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Organic Chem MCQ
Revision For 2012 CT 1
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2010 Organic Chemistry MCQ 1 After heating acidified potassium permanganate with the molecule below, how many
sp2 carbons are there present in the resultant compound?
OH
CH3 O
OH
A 6 B 9 C 10 D 11 ACJC Prelim 2010
2 How many stereoisomers are there in the compound shown?
A 2 B 4 C 6 D 8
ACJC Prelim 2010 3 When excess BrCl is added to the methylbenzene in the presence of UV light, which
organic compound will be produced in the smallest proportion?
A CH2Br
C CHBr2
B CH2Cl
D
CH2CH2
ACJC Prelim 2010
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4 When the following compound shown below is oxidized with alkaline potassium manganate(VII), one of the products include
ClH2CH2C
H
ClCH2CH2
CH3CO2
A
O
ClH2CH2C
H
HOCH2CH2
CH3CO2 C
O
ClH2CH2C
H
HOCH2CH2
CO2
B
O
ClH2CH2C
H
ClCH2CH2
CO2 D
O
ClH2CH2C
H
OOCCH2
O
ACJC Prelim 2010 5 Which one of the following alcohols will give the largest number of alkenes when
treated with concentrated sulphuric acid?
A C
B D ACJC Prelim 2010
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6 A 1,2-‐hydride shift is common in producing a more stable carbocation. For example, when removing the halogen from CH3CH2CH2Cl, a hydride shift will take place to produce a more stable carbocation.
C C C+
H
H H
HH
H
H C C+
C
H
H
HH
H
H HHydride shift
What will be the most likely product formed when (CH3)2CHCHClCH3 is added to AlCl3 and then the mixture is added to benzene? (Ph represents benzene) A CH3CH2CH2CH2CH2Ph C (CH3)2CHCH(Ph)CH3 B (CH3)2CHCH2CH2Ph D (CH3)2C(Ph)CH2CH3
ACJC Prelim 2010
7 Ethanal reacts with CN− from HCN in the presence of a weak base as shown below
CH3 C
O
H + HCN CH3 C
OH
H
CN In a similar reaction, −CH2COCH3 ions are generated when CH3COCH3 reacts with a strong base. Which one of following compounds is the product when ethanal reacts with −CH2COCH3? A CH3CH(OH)CH2COCH3 C (CH3)2C(CHO)CH2OH B CH3)2C(OH)CH2CHO D (CH3)2C(OH)COCH3
ACJC Prelim 2010 8 Phenol has a pKa of 5.7. Which one of the following has a lower pKa value?
A (CH3)3CCOOH C 2,4,6-‐trimethylphenol
B D ACJC Prelim 2010
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9 A liquid P is sparingly soluble in water but dissolves readily in cold hydrochloric acid. Evaporation of this solution yields a crystalline solid. Which of the following could be P? A C6H5COCH3 C C6H5NH2 B C6H5CN D C6H5OH
ACJC Prelim 2010
10 Acetaminophen is a drug used in headache remedies. It has the structure
N
H
C
CH3OOH
Which of the following equations gives the best method for its synthesis?
A N
H
C
CH3OOHClOH + H2NC
CH3O + HCl
B N
H
C
CH3OOHNH2OH + + HClCH3COCl
C N
H
C
CH3OOHNHCOClOH + + Cl2CH3Cl
D N
H
C
CH3OOHNHNH2OH + + NH3CH3CHO
ACJC Prelim 2010
11 Some chlorobutanes were separately treated with hot ethanolic sodium hydroxide.
Two of these gave the same hydrocarbon, C4H6. From which pair of chlorobutanes was this hydrocarbon obtained? A CH3CH2CH2CH2Cl and CH3CH2CCl2CH3 B CH3CH2CH2CH2Cl and ClCH2CH2CH2CH2Cl C CH3CHClCHClCH3 and ClCH2CH2CH2CH2Cl D CH3CH2CH2CH2Cl and CH3CH2CH2CHCl2.
CJC Prelim 2010
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12 In recent years, a number of athletes have been banned from sports because of their illegal use of synthetic testosterone.
CH3
CH3 OH
O
testosterone Testosterone is first refluxed with concentrated KMnO4, and the product is then reacted with HCN in trace of NaOH. How many chiral centres are present in the final product? A 6 B 7 C 8 D 9
AJC Prelim 2010 13 Use of the Data Booklet is relevant to this question.
The bond energy of the C–H bond (438 kJ mol–1) in CH4 is typically stronger than most other aliphatic C–H bonds. This has an effect on the first step of the propagation stage of the reaction between CH4 and the halogen. CH4 + X• → •CH3 + HX where X = F, Cl, Br or I On the basis of bond energies, which statement about the reaction between CH4 and the halogen is incorrect? A Bromine and iodine essentially do not react with methane. B Fluorine is so reactive that neither UV light or heat is needed. C The order of halogen reactivity is due to the decreasing strength of the HX bond. D The ΔH for the first propagation step is more endothermic for the chlorination of
C2H6. AJC Prelim 2010
14 Which reagent reacts with a secondary alcohol, under suitable conditions, to give an
organic product with the same number of oxygen atoms as the alcohol? A Al2O3 B CH3CO2H C K2Cr2O7 D PCl5
AJC Prelim 2010
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15 Deuterium, D, is a heavy isotope of hydrogen. Deuteriobenzene is reacted with a mixture of nitric acid and sulfuric acid under controlled conditions, so that only mononitration takes place. Assuming that the carbon–deuterium bond is broken as easily as a carbon–hydrogen bond, which proportion of the nitrated products will be 3–nitrodeuteriobenzene?
D D
NO2deuteriobenzene 3-nitrodeuteriobenzene
A 16% B 20% C 33% D 45%
AJC Prelim 2010
16 Four drops of 1–chlorobutane, 1–bromobutane, 1–iodobutane were put separately into three test–tubes containing 1.0 cm3 of aqueous silver nitrate at 60 °C. A hydrolysis reaction occurred. (R represents the butane chain C4H9– and X the halogen atom)
H2O(l) + R–X(l) + Ag+(aq) → R–OH(aq) + AgX(s) + H+(aq) The rate of formation of cloudiness in the tubes was in the order RCl < RBr < RI. What helps to explain this observation? A The bond energy of R–X decreases from RCl to RI. B The ionisation energy of the halogen decreases from Cl to I. C The R–X bond polarity decreases from RCl to RI. The solubility of AgX(s) decreases from AgCl to AgI.
AJC Prelim 2010 17 In what way is propene similar to propane?
A Both can be obtained by the dehydration of alcohols. B Both can react with chlorine under suitable conditions. C Both can be hydrogenated using a suitable catalyst. D Both can undergo polymerisation under suitable conditions.
CJC Prelim 2010
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18 The compound T, CH3COCH2CHO, was reacted in separate experiments with:
(i) alkaline aqueous iodine; (ii) 2,4–dinitrophenylhydrazine; (iii) Tollens’ reagent [Ag(NH3)2]+(aq); (iv) lithium aluminium hydride in dry ether.
One mole of T could A form two moles of CHI3 in (i). B react with two moles of 2,4–dinitrophenylhydrazine in (ii). C form one mole of CH3COCH2CH2OH and two moles of Ag in (iii). D form a product in (iv) which further reacts with Na to produce two moles of H2 gas.
AJC Prelim 2010
19 Aspartame is widely used as a sweetener in canned drinks.
Aspartame
H2N
CHCONHCHCO2CH3HO2CCH2
CH2
Which compound would be a product of its hydrolysis with aqueous NaOH? A CH3CO2
–
B
H2NCH
CO2H
CH2CO2H
C CH2CH2NH2
D
CH2CHNHCOCH
CO2−
NH2
CH2CO2−
AJC Prelim 2010
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20 Dopamine is a drug used in the treatment of Parkinson’s disease. Which of the following statements about this compound is correct? A It can dissolve in aqueous sodium hydroxide but not hydrochloric acid.
B It can be synthesised from
HO
HO
CH2I
C It decolourises aqueous bromine only in the presence of light. D Three moles of CH3COOH will react with one mole of Dopamine.
AJC Prelim 2010
21 A sample of a peptide of an unknown sequence was tested with enzymes. The sequences of the smaller peptides produced were Leu–Ser Lys–Leu Leu–Ala–Phe–Gln Ser–Tyr–Leu What was the sequence of the original peptide? A Ser–Tyr–Leu–Ala–Phe–Gln–Lys–Leu B Lys–Leu–Ala–Phe–Gln–Ser–Tyr–Leu C Lys–Leu–Ser–Tyr–Leu–Ala–Phe–Gln D Leu–Ser–Tyr–Leu–Ala–Phe–Gln–Lys
AJC Prelim 2010
22 Which of the following about the amino acid, methionine, is true?
A complete combustion of ethene in air B heating methanal with LiAlH4 in dry ether C mixing methane with chlorine gas in the presence of UV light D heating bromoethane under reflux with alcoholic potassium hydroxide
CJC Prelim 2010
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23 The following shows the time taken for appearance of precipitate after adding aqueous
AgNO3 to four halogen derivatives separately. Which of the following would be the best explanation for the observation? A The lattice energy becomes more exothermic from AgCl to AgI. B The ease of electron cloud distortion decreases from chlorobenzene to
2-‐iodobutane. C The carbon-‐halogen bond strength decreases from chlorobenzene to 2-‐iodobutane. D The carbon-‐halogen bond length decreases from 2-‐chlorobutane to 2-‐iodobutane.
CJC Prelim 2010
24 Tyrosol is a naturally occurring oxidant found in olive oil.
OH
OH Tyrosol
Which statement about Tyrosol is incorrect? A 1 mol of Tyrosol will react with 2 mol of Na to give 1 mol of H2. B 1 mol of Tyrosol will react with 2 mol of PCl5 to give 2 mol of HCl. C Tyrosol will react with acidified KMnO4 under reflux to give a carboxylic acid. D Tyrosol will react with H2SO4 under suitable conditions to give an alkene.
CJC Prelim 2010
Halogen Derivative Time for precipitate to appear Chlorobenzene No precipitate 2-‐chlorobutane 10 minutes 2-‐bromobutane 2 minutes 2-‐iodobutane Instantaneous
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25 Catechin is an antioxidant found in tea leaves, chocolates and red wine. It is often studied for its function as an inhibitor to the growth of cancer cells among other health benefits.
O
OH
OH
OH
OH
OH Catechin
O
ring is not involved in any of the following reactions. Which statement about catechin is correct? A It can undergo oxidation with hot acidified K2Cr2O7. B It can undergo electrophilic addition with Br2(aq). C 1 mol of catechin can react with 5 mol of NaOH. D 1 mol of catechin can react with 4 mol of Na2CO3.
CJC Prelim 2010 26 Which of the following about the amino acid, methionine, is true?
A It acts as a buffer in a solution of pH 13. B It exists predominantly as a zwitterion in a solution of pH 2. C It exists as a crystalline solid with high melting point. D It forms covalent disulfide linkage with another methionine molecule.
CJC Prelim 2010 27 Which sequence shows the compounds in order of decreasing pKa values?
A CH3CO2H > CF3CO2H > C2H5OH > C6H5OH B CF3CO2H > CH3CO2H > C6H5OH > C2H5OH C C2H5OH > C6H5OH > CH3CO2H > CF3CO2H D C6H5OH > C2H5OH > CH3CO2H > CF3CO2H
HCI Prelim 2010
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28 Compound X undergoes oxidative cleavage with hot acidified KMnO4 to give a single organic product. The organic product formed gives a yellow precipitate when heated with aqueous alkaline iodine, but does not react with sodium carbonate. Which could be the identity of Compound X?
CJC Prelim 2010
29 The carbon-‐nitrogen bond length in methylamine is longer than that in formamide.
What helps to explain the shorter carbon-‐nitrogen bond length in formamide?
A It is a sp2-‐sp2 overlap. B Formamide is a weaker base than methylamine. C The electrons in the filled p orbitals on C and N of methylamine repel each other. D The electron withdrawing C=O group in formamide draws the lone pair of electrons
CJC Prelim 2010
30 An alkane E with the molecular formula C4H10 reacts with chlorine gas in the presence
of light to form two monochlorinated alkanes F and G in the molar ratio of 9:1. What are the structures of E and F? E F A B C D
CH3CH2CH2CH3
CH3CH2CH2CH3
CH3CH(CH3)CH3
CH3CH(CH3)CH3
CH3CH2CH2CH2Cl CH3CH2CHClCH3 CH3CCl(CH3)CH3 CH3CH2CH2CH2Cl
HCI Prelim 2010
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31 Hydrocortisone is a steroid hormone produced by the adrenal gland and is released in response to stress. It is commonly used as an active ingredient in anti-‐inflammatory creams.
Which of the following statements about hydrocortisone is true? A Treated with NaBH4 in the presence of methanol, it forms a compound containing 5
hydroxy groups. B When warmed with aqueous alkaline iodine, a yellow precipitate is observed. C When treated with cold dilute KMnO4, it forms a compound containing 2 hydroxy
groups. D When treated with an excess of hot concentrated acidified KMnO4, it forms a
compound containing 7 chiral centres. CJC Prelim 2010
32 Loviride was once used as an antiviral drug in clinical trials and is structurally similar to
Compound Z.
Which reagent could be used to distinguish Loviride from Compound Z? A aqueous alkaline iodine B aqueous bromine C aqueous sodium hydroxide D hot acidified potassium manganate(VII)
CJC Prelim 2010
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33 A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Compound A below is an example of pheromones.
HO
CH3
CH3OH
Compound A
How many possible isomers, including stereoisomers, can be obtained when A is heated with excess concentrated sulfuric acid?
A 26 B 27 C 28 D 29
HCI Prelim 2010
34 Benzene undergoes Friedel-‐Crafts acylation with ethanoyl chloride to form phenyl ethanoate, which can be represented as follow:
C
O
CH3CH3COCl
AlCl3
The mechanism of the above reaction is similar to that of the bromination of benzene. Which of the following statements is not correct about the mechanism? A The organic intermediate has a ring with one sp3 hybridised carbon. B The mechanism involves CH3CO+ as an electrophile. C The overall order of reaction is 1. D AlCl3 is a homogeneous catalyst.
HCI Prelim 2010
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35 Saccharin was an artificial sweetener used in some soft drinks. It was manufactured from methylbenzene by a series of reactions.
CH3
ClSO3H
I
CH3
SO2Cl
CH3
SO2NH2 SO2
NC
OH
II
NH3
Which of the following shows the correct reaction type for steps I and II? I II A B C D
electrophilic substitution electrophilic substitution nucleophilic substitution nucleophilic substitution
electrophilic addition nucleophilic substitution electrophilic substitution nucleophilic addition
HCI Prelim 2010
36 The following compound is tested with two reagents separately.
OH
C
C
O
H
O CH3 What are the expected observations? Warm with Fehling’s reagent Warm with Tollens’ reagent A B C D
Brick-‐red precipitate No precipitate
Brick-‐red precipitate No precipitate
Silver mirror Silver mirror
No silver mirror No silver mirror
HCI Prelim 2010
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37 1 mole of an organic compound X reacts with 1 mole of NaOH. 1 mole of X also reacts with PCl5 to produce 1 mole of hydrogen chloride. Which compound could be X?
A C
B D HCI Prelim 2010
38 Paracetamol is a common analgesic used in the treatment of fever and headaches.
HO
N
H
CCH3
O
paracetamol Which deduction about paracetamol can be made from this structure? A It is a planar molecule. B It contains an amine group. C It reacts with sodium metal. D It gives an orange precipitate with 2,4-‐dinitrophenylhydrazine.
HCI Prelim 2010
39 The same product is obtained when separate samples of P and Q are respectively heated in a sealed tube with ammonia and reacted with lithium aluminium hydride in dry ether. Which are the structures of P and Q? P Q A B C D
C6H5Br CH3CH(Br)CH3
CH3CH2CH2Br CH3CH(Br)CH3
C6H5CN CH3CH(CN)CH3
CH3CH2CN CH3CH2CN
HCI Prelim 2010
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40 The reaction scheme below shows the synthesis of compound S.
CH3
Cl Br
NaOH(aq)
heat
K2Cr2O7/H2SO4(aq)
heatS
Which of the following can be S?
A
CH3
Cl O
C
C OH
CC
OH O
O
CH3O
OH
B
CH3
OH O
D
COH
OHCC
Cl OO
HO
O
HCI Prelim 2010
41 Estragole is an organic compound found in the essential oils of various plants. It can be synthesised from chavicol, a compound used in perfumes.
OCH3
estragole
OH
chavicol Which of the following reagents and conditions can be used to carry out the above conversion? A NaOH, followed by CH3OH C NaOH, followed by CH3Br B Na2CO3, followed by CH3I D Na2CO3, followed by CH3OH
IJC Prelim 2010
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42 Carbonyl compounds undergo condensation reactions with 2,4 dinitrophenylhydrazine as shown in the equation below.
Which pair of compounds could be used to form the compound shown below?
CH3C
N N C
CH3
A C6H5(CH3)C=NH and C6H5(CH3)C=NH B C6H5CHO and C6H5(CH3)C=NNH2
C C6H5COCH3 and H2NNH2
D C6H5COCH3 and C6H5(CH3)C=NH
IJC Prelim 2010
43 The antibiotic chlortetracycline is commonly used to treat conjunctivitis in cats. It has the formula shown.
O
O
OOH
OH OH
HON Cl
OH
H2N
H H
How many stereoisomers are possible for chlortetracycline? A 24 C 26 B 25 D 27
IJC Prelim 2010
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44 What is the number of sp2 and sp3 carbon atoms in the structure given below?
C C C
O
CH3
H H
H
H
sp2 sp3 A B C D
7 1 4 3
3 3 6 7
IJC Prelim 2010
45 A new industrial preparation of ethyl ethanoate has been developed using cheap sources of ethanol.
CH3CH2OH CH3CHOCu catalyst
- H2
Cu catalyst
+ CH3CH2OHCH3CH(OH)OCH2CH3
CH3CO2CH2CH3
Cu catalyst - H2
Which process is involved at some stage in this reaction sequence? A disproportionation C nucleophilic addition B electrophilic addition D reduction
IJC Prelim 2010
46 A certain organic compound reacts vigorously with water to give an acidic solution which instantly yields a precipitate of silver bromide when treated with aqueous silver nitrate. What could be the compound? A BrCH2CH2COOH C CH3CH2COBr B C6H5Br D CH3CH(OH)CH2Br
IJC Prelim 2010
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47 Concentrated sulfuric acid is often used in organic reactions as a strong acid, dehydrating agent, catalyst or oxidising agent. In which of the following reactions is concentrated sulfuric acid not acting in one of the above functions?
A CH3CH2OH C2H4conc. H2SO4
+ H2O
B CH3CH2OHconc. H2SO4
CH3CO2CH2CH3 + H2O+ CH3COOH
C
C2H4 + H2SO4 C C
H
H
H
H
H
OSO3H
D IJC Prelim 2010 48 Chlorofluroalkanes, commonly known as CFCs, undergo homolytic fission in the
presence of ultraviolet radiation in the stratosphere. Which radical is likely to be produced from the radiation on CHFClCF2Cl?
A CHFCF2Cl C CHClCF2Cl
B CHFClCFCl D CFClCF2Cl IJC Prelim 2010 49 In the tertiary structure of a water-‐soluble globular protein extracted from barley
grains, it was found that the types of amino acid residues present on the outer surface of the protein were different from those present on the inside. Which of the following amino acids is most likely to be incorporated into the outer surface of such proteins?
A
N C
H
H
H
COOH
CH(CH3)2 C
N C
H
H
H
COOH
CH2SH
B
N C
H
H
H
COOH
CH2COOH D
N C
H
H
H
COOH
H
IJC Prelim 2010
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50 When ethene reacts with HBr in the presence of aqueous NaNO3, what are the two possible products formed?
A
C C
H
H
Br
H
H
Br
C C
H
H
Br
H
H
OH
and
B
C C
H
H
H
H
H
Br
C C
H
H
Br
H
H
ONO2
and
C
C C
H
H
H
H
H
Br
C C
H
H
H
H
H
OH
and
D
C C
H
H
Br
H
H
OH
C C
H
H
H
H
H
ONO2
and
IJC Prelim 2010
51 The psychoactive drug in cannabis has the following structure.
H3C
C CH2H3C
HO
OH
Which statement about the above molecule is incorrect? A Effervescence is observed when heated with purple potassium permanganate (VII). B It has 8 stereoisomers. C It produces 5 moles of HBr when reacted with aqueous bromine under room
temperature. D The solubility of the compound increases in aqueous NaOH.
IJC Prelim 2010
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52 Glutamic acid has a pKa value of 4.3 and residues of this amino acid are present in the β-‐chains of haemoglobin.
Which of the following structures shows glutamic acid residue in its most stable state when a sample of haemoglobin is hydrolysed and the solution is subsequently adjusted to pH=7?
A C
B D
IJC Prelim 2010
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53 2,2-‐dimethylbutane was reacted with limited chlorine in the presence of UV light.
Assuming that only mono-‐chlorination takes place, what is the ratio of the products obtained? 1-‐chloro-‐2,2-‐
dimethylbutane 3-‐chloro-‐2,2-‐
dimethylbutane 1-‐chloro-‐3,3-‐
dimethylbutane A B C D
3 3 9 9
3 2 2 2
3 3 3 2
MJC Prelim 2010
54 A nitrile Q is treated with LiAlH4 to give a compound of the formula C2H7N.
In a separate reaction, Q was hydrolysed in acidic medium. What would be formed if the products from these two reactions were mixed together? A CH3CONHCH2CH3
B CH3CH2CONHCH2CH3
C (CH3CO2−)(CH3CH2NH3+)
D (CH3CH2CO2−)(CH3CH2NH3+)
MJC Prelim 2010
55 Which method is able to separate benzene from a mixture of benzene, methylbenzene and phenol? A shaking the mixture with aqueous Br2 B shaking the mixture with hot ethanoic acid and concentrated H2SO4
C shaking the mixture with hot concentrated HNO3 and concentrated H2SO4
D shaking the mixture with hot acidified KMnO4, followed by excess dilute NaOH
MJC Prelim 2010
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56 Which of the following shows a correct mechanistic step in the reaction between the stated reagents? Reagents Step A
chloropropane and ethanolic sodium hydroxide, heat
B propanal and hydrogen cyanide, trace amount of sodium hydroxide, cold
C benzene and chlorine in presence of iron catalyst
D propene and bromine monochloride in tetrachloromethane
MJC Prelim 2010 57 A new industrial preparation of propyl propanoate has been developed using cheap
sources of propanol.
Which process is involved at some stage in this reaction sequence?
A Disproportionation B Electrophilic Addition C Nucleophilic Addition D Reduction MJC Prelim 2010
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58 . Which statement about Pravastatin is likely to be correct?
A It reacts with only 3 moles of phosphorus pentachloride at room temperature and pressure.
B It reacts with only 3 moles of hydrogen gas in the presence of nickel catalyst and heat.
C It reacts with acidified potassium manganate(VII) under reflux to form one organic product.
D It reacts with liquid bromine in tetrachloromethane to form a compound with 12 chiral centres.
MJC Prelim 2010
59 Which of the following is arranged in decreasing order of solubility in water?
A sodium propanoate, propanoic acid, propanol, propanal B sodium propanoate, propanoic acid, propanal, propanol C propanoic acid, propanol, propanal, sodium propanoate D propanal, propanol, propanoic acid, sodium propanoate
MJC Prelim 2010
60 What is the correct order of increasing pKa for the following compounds?
A E, F, H, G
B G, E, F, H C G, F, E, H
D H, F, E, G MJC Prelim 2010
Pravastatin
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61 Deuterium, D, is an isotope of hydrogen, 21 .H Which reaction will not yield a stable organic compound containing deuterium?
A
B
C
D MJC Prelim 2010
62 Which reagent will give a visible observation when it is added to compound K?
Compound K
A hot alkaline iodine B hot hydrochloric acid C aqueous sodium hydrogencarbonate D hot acidified potassium dichromate(VI)
MJC Prelim 2010
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63 A polypeptide was digested using two different enzymes. The fragments obtained were separated using electrophoresis. Analysis of the fragments from each digestion gave the following results: Digestion using enzyme N: Digestion using the enzyme O:
thr-‐phe-‐leu val-‐asp-‐cys-‐thr cys-‐glu-‐val phe-‐leu-‐ser ser-‐glu-‐cys glu-‐cys asp-‐cys cys-‐glu What is the correct sequence of the polypeptide structure?
A cys-‐glu-‐val-‐ser-‐glu-‐cys-‐asp-‐cys-‐thr-‐phe-‐leu B cys-‐glu-‐val-‐asp-‐cys-‐thr-‐phe-‐leu-‐ser-‐glu-‐cys C glu-‐cys-‐glu-‐val-‐asp-‐cys-‐thr-‐phe-‐leu-‐ser-‐glu D ser-‐glu-‐cys-‐glu-‐val-‐asp-‐cys-‐thr-‐phe-‐leu-‐ser MJC Prelim 2010
64 Which of the following statements about the molecule shown below is correct?
A It can exist as geometric isomers. B It reacts with 3 moles of hydrogen bromide. C It undergoes nucleophilic addition reactions. D It reacts with acidified potassium dichromate(VI). NJC Prelim 2010
65 The structure of cortisone is shown below.
When it is completely reacted with lithium aluminum hydride with ether at room temperature, how many chiral centres does the product molecule possess? A 7 B 8 C 9 D 10
NJC Prelim 2010
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66 The following are the likely products when 2-‐bromo-‐2-‐methylbutane reacts with ethanolic potassium hydroxide except A 2-‐methylbut-‐1-‐ene B 1-‐methylbutan-‐2-‐ol C 2-‐methylbutan-‐2-‐ol D 2-‐methylbut-‐2-‐ene NJC Prelim 2010
67 The Williamson’s ether synthesis involves a nucleophilic substitution of an organic
halogen compound. Which of the following reagents can be used for the synthesis of methoxyethane, CH3CH2OCH3 starting from bromoethane? A sodium hydroxide in methanol B sodium with methanol C potassium ethoxide D methanol NJC Prelim 2010
68 The reaction of ethanol with sulfuric acid is shown in the scheme below:
Which of the following is not true of the above scheme? A Concentrated phosphoric acid can be used in place of concentrated sulfuric acid in
reaction I. B This reaction always yields a mixture of the two products. C Reactions I and III involve the same mechanism. D Reaction II shows the elimination of water.
NJC Prelim 2010
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69 Which of the following cannot be used to distinguish between the following compounds?
O CHOHOO
A Hot acidified K2Cr2O7
B Neutral iron(III) chloride C Silver diammine complex D 2,4-‐dinitrophenylhydrazine NJC Prelim 2010
70 A student treated benzene in a 3-‐step reaction to yield N–phenyethanamide,
NHCOCH3
Which of the following gives the correct sequence? Step 1 Step 2 Step 3 A B C D
Ethanolic potassium cyanide Conc H2SO4 and conc HNO3 Conc H2SO4 and conc HNO3 Chlorine in presence of FeCl3
Sn, conc HCl LiAlH4 in dry ether
Zn, conc HCl Ethanolic ammonia
Propanone Ethanoyl chloride Ethanoyl chloride Ethanoyl chloride
NJC Prelim 2010
71 Which of the following shows the correct order of increasing base strength?
NJC Prelim 2010
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72 Which of the following is the least likely reaction of compound X?
NJC Prelim 2010
73 Anhydrides are acid derivatives which can be considered to be formed from the
dehydration of acids. The chemistry of the acid anhydrides is very similar to that of the acid chlorides, except that they are a little less reactive. The formation of benzoic anhydride is shown below:
COOH
COOH
CO
COO
Which of the following is not true for benzoic anhydride? A It reacts with ethanol. B It has little solubility in water. C It reacts with aqueous sodium hydroxide to give the sodium salt. D It gives an orange solid when reacted with 2,4-‐dinitrophenylhydrazine.
NJC Prelim 2010
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74 A carbonyl compound can be converted into an alkene by means of the Wittig reaction where a phosphorus ylide is involved as follows:
Which of the following pairs of compounds might you use to prepare the following alkene?
CH3
NJC Prelim 2010
75 As the number of carbon atoms in the homologous series of alkane molecules
increases, which property of the alkanes does the numerical value decrease? A density B enthalpy change of vaporisation
C number of isomers D vapour pressure
NYJC Prelim 2010
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76 A compound has the following structural formula:
SO3H
CO2CH3 What is the shape of the molecule with respect to the S atom and how many p electrons are present in one molecule of the compound? shape Π A B C D
trigonal bipyramidal tetrahedral
trigonal bipyramidal tetrahedral
10 10 12 12
NYJC Prelim 2010
77 The drug cortisone has the formula shown below.
O
O
COOH
CH2OH
How many chiral centres are present when cortisone is treated with cold acidified KMnO4(aq)? A 5 B 6 C 7 D 8
NYJC Prelim 2010
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78 Oxidation of an alkene X gives a diol; further oxidation gives a diketone. Which one of the following could be X? A (CH3)2C=C(CH3)2 B CH3CH=C(CH3)2 C C6H5CH=CHC6H5
D (C6H5)2C=CH2 NYJC Prelim 2010
79 Compound B is formed from compound A in the presence of AlCl3.
O
CH2Cl
O CH3
+ AlCl3
Compound A Compound B What is the mechanism of the above reaction? A electrophilic addition
B electrophilic substitution
C nucleophilic substitution
D nucleophilic addition NYJC Prelim 2010
80 Which reagent gives a colourless homogeneous solution when added to phenol? A aqueous bromine B aqueous sodium carbonate C aqueous sodium hydroxide D neutral aqueous iron(III) chloride NYJC Prelim 2010
81 The following molecule CH3CH2CH(COCl)CH(CH3)OCOH is subjected to heating with
alkali. What are the products of this reaction? A CH3CH2CH(CO2
-‐)CH(CH3)OH + CO32-‐
B CH3CH2CH(CO2H)CH(CH3)O-‐ + HCO2-‐
C CH3CH2CH(CO2-‐) CH(CH3)OH + HCO2
-‐ D CH3CH2CH(CO2H)CH(CH3)OH + CO3
2-‐ NYJC Prelim 2010
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82 In which sequence is it correctly stated that the value of pKa decreases continuously?
A
OHOHCOOH
H2N
COOH
O2N
B
OHOHCOOH
H2N
COOH
O2N
C NC CH3O
OH OH COOH COOH
D CH3O NC
OH COOH OH COOH
NYJC Prelim 2010 83 Which of the following compounds is least soluble in water?
A CH3CH(NH2)COOH
B C6H5CH(OH)CH3
C C6H5CH2N(CH3)2 D C6H5CO2Na NYJC Prelim 2010
84 In a beehive, the queen bee secretes the substance below to cause worker bees to
begin constructing royal colony cells.
CH3CO(CH2)5CH=CHCO2H queen bee substance
From the structure shown, which one of the following statements about the queen bee substance is correct? A It gives a positive test with an aqueous solution containing Ag(NH3)2+ B It gives an orange precipitate with alkaline aqueous iodine. C It gives fumes of HCl gas with PCl5. D Reaction with hydrogen over a catalyst produces CH3CH(OH)(CH2)8OH.
NYJC Prelim 2010
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85 Maytansine is a potent antitumour agent. How many chiral centres are present in the product of the reaction between Maytansine and Br2 in CCl4 in the dark?
Cl
CH3O
N
OCH3
O
OOH
N
O O
O
N
OO
Maytansine
A 8 C 12 B 10 D 14 RJC Prelim 2010
86 How many H atoms are in the same plane as Ha in the following molecule?
C C CH
Ha H
H A 0 C 2 B 1 D 3
RJC Prelim 2010
87 Arrange the following compounds in order of decreasing Kb.
CH3 C
O
NN
HI II III IV
NH2CH3CH2 NH2
A I, IV, III, II C II, IV, III, I B I, III, IV, II D II, III, IV, I
RJC Prelim 2010
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88 In which of the following pairs does reaction I take place more rapidly than reaction II?
A
CH3CH2CH2Br + CH3S− CH3CH2CH2SCH3 + Br−
CH3CH2CH2Br + CH3SH CH3CH2CH2SCH3 + HBr
I
II
B
(CH3)3CCl + H2O (CH3)3COH + HCl
(CH3)3CBr + H2O (CH3)3COH + HBr
I
II
C
(CH3)3CCl (1 mol dm−3) + CH3CH2O− (2 mol dm−3)
(CH3)3COCH2CH3 + Cl−I
(CH3)3CCl (1 mol dm−3) + CH3CH2O− (1 mol dm−3)
(CH3)3COCH2CH3 + Cl−II
D (CH3)3CCl + H2O (CH3)3COH + HCl
C6H5Cl + H2O C6H5OH + HClI
II RJC Prelim 2010
89 A chloroalkane W with molecular formula of C5H11Cl exhibits optical activity. On
warming W with alcoholic NaOH, two alkenes X and Y are formed, X being the major product. One of the products of the reaction between X and hot acidified potassium manganate(VII) gives a yellow precipitate with alkaline aqueous iodine. Which of the following could be W? A CH3CHClCH2CH2CH3 C CH3CH(CH3)CHClCH3 B CH3CH2CHClCH2CH3 D CH3CCl(CH3)CH2CH3 RJC Prelim 2010
90 An organic compound has the following properties:
(i) It gives a yellow precipitate with alkaline aqueous iodine solution. (ii) It gives an orange precipitate with 2,4-‐dinitrophenylhydrazine. (iii) It forms a brick-‐red precipitate with Fehling’s solution. Which compound could give these results?
A CH3COCH2C(OH)(CH3)CH2CHO
B CH3COCH=CHCH(CH3)CO2H
C CH3COCH2COCH2CH3
D CH3COCH2C6H4CHO RJC Prelim 2010
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91 Which of the following can be used to distinguish between the following two compounds?
O
OH O
O
OH O
CH2=CH
A hot acidified K2Cr2O7
B hot acidified KMnO4
C neutral FeCl3(aq)
D Br2(aq) RJC Prelim 2010 92 Consider the reaction between butanone and hydrogen cyanide in which the enthalpy
change of the reaction is near zero. Which one of the following statements is incorrect?
A The reaction is catalysed by a small amount of base. B The slow step involves the formation of a C−C bond. C The Gibbs free energy of the reaction is positive at high temperatures. D The reaction between butanal and hydrogen cyanide is slower than the reaction
between butanone and hydrogen cyanide. RJC Prelim 2010
93 How many stereoisomers are possible for the following compound?
A 0 C 4 B 2 D 8
SAJC Prelim 2010
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94 What is the structure of Q in the following reaction scheme?
CCH3 CH3
CH3
HOCH2CH2 COCH3
KMnO4 / aq H2SO4heat
SOCl2P Q
A
C
C C
O
Cl
O
Cl
ClO
C
CCH3 CH3
CH3
C C
O
Cl
O
Cl
B
C
C C
O
CH3
O
Cl
ClO
D
CCH3 CH3
CH3
CH2 C
O
ClCCl
O
RJC Prelim 2010 95 The Russian composer Borodin was also a research chemist who discovered a reaction
in which two ethanal molecules combine to form a compound commonly known as aldol (reaction I). Aldol forms another compound on heating (reaction II). I 2CH3CHO → CH3CH(OH)CH2CHO II CH3CH(OH)CH2CHO → CH3CH=CHCHO + H2O Which one of the following would be produced when acetone, CH3COCH3 undergoes the same reactions? A CH3CH=CHCOCH3 C CH3COCH=C(CH3)2 B C(CH3)2=CHCHO D CH3CH=CHCH3
SAJC Prelim 2010
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96 A key molecule in the chemistry of vision is the highly conjugated rhodopsin, which is synthesised in the rod cells of the eye from 11-‐cis-‐retinal and a primary amine in the protein opsin.
H O
NH2 opsin
H N opsin
rhodopsin11-cis-retinal Which of the following statements is correct? A 1 mole of 11-‐cis-‐retinal reacts with 5 moles of hydrogen gas. B The reaction between 11-‐cis-‐retinal and NH2-‐opsin is a condensation reaction. C The reaction of 11-‐cis-‐retinal with LiAlH4 produces a product that is optically active. D The reaction between 11-‐cis-‐retinal with hot acidified potassium manganate(VII)
produces a total of five different organic products.
RJC Prelim 2010 97 Which sequence shows the compounds in increasing order of pKa values?
OH
CH3CH2
I
OH
CH3NH
II
OH
F
III
OH
IV A I, II, III, IV C II, I, III, IV B IV, II, III, I D III, IV, I, II
SAJC Prelim 2010
98 Which of the following compounds, on complete oxidation with hot acidified potassium manganate(VII), would give two organic compounds? A (CH3)2C=CHCH2CH2CH=CH2 C CH3(CH2)2CH=CH(CH2)2CH3 B CH3(CH2)4CH=CHCH2OH D C6H5CH2CH3
SAJC Prelim 2010
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99 Aspartame, a non-‐nutritive sweetener marketed under the trade name NutraSweet, is the methyl ester of a simple dipeptide, Asp−Phe−OCH3. The structures of Asp and Phe are shown as follows:
H2N C
CH2COOH
H
COOH
H2N C
CH2
H
COOH
Asp Phe
The isoelectric point of aspartame is 5.9. Which of the following is the predominant species present in an aqueous solution at physiological pH 7.3?
A
H3N C
CH2
H
C
O
NH C
H
COOCH3CH2
COO−
B
H2N C
CH2
H
C
O
NH C
HCOO−
CH2COOCH3
C
H3N C
CH2
H
C
O
NH C
HCOO−
CH2COOCH3
D
H2N C
CH2
H
C
O
NH C
H
COOCH3CH2
COO−
RJC Prelim 2010
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100 The structures of some amino acids are shown below:
glutamic acid
H2N C
(CH2)2
H
COOH
COOH lysine
H2N C
(CH2)4
H
COOH
NH2 phenylalanine
H2N C
CH2
H
COOH
serine
H2N C
CH2OH
H
COOH
valine
H2N C
CH
H
COOH
CH3 CH3 Which of the following pairs of amino acids are likely to be found on the outside of a globular protein, and which on the inside? on the outside on the inside A glutamic acid and lysine valine and phenylalanine B valine and phenylalanine glutamic acid and lysine C serine and lysine valine and glutamic acid D glutamic acid and valine phenylalanine and serine
RJC Prelim 2010
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101 A hexapeptide gave the following peptide residues upon partial hydrolysis: Val-‐His, Leu-‐Ala, Val-‐Phe, His-‐Val and Phe-‐Leu. What is the structure of the hexapeptide? A Val-‐His-‐Val-‐Phe-‐Leu-‐Ala C Phe-‐Leu-‐Ala -‐His-‐Val-‐Phe B Ala-‐Leu-‐Phe-‐Val-‐His-‐Val D His-‐Val-‐Phe-‐Leu-‐Ala-‐Val
SAJC Prelim 2010 102 A compound U has all the following properties.
-‐ It reacts with aqueous Na2CO3 -‐ It gives a brick red precipitate with Fehling’s solution. -‐ It gives a green colouration with hot acidified K2Cr2O7. What could U be?
A C
B D
SAJC Prelim 2010 103 Which of the following organic compounds would give a yellow precipitate on heating
with aqueous alkaline iodine?
A C
B D
SAJC Prelim 2010
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104 The structure of Q is as shown:
What would be formed by prolonged boiling of Q with aqueous sodium hydroxide?
A C
B D SAJC Prelim 2010
105 The two-‐stage reaction sequence given below shows a possible mechanism for the
reaction between hydroxide ion and an organic compound:
The overall reaction should be classified as A Electrophilic addition C Nucleophilic addition B Electrophilic substitution D Nucleophilic substitution SAJC Prelim 2010
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106 Which of the following synthetic routes does not produce ethanoic acid?
A CH3CH(OH)CH3
aqueous alkaline iodineheat
H+
r.t.p.
B CH3CH(OH)CH2CH3
acidic K2Cr2O7heat
excess conc H2SO4180oC
C CH3Br
alcoholic KCNreflux
dil HClheat
D CH3CHO
[Ag(NH3)2]+
heatH+
r.t.p. TJC Prelim 2010
107 What reagent can be used to distinguish between the following isomers?
NH2
CO2H
CONH2
OH
A Aqueous NaOH, heat B Na metal, room temperature and pressure C Aqueous bromine, room temperature and pressure D LiAlH4, dry ether, room temperature and pressure TJC Prelim 2010
108 Compound X shows the following chemical properties.
I) It does not give any observation with Fehling’s solution. II) 1 mole of compound X reacts with 2 moles of sodium metal. III) When PCl5(s) is added to compound X, a sweet smelling product is obtained. Which of the following structures can compound X be? A HO2CCH2CH2CH2CO2H
B HO2CCH2CH2CH2CHO
C
CH2CH2OH
OH
CH
O
D
CH2CO2H
OH
CH
O
TJC Prelim 2010
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109 The uncatalysed addition of HCN to a carbonyl group to give a cyanohydrin proceeds by two steps.
H3CH2C CO
H:CN + H3CH2C C
CN
H
O-
H3CH2C C
CN
H
O:- + H H3CH2C C
CN
H
OH :CN+
Step I
Step II
δ+
δ-
CN
-
-
The rate equation for the formation of cyanohydrin is as follows. Rate = k[CH3CH2CHO][CN-‐] Which of the following statements is correct? A Step II is rate determining. B The reaction will proceed slower if small amount of NaOH is added. C A same product can be obtained by refluxing 1-‐chloropropan-‐1-‐ol with HCN. D The uncatalysed addition of HCN to propanone occurs at slower rate than that for
propanal. TJC Prelim 2010
110 Which of the following shows the correct order of increasing acidity?
A
B
C
D
TJC Prelim 2010
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111 1,2-‐dibromo-‐3-‐chloropropane (DBCP) has been used in the control of earthworms in agricultural land. Which of the following would be the best synthesis of this compound?
A CH3CH2CH2Cl + 2Br2 → DBCP + 2HBr B CH2BrCHBrCH3 + Cl2 → DBCP + HCl C ClCH2CH=CH2 + PBr5 → DBCP + PBr3 D CH2=CHCH2Cl + Br2 → DBCP TJC Prelim 2010
112 α-‐Cadinene is present in the oil derived from the plant juniper woods. X is the major
compound when α-‐Cadinene is reacted with HBr in CCl4. How many chiral carbons does X have?
CH3
H3C
H3C CH3
HBr/ CCl4Major product X
A 3 C 5 B 4 D 6
TJC Prelim 2010 113 The structure of the alkaloid ephedrine is shown below.
C
OH
H
C
CH3
H
NH
CH3 Which of the following will be properties of the alkaloid? A It reacts with excess concentrated H2SO4 at 180°C to give a chiral product. B It gives a violet complex with neutral FeCl3. C When warmed with acidic KMnO4, its product gives a silver mirror with Tollen’s
reagent. D 0.2 mol of ephedrine reacts with 0.1 mol of HCl(aq) to give a buffer solution.
TJC Prelim 2010
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114 Four drops of 1-‐chorobutane, 1-‐bromobutane and 1-‐iodobutane were put separately into three test-‐tubes containing 1.0 cm3 of aqueous silver nitrate at 60°C.
A hydrolysis reaction occurred. (R represents the butane chain C4H9 – and X the halogen atom.)
H2O(l) + R–X(l) + Ag+(aq) → R–OH(aq) + AgX(s) + H+(aq) The rate of formation of cloudiness in the tubes was in the order RCl < RBr < RI. Why is this? A The R-‐X bond polarity decreases from RCl to RI. B The solubility of AgX(s) decreases from AgCl to AgI. C The ionisation energy of the halogen decreases from Cl to I. D The bond energy of R-‐X decreases from RCl to RI.
TJC Prelim 2010 115 Ethanol reacts explosively with sodium metal to form a salt, sodium ethoxide. What is
the product of the reaction between 2-‐iodobutane and sodium ethoxide? A CH3CH=CHCH3
B (CH3)2CHCH2OCH2CH3
C CH3CH2CH(OCH3)CH2CH3
D CH3CH2CH(CH3)OCH2CH3 TJC Prelim 2010 116 β-‐Caryophyllene is an odiferous sesquiterpene used by the cotton plant to attract
the male cotton boll weevil. CH3
CH2CH3CH3
β-Caryophyl lene X is the major product formed when β-‐caryophyllene is reacted with HBr in CCl4. How many stereoisomers does X have? A 4 C 16 B 8 D 32
VJC Prelim 2010
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117 An alkyne (C≡C) undergoes hydration in a similar mechanism as an alkene. However, the formation of enol (C=C-‐OH) is unstable and would undergo rearrangement to form a carbonyl compound.
C CR Hhydration
C CR H
OH Hrearrangement
C CR H
O H
H Which compound will not be formed when the following alkynes undergo hydration?
A
B
C
D
VJC Prelim 2010
118 Which statement best describes the reaction mechanism involved in the single step conversion of chloroethane to ethanol?
A The reaction involves removal of HCl, followed by the addition of H2O. B The reaction involves heterolytic fission of the C–Cl bond, followed by a reaction
with H2O. C The reaction involves nucleophilic attack of OH– in a bimolecular mechanism. D The reaction mechanism involves a carbocation.
VJC Prelim 2010
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119 Which type of reaction does the following compound not undergo?
CO2HHOCH2CH2COCH2 A electrophilic addition C nucleophilic addition B electrophilic substitution D nucleophilic substitution
VJC Prelim 2010
120 Which of the following compounds react with hot acidified KMnO4 and the resultant product formed will give a positive test with both 2,4-‐dinitrophenylhydrazine and PCl5?
A C
B D
VJC Prelim 2010
121 Consider the compound Y which has the structural formula as shown.
CH=CHCH2Cl
CH2Cl
Cl
compound Y
1 mole of compound Y is warmed with excess aqueous sodium hydroxide. The resulting solution is cooled and acidified with dilute nitric acid. How many moles of silver chloride will be precipitated out when excess aqueous silver nitrate is then added?
A 0 B 1 C 2 D 3 VJC Prelim 2010
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122 Which of the following 2-‐stage processes will not yield the final product as shown?
A
B
C
D
VJC Prelim 2010
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123 A mixture is made by mixing excess aqueous sodium carbonate with phenylmethanol, phenol and methanoic acid. Which organic species is/are present in the organic layer of the solution?
A phenylmethanol C phenylmethanol and phenol B methanoic acid D phenylmethanol, phenol and methanoic acid
VJC Prelim 2010 124 Enalapril is used to treat hypertension.
CH2CH2CHCO2CH2CH3NHCH(CH3)CONH
CO2H
Enalapril Which of the following statements about Enalapril is true?
A Enalapril decolourises acidified K2Cr2O7. B Enalapril gives an orange precipitate with 2,4-‐dinitrophenylhydrazine. C One mole of Enalapril reacts with 3 moles of CH3COCl. D One mole of Enalapril reacts with 3 moles of NaOH.
VJC Prelim 2010 125 Compound M can be synthesised as shown below.
Compound MHO OH
O
MII IIII
HOCH2CH2CH=CH2 What are the reagents used for steps I, II and III? I II III A B C D
H+/KMnO4(aq) H+/KMnO4(aq)
1. concentrated H2SO4 2. H2O 1. concentrated H2SO4 2. H2O
PCl5 PCl5
NaOH(aq), I2(aq)
OH–/KMnO4(aq)
NaOH(aq) H2O
HCl(aq)
HCl(aq)
VJC Prelim 2010
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126 When equimolar amounts of organic compounds R, S, T and U are added separately to water, solutions of increasing pH values are obtained.
Which set of identities of compounds R to U is correct?
R S T U A B C D
CH3CH2CO2H CH3CH2CO2H CH3CH2COCl CH3CH2COCl
CH3CH2COCl CH3CH2COCl CH3CH2CO2H CH3CH2CO2H
CH3CH2CO2H CH3CHClCH2NH2 CH3CH2CO2H
CH3CHClCH2NH2
CH3CHClCH2NH2 CH3CH2CO2H
CH3CHClCH2NH2 CH3CH2CO2H
VJC Prelim 2010
127 Which compound decolourise brown bromine in the dark?
A
OH
NO2 C
CH3CH2NH2
B
CN
Cl D
CO2H
NH2
VJC Prelim 2010
128 Ibuprofen is a powerful painkiller.
CH2C
H
OH
C
CH3
CH3
OH
COOH
CH3
Ibuprofen
Which of the following statements about Ibuprofen is correct? A 1 mol of Ibuprofen can evolve 3 mol of H2. B 1 mol of Ibuprofen reacts with 2 mol of HCl. C The bond angle around all carbon atoms is 109.5o. D It will decolourise aqueous bromine to give a white precipitate.
PJC Prelim 2010
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129 Which of the following represents the correct sequence of increasing pKa value of the four acids?
A CCl3CO2H < CH3CO2H < C6H5OH < C2H5OH
B CCl3CO2H < CH3CO2H < C2H5OH < C6H5OH
C C6H5OH < C2H5OH < CCl3CO2H < CH3CO2H
D C6H5OH < C2H5OH < CH3CO2H < CCl3CO2H
PJC Prelim 2010
130 Which of the following pairs of protein segments has an interaction which is likely to be broken due to a change in pH?
A CH2O CH
NH
CO
and (CH2)4+NH3 CH
NH
CO
B CH2HS CH
NH
CO
and CH2HS CH
NH
CO
C CH
NH
COCH2
CH2CH2 and CO CH
NH
CO
O
D CH2 CH
NH
CO
HO and CH2 CH
NH
CO
HS
VJC Prelim 2010
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The responses A to D should be selected on the basis of
A B C D 1, 2 and 3 are correct
1 and 2 only are correct
2 and 3 only are correct
1 only is correct
131 Which of the following is a suitable chemical test to distinguish the below two
compounds?
CH3 CH3
CH3
O OCH3
OH CH3 CH3
CH3
O OCH3
OH
X Y
1. Cold dilute KMnO4 2. Hot acidified K2Cr2O7 3. Warm alkaline I2
ACJC Prelim 2010
132 Which compounds liberate ammonia when boiled with aqueous sodium hydroxide?
1. CH3CH2CN 2. CH3CH2CONH2 3. CH3CH2CO2NH4
ACJC Prelim 2010
133 Which of the following statements are true for compound A?
1. It gives a orange precipitate with 2,4-‐dinitrophenylhydrazine. 2. It gives a silver precipitate with Tollens’ reagent. 3. It undergoes esterification with phenol.
ACJC Prelim 2010
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134 Which of the following tests can be used to distinguish between the compounds W and X?
1. Na metal 2. hot aqueous AgNO3 3. hot acidified K2Cr2O7 ACJC Prelim 2010
135 A compound has a relative molecular mass of 88 and its molecule contains only four
carbon atoms. What could this compound be? 1. a primary alcohol containing a ketone group 2. a secondary alcohol containing an aldehyde group 3. a saturated non–cyclic diol AJC Prelim 2010
136 Which statements are true for an SN2 reaction? 1. One bond is broken before another bond is formed. 2. The formation of a transition state involves the collision of two molecules or ions. 3. A carbon atom in the transition state is bonded, either fully or partially, to five other
atoms. AJC Prelim 2010
137 A manufacturer needs a stronger base than methylamine, CH3NH2, to add to a
cleansing fluid. Which of the following would not be appropriate? 1. (CH3)2NH 2. CH3NH3
+Cl– 3. CH3CONH2
AJC Prelim 2010
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138 Consider the organic intermediate which will be formed in each of the reactions given below.
In which reaction does the reactive carbon atom change from being sp3 hybridised to being sp2 hybridised?
1. CH2CH3 + Cl2 in UV light
2. C(CH3)2I + NaOH (aq), heat
3. CH3 + Br2 in the presence of iron
AJC Prelim 2010
139 Saccharin is an artificial sweetening agent. It can be synthesised from methylbenzene through a series of reactions as shown.
CH3 CH3SO2Cl
CH3SO2NH2 SO2NH2
CO2H C NH
SO2
O
saccharin What types of reactions are involved in the series? 1. condensation 2. electrophilic substitution 3. nucleophilic substitution AJC Prelim 2010
140 Deuterium, D, is the 2H isotope of hydrogen.
Which of the reactions will give an organic product containing deuterium?
1.
2.
3. CJC Prelim 2010
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141 In an aldol condensation, an aldehyde loses its α hydrogen atom when a base is added. The intermediate then undergoes nucleophilic addition with another aldehyde molecule. When alcoholic potassium hydroxide is added to ethanal, the following reaction occurs:
What are the possible products when alcoholic potassium hydroxide is added to an equimolar mixture of ethanal and propanal? 1. CH3CH(OH)CH2CHO 2. CH3CH2CH(OH)CH2CHO 3. CH3CH2CH(OH)CH(CH3)CHO CJC Prelim 2010
142 Fluocortin is a glucocorticoid that is involved in the regulation of glucose metabolism.
Fluocortin is first reacted with hydrogen in the presence of a platinum catalyst to obtain a Compound Y. Which of the statements concerning Compound Y are true? 1. Oxidation of Y produces an organic compound that reacts completely with 3 mol of
2,4-‐dinitrophenylhydrazine 2. It has three chiral centres more than Fluocortin. 3. It can be distinguished from Fluocortin by using sodium carbonate.
CJC Prelim 2010
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143 Methylparaben is used as both a food preservative and a anti-‐fungal agent in cosmetics.
OH
O CH3
O
Methylparaben
Which of the statements about methylparaben are correct? 1. It is likely to be more acidic than phenol. 2. It can react with ethanoyl chloride to form an ester. 3. It can react with 2,4-‐dinitrophenylhydrazine to give an orange precipitate.
CJC Prelim 2010
144 Which of the following statements are true regarding compound Z?
1. There is only one sp hybridised carbon atom in a molecule of Z. 2. A molecule of Z contains four π bonds. 3. After Z reacts with LiAlH4, all the carbon atoms in the product formed are sp3
hybridised. HCI Prelim 2010
145 The diester R, which is used in perfumes, has the molecular formula C7H12O4. It is
found that one of the products of acid hydrolysis of R produces effervescence when heated with acidified KMnO4(aq).
Which of the following structures can be compound R? 1. CH3CO2CH2CH2OCOCH2CH3 2. CH3CH2OCOCH2CO2CH2CH3 3. CH3CO2CH2CH2CO2CH2CH3
HCI Prelim 2010
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146 Adrenaline and hydrocortisone are hormones produced by the adrenal glands.
Which of the following reagents are able to distinguish the two hormones? 1. Aqueous neutral FeCl3 2. Hot aqueous potassium dichromate(VI), K2Cr2O7(aq) 3. Aqueous bromine, Br2(aq)
HCI Prelim 2010 147 1-‐bromopropane can be converted to propanone in exactly three steps.
Which of the following reagents can be used in the conversion? 1. Aqueous NaOH 2. Ethanolic NaOH 3. Acidified KMnO4
HCI Prelim 2010 148 Consider the following reaction.
(CH3)3SiCl + CH3CH2O–Na+ (CH3)3SiOCH2CH3 + Cl–
Which of the following statements are likely to be true? 1. The reaction involves a nucleophilic attack by the ethoxide ion. 2. Chlorine is displaced by the ethoxide ion. 3. The carbon-‐oxygen bond is broken.
IJC Prelim 2010
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149 A tripeptide, cys-‐ala-‐his, was analysed using electrophoresis. The tripeptide was hydrolysed and the resulting solution was added to a buffer solution of pH 6.00 which was then placed at the centre of the plate. A potential difference was then applied across the plate.
Amino acid
cysteine (cys)
alanine (ala)
histidine (his)
Isoelectric point 5.05 6.00 7.60 With reference to the above table, which of the following statements are correct? 1. Alanine would remain at the centre of the plate. 2. Cysteine would migrate towards the anode. 3. Histidine would migrate towards the cathode.
HCI Prelim 2010
150 Lycra is a polyurethane fibre widely used in sportswear and fashion. A repeat unit of
the polymer is shown below. (The values of x and y are usually between 3 and 8.)
O C
O
N (CH2)x
H
N C
O
O (CH2)y
H
n What are the organic products formed when Lycra is heated with aqueous NaOH?
1. HO C
O
N (CH2)x
H
N C
O
OH
H
2. HO (CH2)y OH
3. H N (CH2)x
H
N H
H
IJC Prelim 2010
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151 Tert-‐butyl-‐bromide can form a Grignard reagent by reacting with magnesium metal.
Because magnesium is more electropositive than carbon, the carbon-‐magnesium is polarised Cδ––Mg δ+.
The Grignard reagent can subsequently react with water as shown in reaction I.
Which of the following statements are correct? 1. Reaction I is an acid-‐base reaction. 2. The product of reaction I is (CH3)3CH. 3. Carbonyl compounds react with Grignard reagents via nucleophilic addition.
IJC Prelim 2010
152 For the following reaction:
(CH3)3CSO2Cl + CH3CH2OH → (CH3)3CSO3CH2CH3 + HCl Which statements are likely to be true?
1. The C−O bond is not broken. 2. Cl− is displaced by CH3CH2O−. 3. The reaction involves a nucleophile.
MJC Prelim 2010
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153 α-‐aminobutyric acid and γ-‐aminobutyric acid are isomers.
α-‐aminobutyric acid γ-‐aminobutyric acid
Which statements are true? 1. Both are soluble in water. 2. Both can form zwitterions. 3. Both can be obtained from the hydrolysis of protein. MJC Prelim 2010
154 The Grignard reaction is a very important tool in organic reactions involving the formation of carbon-‐carbon bond. Grignard reagents are formed by reacting halogenoalkane, R-‐X, with magnesium in dry ether. For example, reaction of CH3Cl with Mg,
Grignard reagents allow the carbon chain of carbonyl compounds to be lengthened. For example,
Which compounds could be made from a ketone and a Grignard reagent? 1. CH3C(CH2CH3)2OH 2. CH3CH2CH2CH2OH 3. (CH3CH2)2CHOH
MJC Prelim 2010
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155 Salicylic acid is an important compound in its medicinal and cosmetic uses.
COOH
OH Salicylic acid
Which compounds give salicylic acid on acid hydrolysis?
1.
2.
3. MJC Prelim 2010
156 The rod cells in the retina at the back of the eye contain an alcohol called retinol which is responsible for their sensitivity to light. Retinol is oxidised by an enzyme-‐catalysed reaction to retinal with the following structure:
O
Which of the following statements about retinal are correct? 1. The molecular formula of retinal is C20H28O. 2. It can react with NH2OH.
3. The structure of its cis isomer is O NJC Prelim 2010
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157 The French chemist, Eugene Peligot, discovered that Group II salts of carboxylic acids on heating decompose to give a metal carbonate and a carbonyl compound. An example of such decomposition is as shown:
(RCOO)2Ca → CaCO3 + R2CO
The likely products(s) obtained when a mixture of calcium ethanoate and calcium methanoate is heated are: 1. CH3COCH3 2. CH3CHO 3. HCHO NJC Prelim 2010
158 Which mixtures, on heating, produce an alkaline gas containing deuterium, D?
1. CH3CH2CONHCH3 and NaOD in D2O 2. (ND2H2)2SO4 and NaOD in D2O 3. C6H5CH2CN and DCl in D2O NJC Prelim 2010
159 Compound A was used in the following synthetic route.
Which statement is true regarding the synthetic route? 1. There are 3 sp3, 6 sp2 and 1 sp hybridized carbon atoms in Compound B. 2. The synthetic route involves addition and reduction reactions. 3. Compound B is optically active.
NJC Prelim 2010
160 Which of the following reagents will convert nitrobenzene to phenylamine? 1. tin, concentrated hydrochloric acid, followed by aqueous sodium hydroxide 2. hydrogen, nickel catalyst 3. lithium aluminium hydride in dry ether
NYJC Prelim 2010
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161 Which of the following pairs illustrate geometric isomerism?
1.
2.
3.
NYJC Prelim 2010
162 Salicylic acid is prepared from the Kolbe-‐Schmitt process. In one of the steps, the phenoxide ion reacts with the weak electrophile, carbon dioxide, to give sodium salicylate as a product.
OH
CO2Na
sodium salicylate
Which of the following statements are correct? 1. The phenoxide ion is more reactive towards electrophilic attack than phenol. 2. The phenoxide ion undergoes an electrophilic substitution mechanism. 3. A hydroxyl group makes the benzene ring less susceptible to electrophilic attack.
NYJC Prelim 2010
CC
Br
H
CH3CH2
CH3
CC
CH3
CH2CH3
Br
H
CC
Br
H
H
CH3
CC
Br
CH3
H
H
CC
Br
H
H
CH3
CC
H
CH3
Br
H
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163 Which of the following reacts with aqueous bromine to give an organic molecule containing three bromine atoms?
1.
2.
3. NYJC Prelim 2010
164 The structures and pKa values of fumaric acid and maleic acid are given below:
pKa1 pKa2
H
HOOC H
COOH fumaric acid
3.0 4.5
H
HOOC COOH
H maleic acid
1.9 ?
Which of the following statements are correct? 1. Maleic acid has a lower boiling point than fumaric acid as it can form intra-‐molecular
hydrogen bonding. 2. pKa2 of maleic acid is larger than that of fumaric acid because the acidic hydrogen
atom in maleic acid can be stabilised by intra-‐molecular hydrogen bonding, hence making it more difficult to remove.
3. For each acid, pKa2 is larger than pKa1 because it is easier to remove a second proton from the conjugate base formed in the first ionisation. RJC Prelim 2010
NH2
NH2
CH3
NO2
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165 Which products are formed when phenyl propanoate undergoes acidic hydrolysis in the presence of water labeled with the 18O isotope?
1. CH3 CH2CO18OH 2. C6H5
18OH 3. C6H5CO18OH
RJC Prelim 2010 166 Consider the following reaction scheme.
CH3CH2SH + CH3O− CH3CH2S− + CH3OHI
CH3CH2S− + CH2 CH2
OCH3CH2SCH2CH2O−
CH3CH2SCH2CH2O− + H2O CH3CH2SCH2CH2OH + OH−
II
III
Which of the following types of reactions are shown in reactions I, II and III? 1. oxidation 2. nucleophilic substitution 3. neutralisation
RJC Prelim 2010 167 Which of the following pairs of reagents will give a water-‐soluble organic product
when reacted together? 1. CH3CH2COOH and LiAlH4 2. CH3CH2COOH and CH3CH2NH2 3. CH3CH2COCl and (CH3CH2)2NH
RVHS Prelim 2010 168 Which statements about the following reaction sequence are correct?
C C
H
H
H
HBr2 in CCl4 excess conc NH3
in sealed tube
X Y ZCu2+(aq)
I II III
1. Compound X is 1,2-‐dibromoethane 2. Step II involves nucleophilic substitution 3. Step III involves ligand exchange TJC Prelim 2010
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169 Propanone and hydrazine can react to form hydrazine derivatives as shown below:
C
H3C
H3CO + NH2NH2 C
H3C
H3CNNH2 + H2O
The reaction involves addition reaction, followed by elimination. Which of the following are possible steps in the reaction?
1. C
H3C
H3CO + NH2NH2 C
H3C
H3CO H + NH2NH-
2.
C
H3C
H3CO + NH2NH2 C
H3C
H3C
O
NH2NH2
3. C
H3C
H3C
O
NH2NH2C
H3C
H3C
OH
NHNH2
TJC Prelim 2010 170 Which of the following reactions give products that do not rotate the plane of
polarised light? 1. Propene reacted with bromine dissolved in organic solvent. 2. Ethanal reacted with HCN, trace NaOH, 10 – 20°C 3. 3-‐chloro-‐3-‐methylhexane refluxed with aqueous KOH. TJC Prelim 2010
171 When a compound W was heated in the tube containing reagent X, a colour change was observed in the tube. A precipitate was noted when reagent Y was heated with the products from reaction of W and X. Which of the following combinations could be W, X and Y?
W X Y 1. 2. 3.
CH2=CH2
CH2=CHCH3
CH3CH2Br
aqueous bromine acidified KMnO4(aq)
NaOH(aq)
CH3CO2-‐Ag+
Fehling’s solution alkaline aqueous
iodine TJC Prelim 2010
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172 The following compound, Z, is a by-‐product formed in the body that counteracts the effect of the drug administered to patients to treat herpes.
H2N N N
NH
H NH2
O
H
OH
NH2
O Which of the following statements about this compound are correct? 1. Z undergo nucleophilic substitution with chloroethane 2. One mole of Z can be hydrolyzed to produce 2 moles of amino acids 3. When an aqueous solution of Z at pH 3 is analysed by electrophoresis, it is found
near the anode TJC Prelim 2010
173 Compound Z gives white fumes with PCl5, and releases ammonia gas upon addition of
hot aqueous NaOH. Which compounds could be Z? 1. HO2CCH2CH2CN 2. HOCH2CH2CONH2 3. HOCH(CH3)CH2NH2 VJC Prelim 2010
174 Psilocin is a psychedelic mushroom alkaloid which is the active compound that
produces hallucinations from ingesting “magic mushrooms” and amplifies sensory experience. Compound K is a derivative of Psilocin.
OH
N
H
CH2CH2NHCH3
compound K Which statements are correct for compound K? 1. It gives white fumes with CH3COCl. 2. It reacts with both aqueous acids and alkalis. 3. The nitrogen–containing group in the ring has a lower pKb than the nitrogen–
containing group in the side chain. VJC Prelim 2010
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175 In some reactions, the reactive carbon atom is not sp3 hybridised in the reactant molecule but becomes sp3 hybridised in the organic intermediate.
To which of the following reactions does this statement apply?
1.
2.
3.
VJC Prelim 2010
176 Which reactions would produce benzene–1,3–dicarboxylic acid?
1.
CN
CO2CH3
+ aqueous H2SO4, reflux
2.
3.
CH(OH)CH3
COCH3
+ akaline aqueous iodine followed by acidification
VJC Prelim 2010