogen atoms of methane are replaced by halogen atoms, for example $\mathrm{CHF}_{3}$ .

(a)

A different trihalomethane, $\mathrm{CHCl}_{3}$ , reacts with $\mathrm{O}_{2}$ to produce carbonyl dichloride. HCl(g) is also released as a product of this reaction.

carbonyl dichloride

[ 3 ]

(i)

The conversion of $\mathrm{CHCl}_{3}$ to carbonyl dichloride can be monitored by infra-red spectroscopy. The infra-red spectrum of carbonyl dichloride is shown.

On the infra-red spectrum of carbonyl dichloride identify with an X the absorption that would not be present in an infra-red spectrum of $\mathrm{CHCl}_{3}$ .

Explain your answer.

[ 2 ]

(ii)

Suggest another difference between the infra-red spectra of $\mathrm{CHCl}_{3}$ and carbonyl dichloride.

[ 1 ]

[Maximum number: 1]

The infrared spectrum shown was obtained from a compound J .

Which statement about J is correct?

Both C=O and $\mathrm{C} \equiv \mathrm{N}$ are present.

Neither C=O nor $\mathrm{C} \equiv \mathrm{N}$ are present.

C=O is present but not $\mathrm{C} \equiv \mathrm{N}$ .

$\mathrm{C} \equiv \mathrm{N}$ is present but not C=O.

[Maximum number: 1]

The infra-red spectrum of a substance with empirical formula $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}$ is shown.

Which bonds are responsible for peak X and peak Y ?

peak X

peak Y

C-H

C=C

C-H

C=O

O-H

C=C

O-H

C=O

[Maximum number: 2]

Phosphoric (V) acid, $\mathrm{H}_{3} \mathrm{PO}_{4}$ , is used in both inorganic and organic reactions.

(a)

Fig. 3.1 shows a reaction scheme that involves $\mathrm{H}_{3} \mathrm{PO}_{4}$ in several reactions.

Fig. 3.1

[ 2 ]

(i)

Reaction 3 is monitored using infrared spectroscopy. It is not possible to use the O-H absorption frequency to monitor the reaction.

Use Table 3.2 to identify a suitable bond whose absorption frequency can be used to monitor the progress of reaction 3.

State the change you would see in the infrared spectrum during reaction 3.
bond change in infrared spectrum