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Aldehydes And Ketones Flashcards

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1
Q

Which alcohol could not be produced by the reduction of an aldehyde or a ketone?

A 2-methylbutan-1-ol

B 2-methylbutan-2-ol

C 3-methylbutan-1-ol

D 3-methylbutan-2-ol

A
  • B ( Methyl group and alcohol group cannot be on the same carbon )
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2
Q

Which one of the following reactions will produce an organic compound that has optical isomers?

A dehydration of butan-2-ol by heating with concentrated sulphuric acid

B reduction of pentan-3-one by warming with NaBH4

C addition of Br2 to 3-bromopropene

D reduction of 2,3-dimethylpent-2-ene with H2 in the presence of a nickel catalyst

A
  • D ( Reduced means nucleophilic addition )
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3
Q

In which one of the following mixtures does a redox reaction occur?

A ethanal and Tollens’ reagent

B ethanoyl chloride and ethanol

C ethanal and hydrogen cyanide

D ethanoic acid and sodium hydroxide

A
  • A ( Aldehyde reacts with tollens’ reagent to produce silver mirror, aldehyde is oxidised while ammoniacal silver nitrate is reduced )
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4
Q

Propanone can be reduced to form an alcohol.
A functional group isomer of the alcohol formed is

A CH3CH2CH2OH

B CH3CH2CHO

C CH3OCH2CH3

D CH3COCH3

A
  • C ( Propanone reduced forms a secondary alcohol )
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5
Q

Which one of the following is not a correct general formula for the non-cyclic compounds listed?

A alcohols CnH2n+2O

B aldehydes CnH2n+1O

C esters CnH2nO2

D primary amines CnH2n+3N

A
  • B
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6
Q

Which one of the following would not reduce an acidified aqueous solution of potassium
dichromate ( VI )?

A CH3COOH

B Zn

C CH3CHO

D Fe2+ ( aq )

A
  • A ( Carboxylic acid is FORMED from potassium dichromate, so it can’t undergo further reactions with it )
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7
Q

Which one of the following statements about but-2-enal, CH3CH=CHCHO, is not true?

A It has stereoisomers.

B It shows a strong absorption in the infra-red at about 1700 cm^-1.

C It will turn an acidified solution of potassium dichromate(VI) green.

D It can be dehydrated by concentrated sulphuric acid.

A
  • D ( It’s not an aldehyde, cannot turn into a carboxylic acid )
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8
Q

The compound lithium tetrahydridoaluminate ( III ), LiAlH4, is a useful reducing agent.
It behaves in a similar fashion to NaBH4. Carbonyl compounds and carboxylic acids are reduced to alcohols.
However, LiAlH4 also reduces water in a violent reaction so that it must be used in an organic
solvent.
Which one of the following can be reduced by LiAlH4 to a primary alcohol?

A ( Shows a hexagon with a double bonded O on the right vertices )

B ( A hexagon with a carboxylic functional group on the right vertices )

C ( A hexagon with a double bond C = O and a CH3 attached to that same carbon on the right vertices )

D ( A hexagon with a double bond O on the right vertices and a CH3 on the right top vertices )

A
  • B ( It’s a carboxylic acid )
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9
Q

Which one of the following can act as an oxidising agent but not as a reducing agent?

A CH3CHO

B Fe2+

C I^-

D MnO4^-

A
  • D ( Can be reduced but an oxygen cannot be added to it )
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10
Q

Certain chemical tests were performed on the pain-relief drug ibuprofen.
The results of these tests are given in the table below.

Test

1 ) Aqueous sodium carbonate

2 ) Bromine water

3 ) Acidified potassium dichromate( VI ) and heat

4 ) Fehling’s solution and heat

Result

1 ) Effervescence

2 ) Remained orange

3 ) Remained orange

4 ) Remained blue

Which one of the following functional groups do these results suggest that ibuprofen contains?

A COH ( Note that all of them are in displayed formula )

B CH2OH

C C = C ( With lines going out to show it can bond to other atoms )

D COOH

A
  • D ( Remains orange in potassium dichromate as it has already formed it carboxylic acid functional group, remains orange with bromine water which shows it cannot be an alkene )
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11
Q

On reduction, a racemate can be formed by

A CH3CH2CH2CH2CHO

B CH3CH2CH2COCH3

C CH3CH2COCH2CH3

D CH3CH=CHCH2CHO

A
  • B ( Reduced ketone, nucleophilic addition, turns into a secondary alcohol, which has optical isomerism )
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12
Q

How many structural isomers, which are aldehydes, have the molecular formula C5H10O?

A 2

B 3

C 4

D 5

A
  • C
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13
Q

Which one of the following will undergo nucleophilic addition?

A hex-3-ene

B hexan-3-one

C 3-bromohexane

D hexan-3-ol

A
  • B ( Only ketones or aldehydes can undergo nucleophilic addition as they have a carbonyl group ( C = O ) )
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14
Q

Which one of the following isomers is not oxidised under mild reaction conditions?

A ( CH3 )2CHCH( OH )COCH3

B ( CH3 )2C( OH )CH2COCH3

C ( CH3 )2CHCH( OH )CH2CHO

D ( CH3 )2C( OH )CH2CH2CHO

A
  • B ( Contains many R groups around the functional group ( O - H ) )
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15
Q

In which of the following is a curly arrow used incorrectly?

( It’s an image which can’t be drawn out here, yikes )

A
  • C ( Electron movement in NH3^+ to remove hydrogen in going the wrong way )
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16
Q

Which one of the following can react both by nucleophilic addition and by nucleophilic substitution?

A CH3COCHCH2 ( All in displayed formula )

B CH2ClCH2COH

C CH2ClCHCH2

D CH3CO( Benzene ring )

A
  • B ( An aldehyde can undergo nucleophilic addition, as well as it having a strong electronegativity difference between the C = O bond )
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17
Q

In which one of the following are the curly arrows not used correctly?

A An alkene interacting with H - Br

B Hexagon losing Br and gaining CN

C Hexagon with a OH molecule which has its lone pair of electrons moving to a hydrogen on a HBr molecule

D A hexagon with a C = O bond which has a CN molecule’s electrons moving towards the double bond and the O’s electrons are moving towards the double bond

A
  • D ( Two arrows cannot go to one double bond )
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18
Q

CH2O is the empirical formula of

A methanol

B methyl methanoate

C ethane-1,2-diol

D butanal

A
  • B
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19
Q

Which one of the following does not represent an oxidation?

A propene → propane

B propan-l-ol → propanal

C propan-l-ol → propanoic acid

D propanal → propanoic acid

A
  • A ( Alkenes don’t gain electrons to become alkanes )
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20
Q

Which one of the following is not a suitable method for the preparation of ethanol?

A oxidation of ethane

B hydration of ethene

C reduction of ethanal

D hydrolysis of bromoethane

A
  • A ( Produces an aldehyde not alcohol )
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21
Q

Which one of the following reactions involves nucleophilic addition?

A CH3CH = CH2 + HBr → CH3CHBrCH3

B CH3CH2CH3 + Cl2 → CH3CHClCH3 + HCl

C CH3CH2CH2Br + NaOH → CH3CH2CH2OH +
NaBr

D CH3CH2CHO + HCN → CH3CH2CH(OH)CN

A
  • D ( Nucleophilic addition occurs with CN or NaBrH4 )

- ( Note that the minus would be on the “ C “ in the nucleophilic addition mechanism )

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22
Q

Which one of the following conversions does not represent a reduction?

A propene → propane

B propanal → propan-l-ol

C propanal → propanoic acid

D propanone → propane

A
  • C ( Aldehydes turn into carboxylic acids by oxidation, not reduction )
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23
Q

Butanone is reduced in a two-step reaction using NaBH4 followed by dilute hydrochloric acid.

Write an overall equation for the reduction of butanone using [H] to represent the reductant.

A
  • CH3CH2COCH3 + 2[ H ] - > CH3CH2CH( OH )CH3

- ( Two hydrogens are required to reduce the ketone completely into an alcohol )

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24
Q

By considering the mechanism of the reaction, explain why the product has no effect on plane polarised light.

( Butanone + NaBrH4 - > Butan - 2 - ol )

A
  • The product is formed from a nucleophilic attack
  • The H^- can attack from either side
  • The product from step 1 can exist in two chiral forms which forms a racemic mixture
  • The enantiomers are in a racemic mixture so rotate the plane of polarised light equally
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25
Q

The carbonyl compound CH3CH2CHO reacts very slowly with HCN

Name and outline a mechanism for the reaction of CH3CH2CHO with HCN

A
  • Nucleophilic addition
  • CH3CH2CHO ( ^-CN, with lone pair of electrons, attacks the delta positive carbon attached to the O )
  • ( Arrows are drawn from the lone pair on CN to the carbon, then an arrow from the double bond in C = O to the oxygen )
  • ( The oxygen now has a lone pair of electrons and a negative charge )
  • ( The lone pair of electrons move to a H^+ which is freely in the “ Solution “ creating a O - H bond )
  • ( The name would be 2 - HydroxyButanenitrile )
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26
Q

The reaction in part (a) produces a pair of enantiomers.

( 2 - Hydroxybutanenitrile )

Draw the structure of each enantiomer to show how they are related to each other.

A
  • CH2CH3 on the left, C in the middle, OH on the top, H on the right, CN on the bottom
  • CN will contain the triangle bond
  • H will contain the lined bond
  • Draw the mirror image of it, being precise with what atoms the bonds connect to
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27
Q

State and explain how you could distinguish between the two enantiomers.

A
  • Plane polarized light

- Rotated in opposite directions equally

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28
Q

Give the IUPAC name of the product of the reaction in part ( a ).

( CH3CH2CHOHCN )

A
  • 2 - Hydroxybutanenitrile
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29
Q

In practice, KCN rather than HCN is added to the carbonyl compound.
Given that Ka for HCN = 4.0 × 10^-10 mol dm^-3, suggest why the reaction with HCN is very slow.

A
  • Weak acid

- Concentration of CN is very low

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30
Q

Acrylic fibres are used as a substitute for wool.
Acrylics are copolymers of acrylonitrile with other compounds.

Acrylonitrile is the common name for the following compound.

H2C = CH - C ≡ N

Acrylonitrile can be formed from propene.

Write an equation for the reaction of propene with ammonia and oxygen to form acrylonitrile and one other product.

A
  • H2C = CH - CH3 + NH3 + 3 / 2 O2 - > H2C = CH - CN + 3 H2O
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31
Q

The term copolymer is used to describe the product obtained when two or more different monomers form a polymer.

Draw the repeating unit of the acrylic copolymer that contains 75% acrylonitrile monomer and 25% chloroethene monomer.

A
  • -CH2CHCNCH2CHCNCH2CHCl -

- ( Must show trailing bonds, at the ends, and the CN functional groups are connected to the main carbon chain )

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32
Q

Name the type of polymerisation involved in part ( ii )

( The term copolymer is used to describe the product obtained when two or more different monomers form a polymer.

Draw the repeating unit of the acrylic copolymer that contains 75% acrylonitrile monomer and 25% chloroethene monomer. )

A
  • Addition polymerization
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33
Q

Suggest one reason why Tollens’ reagent is used as the oxidising agent in the specific test for aldehydes rather than the less expensive acidified potassium dichromate( VI ).

A
  • Dichromate( VI ) also shows a positive test for alcohols
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34
Q

This question is about some isomers of C5H8O2

Compound H is a cyclic ester that can be prepared as shown.

On the structure of H, two of the carbon atoms are labelled.

HOCH2CH2CH2CH2COCl - > ( In a hexagon from left vertices to around ) H2C - CH2 - C = O - O - H2C - H2C - ( Connects back to first vertices ) + HCl

Name and outline a mechanism for this reaction.

( a = the second carbon round )

( b = fourth carbon round )

Use Table C on the Data Sheet to give the 13^C n.m.r. δ value for the carbon atom labelled a and the δ value for the carbon atom labelled b.

A
  • Nucleophilic addition - elimination
  • ( Drawn mechanism )
  • An OH^- with a lone pair existed before the “ O “ in the hexagon, this lone pair bonds to carbon “ a “ which used to exist as C = O, so an arrow from the OH^- to the “ C “ in C = O and another arrow from the double bond of C = O to the oxygen
  • The oxygen gains a lone pair and a negative charge, the “ O “ from the OH gains a positive charge which is attached to the H atom still however also connected to the C atom from the used to be C = O
  • The hydrogen from OH bond has electrons moved to the oxygen atom due to the positive charge, which removes the H atom, the oxygen from the used to be C = O has its lone pair of electrons moved to the single bond to form a double bond again, however the final product isn’t shown in the answer as it’s already in the question
  • Due to this movement on the “ O “ in the used to be C = O, electrons from the C - Cl bond move to the Cl to remove it, which goes onto forming the HCl
  • ” a “ has a 20 - 50 ppm
  • ” b “ has a 50 - 90 ppm
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35
Q

HOCH2CH2CH2CH2COCl can also react to form a polyester in a mechanism similar to that in part ( i ).

Draw the repeating unit of the polyester and name the type of polymerisation involved.

( HOCH2CH2CH2CH2COCl - > ( In a hexagon from left vertices to around ) H2C - CH2 - C = O - O - H2C - H2C - ( Connects back to first vertices ) + HCl )

A
  • ( Drawn in a displayed formula )
  • -CH2CH2CH2CH2COO-
  • ( Must have trailing bonds at the ends )
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36
Q

State how you could distinguish between compounds J and K by a simple test-tube
reaction.

State how you could distinguish between J and K by giving the number of peaks in
the 1^H n.m.r. spectrum of each compound.

( Both drawn in a displayed formula )

J:

CH3COCH2COCH3

K:

CH3COCH2CH2COH

A
  • Tollens’ reagent
  • J shows no visible change
  • K shows a silver mirror
  • J has two peaks
  • K has four peaks
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37
Q

*Draw the structure of each of the following isomers of C5H8O2.
Label each structure you draw with the correct letter L, M, N, P or Q.

L is methyl 2-methylpropenoate.

M is an ester that shows E - Z
stereoisomerism.

N is a carboxylic acid with a branched carbon chain and does not show stereoisomerism.

P is an optically active carboxylic acid.

Q is a cyclic compound that contains a ketone group and has only two peaks in its
1^H n.m.r. spectrum.

A

L: ( Ester ) ( All in displayed formula )

  • H2C = C( CH3 )COOCH3

M: ( Ester )

  • CH3CH = CHCOOCH3 ( H atoms are on the same side )

N: ( Acid )

  • ( CH3 )2C = CHCOOH

P: ( Acid )

  • CH3CH( COOH )CH = CH2

Q:

  • ( In a hexagon from left vertices around )
  • H2CCH2COH2CCH2O
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38
Q

Ethanol can be oxidised by acidified potassium dichromate( VI ) to ethanoic acid in a two-step process.

ethanol - > ethanal - > ethanoic acid

In order to ensure that the oxidation to ethanoic acid is complete, the reaction is carried out under reflux.

Describe what happens when a reaction mixture is refluxed and why it is necessary, in this case, for complete oxidation to ethanoic acid.

A
  • A mixture of liquids is heated to boiling point for a prolonged time
  • The vapour formed escapes from the liquid mixture and is changed back to a liquid and returned to the liquid mixture
  • Any ethanal and ethanol that initially evaporates can then be oxidised
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39
Q

Write a half-equation for the overall oxidation of ethanol into ethanoic acid.

A
  • CH3CH2OH + H2O - > CH3COOH + 4H+

+ 4e-

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40
Q

The boiling points of the organic compounds in a reaction mixture are shown in the following table.

Compound:

1 ) Ethanol

2 ) Ethanal

3 ) Ethanoic acid

Boiling point / °C:

1 ) 78

2 ) 21

3 ) 118

Use these data to describe how you would obtain a sample of ethanal from a mixture of these three compounds.
Include in your answer a description of the
apparatus you would use and how you would minimise the loss of ethanal.
Your description of the apparatus can be either a description in words or a labelled
sketch.

A
  • Mixture is heated in a suitable flask
  • With a still head containing a thermometer
  • Water cooled condenser is connected to the still head and a suitable cooled collecting vessel
  • Collect the sample at the boiling point of ethanal
  • The cooled collection vessel is necessary to reduce evaporation of ethanal
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41
Q

Use your knowledge of structure and bonding to explain why it is possible to
separate ethanal in this way.

( Separation of ethanal by distillation )

A
  • No hydrogen bonding in ethanal

- Dipole - dipole forces are weaker than hydrogen bonding

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42
Q

A student obtained a sample of a liquid using the apparatus in part (c).
( Distillation with a cooled collection vessel )

Describe how the student could use chemical tests to confirm that the liquid contained ethanal and did not contain ethanoic acid.

A
  • Add Tollens’ reagent
  • A positive test for an aldehyde will show a silver mirror
  • To confirm the absence of ethanoic acid, add sodium carbonate to the liquid
  • No effervescence observed hence no acid present
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43
Q

Lactic acid, CH3CH( OH )COOH, is formed in the human body during metabolism and exercise.
This acid is also formed by the fermentation of carbohydrates such as sucrose, C12H22O11.

Give the IUPAC name for lactic acid.

A
  • 2 - hydroxypropanoic acid
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44
Q

Write an equation for the formation of lactic acid from sucrose and water.

( Lactic acid, CH3CH( OH )COOH, is formed in the human body during metabolism and exercise.
This acid is also formed by the fermentation of carbohydrates such as sucrose, C12H22O11. )

A
  • C12H22O11 + H2O - > 4CH3CH( OH )COOH
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45
Q

A molecule of lactic acid contains an asymmetric carbon atom.
The lactic acid in the body occurs as a single enantiomer.
A racemic mixture ( racemate ) of lactic acid can be formed in the following two-stage
synthesis.

           ( Stage 1 )                 ( Stage 2 ) ( CH3 )CHO - > ( CH3 )CHOHCN - > ( CH3 )CHOHCOOH

( All in displayed formula )

Name and outline a mechanism for Stage 1.
( HCN )

A
  • Name of mechanism, nucleophilic addition

Mechanism:

  • ( ^-CN, with lone pair of electrons, attacks the delta positive carbon attached to the O )
  • ( Arrows are drawn from the lone pair on CN to the carbon, then an arrow from the double bond in C = O to the oxygen )
  • ( The oxygen now has a lone pair of electrons and a negative charge )
  • ( The lone pair of electrons move to a H^+ which is freely in the “ Solution “ creating a O - H bond )
  • ## Show the formed product
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46
Q

Give the meaning of the term racemic mixture ( racemate ).

A
  • Equal mixture of enantiomers
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47
Q

Explain how you could distinguish between a racemic mixture ( racemate ) of lactic acid and one of the enantiomers of lactic acid.

A
  • Plane polarized light

- Polarised light is rotated by single enantiomer but unaffected by racemate

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48
Q

A mixture of lactic acid and its salt sodium lactate is used as an acidity regulator in some
foods.
An acidity regulator makes sure that there is little variation in the pH of food.

Write an equation for the reaction of lactic acid with sodium hydroxide.

( Lactic acid = CH3CH( OH )COOH )

A
  • CH3CH( OH )COOH + NaOH → CH3CH( OH )COONa + H2O
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49
Q

The acid dissociation constant Ka for lactic acid has the value 1.38 × 10^-4 mol dm^-3 at
298 K.

Calculate the pH of an equimolar solution of lactic acid and sodium lactate.

A
  • [ H+ ] = Ka
  • pH = - log [ H^+ ]
  • pH = - log [ 1.38 × 10^-4 ] = 3.86
  • pH = 3.86
50
Q

Suggest an alternative name for the term acidity regulator.
Explain how a mixture of lactic acid and sodium lactate can act as a regulator when natural processes increase the acidity in some foods.

A
  • Name: buffer
  • Large lactate concentration in buffer
  • Added acid reacts with lactate ion
51
Q

The cup shown is made from PLA, poly( lactic acid ).
PLA is the condensation polymer formed from lactic acid.

The polymer is described as 100% biodegradable and 100% compostable.

Compostable material breaks down slowly in contact with the moist air in a garden bin.
This produces compost that can be used to improve soil.

The manufacturers stress that PLA cups differ from traditional plastic cups that are neither biodegradable nor compostable.

Draw a section of PLA that shows two repeating units.

A
  • -OCH( CH3 )COOCH( CH3 )CO-

- ( Must have trailing bonds at the ends )

52
Q

Name the type of condensation polymer in PLA.

( The cup shown is made from PLA, poly( lactic acid ).
PLA is the condensation polymer formed from lactic acid.

The polymer is described as 100% biodegradable and 100% compostable.

Compostable material breaks down slowly in contact with the moist air in a garden bin.
This produces compost that can be used to improve soil.

The manufacturers stress that PLA cups differ from traditional plastic cups that are neither biodegradable nor compostable. )

A
  • Polyester
53
Q

An intermediate in the production of PLA is a cyclic compound ( C6H8O4 ) that is formed from two PLA molecules.

Draw the structure of this cyclic compound.

( The cup shown is made from PLA, poly( lactic acid ).
PLA is the condensation polymer formed from lactic acid.

The polymer is described as 100% biodegradable and 100% compostable.

Compostable material breaks down slowly in contact with the moist air in a garden bin.
This produces compost that can be used to improve soil.

The manufacturers stress that PLA cups differ from traditional plastic cups that are neither biodegradable nor compostable. )

A
  • ( In a hexagon structure )

- From the left vertices, CH( CH3 )COOCH( CH3 )COO, connects back to the first

54
Q

Traditional non - biodegradable plastic cups can be made from poly( phenylethene ), commonly known as polystyrene.
Draw the repeating unit of poly( phenylethene ).

( The cup shown is made from PLA, poly( lactic acid ).
PLA is the condensation polymer formed from lactic acid.

The polymer is described as 100% biodegradable and 100% compostable.

Compostable material breaks down slowly in contact with the moist air in a garden bin.
This produces compost that can be used to improve soil.

The manufacturers stress that PLA cups differ from traditional plastic cups that are neither biodegradable nor compostable. )

A
  • -CH2CH( C6H5 )- ( with trailing bonds )
55
Q

The manufacturers of PLA claim that the material will break down to compost in just 12 weeks.
Suggest one reason why PLA in landfill may take longer than 12 weeks to break down.

( The cup shown is made from PLA, poly( lactic acid ).
PLA is the condensation polymer formed from lactic acid.

The polymer is described as 100% biodegradable and 100% compostable.

Compostable material breaks down slowly in contact with the moist air in a garden bin.
This produces compost that can be used to improve soil.

The manufacturers stress that PLA cups differ from traditional plastic cups that are neither biodegradable nor compostable. )

A
  • In a landfill, there’s no air to assist decay
56
Q

The triiodomethane reaction is often used as a test for aldehydes and ketones that contain the CH3CO group shown.

CH3CO- ( With a trailing bond )

The aldehyde or ketone is reacted with an alkaline solution of iodine.
Triiodomethane ( CHl3 ) is formed as a precipitate.
Compounds that contain a group that can be oxidised to the CH3CO group will also give a positive result in this test.

State, with a reason, whether or not ethanol will give a positive result in the triiodomethane reaction.

A
  • Yes, because it is oxidised to ethanal
57
Q

The equation for the reaction of ethanal with an alkaline solution of iodine is

CH3CHO + 3l2 + 4NaOH - > CHl3 + HCOONa + 3Nal + 3H2O

In an experiment using this reaction, the yield of triiodomethane ( CHl3 ) obtained by a student was 83.2%.

Calculate the minimum mass of iodine that this student would have used to form 10.0 g of triiodomethane.
Give your answer to the appropriate precision.
Show your working.

A
  • Mr of CHI3 = 393.7
  • Moles CHI3 = 10 / 393.7 = 2.54 × 10^-2
  • Moles I2 = 7.62 × 10^-2 ( 3:1 ratio )
  • Mass I2 = 7.62 × 10^-2 × 253.8 = 19.34 g
  • Scaling 19.34 / 83.2 x 10^-3 = 23.2 g
58
Q

Triiodomethane can be separated from the reaction mixture by filtration.
State one reason why the solid residue is then washed with water after the filtration.

A
  • To remove soluble impurities
59
Q

State one reason, other than cost or availability, why water is suitable for washing this solid residue after the filtration.

( Solid residue = Triiodomethane )

A
  • It will not dissolve the solid
60
Q

Each of the following conversions involves reduction of the starting material.

Consider the following conversion.

O2N - Benzene ring - NO2 - > H2N - Benzene ring - NH2

Identify a reducing agent for this conversion.

Write a balanced equation for the reaction using molecular formulae for the nitrogencontaining compounds and [ H ] for the reducing agent.

Draw the repeating unit of the polymer formed by the product of this reaction with benzene1,4-dicarboxylic acid.

A
  • Fe / HCl ( Reducing agent )
  • C6H4N2O4 + 12 [ H ] → C6H8N2 + 4H2O
  • -CO-Benzene ring-CO-NH-Benzene ring-NH-
  • ( Must contain trailing bonds )
61
Q

Consider the following conversion.

Benzene ring - > Hexagon

Identify a reducing agent for this conversion.

State the empirical formula of the product.

State the bond angle between the carbon atoms in the starting material and the bond angle between the carbon atoms in the product.

A
  • H2 ( Reducing agent )
  • CH2 ( empirical formula for product )
  • Benzene has a bond angle of 120 degrees between carbon atoms
  • Cyclohexane has a bond angle of 109 degrees between carbon atoms
62
Q

The reducing agent in the following conversion is NaBH4

CH3COCH2CH3 - > CH3CHOHCH2CH3
( Displayed formula )

Name and outline a mechanism for the reaction.

A
  • Name = Nucleophilic addition

Mechanism:

  • H^- ion bonds to “ C “ on C = O
  • ” O “ in C = O gains electrons from double bond causing it to have a lone pair and negative charge
  • lone pair on “ O “ from used to be C = O bonds to a H^+ ion to make OH bond
63
Q

By considering the mechanism of this reaction, explain why the product formed is optically inactive.

( Mechanism = Nucleophilic addition )
( Product =CH3CHOHCH2CH3 )
( Reaction = CH3COCH2CH3 - > CH3CHOHCH2CH3 )

A
  • It had a planar C = O
  • Attack is equally likely from either side
  • Racemic mixture is formed
64
Q

Chemists have to design synthetic routes to convert one organic compound into another.

Propanone can be converted into 2-bromopropane by a three-step synthesis.

Step 1: propanone is reduced to compound L.
Step 2: compound L is converted into compound M.
Step 3: compound M reacts to form 2-bromopropane.

Deduce the structure of compounds L and M.

For each of the three steps, suggest a reagent that could be used and name the mechanism.

Equations and curly arrow mechanisms are not required.

A

L:

  • CH3CHOHCH3 ( Displayed formula )

M:

  • CH3CH=CH2
  • Step 1, reagent = NaBH4
  • Mechanism = Nucleophilic addition
  • Step 2, reagent = Concentrated H2SO4
  • Mechanism = elimination
  • Step 3, reagent = HBr
  • Mechanism = Electrophilic addition
65
Q

Propanoic acid can be made from propan-1-ol by oxidation using acidified potassium dichromate( VI ).
Propanal is formed as an intermediate during this oxidation.

State the colour of the chromium species after the potassium dichromate( VI ) has reacted.

A
  • Green
66
Q

Describe the experimental conditions and the practical method used to ensure that the acid is obtained in a high yield.
Draw a diagram of the assembled apparatus you would use.

A

Conditions:

  • Excess acidified potassium dichromate ( VI )
  • Reflux

Diagram must include:

  • Reflux apparatus
  • A vertical condenser
  • an apparatus that will clearly work
67
Q

Describe the different experimental conditions necessary to produce propanal in high yield rather than propanoic acid.

A
  • Distillation

- Immediately ( the reagents are mixed )

68
Q

Propan-1-ol is a volatile, flammable liquid.

Give one safety precaution that should be used during the reaction to minimise this hazard.

A
  • Keep away from naked flames
69
Q

A student followed the progress of the oxidation of propan-1-ol to propanoic acid by extracting the organic compounds from one sample of reaction mixture.

Give a chemical reagent which would enable the student to confirm the presence of propanal in the extracted compounds.
State what you would observe when propanal reacts with this reagent.

A
  • Reagent = Tollens’ reagent

- Silver mirror is produced

70
Q

A student followed the progress of the oxidation of propan-1-ol to propanoic acid by
extracting the organic compounds from one sample of reaction mixture.

Give a chemical reagent that would enable the student to confirm the presence of propanoic acid in the extracted compounds.
State what you would observe when propanoic acid reacts with this reagent.

A
  • Sodium carbonate

- Effervescence

71
Q

Predict which one of the compounds, propan-1-ol, propanal and propanoic acid will have the highest boiling point.
Explain your answer.

A
  • Propanoic acid
  • Contains hydrogen bonding
  • Propanal has only dipole - dipole intermolecular forces
  • Which is weaker than hydrogen bonding, therefore propanal has a lower boiling point
72
Q

A possible synthesis of phenylethene ( styrene ) is outlined below

  • ( Diagram shows:
    Benzene ring - > Benzen ring with a carbonyl group and methyl group ( COCH3 ) - > Benzene ring with a CHOHCH3 attached to it - > Benzene ring with CH = CH2 attached to it )
  • ( Arrows are labelled Reaction 1, 2 and 3 consequently )

In Reaction 1, ethanoyl chloride and aluminium chloride are used to form a reactive species which then reacts with benzene.
Write an equation to show the formation of the reactive species.
Name and outline the mechanism by which this reactive species reacts with
benzene.

A
  • CH3COCl + AlCl3 - > [ CH3CO ]^+ + AlCl4^-
  • Electrophilic substitution ( Mechanism )
  • ( Curly arrow from within the right side of the benzene ring and a positive charge within it ( Top right side of the hexagon ) to the positive “ C “ from the COCH3 )
  • ( The benzene ring now has a horse shoe ( The circle in the middle of it now doesn’t cross the second or fourth carbon from the left vertices ) and show the bond with the COCH3 and H which is on the same vertices )
  • ( There is now an arrow from the hydrogen bond to the inside of the benzene ring to show it being broken off )
73
Q

A possible synthesis of phenylethene ( styrene ) is outlined below

  • ( Diagram shows:
    Benzene ring - > Benzen ring with a carbonyl group and methyl group ( COCH3 ) - > Benzene ring with a CHOHCH3 attached to it - > Benzene ring with CH = CH2 attached to it )
  • ( Arrows are labelled Reaction 1, 2 and 3 consequently )

NaBH4 is a possible reagent for Reaction 2.
Name and outline the mechanism for the reaction with NaBH4 in Reaction 2.
Name the product of Reaction 2.

A
  • Nucleophilic addition ( Mechanism )
  • ( A H^- ion has lone pairs which attach to the carbon with the C = O, shown by an arrow )
  • ( An arrow from the bond between C = O goes to the oxygen where it gains a lone pair and a negative charge )
  • ( The lone pair from the “ O “ attaches to a H^+ ion where it becomes a O - H bond )
  • 1-phenylethan-1-ol ( Name of the product )
74
Q

A possible synthesis of phenylethene ( styrene ) is outlined below

  • ( Diagram shows:
    Benzene ring - > Benzen ring with a carbonyl group and methyl group ( COCH3 ) - > Benzene ring with a CHOHCH3 attached to it - > Benzene ring with CH = CH2 attached to it )
  • ( Arrows are labelled Reaction 1, 2 and 3 consequently )

Name the type of reaction involved in Reaction 3 and give a reagent for the reaction.

A
  • Elimination ( dehydration )

- ( Concentrated ) sulphuric acid

75
Q

Many synthetic routes need chemists to increase the number of carbon atoms in a
molecule by forming new carbon - carbon bonds.
This can be achieved in several ways
including

  • reaction of an aromatic compound with an acyl chloride
  • reaction of an aldehyde with hydrogen cyanide.

Consider the reaction of benzene with CH3CH2COCl

Write an equation for this reaction and name the organic product.
Identify the catalyst required in this reaction.
Write equations to show how the catalyst is used to form a reactive intermediate and how the catalyst is reformed at the end of the reaction.

A
  • C6H6 + CH3CH2COCl → C6H5COCH2CH3 + HCl
  • Phenylpropanone ( Name of the product )
  • AlCl3 ( Catalyst used )
  • CH3CH2COCl + AlCl3 → CH3CH2CO^+
    + AlCl4^- ( How the catalyst is used )
  • AlCl4^- + H^+ → AlCl3 + HCl
76
Q

( Many synthetic routes need chemists to increase the number of carbon atoms in a
molecule by forming new carbon - carbon bonds.
This can be achieved in several ways
including

  • reaction of an aromatic compound with an acyl chloride
  • reaction of an aldehyde with hydrogen cyanide.

Consider the reaction of benzene with CH3CH2COCl )

Name and outline a mechanism for the reaction of benzene with this reactive
intermediate.

A
  • Electrophilic substitution
  • ( Curly arrow from within the right side of the benzene ring ( Top right side of the hexagon ) to the positive “ C “ from the COCH2CH3 )
  • ( The benzene ring now has a horse shoe and a positive charge within it ( The circle in the middle of it now doesn’t cross the second or fourth carbon from the left vertices ) and show the bond with the COCH2CH3 and H which is on the same vertices )
  • ( There is now an arrow from the hydrogen bond to the inside of the benzene ring to show it being broken off )
77
Q

Consider the reaction of propanal with HCN

Write an equation for the reaction of propanal with HCN and name the product.

A
  • CH3CH2CHO + HCN → CH3CH2CH( OH )CN
78
Q

Name and outline a mechanism for the reaction of propanal with HCN.

A
  • nucleophilic addition ( Name of the mechanism )
  • ( ^-CN, with lone pair of electrons, attacks the delta positive carbon attached to the O )
  • ( Arrows are drawn from the lone pair on CN to the carbon, then an arrow from the double bond in C = O to the oxygen )
  • ( The oxygen now has a lone pair of electrons and a negative charge )
  • ( The lone pair of electrons move to a H^+ which is freely in the “ Solution “ creating a O - H bond )
79
Q

The rate-determining step in the mechanism in part ( b ) ( ii ) involves attack by the nucleophile. ( Nucleophilic addition mechanism )
Suggest how the rate of reaction of propanone with HCN would compare with the rate of reaction of propanal with HCN
Explain your answer.

A
  • propanal faster rate of reaction

- easier for a nucleophile to attack at the end of chain

80
Q

Consider the sequence of reactions below.

CH3CH2CHO - > CH3CH2CHOHCN - > CH3CH2CHOHCOOH

  • ( Compounds are name P, Q and R consecutively )
  • ( First arrow is labelled reaction 1 with HCN and second arrow is labelled reaction 2 )

Name and outline a mechanism for Reaction 1.

A
  • Nucleophilic addition ( Mechanism )
  • ( ^-CN, with lone pair of electrons, attacks the delta positive carbon attached to the O )
  • ( Arrows are drawn from the lone pair on CN to the carbon, then an arrow from the double bond in C = O to the oxygen )
  • ( The oxygen now has a lone pair of electrons and a negative charge )
  • ( The lone pair of electrons move to a H^+ which is freely in the “ Solution “ creating a O - H bond )
81
Q

Name compound Q

( Consider the sequence of reactions below.

CH3CH2CHO - > CH3CH2CHOHCN - > CH3CH2CHOHCOOH

  • ( Compounds are name P, Q and R consecutively )
  • ( First arrow is labelled reaction 1 with HCN and second arrow is labelled reaction 2 ) )
A
  • 2 - hyrdroxybutanenitrile
82
Q

The molecular formula of Q is C4H7NO.
Draw the structure of the isomer of Q which shows geometrical isomerism and is formed by the reaction of ammonia with an acyl chloride.

( Consider the sequence of reactions below.

CH3CH2CHO - > CH3CH2CHOHCN - > CH3CH2CHOHCOOH

  • ( Compounds are name P, Q and R consecutively )
  • ( First arrow is labelled reaction 1 with HCN and second arrow is labelled reaction 2 ) )
A
  • CH3CH = CHCONH2 ( showing E - isomerism )
83
Q

Draw the structure of the main organic product formed in each case when R reacts separately with the following substances:

( R = CH3CH2CHOHCOOH )

methanol in the presence of a few drops of concentrated sulphuric acid;

A
  • ( Nucleophilic addition )
  • CH3CH2CHOHCOOCH3 ( Drawn )
  • ( H on the last carbon is converted to a CH3 molecule )
84
Q

Draw the structure of the main organic product formed in each case when R reacts separately with the following substances:

( R = CH3CH2CHOHCOOH )

acidified potassium dichromate(VI);

A
  • ( Elimination??? )
  • CH3CH2COCOOH
  • ( Loses HOH on third carbon )
85
Q

Draw the structure of the main organic product formed in each case when R reacts separately with the following substances:

( R = CH3CH2CHOHCOOH )

concentrated sulphuric acid in an elimination reaction.

A
  • CH3CH = CHCOOH ( Drawn )
  • ( Loses a H on second carbon )
  • ( Loses OH on third carbon )
  • ( Making a H2O molecule )
86
Q

Two stereoisomers are formed by the dehydration of Q.
Give the structures of these two isomers and name the type of stereoisomerism shown.

( Q = CH3CH2CHOHCN )

A
  • CH3CH = CHCOOH
  • ( Showing both E and Z isomers )
  • Geometrical isomerism
87
Q

An isomer of Q which has the structure shown below is polymerised to form the biodegradeable polymer known as PHB.

( Isomer of Q = CH3CH = CHCOOH, in E or Z isomerism )
( PHB has a molecular formula of, CH( CH3 )OHCH2COOH, drawn in displayed formula )

Draw the repeating unit of the polymer PHB.

A
    • OC( CH3 )HCH2CO -

- ( With trailing bonds )

88
Q

Suggest a reason why the polymer is biodegradeable.

PHB has a molecular formula of, CH( CH3 )OHCH2COOH, drawn in displayed formula

A
  • Can be hydrolysed
89
Q

The amino acid R is shown below.

( Displayed formula of CH3CH2CHNH2COOH )

Draw the structure of the zwitterion formed by R.

A
  • CH3CH2CHNH3^+COO^-
  • ( Hydrogen from COOH was moved to the NH2 )
  • ( In displayed formula )
90
Q

Draw the structure of the major organic product formed when an excess of R is reacted with bromomethane.

( R = CH3CH2CHNH2COOH )

A
  • CH3CH2CHNHCH3COOH

- ( Methyl group replaces one of the H in the amine group )

91
Q

Name the mechanism of the reaction which results in the formation of the product given in part ( ii ).

( Draw the structure of the major organic product formed when an excess of R is reacted with bromomethane.

( R = CH3CH2CHNH2COOH ) )

A
  • Nucleophilic substitution
92
Q

Give a suitable reagent and state the necessary conditions for the
conversion of propan-2-ol into propanone.
Name the type of reaction.

A
  • Reagent = Potassium dichromate( VI )
  • Conditions = H2SO4
  • Type of reaction = Oxidation
93
Q

Propanone can be converted back into propan-2-ol.
Give a suitable reagent and write an equation for this reaction.
( Use [ H ] to represent the reagent in your equation. )

A
  • Reagent = NaBH4

Equation:

  • CH3COCH3 + 2[ H ] - > CH3CH( OH )CH3
  • ( Nucleophilic addition reaction )
  • ( 2 hydrogens are given )
94
Q

Propanal is an isomer of propanone.

Draw the structure of propanal.

A
  • CH3CH2CHO ( Drawn )
95
Q

A chemical test can be used to distinguish between separate samples of propanone and propanal.
Give a suitable reagent for the test and describe what you would observe with propanone and with propanal.

A
  • Reagent = Tollens’ reagent
  • observation with propanone = colourless
  • observation with propanal = silver mirror
96
Q

In which one of the following mixtures does a redox reaction occur?

A ethanal and Tollens’ reagent

B ethanoyl chloride and ethanol

C ethanal and hydrogen cyanide

D ethanoic acid and sodium hydroxide

A
  • A
97
Q

Describe how propanal, CH3CH2CHO, and propanone, CH3COCH3, can be distinguished using a chemical test.

A
  • Tollens’ reagent
  • silver mirror for propanal
  • no reaction with propanone
98
Q

Describe how propanal, CH3CH2CHO, and propanone, CH3COCH3, can be distinguished using the number of peaks in their proton n.m.r. spectra.

A
  • Propanal has 3 peaks

- Propanone has 1 peak

99
Q

Compound Z can be produced by the reaction of compound X with compound Y as shown in the synthesis outlined below.

CH3CH2CHO - > X – > CH3CH2COOCH( CH3 )2

CH3COCH3 - > Y – > CH3CH2COOCH( CH3 )2
( Second set of arrows join together to that single product )
( The arrow before the X is labelled step 1 and the arrow before the Y is labelled step 2 )
( The arrow going to the product is labelled step 3 )
( The product is labelled Z )

Identify compounds X and Y.
For each of the three steps in the synthesis, name the type of reaction involved and give reagents and conditions. Equations are not required.

A
  • X is propanoic acid
  • Y is propan-2-ol
  • Step 1 requires oxidation with acidified potassium dichromate
  • Step 2 requires nucleophilic addition with NaBH4 in methanol
  • Step 3 requires nucleophilic addition - elimination
  • With concentrated H2SO4
  • Warm under reflux
100
Q

Addition reactions to both alkenes and carbonyl compounds can result in the formation of isomeric compounds.

Choose an alkene with molecular formula C4H8 which reacts with HBr to form two structural isomers.
Give the structures of these two isomers and name the type of structural isomerism shown.

Outline a mechanism for the formation of the major product.

A
  • CH3CH2CHCH2 ( Drawn in displayed formula )
  • Show two isomers
  • ( CH3CHCHCH3 )
  • ( CH3 = C( CH3 )CH2 )
  • Mechanism = electrophilic addition
  • ( A delta positive hydrogen from the HBr molecule attaches to the first( last ) carbon )
  • ( in the HBr molecule the hydrogen is delta positive and the Br is delta negative )
  • ( Therefore electrons move from the hydrogen to Br bond to the Br molecule )
  • ( to sum up, there’s an arrow coming from the double bond of the carbon to the delta positive hydrogen and an arrow coming from the hydrogen to Br bond to the bromine molecule )
  • ( Carbocation forms therefore there’s a positive charge under third carbon which a Br^- with a lone pair of electrons attaches to )
  • ( Creating the final product )
101
Q

Using HCN and a suitable carbonyl compound with molecular formula C3H6O, outline a mechanism for an addition reaction in which two isomers are produced.
Give the structures of the two isomers formed and state the type of isomerism shown.

A
  • CH3CH2CHO
  • mechanism = nucleophilic addition
  • ( ^-CN, with lone pair of electrons, attacks the delta positive carbon attached to the O )
  • ( Arrows are drawn from the lone pair on CN to the carbon, then an arrow from the double bond in C = O to the oxygen )
  • ( The oxygen now has a lone pair of electrons and a negative charge )
  • ( The lone pair of electrons move to a H^+ which is freely in the “ Solution “ creating a O - H bond )
  • ( To show the isomers, you must draw their optical isomers ( the mirror image ) )
  • ( CH3CH2CHOHCN )
  • Type of isomerism = optical isomerism
102
Q

Explain why ethanoyl chloride reacts readily with nucleophiles.
Write an equation for one nucleophilic addition-elimination reaction of ethanoyl chloride.
( A mechanism is not required. )

A
  • There’s a large charge on the carbonyl carbon atom due bonding of oxygen and chlorine
  • Nucleophiles have electron pairs which can be donated
  • CH3COCl + HCN - > CH3COCN + HCl ( ? )
103
Q

In which of the following is a curly arrow used incorrectly?

( The choices A, B, C, and D are all images of mechanisms )

A ( Shows nucleophilic substitution )

B ( Shows electrophilic addition )

C ( Shows nucleophilic addition )

D ( Shows a dehydration mechanism )

A
  • B
  • ( The arrow for the attachment of bromine on the carbocation is not pointing towards the positive sigh )
  • ( Instead it’s pointing the the opposite side of that carbon atom )
104
Q

Compounds C and D, shown below, are isomers of C5H10O

C = CH3COCH2CH2CH3
( D = CH2CH2CHOHCH2CH2, in a hexagon shape starting from the left vertices )

A
  • C = Pentan-2-one
105
Q

Use Table 2 on the Data Sheet to help you to answer this question.

Suggest the wavenumber of an absorption which is present in the infra-red spectrum of C but not in that of D.

( C = CH3COCH2CH2CH3 )
( D = CH2CH2CHOHCH2CH2, in a hexagon shape starting from the left vertices )

A
  • 1680 - 1750
106
Q

Suggest the wavenumber of an absorption which is present in the infra-red spectrum of D but not in that of C.

( Use Table 2 on the Data Sheet to help you to answer this question. )
( C = CH3COCH2CH2CH3 )
( D = CH2CH2CHOHCH2CH2, in a hexagon shape starting from the left vertices )

A
  • 3230 - 3550
107
Q

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

( C = CH3COCH2CH2CH3 )

A
  • 4
108
Q

Identify a reagent that you could use to distinguish between C and D.
For each of C and D, state what you would observe when the compound is treated with this reagent.

( C = CH3COCH2CH2CH3 )
( D = CH2CH2CHOHCH2CH2, in a hexagon shape starting from the left vertices )

A
  • Reagent = K2Cr2O7/H^+ ( acidified potassium dichromate )
  • Observation with C = no reaction
  • Observation with D = Goes screen
109
Q

Compound E, CH3CH2CH2CH2CHO, is also an isomer of C5H10O

Identify a reagent which will react with E but not with C or D.
State what you would observe when E is treated with this reagent.

A
  • Reagent = Tollens’ reagent

- Observation with E = Silver mirror

110
Q

Outline a mechanism for the reaction of CH3OH with CH3CH2COCl and name the organic product.

A
  • ( Nucleophilic addition elimination )

( Lone pair of electrons on “ O “ molecule in CH3OH attach to the carbon on C = O )

  • ( Causes O on used to be C = O to gain a lone pair of electrons and a negative charge shown by an arrow )
  • ( The lone pair on the O make the double bond again, shown by an arrow from the lone pair to the bond between the C - O )
  • ( At the same time, Cl is broken off shown by an arrow from the C - Cl bond to the Cl molecule )
  • ( The “ O “ molecule from the CH3OH has a positive charge due to the bonding to the “ C “ atom, which causes the loss of the “ H “ molecule )
  • ( Shown by an arrow from the “ H “ molecule to the positive “ O “ )
  • ( Show the product of the reaction )
  • CH3CH2COOCH3
  • Name = Methyl propanoate
111
Q

An equation for the formation of phenylethanone is shown below. In this reaction a reactive intermediate is formed from ethanoyl chloride.
This intermediate then reacts with benzene.

( Benzene ring + CH3COCl - > Benzene ring with COCH3 functional group + HCl )
( Arrow is labelled AlCl3 )

Give the formula of the reactive intermediate.

A
  • CH3CO^+
112
Q

Outline a mechanism for the reaction of this intermediate with benzene to form phenylethanone.

( Benzene ring + CH3COCl - > Benzene ring with COCH3 functional group + HCl )
( Arrow is labelled AlCl3 )
( Reaction reactant = CH3CO^+ )

A
  • ( Arrow comes out of the inside of the ring from fourth vertices from the left of the benzene ring bonding to the positive carbon from CH3CO^+ )
  • ( Horseshoe is formed with a positive charge, which doesn’t go beyond the newly bonded COCH3 )
  • ( The “ H “ atom from the same vertices has a curly arrow going within the horseshoe towards the positive charge breaking off the “ H “ atom )
113
Q

The three compounds CH3CH2CH2CH2OH, ( CH3 )3COH and CH3CH2CH2CHO can be distinguished by use of the following three reagents

  1. potassium dichromate( VI ) acidified with dilute sulphuric acid
  2. Tollens’ reagent
  3. ethanoic acid, together with a small amount of concentrated sulphuric acid.

Identify which of these three organic compounds would reduce acidified potassium dichromate( VI ).
Give the structures of the organic products formed.
Write a half-equation for the reduction of dichromate( VI ) ions in acidic solution.

A
  • acidified potassium dichromate is reduced by CH3CH2CH2CH2OH
  • CH3CH2CH2CH2OH is oxidised to CH3CH2CH2CHO and CH3CH2CH2COOH
  • CH3CH2CH2CHO is oxidised to CH3CH2CH2COOH
  • Cr2O7^2- + 14H^+ + 6e^- → 2Cr3^+ + 7H2O
  • ( Half equation for the reduction of dichromate( VI ) ions in acidic solution )
114
Q

Identify which one of these three organic compounds would reduce Tollens’ reagent.
Give the structure of the organic product formed.
Write a half-equation for the reduction of Tollens’ reagent.

( The three compounds CH3CH2CH2CH2OH, ( CH3 )3COH and CH3CH2CH2CHO can be distinguished by use of the following three reagents

  1. potassium dichromate( VI ) acidified with dilute sulphuric acid
  2. Tollens’ reagent
  3. ethanoic acid, together with a small amount of concentrated sulphuric acid. )
A
  • Tollens’ reagent reduced by CH3CH2CH2CHO
  • CH3CH2CH2CHO oxidised to CH3CH2CH2COOH
  • [ Ag( NH3 )2 ]^+ + e^- → Ag + 2NH3
  • ( Half equation for the reduction of Tollens’ reagent )
115
Q

Identify which of these three organic compounds would react with ethanoic acid in the presence of concentrated sulphuric acid.
In each case, give the structure of the organic product formed.

( The three compounds CH3CH2CH2CH2OH, ( CH3 )3COH and CH3CH2CH2CHO can be distinguished by use of the following three reagents

  1. potassium dichromate( VI ) acidified with dilute sulphuric acid
  2. Tollens’ reagent
  3. ethanoic acid, together with a small amount of concentrated sulphuric acid. )
A
  • CH3CH2CH2CH2OH reacts with ethanoic acid
  • Produces CH3CH2CH2CH2OOCCH3
  • ( CH3 )3COH reacts with ethanoic acid
  • Produces ( CH3 )3COOCCH3
116
Q

State the number of peaks in the proton n.m.r. spectra of CH3CH2CH2CH2OH and of ( CH3 )3COH.
(Analysis of peak splitting is not required.)

A
  • CH3CH2CH2OH has five peaks

- ( CH3 )3COH has two peaks

117
Q

Consider the following pair of isomers.

( C = CHOOCH2CH2CH3 )
( D = COOHCH2CH2CH3 )

Name compound C.

A
  • Propyl methanoate
118
Q

Identify a reagent which could be used in a test-tube reaction to distinguish between C and D.
In each case, state what you would observe.

( C = CHOOCH2CH2CH3 )
( D = COOHCH2CH2CH3 )

A
  • Reagent = acidified potassium dichromate
  • Observation with C = Goes green
  • Observation with D = no change
119
Q

Consider the following pair of isomers.

( E = CH3COCH2CH2CH3 )
( F = CHOCH2CH2CH2CH3 )

Name compound E.

A
  • Pentan-2-one
120
Q

Identify a reagent which could be used in a test-tube reaction to distinguish between E and F.
In each case, state what you would observe.

( E = CH3COCH2CH2CH3 )
( F = CHOCH2CH2CH2CH3 )

A
  • Reagent = Tollens’ reagent
  • Observation with E = no visible change
  • Observation with F = silver mirror
121
Q

Draw the structure of the chain isomer of F which shows optical isomerism.

( F = CHOCH2CH2CH2CH3 )

A
  • Chain isomer of F = CHOCH( CH3 )CH2CH3
  • ( Optical isomerism is present in the second carbon )
  • ( Which you have to show only one of the isomers )

Chemistry (13 decks)

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