2010 organic chem mcq

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Twig Learning Center

Organic Chem MCQ

Revision For 2012 CT 1


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


122 Which of the following 2-‐stage processes will not yield the final product as shown?

A

B

C

D

VJC Prelim 2010


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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

2010 organic chem mcq

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