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Edexcel | Chemistry WCH0 | W 19 5 1 | 1 hour 45 minutes
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22
(a) (I)
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2 Mark s

Phenylamine, , does not occur naturally, but can be prepared from benzene. 

However, it cannot be prepared in the same way as aliphatic amines.  These can be

prepared by simply reacting a bromoalkane with ammonia or an amine.

Many different aromatic compounds are synthesised using phenylamine as a starting

material.  In 1850 the chemist Hofmann made N,N-dimethylphenylamine, 

Using this compound and another compound derived from 4-aminobenzenesulfonic acid,

the indicator methyl orange can be made. 

Other indicators such as methyl yellow and methyl red are also prepared using

phenylamine.

Sulfonamide drugs are also synthesised from phenylamine.  They were the first

anti-bacterial agents, but some of this class of drugs, such as carbutamide, act as 

anti-diabetes drugs.

Phenylamine is also the starting point for the production of many anaesthetics.  

Most local anaesthetics contain an ester or amide link, and a tertiary amine group, in which

a nitrogen atom is joined to three other groups.  Examples of these are shown on the

structures below.  The symbol R represents an alkyl group.

Phenylamine can be prepared from benzene.

Phenylamine can be prepared from benzene.

 Identify Compound A and state the reagents and conditions needed to carry

out Step 1.

 

Concentrated nitric acid + concentrated sulfuric acid

and

temperature 55°C

ALLOW

“Concentrated nitric and sulfuric acid”

50 - 60°C

“Heat at less than 55°C”

(1)

22
(a) (II)
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1 Mark

State the reagents needed for Step 2.

 

Tin + (concentrated) hydrochloric acid / Sn + HCl

ALLOW

Iron/Fe for tin

IGNORE

Hydrogen H2

followed by NaOH

22
(b)
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1 Mark

Suggest an equation for the reaction of phenylamine with iodomethane, forming 

N,N-dimethylphenylamine.

22
(c)
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2 Mark s

Methyl orange is the sodium salt of compound X.

Compound X cannot be formed by a direct reaction of 

4-aminobenzenesulfonic acid with N,N-dimethylphenylamine.

  4-aminobenzenesulfonic acid must first be converted into a diazonium salt. 

Give the reagents and conditions for this reaction.

NaNO2 + HCl / sodium nitrite plus hydrochloric acid

ALLOW

Nitrous acid / HNO2

Sulfuric acid for hydrochloric (1)

A temperature in the range of

0 – 10 (°C)

ALLOW

< 10 (°C) (1)

Mark independently

22
(d) (I)
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1 Mark

Draw a circle round an amide group in the formula of carbutamide.

 

22
(d) (II)
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2 Mark s

Write an equation showing the reaction of phenylamine with ethanoyl chloride.

   Show the displayed structure of the amide group in the product of this reaction.

22
(e) (I)
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1 Mark

Benzocaine is an anaesthetic with the structure shown.

Deduce the molecular formula of benzocaine.

 

22
(e) (II)
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3 Mark s

The mass spectrum of benzocaine has significant peaks at

   m / e = 92 and m / e = 120

Suggest the formula of the species responsible for each of these peaks

   92 ..........................................................................................................................................................................

   120 ..........................................................................................................................................................................

22
(e) (III)
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2 Mark s

Suggest the formulae of the organic products which would form when

benzocaine is hydrolysed with dilute hydrochloric acid.

22
(f) (I)
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4 Mark s

Procaine, also called novocaine, is a local anaesthetic. 

  It contains thirteen carbon atoms per molecule.  

  On combustion, 100.0 g of procaine produced 242.4 g of carbon dioxide and

76.30 g of water.  The mass of nitrogen atoms in 100.0 g was 11.86 g.

 Use these data to calculate the mass of oxygen atoms in 100.0 g of procaine

and hence its empirical formula, which is the same as its molecular formula.

Ignore SFs in M1,2,3

M1

242.4 of CO2 contains

((242.4 x12)/44) =66.11 g C

76.30 g H2O contains((76.3 x 2)/18)

= 8.48 g H (1)

M2

Mass O =

(100 – 66.11 – 8.48 – 11.86) =

13.55 g

ALLOW

TE on M1 only if calculation method is correct (1)

M3

Moles per 100 g:

C 5.50

H 8.48

N 0.847

O 0.847 ALLOW TE from masses in M1 and M2 (1)

M4

C13H20N2O2

ALLOW

TE on M3 only if there are 13C

Elements in any order

22
(f) (II)
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2 Mark s

Suggest the structure of procaine using the formula you calculated in (f )(i) 

and the structural formula of the local anaesthetic Y given in the introduction

to the question.

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