Download Topic 20 Organic Chemistry

Topic 20
Organic Chemistry
Nucleophillic Substitution
1.
10.7
HL ONLY
The alkaline hydrolysis of primary halogenoalkanes usually follows an SN 2 mechanism. For which
compound would the rate of hydrolysis be fastest?
A.
CH3CH2CH2F
B.
CH3CH2CH2C1
C.
CH3CH2CH2Br
D.
CH3CH2CH2I
2. Which compound reacts most rapidly by a SN1 mechanism?
A. (CH3)3CC1
B. CH3CH2CH2CH2Br
C. (CH3)3CBr
D. CH3CH2CH2CH2C1
3. What is the major product when an halogenoalkane is reacted with a large excess of
ammonia?
A.
An amine
B.
An amide
C.
An amino acid
D.
An alkene
4.
Which one of the chloroalkanes below will hydrolyse most rapidly?
A.
CH3CH2CH2CH2C1
5. Which molecule does not act as a nucleophile in a reaction with a halogenoalkane?
A. Ethane
B. Ethanol
C. Ethylamine
D. Water
6. (i) Draw the structure of the four structural isomers of C4H9Cl. [2]
.
(ii) Identify one isomer in (iii) that undergoes a substitution reaction mainly by an SN1 [1]
mechanism.
(iii) Write the mechanism for the reaction that occurs when the isomer identified in (ii) is [3]
warmed with aqueous sodium hydroxide. Use curly arrows to present the movement of
electron pairs.
7. (a) (i)
(ii)
Draw the structures of 2-chloropropanoic acid and 2-hydroxypropanoic acid.
[2]
2-chloropropanoic acid can be converted to 2-hydroxypropanoic acid by nucleophilic
substitution. Define the term nucleophile and state the nucleophile required for this
reaction.
[2]
(b) Deduce how the rate of reaction of CH2CH2CH2Br with NaOH would compare with that of the
compound CH2CH2CH2Cl with NaOH. Explain your answer by referring to the Data Booklet.
[2]
Topic 10
Organic Chemistry
Condensation Reactions
10.8
HL ONLY
1. What is the name of the compound CH3CH2CH2COOCH3 ?
A.
Butyl methanoate
B.
Methyl butanoate
C.
Methyl propanoate
D.
Pentanone
2.
From which two chemicals could this compound be synthesised?
A.
butanoic acid and pentan-1-ol
B.
butanoic acid and butan-1-ol
C.
butanal and pentan-1-ol
D.
pentanoic acid and butan-1-ol
CH3OH + CH3CH2COOH → CH3CH2COOCH3 + H2O
3.
The forward reaction represented by the equation above is
A.
addition.
B.
esterification.
C.
hydrolysis.
D.
neutralisation.
4. Consider the following reaction:
heat
CH3COOH + NH3→ CH3COONH4 → CH3CONH2
What will be the final product if aminoethane (ethylamine) is used instead of NH3 ?
A.
CH3CONHCH2CH3
B.
CH3CONHCH3
C.
CH3CONH 2
D.
CH3CONH2CH2CH3
5. When ethanol is warmed with ethanoic acid in the presence of an acid catalyst a new
product is formed.
(a) Write the balanced equation for the reaction that takes place using the structural
formulas of the organic reactants and products.
[3]
(b) State how the organic product may be distinguished from the reactants and to which
homologous series it belongs.
[2]
(c) State two reasons why concentrated sulfuric acid is used.
[2]
(d) State and explain how the solubility of the product in water compares with the
solubililty of the two reactants in water.
[2]
6. (i) Draw the structural formula of methyl methanoate. State the conditions and the starting
materials for the preparation of methyl methanoate in the laboratory. Write a balanced
chemical equation for the reaction [5]
(ii) Draw the structural formula of an isomer of methyl methanoate. State two physical
properties and one chemical property that would be different for the two compounds.
State how each of these properties differ for the two compounds.
[5]
7. Hexanedioic acid and 1,6-diaminohexane react together to form a synthetic polymer.
There are many natural polymers, some of the most familiar being proteins formed from 2amino acids.
(i)
Give the structural formula of each monomer in the synthetic polymer.
[2]
(ii) State the type of polymerization reaction that occurs between these two monomers
and identify the structural feature needed in the monomers. [2]
(iii) Draw the structure of and state the type of linkage formed in this polymer, and
identify the other product of this polymerization reaction. [3]
8. (a) Given the structures of the repeating units of the polymers below, identify the monomers
from which they are formed.
[4]
-( CH2-CH2 )-( CO-CH(CH3) NH )-( NH-(CH2)6-CO-NH-(CH2)4-CO )-
(b) Describe the essential differences between the structures of monomers that form addition [2]
polymers and the structures of monomers that form condensation polymers.
Topic 10
Organic Chemistry
Stereoisomerism
1. Which molecule possesses a chiral centre?
A. NH2CH2COOH
B. CH3CH(NH2)COOH
C. CH3C(NH2)2COOH
D. (CH3)2C(NH2)COOH
2. Which compound is optically active?
A.
CH3COCH(CH3)2
B.
(CH3)3CCHO
C.
CH3CH2COCH2CH3
D.
CH3CH2CH(CH3)CHO
3. Which one of the following compounds is optically active?
A.
CH3CH2CH2CH2NH2
B.
CH3CH2CHCH3
NH
C.
CH3CH2NCH2CH3
H
D.
CH 3 CH2 NCH3
CH3
10.9
HL ONLY
4. W has the structure
(i) Give the structure of the geometrical isomer of W.
(ii) Explain why W has a geometrical isomer.
(i) Draw two structures for CH3CH2CH(Cl)CH3, showing the relationship between them.
[2]
5. There are geometrical isomers of the cyclic compound C4H6Cl2 Draw the structural
formula of two isomers and explain why these two isomers exist.
[3]
(b) (i) Draw the structural formulas of two isomers of but-2-ene-1,4-dioic acid.
[2]
6. (a) Consider the following compounds:
1-chloropentane, 2-chloropentane, 3-chloropentane
(i) Identify the compound which exhibits optical isomerism and draw the structures of
the two isomers.
[3]
(ii) Describe how these two isomers can be distinguished experimentally.
[1]
7. (a) Draw the structures of the two geometrical (cis/trans) isomers of C4H8 , giving their
full names.
[4]
(b) There are four isomers with the formula C5 H10 which contain a three-membered carbon
ring. Draw these isomers and label them A, B, C and D.
[2]
(ii) Indicate, by writing two letters (chosen from A, B, C and D) a pair of isomers that are
structural isomers and a pair that are geometrical isomers.
[2]
Structural isomers:
Geometrical isomers:
(iii) From the four isomers A, B, C and D, draw the structure of an isomer that shows
optical isomerism and mark the chiral centre with an asterisk (*).
[1]
(c) Use the examples from parts (a) and (b) to explain the existence of geometrical isomers. [1]
8. (a) Explain the term plane-polarized light and describe how the optical isomers of
CH3CH2CHClCH3 could be distinguished using a polarimeter.
[2]
(b) Explain why a sample of CH3CH2CHClCH3 produced did not show optical activity.
[1]
(c) 2-chloropropanoic acid and 2-hydroxypropanoic acid can both show optical activity.
Identify the feature which both molecules possess that accounts for this property.
When 2-hydroxypropanoic acid is formed from 2-chloropropanoic acid, the product
shows no optical activity. Deduce the type of nucleophilic substitution that takes place
and explain your answer.
[4]
Topic 10
Organic Chemistry
Reaction Pathways
10.10
HL ONLY
1. This question is about four compounds A, B, C and D. B, C and D can be made from A by the
following reactions. A, B and C are liquid at room temperature, and each compound's molecular
formula is shown.
Sodium was added to each liquid compound. Gas bubbles formed slowly in A but rapidly in C.
(a)
(b)
(c)
(d)
(e)
Use the information above to identify each of the compounds A, B, C and D, giving the
name and structural formula of each one.
(i)
State the type of reaction occurring when A is converted to B and C, and state a
suitable reagent and conditions for the reaction.
[4]
[3]
(ii) Explain why B is much harder to obtain than C in this reaction.
[1]
Identify the gas formed when A and C react with sodium and write an equation for
the reaction with C. Name the other product of the reaction between sodium and C.
[4]
Arrange the compounds A, B and C in increasing order of boiling point (lowest boiling point
first). Explain your choice.
[4]
None of the compounds A, B, C and D exist as optical isomers. State the structural feature
which is present in a compound that exists as optical isomers. Draw the structural formula of
the isomer of A that exists as optical isomers,
[2]
2. Compound A is a bromoalkane. When compound A reacts with warm
dilute sodium hydroxide solution an organic compound B is formed
which has a relative molar mass of 74.12 and contains 64.81 % carbon,
13.60 % hydrogen and 21.59 % oxygen by mass. Compound B can be
oxidised by an acidified solution of potassium dichromate(VI) to give
compound C which contains the same number of carbon atoms as
compound B.
(a) (i)
(ii)
Calculate the empirical and molecular formula of compound B.
[3 mark]
Give four different possible structural formulas for isomers of
compound B which are consistent with the information that it has
been formed from the reaction of a bromoalkane with NaOH (aq).
[4 marks]
(iii) Which of the four isomers given in (ii) above is not consistent
with the fact that compound B can be oxidised by an acidified
solution of K2Cr2O7 to give compound C? Explain your answer.
(iv)
(b)
[2 marks]
Give
the
structures
of
the
organic
products
which
would
be
formed
when
the remaining three structural isomers
of
compound
B are fully oxidised by acidified K2Cr2O7.
[3 marks]
It is shown that compound B exhibits optical activity.
(i)
Explain what is meant by optical activity and show clearly the two
optical isomers of compound B.
[4 marks]
Give the structural formulas and names of compound A and
compound C.
[4 marks]
(iii) Name the mechanism which describes the reaction between
compound A and dilute sodium hydroxide solution.
[1 mark]
(ii)
(iv)
Give the balanced equation for the
ethanoic
acid
in
the
presence
of
functional group present in the organic product
reaction
sulfuric
of compound B with
acid
and
name
the
[3 marks]