Topic 10
Organic Chemistry
ANSWERS
10.1
Functional Groups and Isomerism SL/HL
1.Which of the following pairs represent members of an homologous series?
A.
C2H4 and C2H6
B.
C2H5Cl and C2H4Cl2
C.
CH3OCH3 and CH3CH2OH
D.
C3H7COOH and C4H9COOH
2. Which names are correct for the following isomers of C6H14?
2-methylpentane
2ethyl-2-methylpropane
2,3-dimethylbutane
A.
I only
B.
I and II only
C.
I and III only
D.
I,II and III
;
3. Which compound is a member of the same homologous series as 1-chloropropane?
A.
1-chloropropene
B.
1-chlorobutane
C.
1-bromopropane
D.
1,1-dichloropropane
4. Which formula represents an amide?
A.
CH3CH2NH2
B.
CH3CH2N(CH3)2
C.
H2NCH2CO2H
D.
CH3CONH2
5. Which of the following is an amine?
A.
CH3CH2NH2
B.
CH3CONH2
C.
-[CH2CONHCH2CO]n_
D.
CH3CH2C ≡ N
6. How many different structural isomers have the formula C4H9C1?
A.
2
B.
3
C.
4
D.
5
7.
How many different isomers have the formula C4H10 ?
A.
1
B.
2
C.
3
D.
4
8.
9. The alkanes are a homologous series of saturated hydrocarbons.
(a) State the meaning of each of the following terms.
(i)
homologous series
(ii) saturated
(b) (i)
Have a general formula
[1]
Contain only C-C single bonds
[1]
State and explain the trend in the boiling points of the first five alkanes.
Increases
[2]
Increase in mass leads to greater Van De Waal forces
(ii) Give the structural formulas for the isomers of molecular formula C4 H10 and state the
name of each one
[2]
CH3CH2CH2CH3 = Butane
CH3CH(CH3)CH3 = 2-methyl propane
10. (i)
group.
List three characteristics of an homologous series, and explain the term functional
[3]
General formula/differ by CH2 grp/gradual change in phys props/similar
chem. Props (any 2)
Func grp = atom or grps of atom responsible for chem. Props of
homologeous series (reactive part of molecule)
(ii) Draw the four structures of alcohols of formula C 4H9OH. Name each one and
label them as either primary, secondary or tertiary alcohols.
[4]
CH3CH2CH2CH2OH = butan-1-ol = primary
CH3CH(CH3)CH2OH = 2-methyl propan-1-ol = primary
CH3CH(OH)CH2CH3 = butan-2-ol = secondary
CH3C(CH3)(OH)CH3 = 2-methyl propan-2-ol = tertiary
(iii) Many organic compounds can exist as isomers. Draw and name an isomer of ethanoic
acid,
HCOOCH3 = methyl methanoate
[2]
Topic 10
Organic Chemistry
10.2
Physical Properties of Organic Compounds
SL/HL
1. When the compounds below are listed in order of decreasing boiling point (highest to lowest) what is the
correct order?
1.
ethane
A.
4,3,1,2
B.
4,3,2,1
C.
3,4,1,2
D.
2,1,3,4
2.
fluoroethane
3.
2. Which of the following is expected to be a gas at 25° C?
3.
Which compound is the most soluble in water?
A.
Methane
B
Propane
C.
Propan-1-ol
D.
Pentan-1-ol
ethanol
4.
ethanoic acid
4. Statement (S): Solubility of alcohols in water decreases with increase in Mr.
Explanation (E): The relative proportion of the hydrocarbon part in alcohol increases with increasing Mr.
A.
Both S and E are true.
B.
Both S and E are false.
C.
S is true but E is false.
D.
S is false but E is true.
5. Explain why the boiling points of ethanol and ethanoic acid are considerably higher than the
boiling point of ethanal.
[3]
Ethanol and ethanoic acid both contain H bonds
Since H is attached to electroneg O atom.
Ethanal has only dipole forces due to C=O
6.
Discuss the factors which affect the boiling points of covalently bonded compounds by reference to
the following pairs of organic substances, whose boiling points are given:
• ethane (184 K) and butane (273 K);
• ethane ( 184 K) and bromoethane (311 K);
• bromoethane (311 K) and ethanol (352 K).


Greater van de waals forces in butane
Caused by larger Mr increases bp.


Dipole forces in bromobutane
Due to polarity of C-Br bond….these are stronger than Van De Waals…higher bp.


Ethanol contains H bonds
Due to O-H bond….these are stronger than dipole…higher bp.
[6]
Topic 10
Organic Chemistry
Reactions of Alkanes and Alkenes
10.3
SL/HL
1. Which statement is correct about the reaction between methane and chlorine?
A.
It involves heterolytic fission and ions. Cl−
B.
It involves heterolytic fission and Cl* radicals.
C.
It involves homolytic fission and ions. Cl−
D.
It involves homolytic fission and Cl * radicals.
2. Which are characteristics typical of a free radical?
I. It has a lone pair of electrons.
II. It can be formed by the homolytic fission of a covalent bond.
III. It is uncharged.
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
3. Which is the best description of the following reaction?
C2H4 + H2O → C2H5OH
A.
Addition
B.
Condensation
C.
Dehydration
D.
Hydrogenation
4. Which chemical is most likely to be a starting material for a common polymer?
A.
CH3CH2CH3
B.
CH3CH2OH
C.
CH3CHCH2
D.
5. What will be formed when CH2 = CH2 reacts with Br2 in the dark?
A.
CH2Br —CH2Br
B.
CH3—CHBr2
C.
CH 2 =CHBr + HBr
D.
CHBr = CHBr + H 2
6. (a) Describe a chemical test to distinguish between alkanes and alkenes, giving the result in each
case. [2]
Bromine water
Alkanes = stays orange….alkenes = turns clear
(b) Name the type of polymerization reaction which C3H6 undergoes and draw the structure of a section
of the polymer chain formed from three monomer molecules.
[3]
Addition polymerization
-(CH(CH3)CH2 ) --(CH(CH3)CH2 ) --(CH(CH3)CH2 ) - (2 marks)
7. Give an equation for the complete combustion of methane, CH 4. Identify two products formed by
the incomplete combustion of methane and identify one harmful effect caused by one of the products.
CH4 + 2 O2 = CO2 + 2 H2O
Carbon monoxide (poisonous/internal suffocation)
Carbon (respiratory problems/asthma/bronchitis)
[4]
8. The plastic PVC, poly(chloroethene), is made from the monomer chloroethene, C2H3C1, by a
polymerization reaction.
CHCl = CH2
(i)
Draw the structural formula of chloroethene.
(ii)
State the type of polymerization reaction that occurs to make poly(chloroethene) and
identify the structural feature needed in the monomer.
[1]
[2]
Addition polymers
C=C (unsaturated)
(iii) Draw the structure of the repeating unit of poly (chloroethene).
[1]
-( CHClCH2 )-
(iv) Explain why monomers are often gases or volatile liquids, whereas polymers are solids.
[2]
Monomers are small molecules…low Mr…weak Van de waal forces..low bp
Polymers are v large molecules…high Mr…stronger Van De Waals..high bp
9. Alkanes are often described as having low reactivity, although they do react with halogens.
(i)
Explain why alkanes are unreactive.
Non polar
Strong C-C and C-H bonds
[2]
(ii) The first step in the reaction of propane with bromine can be represented by the equation.
Br2→ 2Br∙
State the type of species formed in this step and name the type of bond fission.
[2]
Free radical
Hemolytic fission
10. Under certain conditions ethene can be converted to ethanol.
(i)
Give a chemical test to identify ethene and state what would be observed.
(ii) Give a balanced equation for the reaction to form ethanol from ethene.
(iii) State the conditions necessary for the reaction in (ii).
Bromine water
Orange to clear
CH2 = CH2 + H2O = CH3CH2OH
Heat + (almost conc) sulfuric acid (as a catalyst)
[4]
Topic 10
Organic Chemistry
Reactions of Alcohols
10.4
SL/HL
1. Which compound is converted to butanal by acidified potassium dichromate(VI) solution?
A.
butan-1-ol
B.
butan-2-ol
C.
butanone
D.
butanoic acid
2. What is the final product formed when ethanol, CH3CH2OH is reacted with acidified potassium dichromate(VI)?
A.
ethanal
B.
ethane
C.
ethanoic acid
D.
ethene
3. Which compound will undergo oxidation when treated with acidified potassium dichromate(VI)?
A.
CH3CH2CHO
B.
CH3COCH3
C.
CH3COOH
D.
(CH3)3COH
4. (a) Propan-1-ol, in the presence of a small amount of oxidising agent, forms compound X,
and when refluxed with an excess of oxidising agent, forms compound Y.
(i)
Identify a suitable oxidising agent and state the colour change.
[2]
(ii) Draw the structural formulas of both compound X and compound Y.
[2]
Cr2O72- / H+
Orange to (dirty) green
X = CH3CH2CHO
Y = CH3CH2COOH
(b) Some alcohols are oxidized by heating with acidified potassium dichromate(VI). If oxidation
does occur, identify the possible oxidation products formed by each of the alcohols below.
Indicate if no oxidation occurs.
Butan–1–ol
Butanal and then butanoic acid
Butan–2–ol
Butanone
2–methylpropan–2–ol
No oxidation (tertiary alcohol)
5. This question is concerned with compounds having the molecular formula C3H8O.
(a)
Draw the full structural formulas of the three possible isomers and give the name of each.
[5]
CH3CH2CH2OH = propan-1-ol
CH3CH(OH)CH3 = Propan-2-ol
CH3-O-CH2CH3 = methoxy ethane (extension)
(b)
Predict how each of these isomers would behave when reacted with limited (i.e. not in
excess) acidified potassium dichromate(VI) solution and describe any observation that
could be made. Write the structures of any organic products formed and give their names.
Propan-1-ol = propanal
CH3CH2CHO
Propan-2-ol = propanone CH3C=OCH3
Observations =orange to dirty green.
Methoxy methane = no reaction.
[6]
[4]
Topic 10
Organic Chemistry
10.5
Reactions of Halogenoalkanes
SL/HL
1. The reaction between 1-bromopropane and warm dilute sodium hydroxide solution is described as an
SN 2 nucleophilic substitution reaction.
(i)
Substitution, nucleophilic, second order
Explain each of the terms in SN 2.
[3]
(ii) Write an equation and a mechanism for the reaction.
CH3CH2CH2Br + NaOH =
Polarity of C-Br bond
CH3CH2CH2OH +
[5]
NaBr
curly arrow from OH- nucleophile
Correct activated complex formed
Curly arrow from Br- leaving group
2. (i) 1-bromopropane is described as a primary halogenoalkane and 2-bromopropane is
described as a secondary halogenoalkane. Explain these terms with reference to the
two examples given.
Primary = 1 carbon group attached to functional group
[2]
Secondary = two carbon groups attached to functional group
(ii) Give the structural formula of a tertiary halogenoalkane.
CH3C(CH3)2Br
[1]
(iii) State the type of substitution reaction undergone by tertiary halogenoalkanes.
[1]
SN1
3. Give the structural formulas of the four isomers of molecular formula C4H9Cl. State the
name of each one and classify it as primary, secondary, or tertiary.
CH3CH2CH2CH2Cl = 1-chlorobutane = primary
CH3CH(Cl)CH2CH3 = 2-chlorobutane = secondary
CH3CH(CH3)CH2Cl = 2-methyl 1-chloropropane = primary
CH3C(CH3)2Cl = 2-methyl 2-chloropropane = tertiary
[8]
(b) Each of the isomers reacts with aqueous sodium hydroxide. State what class of compound is
produced by this reaction.
alcohols
[1]
(c) (i) Identify the type of isomer (primary, secondary or tertiary) which will react with
aqueous sodium hydroxide almost exclusively by an SN1 mechanism. State the
meaning of the symbols in the term SN1 mechanism.
Tertiary
Sub, nucleophilic 1st order reaction
[2]
Topic 10
Organic Chemistry
10.6
Reaction Pathways
SL/HL
1. This question refers to the compounds in the following reaction scheme.
Na0H
C3H7Br →
C3H8O→0xidation C3H6O
A
B
C
0xidation
→ C3H6O2
D
(a) State a suitable reagent for the oxidation of B to C and C to D. Explain how the oxidation
of B to C could be achieved without further oxidation to D. [3]
Acidified/H+
potassium dichromate
product must be distilled off before further oxidation
(b) The conversion of A to B takes place by an SN 2 mechanism. State what is meant by the
term SN2 and describe, by using "curly arrows" to show the movement of electron pairs, the
mechanism of this conversion.
[6]
nd
Sub, nucleophilic, 2 order (1 mark)
Polarity of C-Br bond
Curly arrow showing C-Br bond breaking
Forrnation of correct carbocation
slowest step is first step
Curly arrow showing attack of OH- on cation
2. This question is about four compounds A, B, C and D, which can be made from ethene by
the following reactions. All four compounds are liquid at room temperature, and each
compound's molecular formula is shown.
(a)
C2H4
C2H5O
A
B
C2H4O
C2H5O2
C
D
Use the information above to identify each of the compounds A, B, C and D giving the
name and structural formula of each one.
[8]
A = Ethene = CH2CH2
B= Ethanol = CH3CH2OH
C= Ethanal = CH3CH2CHO
D = Ethanoic acid = CH3CH2COOH
(b) State the type of reaction occurring when A is converted to B and state the reagent required.
Addition
reagent = H2O (and a sulfuric acid catalyst)
[2]
(c) Compound A can react with bromine. Write an equation for this reaction and
name the product. State a visible change which accompanies the reaction.
[3]
CH2CH2 + Br2 =
Orange to clear
CH2BrCH2Br
1,2-dibromoethane
Topic 10
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]
.
CH3CH2CH2CH2Cl
CH3CH(Cl)CH2CH3
CH3CH(CH3)CH2Cl
CH3C(CH3)(Cl)CH3 tertiary
(ii) Identify one isomer in (iii) that undergoes a substitution reaction mainly by an SN1 [1]
mechanism.
Tertiary one
(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.
Polarity of C-Br bond
Curly arrow showing C-Br bond breaking
Forrnation of correct carbocation
7. (a) (i)
Curly arrow showing attack of OH- on cation
Draw the structures of 2-chloropropanoic acid and 2-hydroxypropanoic acid.
CH3CH(Cl)COOH
(ii)
slowest step is first step
[2]
CH3CH(OH)COOH
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]
Nucleophile = electron rich species/non bonded e pair/attracted to positive species
Warm dilute NaOH
(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.
Bromo is faster
Data booklet shows that strength of C-Br bond is weaker (since less polar) and so can be broken
more easily.
[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]
CH3CH2OH +
CH3COOH
CH3COOCH2CH3 + H2O
1 mar for products and reactants….1 mark for eq sign
(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]
Ester has low bp/volatile…has strong smell.
As a catalyst
shifts eq to RHS (as increase acidity on LHS)
(d) State and explain how the solubility of the product in water compares with the
solubililty of the two reactants in water.
[2]
Less soluble
Esters have no H bonding
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]
HCOOCH3
materials = methanol and methanoic acid
Conditions = heat + acid (sulfuric) catalyst
CH3OH + HCOOH
HCOOCH3 + H2O
(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]
Isomer = CH3COOH
Physical = solubility in water/boiling point/volatility
Esters cannot H bond but carboxylic acids can
Chemical = Acidity
Carboxylic acids will react with carbonates/metals….esters won t.
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.
NH2(CH3)6NH2
[2]
HOOC (CH3)4 COOH
(ii) State the type of polymerization reaction that occurs between these two monomers
and identify the structural feature needed in the monomers. [2]
Condensation polymer
2 functional groups per molecule
(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]
Amide link
(-C=O – NH -)
other product = water
8. (a) Given the structures of the repeating units of the polymers below, identify the monomers
from which they are formed.
[4]
CH2=CH2
-( CH2-CH2 )-
HOOC-CH(CH3)-NH2
-( CO-CH(CH3) NH )-( NH-(CH2)6-CO-NH-(CH2)4-CO )-
NH2(CH3)6NH2 and HOOC (CH3)4 COOH
(2 marks)
(b) Describe the essential differences between the structures of monomers that form addition [2]
polymers and the structures of monomers that form condensation polymers.
Addition = C=C
Condensation = C=O group + nucleophile (NH3,OH- CN- etc)
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.
CH3
H
C=C
H
CH2CH3
(ii) Explain why W has a geometrical isomer.
No rotation of C=C bond
(iii) Draw two structures for CH3CH2CH(Cl)CH3, showing the relationship between them.
[2]
Mirror images of enantiomers drawn in 3D…(2 marks)
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 D drawing of cis and trans cyclic isomers
Restricted rotation in ring structures
[3]
(b) (i) Draw the structural formulas of two isomers of but-2-ene-1,4-dioic acid.
drawing of cis and trans cyclic isomers
[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.
2-chloropentane
Mirror images of enantiomers drawn in 3D…(2 marks)
[3]
(ii) Describe how these two isomers can be distinguished experimentally.
Rotation/effect on plane polarized light.
[1]
7. (a) Draw the structures of the two geometrical (cis/trans) isomers of C4H8 , giving their
full names.
[4]
drawing of cis and trans cyclic isomers… 2 marks
correctly labeled as cis but-2-ene and trans but-2-ene
(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.
3 D drawing of cyclic isomers…. 2 marks
[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:
Chain isomers 2 x CH3 on same C’s..or CH3CH2 (2 marks)
Cis and trans isomers …2 x CH3 groups on different C’s….(2 marks)
(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]
Either of the geometric isomers
(c) Use the examples from parts (a) and (b) to explain the existence of geometrical isomers. [1]
Restricted rotation of a ring structure
8. (a) Explain the term plane-polarized light and describe how the optical isomers of
CH3CH2CHClCH3 could be distinguished using a polarimeter.
Light vibrating in one plane
One isomer rotates it to left, other to right
[2]
(b) Explain why a sample of CH3CH2CHClCH3 produced did not show optical activity.
Racemic mixture
(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.
SN1
Formation of carbocation intermediate is planar by SN1 mechanism
Nucleophile can then attack with equal chance on either side of cation.
Equal chance of both optical isomers being formed = racemic mixture.
[1]
[4]
Topic 10
Organic Chemistry
10.10
Reaction Pathways
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)
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.
(ii) Explain why B is much harder to obtain than C in this reaction.
[4]
[3]
[1]
(c) Identify the gas formed when A and C react with sodium and write an equation for the
reaction of C. Name the other product of the reaction between sodium and C. [4]
(d)
(e)
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]
a) A = butanol = CH3CH2CH2CH2OH
B= Butanal = CH3CH2CH2CHO
C = butanoic acid = CH3CH2CH2COOH
D = But-1-ene = CH2=CHCH2CH3
b) i) oxidation
K2Cr2O7
Acid and heat
ii) Hard to stop complete oxidation…need to distil product B away from ox agent.
c) H2 gas
product = sodium butanoate
2 Na = 2 CH3CH2CH2COOH = 2 CH3CH2CH2COONa
d) butanal….butanol….butanoic acid
butanol = dipole (weaker intermolecular force)
Butanol = H- bonds (stronger intermolecular force)
Butanoic acid = stronger H-bonds + dipole
e) asymmetric carbon/4 different grps attached
CH3CH(OH)CH2CH3
+
H2
(2 marks)
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)
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.
[2 marks]
[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 reaction of compound B with
ethanoic acid in the presence of sulfuric acid and name the
functional group present in the organic product
[3 marks]