CIE AS Chemistry

Topic Questions

ASChemistryCIETopic Questions3. Organic Chemistry3.4 Hydroxy Compounds

Syllabus Edition

First teaching 2020

Last exams 2024

|

3.4 Hydroxy Compounds

DownloadView
Easy
Medium
Hard
Easy
Medium
Hard
1a2 marks

Butan-1-ol can undergo different reactions. State the equation for the combustion of butan-1-ol.

How did you do?

1b3 marks

A flow chart for some reactions of butan-2-ol is shown below. 

4-4_q4b-ocr-a-as--a-level-easy-sq

State the reagents and conditions required for reactions 1 and 3.

Reaction 1 ………………………………………………………..

Reaction 3 ………………………………………………………..

How did you do?

1c1 mark

Name compound A.

How did you do?

Did this page help you?

2a4 marks

State to which class of alcohol the following alcohols belong to in Table 2.1.


Table 2.1

Alcohol Class of Alcohol 
2-methylpropan-2-ol   
Butan-1-ol  
Butan-2-ol   
2-methylpropan-1-ol  

How did you do?

2b2 marks

Write equations for


The dissociation of water ............................................................................................................................

The dissociation of butan-1-ol ............................................................................................................................

How did you do?

2c3 marks

Explain why alcohols are weaker acids than water.

How did you do?

Did this page help you?

3a2 marks

Three different alcohols, A, B and C are shown in Fig. 3.1.

3-4-3a-e-alcohol-a-b-and-c

Fig. 3.1

Name alcohol C and state the class of alcohol to which it belongs.

Name ...............................................................................................


Class of alcohol ...............................................................................

How did you do?

3b2 marks

Alcohol A is refluxed with acidified potassium dichromate.

i)
Name the organic formed
[1]
ii)
State the colour change observed in this reaction.
[1]

How did you do?

3c1 mark

Alcohols A, B and C are heated separately with an alkaline solution of iodine. State which alcohol will give a yellow precipitate during this reaction.

How did you do?

Did this page help you?

1a3 marks

Four reactions on butan-2-ol are shown below

  • Reaction 1: Butan-2-ol rightwards arrow from Heat to straight H subscript 3 PO subscript 4 of compound A

  • Reaction 2: Butan-2-olrightwards arrow from blank to reagent space bold X of spacecompound B + HCl + SO2

  • Reaction 3: Butan-2-ol rightwards arrow from room space temp to PBr subscript 3 ofcompound C

  • Reaction 4: Butan-2-ol rightwards arrow from room space temp to reagent space bold Y of2-chlorobutane

Compound A is a stereoisomer of cis-but-2-ene.
 


i)
Draw the structure of the stereoisomer of cis-but-2-ene.
 
[1]
 
ii)
Explain why compound A is less soluble than butan-2-ol.
 
[2]

How did you do?

1b3 marks

The reaction to form 2-chlorobutane produces three products.

 
i)
State the name of reagent Y.
 
[1]
 
ii)
Give the formulae of the two other products formed in this reaction. 
 
[2]

How did you do?

1c2 marks

Give the equation for the overall reaction between butan-2-ol and phosphorus tribromide which occurs at room temperature.

How did you do?

1d2 marks

Draw the structure of compound B and identify reagent X.

How did you do?

Did this page help you?

2a3 marks

The structure of glycolic acid is shown in Fig. 2.1.

screen-shot-2023-03-22-at-13-52-18

Fig. 2.1

Complete Table 2.1 to show what you would observe when an aqueous solution of glycolic acid is added separately to each of the reagents. If a reaction occurs, state the functional group of glycolic acid that is responsible for the reaction.

 
Table 2.1
 
Reagent Observation with glycolic acid Functional group
Mg (s)    
2,4-DNPH    
Acidified KMnO4    
 

How did you do?

2b4 marks

Glycolic acid can also be made by reacting glyoxylic acid with NaBH4 as shown in Fig. 2.2.

screen-shot-2023-03-22-at-14-05-34

Fig. 2.2

i)
State the role of NaBH4 in this reaction.
 
[1]
 
ii)
Write an equation for this reaction using molecular formulae. Use [H] to represent NaBH4.
 
[2]
 
iii)
Explain why NaBH4 is a suitable reducing agent for this reaction.
 
[1]

How did you do?

2c4 marks

When glycolic acid is heated in the presence of a sulfuric acid catalyst, a new compound, Y, C4H4O4, is formed. The equation for the reaction is given.

2CH2(OH)CO2H → C4H4O4  + 2H2O
glycolic acid   Y  


The infrared spectrum of Y is shown in Fig. 2.3.

screen-shot-2023-03-22-at-14-11-45

Fig. 2.3

i)
State how this spectrum differs from an infra-red spectrum of glycolic acid. Using Table 2.1, explain your answer with particular reference to the peaks within the range 1500 – 4000 cm–1.
 
Table 2.1
 
Bond  Functional groups containing
the bond		 Characteristic infrared absorption range (in wavenumber) / cm–1
C−O  hydroxy, ester  1040 – 1300
C=C  aromatic compound, alkene  1500 – 1680
C=O  amide
carbonyl, carboxyl
ester		 1640 – 1690
1670 – 1740
1710 – 1750
C≡N  nitrile  2200 – 2250
C−H  alkane  2850 – 2950
N−H   amine, amide 3300 – 3500
O−H  carboxyl
hydroxy		 2500 – 3000
3200 – 3600
 
[2]
 
ii)
Suggest a structure for Y.
 
[2]

How did you do?

Did this page help you?

3a
Sme Calculator3 marks

Compounds W, X and Y are all straight chain carbohydrates with X and Y each containing five carbons. Compound W and a by-product, compound Z, are formed from the reaction between compound X and Y.


Compound X can be fully oxidised by the reaction with acidified potassium manganate(VII) to give compound Y. 5.508 g of compound Y contains 0.054 moles.

State the name of compound Y. Justify your answer.

How did you do?

3b2 marks
i)
Draw the full displayed formula of compound W 











W

[1]

ii)
Explain how compound Z is formed in the reaction
 
[1]

How did you do?

3c4 marks

Compound X will oxidise to compound Y if allowed to fully oxidise.



Explain how a student could stop the full oxidation of compound X.

How did you do?

3d5 marks
i)
Write the structural formula of an isomer of compound X that will not react with acidified potassium manganate(VII).

ii)
Using your knowledge of bonds present in the oxidation products of different classes of alcohols, suggest why the isomer you have drawn will not react with acidified potassium manganate(VII).

How did you do?

Did this page help you?

1a7 marks

Alcohol A has the formula (CH3)3CCH(OH)CH3 and alcohol B has the formula (CH3)3CCH2CH2OH

i)
Draw the displayed formula of alcohol A and state its name in Table 1.1
[2]

Table 1.1

Name  Displayed formula of alcohol A
...................................................







ii)
In Table 1.2 draw the displayed formula of the organic product formed when alcohol A is heated under reflux with acidified potassium dichromate(VI) 
[1]
Table 1.2

Displayed formula 










iii)
When alcohol B is heated under reflux with acidified potassium dichromate(VI), a different organic product is formed. 
  • Draw the displayed formula of this product in Table 1.3 

Table 1.3

Displayed formula of product








  • Explain why this product is different to the one formed in part (ii)

[4]

How did you do?

1b3 marks

2-bromobutane can be prepared by the following reaction:

CH3CH(OH)CH2CH3 + Br- → CH3CH(Br)CH2CH3 + OH- 

i)

Name the type of reaction occuring.

[1]

ii)

Suggest suitable reagents for this reaction.

[2]

How did you do?

1c2 marks

Explain why both alcohols A and B are soluble in water.

How did you do?

1d2 marks

Alcohols A and B are heated with an alkaline solution of iodine. Complete Table 1.4 stating the observations of for each alcohol.

Table 1.4

Alcohol A observation Alcohol B observation
   

How did you do?

Did this page help you?

2a3 marks

When pentan-2-ol reacts with concentrated phosphoric acid under reflux, three alkenes are formed, X, Y and Z.

X and Y are stereoisomers of one another.

Draw the structures of alkenes, X, Y and Z.

How did you do?

2b2 marks

State how the stereoisomers formed in part (a) arise.

How did you do?

2c6 marks

Pentan-2-ol can undergo different reactions.

Write the equations for the reaction of pentan-2-ol with the following reagents. You do not need to include state symbols

i)
Oxygen

..........................................................................................................................
[2]

ii)
Sodium

..........................................................................................................................
[2]

iii)
Phosphorus(V) chloride

.........................................................................................................................
[2]

How did you do?

2d4 marks

Pentan-2-ol can undergo oxidation when reacted with potassium dichromate(VI) to form a ketone. 

Draw and label the apparatus which would be necessary to ensure that pentan-2-ol was oxidised to the ketone.

How did you do?

Did this page help you?

3a1 mark

This question is about the formation of alcohols.

2-bromobutane reacts with OH– in aqueous conditions to produce alcohol A. 


Draw the structure of alcohol A

How did you do?

3b3 marks

Draw the reaction mechanism for the formation of alcohol A in part (a).

How did you do?

3c1 mark

Alcohol A reacts with ethanoic acid in the presence of concentrated sulfuric acid to form compound B. Draw the structurs of compound B.

How did you do?

3d3 marks

Both alcohol A and water can act as weak acids. Explain why alcohol A is a weaker acid than water.

How did you do?

Did this page help you?

4a2 marks

Butan-1-ol can be oxidised by acidified potassium manganate(VII), KMnO4 , using two different methods.

In the first method, butan-1-ol is added dropwise to acidified potassium manganate(VII), KMnO4 and the product is distilled off immediately.

Using the symbol [O] for the oxidising agent, write an equation for this oxidation of butan-1-ol, showing clearly the structure of the product.


State what colour change you would observe ..................................................

[1]


Equation ...........................................................................................................

[1]

How did you do?

4b1 mark

In a second method, the mixture of butan-1-ol and acidified potassium manganate(VII), KMnO4 ,is heated under reflux.

Identify the product which is obtained by this reaction.

How did you do?

4c4 marks

Give the structures and names of two branched chain alcohols which are both isomers of butan-1-ol.

Only Isomer 1 is oxidised when warmed with acidified potassium manganate(VII).

Isomer 1 Isomer 2
Name
.......................................................		 Name
..........................................................

 Structure

fgdfgd

Structure

fgdfgd

How did you do?

4d2 marks

Write the half equation for the reduction of MnO4-  in this reaction.

How did you do?

Did this page help you?