1. Which of the structures below is an aldehyde? O O A. CH 3CH 2 CH B. CH 3CCH3 C. CH 3CH 2 COH D. CH COCH 2. What product results from the reaction of CH 2 ==CH 2 with Br 2? A. CHBrCHBr B. CH 2 CHBr C. CH 3 CH 2 Br D. CH 2 BrCH 2 Br 3. What is the final product formed when CH 3 CH 2 OH is refluxed with acidified potassium dichromate(vi)? O O 3 3 A. CH 3 CHO B. CH 2 ==CH 2 C. CH 3 COOH D. HCOOCH 3 4. Which of the substances below is least soluble in water? A. CH 2 OHCHOHCH 2 OH B. O CH CCH 3 3 O C. CH CH COH 3 2 O D. CH COCH 3 3 5. 6. Which substance(s) could be formed during the incomplete combustion of a hydrocarbon? I. Carbon II. Hydrogen III. Carbon monoxide A. I only B. I and II only C. I and III only D. II and III only 7. Which formulas represent butane or its isomer? I. CH 3 (CH 2 ) 2 CH 3 II. CH 3 CH(CH 3 )CH 3 III. (CH 3 ) 3 CH A. I and II only B. I and III only C. II and III only D. I, II and III 8. Which compound can exist as optical isomers? A. CH 3 CHBrCH 3 B. CH 2 BrCHBrCH 3 9. C. CH 2 BrCHBrCH 2 Br D. CHBr 2 CHBrCHBr 2 10. Which statement about the reactions of halogenoalkanes with aqueous sodium hydroxide is correct? A. Primary halogenoalkanes react mainly by an S N 1 mechanism. B. Chloroalkanes react faster than iodoalkanes. C. Tertiary halogenoalkanes react faster than primary halogenoalkanes. D. The rate of an S N 1 reaction depends on the concentration of aqueous sodium hydroxide. 11. Which statement about neighbouring members of all homologous series is correct? A. They have the same empirical formula. B. They differ by a CH 2 group. 1
C. They possess different functional groups. D. They differ in their degree of unsaturation. 12. Which type of compound must contain a minimum of three carbon atoms? A. An aldehyde B. A carboxylic acid C. An ester D. A ketone 13. What is the IUPAC name for CH 3 CH 2 CH(CH 3 ) 2? A. 1,1-dimethylpropane B. 2-methylbutane C. isopentane D. ethyldimethylmethane 14. Which compound can exist as optical isomers? A. H 2 NCH 2 COOH B. CH 2 ClCH 2 Cl C. CH 3 CHBrI D. HCOOCH 3 15. Which product is formed by the reaction between CH 2 CH 2 and HBr? A. CH 3 CH 2 Br B. CH 2 CHBr C. BrCHCHBr D. CH 3 CHBr 2 16. 17. Which reaction(s) involve(s) the formation of a positive ion? I. CH 3 CH 2 CH 2 Br + OH II. (CH 3 ) 3 CBr + OH A. I only B. II only C. Both I and II D. Neither I nor II 18. Which compound has the lowest boiling point? A. CH 3 CH 2 CH(CH 3 )CH 3 B. (CH 3 ) 4 C C. CH 3 CH 2 CH 2 CH 2 CH 3 D. CH 3 CH 2 OCH 2 CH 3 19. Which species will show optical activity? A. 1-chloropentane B. 3-chloropentane C. 1-chloro-2-methylpentane D. 2-chloro-2-methylpentane 20. What type of reaction does the equation below represent? CH 2 =CH 2 + Br 2 BrCH 2 CH 2 Br A. substitution B. condensation C. reduction D. addition 21. Consider the following compounds. I. CH 3 CH 2 CH(OH)CH 3 II. CH 3 CH(CH 3 )CH 2 OH III. (CH 3 ) 3 COH The compounds are treated separately with acidified potassium dichromate(vi) solution. Which will produce a colour change from orange to green? A. I and II only B. I and III only C. II and III only D. I, II and III 22. Which compound reacts most rapidly by a S N 1 mechanism? 2
A. (CH 3 ) 3 CCl B. CH 3 CH 2 CH 2 CH 2 Br C. (CH 3 ) 3 CBr D. CH 3 CH 2 CH 2 CH 2 Cl 23. Which compound is a member of the same homologous series as 1-chloropropane? A. 1-chloropropene B. 1-chlorobutane C. 1-bromopropane D. 1,1-dichloropropane 24. Which formula is a correct representation of pentane? A. CH 3 CH 2 CHCH 2 CH 3 B. (CH 3 CH 2 ) 2 CH 3 C. CH 3 (CH 2 ) 3 CH 3 D. CH 3 (CH 3 ) 3 CH 3 25. What is the organic product of the reaction between ethanol and ethanoic acid? A. CH 3 CHO B. CH 3 COOCH 3 C. CH 3 CH 2 COOCH 3 D. CH 3 COOCH 2 CH 3 26. Which statement is correct about the reaction between methane and chlorine? A. It involves heterolytic fission and Cl ions. B. It involves heterolytic fission and Cl radicals. C. It involves homolytic fission and Cl ions. D. It involves homolytic fission and Cl radicals. 27. Which formula is that of a secondary halogenoalkane? A. CH 3 CH 2 CH 2 CH 2 Br B. CH 3 CHBrCH 2 CH 3 C. (CH 3 ) 2 CHCH 2 Br D. (CH 3 ) 3 CBr 28. Which compound is converted to butanal by acidified potassium dichromate(vi) solution? A. butan-1-ol B. butan-2-ol C. butanone D. butanoic acid 29. How many structural isomers are possible with the molecular formula C 6 H 14? A. 4 B. 5 C. 6 D. 7 30. Which compound is a member of the aldehyde homologous series? A. CH 3 COCH 3 B. CH 3 CH 2 CH 2 OH C. CH 3 CH 2 COOH D. CH 3 CH 2 CHO 31. Which compound can exist as optical isomers? A. CH 3 CHBrCH 3 B. CH 2 ClCH(OH)CH 2 Cl C. CH 3 CHBrCOOH D. CH 3 CCl 2 CH 2 OH 32. Which type of compound can be made in one step from a secondary alcohol? A. an aldehyde B. an alkane C. a carboxylic acid D. a ketone 33. Which formula represents a tertiary alcohol? 3
A. CH 3 CH CH 2 CH 3 B. CH 3 CH CH 2 CH 2 OH CH 2 OH CH 3 C. CH 3 D. CH 3 CH 3 C CH 2 CH 3 CH 3 CH CH CH 3 OH OH 34. Which reaction type is typical for halogenoalkanes? A. nucleophilic substitution B. electrophilic substitution C. electrophilic addition D. nucleophilic addition 35. Which substance is not readily oxidized by acidified potassium dichromate (VI) solution? A. propan-1-ol B. propan-2-ol C. propanal D. propanone 36. What is the correct name of this compound? CH3 CH3 CH CH2 CH2 CH3 A. 1,3-dimethylbutane B. 2,4-dimethylbutane C. 2-methylbutane D. 2-methylpentane 37. Propane, C 3 H 8, undergoes incomplete combustion in a limited amount of air. Which products are most likely to be formed during this reaction? A. Carbon monoxide and water B. Carbon monoxide and hydrogen C. Carbon dioxide and hydrogen D. Carbon dioxide and water 38. What is/are the product(s) of the reaction between ethene and hydrogen bromide? A. CH 3 CH 2 Br B. CH 3 CH 2 Br and H 2 C. CH 2 BrCH 2 Br D. CH 3 BrCH 2 Br and H 2 39. Which are characteristics typical of a free radical? I. It has a lone pair of electrons. II. It can be formed by the homolytic fission of a covalent bond. III. It is uncharged. A. I and II only B. I and III only C. II and III only D. I, II and III 40. Which of the following products could be formed from the oxidation of ethanol? I. ethane l II. ethanoic acid III. ethane 4
A. I and II only B. I and III only C. II and III only D. I, II and III 41. Which pair of compounds can be used to prepare CH 3 COOCH 3? A. Ethanol and methanoic acid B. Methanol and ethanoic acid C. Ethanol and ethanoic acid D. Methanol and methanoic acid 42. Which pair of compounds can be used to prepare CH 3 COOCH 3? A. Ethanol and methanoic acid B. Methanol and ethanoic acid C. Ethanol and ethanoic acid D. Methanol and methanoic acid 43. What is the reaction type when (CH 3 ) 3 CBr reacts with aqueous sodium hydroxide to form (CH 3 ) 3 COH and NaBr? A. Addition B. Elimination C. S N 1 D. S N 2 44. Which species is a free radical? A. CH 3 B. + CH 3 C. CH 3 D. :CH 3 45. Which compound is a tertiary halogenoalkane? A. (CH 3 CH 2 ) 2 CHBr B. CH 3 (CH 2 ) 3 CH 2 Br C. (CH 3 ) 2 CHCH 2 CH 2 Br D. CH 3 CH 2 C(CH 3 ) 2 Br 46. Which species reacts most readily with propane? A. Br 2 B. Br C. Br D. Br + 47. Nylon is a condensation polymer made up of hexanedioic acid and 1,6-diaminohexane. Which type of linkage is present in nylon? A. Amide B. Ester C. Amine D. Carboxyl 48. How many chiral carbon atoms are present in a molecule of glucose? A. 1 B. 2 C. 3 D. 4 5
49. An organic compound X reacts with excess acidified potassium dichromate(vi) to form compound Y, which reacts with sodium carbonate to produce CO 2 (g). What is a possible formula for compound X? A. CH 3 CH 2 COOH B. CH 3 CH 2 CH 2 OH C. CH 3 CH(OH)CH 3 D. (CH 3 ) 3 COH 50. Which amino acid can exist as optical isomers? A. B. C. D. 51. Which statement about successive members of all homologous series is correct? A. They have the same empirical formula. B. They differ by a CH 2 group. C. They have the same physical properties. D. They differ in their degree of unsaturation. 52. The following is a three-dimensional representation of an organic molecule. Which statement is correct? A. The correct IUPAC name of the molecule is 2-methylpentane. B. All the bond angles will be approximately 90. 6
C. One isomer of this molecule is pentane. D. The boiling point of this compound would be higher than that of pentane. 53. Which compound forms when hydrogen bromide is added to but-2-ene? A. 2-bromobutane B. 2,3-dibromobutane C. 1-bromobutane D. 1,2-dibromobutane 54. Which products can be potentially obtained from crude oil and are economically important? I. Plastics II. Margarine III. Motor fuel A. I and II only B. I and III only C. II and III only D. I, II and III 55. Propane, C 3 H 8, undergoes incomplete combustion in a limited amount of air. Which products are most likely to be formed during this reaction? A. Carbon monoxide and water B. Carbon monoxide and hydrogen C. Carbon dioxide and hydrogen D. Carbon dioxide and water 56. What is the product of the following reaction? CH 3 CH 2 CH 2 CN + H 2 Ni A. CH 3 CH 2 CH 2 NH 2 B. CH 3 CH 2 CH 2 CH 3 C. CH 3 CH 2 CH 2 CH 2 CH 3 D.CH 3 CH 2 CH 2 CH 2 NH 2 57. What is the correct IUPAC name for the following compound? CH CHCH CH CN 3 2 2 A. 4-methylbutanenitrile B. 4-methylpentanenitrile C. 2-methylbutanenitrile D. 2-methylpentanenitrile CH 58. What is the organic product of the reaction between ethanol and ethanoic acid in the presence of sulfuric acid? 3 A. CH 3 CHO B. CH 3 COOCH 3 C. CH 3 CH 2 COOCH 3 D. CH 3 COOCH 2 CH 3 59. Which compound can exist as optical isomers? A. H 2 NCH 2 COOH B. H 3 CCONH 2 C. H 3 CCHBrI D. HCOOCH 3 60. Two reactions of an alkene, B, are shown below. C H A 4 10 H 2 Ni CH CH 3 C H Br 3 4 9 C C C H B H State the name of A and write an equation for its complete combustion. Explain why the 7
incomplete combustion of A is dangerous. Outline a test to distinguish between A and B, stating the result in each case. (iii) Write an equation for the conversion of B to C. State the type of reaction taking place and draw the structure of C. 61. A compound D has the molecular formula C 2 H 4 O 2 and is obtained from a reaction between methanoic acid and methanol. Write an equation for this reaction and state the name of D. (5) A second compound, E, has the same molecular formula as D and has acidic properties. State the name of compound E. 62. The first synthetic thread was made from a polyester. A section of the polyester is drawn below: CH 2 COO CH 2 COO CH 2 COO Give the structural formula of the monomer (containing two functional groups) that could be used to make this polyester and state the names of the two functional groups. State, giving a reason, whether this polyester is made by a condensation reaction or an addition reaction. 63. Halogenoalkanes undergo nucleophilic substitution reactions. The rates and mechanisms of these reactions depend on whether the halogenoalkane is primary, secondary or tertiary. Explain the term nucleophilic substitution. The formula C 4 H 9 Br represents more than one compound. Using this formula, draw a structure (showing all bonds between carbon atoms) to represent a halogenoalkane that is primary. secondary. (iii) tertiary. 64. Ethanoic acid reacts with ethanol in the presence of concentrated sulfuric acid and heat. Identify the type of reaction that takes place. Write an equation for the reaction, name the organic product formed and draw its structure. State and explain the role of sulfuric acid in this reaction. (iii) State one major commercial use of the organic product from this type of reaction. 65. For the two compounds HCOOCH 2 CH 3 and HCOOCHCH 2 : I II State and explain which of the two compounds can react readily with bromine. 8
Compound II can form polymers. State the type of polymerization compound II undergoes, and draw the structure of the repeating unit of the polymer. 66. Identify which of the compounds butane, chloroethane, propanone and propan-1-ol are insoluble in water and give your reasoning. water soluble and give your reasoning. 67. Draw the two enantiomers of 2-hydroxypropanoic acid. State how the two enantiomers differ in their chemical and physical properties. 68. The compound C 2 H 4 can be used as a starting material for the preparation of many substances. Name the compound C 2 H 4 and draw its structural formula. In the scheme below, state the type of reaction and identify the reagent needed for each reaction. A B C 2 H 4 CH 3 CH 2 OH CH 3 COOH C 2 H 4 can be converted into one of the compounds below in a single step reaction. (d) (e) (f) C 2 H 3 Cl C 2 H 4 Cl 2 Draw the structural formula for each of these compounds and identify the compound which can be formed directly from C 2 H 4. One of the two compounds in has an isomer. Draw the structural formula of the isomer and explain why it can not be formed directly from C 2 H 4. C 2 H 4 can also react to form a polymer. Name this type of polymer and draw the structural formula of a section of this polymer consisting of three repeating units. Polymers can also be formed in a different type of reaction. Identify this type of reaction and name two different types of such polymers. 69. The polymer with the repeating unit H H O N C C CH 3 exists as optical isomers. 9
State a test for optical isomers. Identify the chiral centre in the repeating unit. (iii) Draw the two enantiomeric forms of the repeating unit. 70. Bromoethane reacts with ammonia as follows. CH 3 CH 2 Br + NH 3 CH 3 CH 2 NH + 3 + Br CH 3 CH 2 NH + + 3 + NH 3 CH 3 CH 2 NH 2 + NH 4 The mechanism for this reaction is described as S N 2. State the meaning of each of the symbols in S N 2. State the name of the organic product of the reaction, CH 3 CH 2 NH 2. Explain, using curly arrows to show the movement of electron pairs, the mechanism of the attack by ammonia on bromoethane, and show the structure of the transition state. 71. The plastic PVC, poly(chloroethene), is made from the monomer chloroethene, C 2 H 3 Cl, by a polymerization reaction. Draw the structural formula of chloroethene. State the type of polymerization reaction that occurs to make poly(chloroethene) and identify the structural feature needed in the monomer. (iii) Draw the structure of the repeating unit of poly(chloroethene). (iv) Explain why monomers are often gases or volatile liquids, whereas polymers are solids. 72. Hexanedioic acid and 1,6-diaminohexane react together to form a synthetic polymer. There are many natural polymers, some of the most familiar being proteins formed from 2-amino acids. Give the structural formula of each monomer in the synthetic polymer. State the type of polymerization reaction that occurs between these two monomers and identify the structural feature needed in the monomers. (iii) Draw the structure of and state the type of linkage formed in this polymer, and identify the other product of this polymerization reaction. (iv) The structures of some 2-amino acids are shown in Table 20 of the Data Booklet. Using alanine as an example, explain what is meant by the term optical activity, identify the structural feature that needs to be present and illustrate your answer with suitable diagrams of both isomers. (v) Identify a 2-amino acid from Table 20 which does not show optical activity. (vi) Polyesters are formed in a similar polymerization reaction to proteins. Their monomers are esters. State one use of esters and identify the two compounds that react together to 10
form the ester ethyl methanoate. 73. The hydrolysis of 2-iodo-2-methylpropane by 0.10 mol dm 3 KOH(aq) to form 2-methylpropan-2-ol is an example of nucleophilic substitution. Give equations to illustrate the S N 1 mechanism for this reaction. (Total 2 marks) 74. One of the alcohols containing four carbon atoms exists as optical isomers. Give the structural formula and name of this alcohol and explain why it exists as optical isomers. Outline how these two isomers could be distinguished. 75. The molecular formula C 4 H 9 Br represents four structural isomers, all of which can undergo nucleophilic substitution reactions with aqueous sodium hydroxide. An equation to represent all these reactions is C 4 H 9 Br + NaOH C 4 H 9 OH + NaBr Explain what is meant by the term nucleophilic substitution. The main mechanism for a tertiary halogenoalkane is S N 1. Give the equations for this substitution reaction of the tertiary isomer of C 4 H 9 Br. Show the structures of the organic reactant and product and use curly arrows to show the movement of electron pairs. (d) The main mechanism for a primary halogenoalkane is S N 2. Give the mechanistic equation for this substitution reaction of the straight-chain primary isomer of C 4 H 9 Br, showing the structures of the organic reactant and product, and using curly arrows to show the movement of electron pairs. Give a structural formula for the secondary isomer and for the other primary isomer. State the name of each isomer. 77. Many organic compounds can exist as isomers. Draw and name an isomer of ethanoic acid, CH 3 COOH. 78. Write equations to show the mechanisms of the following reactions. In each case, show the structure of the intermediate and organic product, and use curly arrows to show the movement of electron pairs. the reaction between KOH and CH 3 CH 2 CH 2 CH 2 Cl. the reaction between KOH and (CH 3 ) 3 CCl. 3) 79. Some alcohols are oxidized by heating with acidified potassium dichromate(vi). If oxidation does occur, identify the possible oxidation products formed by each of the alcohols below. Indicate if no oxidation occurs. Butan-1-ol Butan-2-ol 2-methylpropan-2-ol 11
80. Chlorine and ethane react together to form chloroethane. State the condition needed for the reaction to occur. Write equations to represent initiation, propagation and termination steps in the reaction. 81. CH 3 COCH 3 is the first member of the ketone homologous series. Draw the full structural formula of the next member of this homologous series and predict how its melting point compares with that of CH 3 COCH 3. (Total 2 marks) 82. Explain why butan-2-ol, CH 3 CH(OH)CH 2 CH 3, exists as enantiomers, and describe how pure samples of the enantiomers can be distinguished experimentally. 83. Polyesters are formed in a condensation reaction. The structure of the repeat unit of a polyester is C CH C O CH CH O O O Draw the structures of the two monomers that react to form this polyester. Identify the essential feature of the monomers in that enable them to form a condensation polymer. 85. Write an equation for the reaction between but-2-ene and bromine, showing the structure of the organic product. State the type of reaction occurring. 87. CH 3 COCH 3 can be prepared in the laboratory from an alcohol. State the name of this alcohol, the type of reaction occurring and the reagents and conditions needed for the reaction. 88. 2-bromobutane can be converted into butan-2-ol by a nucleophilic substitution reaction. This reaction occurs by two different mechanisms. Give the structure of the transition state formed in the S N 2 mechanism. Write equations for the S N 1 mechanism. 91. Ethene is an unsaturated hydrocarbon used as a starting material for many organic chemicals. Draw the structural formula of ethene and state the meaning of the term unsaturated hydrocarbon. State an equation for the conversion of ethene to ethanol and identify the type of reaction. Describe the complete oxidation of ethanol and name the product. Include the conditions, reagents required and any colour changes. 12
(d) State an equation for the reaction between ethanol and the product of complete oxidation in. Include any other reagent required for this reaction. Name the organic product and state one possible use of this product. 92. State the meaning of the term isomers. Draw the functional group isomers of C 3 H 6 O. (iii) State the meaning of the term optical isomers. Draw the alcohol with the molecular formula C 4 H 10 O which exhibits optical isomerism and identify the chiral carbon atom. 93. Ethene is an unsaturated hydrocarbon used as a starting material for many organic chemicals. State the meaning of the term unsaturated hydrocarbon. State an equation for the conversion of ethene to ethanol and identify the type of reaction. Describe the complete oxidation of ethanol. Include the conditions, reagents required and any colour changes. Name the organic product X. (d) State an equation for the reaction between ethanol and compound X. Include any other reagent required. Name the organic compound Z and state one use of this product. 94. State the meaning of the term isomers. Draw the functional group isomers of C 3 H 6 O. (iii) (iv) State the meaning of the term optical isomers. Draw the alcohol with the molecular formula C 4 H 10 O which exhibits optical isomerism and identify the chiral carbon atom. Other than the optical isomers in (iii), draw the other three alcohol isomers of molecular formula C 4 H 10 O and identify the isomer that does not undergo oxidation. 95. The equation for a reaction of ethane is CH 3 CH 3 + Cl 2 CH 3 CH 2 Cl + HCl The mechanism of this reaction involves initiation, propagation and termination steps. Describe this reaction, including equations for each step and the role of ultraviolet light. 96. Draw the structural formula of the ester propyl ethanoate. Deduce the name and draw the structural formula of the alcohol and carboxylic acid that react to form this ester. 97. Draw the structural formula of propan-2-ol. Identify the alcohol as primary, secondary, or tertiary. 13
(iii) Identify the organic product formed by the oxidation of this alcohol using acidified potassium dichromate(vi) solution. 98. Secondary halogenoalkanes can undergo nucleophilic substitution reactions by both S N 1 and S N 2 mechanisms. The mechanism showing the formation of the transition state in the reaction between 2-bromobutane and potassium hydroxide can be represented as follows. CH CH 2 3 H C Br HO H C CH CH 2 3 Br CH 3 :OH CH Identify the type of mechanism shown. State and explain how the following changes would alter the rate of the reaction by this mechanism. using water instead of potassium hydroxide. using bromoethane instead of 2-bromobuture. 99. The following is a computer-generated representation of the molecule, methyl 2-hydroxy benzoate, better known as oil of wintergreen. Deduce the empirical formula of methyl 2-hydroxy benzoate and draw the full structural formula, including any multiple bonds that may be present. The computer-generated representation shown does not distinguish between single and multiple bonds. In this representation, two of the carbon-oxygen bond lengths shown are 0.1424 nm and 0.1373 nm. Explain why these are different and predict the carbon-oxygen bond length in carbon dioxide. (iii) Name all the functional groups present in the molecule. 14
100. State and explain the trend in the boiling points of the first six alkanes involving straight-chains. Write an equation for the reaction between methane and chlorine to form chloromethane. Explain this reaction in terms of a free-radical mechanism. (5) 101. Identify the formulas of the organic products, A E, formed in the reactions, I IV: I. CH 3 (CH 2 ) 8 OH + K 2 Cr 2 O 7 A B II. (CH 3 ) 3 CBr + NaOH C H H H III. (CH 3 ) 2 CHOH + K 2 Cr 2 O 7 D IV. H 2 C=CH 2 + Br 2 E H 2 C=CH 2 can react to form a polymer. Name this type of polymer and draw the structural formula of a section of this polymer consisting of three repeating units. (5) 102. The compound, 2-bromobutane, CH 3 CHBrCH 2 CH 3, can react with sodium hydroxide to form compounds F, G and H. Compound F, C 4 H 10 O, exists as a pair of optical isomers. Compounds G and H, C 4 H 8, are structural isomers, and compound H exists as a pair of geometrical isomers. Draw the structures of the two optical isomers of F. Outline the use of a polarimeter in distinguishing between the optical isomers. (iii) Draw diagrams to show the shapes of the two geometrical isomers of H. (iv) Draw the mechanism, using curly arrows to represent the movement of electron pairs, to show the formation of G. 103. A compound, J, has the molecular formula C 2 H 4 O 2 and is obtained from a reaction between methanoic acid and methanol. Write an equation for this reaction and state the name of compound J. 104. A student prepared a sample of compound Y from benzene as follows: C 6 H 6 C 6 H 5 CH 2 CH 3 C 6 H 5 CHClCH 3 X Y The first step was the conversion of benzene to compound X, using chloroethane as the reagent and aluminum chloride as a catalyst. Write the equation for the reaction and give equations for the mechanism. Name the type of mechanism that occurs in the second step when X is converted 15
to Y. Draw two structures for compound Y, showing the relationship between them. Explain the term plane-polarized light and describe how the optical isomers of Y could be distinguished using a polarimeter. (iii) Explain why the sample of Y produced by the student did not show optical activity. Samples of compound Y and chlorobenzene are warmed separately with aqueous sodium hydroxide. State, with a reason, whether compound Y or chlorobenzene would react more slowly. 105. The structure of benzene can be represented in two ways. structure A structure B Use information from Table 9 of the Data Booklet to explain why structure B is used instead of structure A. The enthalpy changes for the hydrogenation of cyclohexene and benzene are as follows. C 6 H 10 + H 2 C 6 H 12 H ο = 120 kj mol 1 C 6 H 6 + 3H 2 C 6 H 12 H ο = 210 kj mol 1 Explain how this information can be used to support the statement that structure B is more stable than structure A. 106. The pk b values of some amines are shown in Table 16 of the Data Booklet. Write an equation for the reaction of ethylamine with water. State and explain how the basicity of ethylamine compares to that of ammonia. 107. The compound methylbenzene, C 6 H 5 CH 3, was reacted with chlorine under two different conditions. In the presence of aluminium chloride two organic products, F and G, were formed, both with the molecular formula C 7 H 7 Cl. Under the other set of conditions three organic products, J, K and L, were formed, with molecular formulas of C 7 H 7 Cl, C 7 H 6 Cl 2 and C 7 H 5 Cl 3, respectively. Deduce the structures of F and G. State the type of mechanism that occurs in the formation of F and G. Write equations, using curly arrows to represent the movement of electron pairs, to show the mechanism of the reaction in which either F or G is formed. Use Cl + to represent the 16
attacking species. (d) Deduce the structures of compounds J, K and L. (e) State the type of mechanism that occurs in the formation of J, K and L. (f) Write an equation to show the initiation step that occurs before either J, K or L can be formed, and state the condition needed. (g) Write equations to show two propagation steps in the mechanism for the formation of compound K. (h) Write an equation to show a termination step in which compound L is formed. Predict, giving a reason, whether methylbenzene or compound L undergoes nitration more readily. 108. The compound 2-bromobutane, CH 3 CHBrCH 2 CH 3, can react with sodium hydroxide to form compounds M, N and O. Compound M, C 4 H 10 O, exists as a pair of optically active isomers. Compounds N and O, C 4 H 8, are structural isomers, and compound O exists as a pair of geometrical isomers. Draw diagrams to show the relationship between the two isomers of M. Draw diagrams to show the shapes of the two isomers of O. Write equations, using curly arrows to represent the movement of electron pairs, to show the mechanism of the reaction in which N is formed. 109. The reaction of warm aqueous KOH with 1-bromobutane occurs by an S N 2 mechanism. Draw the mechanism for this reaction, including the structural formulas of 1-bromobutane, the transition state and the organic product. State and explain how the rate of the above reaction is affected when the concentration of the KOH is doubled. State and explain how the rate of reaction of 1-chlorobutane in the above S N 2 reaction compares with that of 1-bromobutane. 110. Methylbenzene, C 6 H 5 CH 3, reacts with Cl 2 to form different products depending on the conditions used. For the gas-phase reaction of C 6 H 5 CH 3 and Cl 2 in ultraviolet light, draw a structural formula for the product C 7 H 7 Cl. provide a stepwise mechanism, clearly labelling each step. explain the role of the ultraviolet light. 111. When hydrogen cyanide reacts with an aldehyde or a ketone the product molecule has one more carbon atom. 17
Give a mechanism for the reaction of hydrogen cyanide with propanone. Write an equation for the acid hydrolysis of this product. State the two functional groups in the organic product. 112. Ethene, propene and but-2-ene are members of the alkene homologous series. Describe three features of members of a homologous series. State and explain which compound has the highest boiling point. Draw the structural formula and give the name of an alkene containing five carbon atoms. (d) Write an equation for the reaction between but-2-ene and hydrogen bromide, showing the structure of the organic product. State the type of reaction occurring. (e) Propene can be converted to propanoic acid in three steps: step1 step 2 step 3 propene propan-1-ol propanal propanoic acid (f) State the type of reaction occurring in steps 2 and 3 and the reagents needed. Describe how the conditions of the reaction can be altered to obtain the maximum amount of propanal, and in a separate experiment, to obtain the maximum amount of propanoic acid. Identify the strongest type of intermolecular force present in each of the compounds propan-1-ol, propanal and propanoic acid. List these compounds in decreasing order of boiling point. (5) 113. Compounds of formula C 4 H 7 Cl exhibits both geometrical and optical isomerism. (iii) Explain why C 4 H 7 Cl shows geometrical isomerism. Draw the cis and trans isomers of C 4 H 7 Cl. Draw the structural formula of C 4 H 7 Cl that shows only optical isomerism. Show the chiral carbon atom with *. b) Explain why 1,2-dichlorocyclopropane has cis and trans isomers. Draw the structural formulas of the two isomers. 114. On being reacted separately with HBr, 2-methylbut-1-ene and 2-methylbut-2-ene produce the same major product but different minor products. Draw the structural formula of the major product and explain why it is formed in terms of the stability and structure of the organic intermediate. Draw the structural formulas of the two minor products. 18
115. Explain why aminoethane (ethylamine) is more basic than ammonia. Explain why 2,4,6-trinitrophenol is more acidic than phenol. 116. State two characteristics of a homologous series. Describe a chemical test to distinguish between alkanes and alkenes, giving the result in each case. 117. Identify the reagents used in the nitration of benzene. Write an equation or equations to show the formation of the species NO 2 + from these reagents. Give the mechanism for the nitration of benzene. Use curly arrows to represent the movement of electron pairs. (d) Predict the structures of the products of the (mono) nitration of methylbenzene methylbenzene (two products) (e) (f) nitrobenzene (one product) Explain why the nitration of methylbenzene is faster than the nitration of benzene. Identify the reagent and catalyst used to convert benzene into methylbenzene. 118. There are geometrical isomers of the cyclic compound C 4 H 6 Cl 2. Draw the structural formula of two isomers and explain why these two isomers exist. cis-isomer trans-isomer Draw the structural formulas of two isomers of but-2-ene-1,4-dioic acid. State and explain which isomer will have a lower melting point. (iii) Describe how the two isomers can be distinguished by a chemical test. Consider the following compounds: 1-chloropentane, 2-chloropentane, 3-chloropentane Identify the compound which exhibits optical isomerism and draw the structures of the two isomers. ii) Describe how these two isomers can be distinguished experimentally. 119. Compounds with the molecular formula C 3 H 4 Cl 2 exist as several structural isomers, some of which are cyclic. Some of these structural isomers exist as geometric isomers. Explain why geometrical isomerism is possible in the non-cyclic isomers. 19
Draw the structure of a non-cyclic structural isomer that does not exist as geometric isomers, and explain why geometrical isomerism is not possible in this compound. (d) 1,3-Dichloropropene exists as geometric isomers. Draw and label the structures of its cis and trans isomers. Draw structures to show the two geometric isomers of 1,2-dichlorocyclopropane. 120. Methylbenzene and chlorine react together in a 1:1 ratio in the presence of iron(iii) chloride. State the type of mechanism of this reaction and write an equation to show how iron(iii) chloride generates the attacking species. Use equations to explain the mechanism of this reaction, representing the movement of electron pairs by curly arrows. 121. The following transition state is formed during the reaction of a halogenoalkane with aqueous sodium hydroxide: HC CH 3 3 HO C Br H Deduce the structure of the halogenoalkane. Classify it as primary, secondary or tertiary, giving a reason for your choice. The mechanism of this reaction is described as S N 2. Explain what is meant by the symbols in S N 2. Predict a rate expression for this reaction. The same halogenoalkane reacts with sodium hydroxide by an S N 1 mechanism. Deduce the structure of the intermediate formed in this reaction. 122. This question is about structural isomers and stereoisomers with the molecular formula C 4 H 6 Cl 2. The compound 1,3-dichlorobut-1-ene can be used to illustrate two types of stereoisomerism. For each type of stereoisomerism, draw two structures to show the relationship between the two. two geometrical isomers two optical isomers Explain the term racemic mixture. Outline how the two optical isomers of 1,3-dichlorobut-1-ene can be distinguished from 20
each other and from a racemic mixture. (d) 1,3-dichlorocyclobutane exists as geometrical isomers. Draw the 3-dimensional structures of these isomers. 123. But-1-ene undergoes an electrophilic addition reaction with iodine chloride, ICl. The major product of this reaction is 2-chloro-1-iodobutane. Show the mechanism of this reaction, using curly arrows to represent the movement of electron pairs. Deduce the name of the minor product of this reaction and explain why only a small amount of it is formed. 124. List two characteristics of a homologous series. Ethanol and ethanoic acid can be distinguished by their melting points. State and explain which of the two compounds will have a higher melting point. Draw the three isomers containing the alcohol functional group of formula C 4 H 9 OH. 125. The molecular formula, C 3 H 4 Cl 2 represents several isomeric compounds. Some isomers are cyclic and some are unsaturated. Draw the structures of two cyclic compounds that are structural isomers and state the names of both isomers. b) Two of the non-cyclic compounds have geometrical isomers. Draw the structures of these compounds and their geometrical isomers. 126. When hydrogen cyanide reacts with an aldehyde or a ketone the product molecule has one more carbon atom. Write an equation to show the addition of hydrogen cyanide to propanone. b) Describe, using curly arrows, a mechanism for the reaction of hydrogen cyanide with propanone. Write an equation for the acid hydrolysis of this product. State the two functional groups in the organic product. 127. The structure of benzene can be represented in two ways. structure A structure B Use information from Table 9 of the Data Booklet to explain why structure B is used in 21
preference to structure A. The enthalpy changes for the hydrogenation of cyclohexene and benzene are as follows. C 6 H 10 + H 2 C 6 H 12 H ο = 120 kj mol 1 C 6 H 6 + 3H 2 C 6 H 12 H ο = 210 kj mol 1 Explain how this information can be used to support the statement that structure B is more stable than structure A. State what the circle in structure B represents. 128. Cyclohexanone can react with 2,4-dinitrophenylhydrazine in aqueous solution. State the type of reaction that takes place. Complete the equation for this reaction using structural formulas for the products. H 2 N N H NO 2 O + NO 2 State why the product from this particular reaction can be used to confirm that the reactant was cyclohexanone and not any other carbonyl compound. 129. Explain how the presence of the NO 2 group on a benzene ring affects the rate of further substitution. 22
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