1. Organic Chemistry Mr Murphy

2. Main Menu Menu Lessons 1-11:  Lesson 1 – Homologous Series Lesson 1 – Homologous Series  Lesson 2 – Isomers Lesson 2 – Isomers  Lesson 3 – Meet the Families Lesson 3 – Meet the Families  Lesson 4 – Alkanes Lesson 4 – Alkanes  Lesson 5 – Alkenes Lesson 5 – Alkenes  Lesson 6 – Alcohols Lesson 6 – Alcohols  Lesson 7 – Halogenoalkanes Lesson 7 – Halogenoalkanes  Lesson 8 – Reaction Pathways Lesson 8 – Reaction Pathways  Lesson 9 – HL – Meet the Families (again) Lesson 9 – HL – Meet the Families (again)  Lesson 10 – HL – S N 1 and S N 2 Revisited Lesson 10 – HL – S N 1 and S N 2 Revisited  Lesson 11 – HL – More Nucleophiles Lesson 11 – HL – More Nucleophiles

3. Main Menu Menu Lessons 12-18:  Lesson 12 – HL – Elimination Reactions Lesson 12 – HL – Elimination Reactions  Lesson 13 – HL – Condensation Reactions Lesson 13 – HL – Condensation Reactions  Lesson 14 – HL – Condensation Polymerisation Lesson 14 – HL – Condensation Polymerisation  Lesson 15 – HL – Geometric Isomerism Lesson 15 – HL – Geometric Isomerism  Lesson 16 – HL – Optical Isomerism Lesson 16 – HL – Optical Isomerism  Lesson 17 – HL – More Reaction Pathways Lesson 17 – HL – More Reaction Pathways  Lessons 18-19 – Internal Assessment Lessons 18-19 – Internal Assessment  Lesson 20 – Test Lesson 20 – Test  Lesson 21 – Test Debrief Lesson 21 – Test Debrief

4. Main Menu Lesson 1 Homologous Series

5. Main Menu Overview  Copy this onto a double-page spread. You should add to it as a regular review throughout the unit.

6. Main Menu We Are Here

7. Main Menu Homologous Series  A homologous series is a family of compounds that differs only by the length of its hydrocarbon chain  Members share:  General formula  Chemical properties  Three such series are the:  Alkanes  Alkenes  Alcohols

8. Main Menu Homologous Series and Boiling Points  What do you think will be the trend in melting/boiling points as you go down a homologous series?  Why?

9. Main Menu Formulas  Draw the compound with the formula C 4 H 8 O

10. Main Menu What did you get?  Clearly a molecular formula is not enough!

11. Main Menu Types of Formula  Empirical Formula C 4 H 8 O C 4 H 8 O  Molecular Formula C 4 H 8 O C 4 H 8 O  Full Structural Formula  Aka displayed formula  Condensed Structural Formula  Note the ‘=‘ used for the C=C double bond  Skeletal formula  Not required but v. useful  Used in data booklet for complicated structures  Do not use in exam answers! CH 2 =CHCH 2 CH 2 OH CH 2 =C(CH 3 )CH 2 OH

12. Main Menu Thinking About Formulas  Produce a table to summarise each of the formulas. Include columns for:  What they show  Pros  Cons  How you make them  Draw full structural, condensed structural and skeletal formulas for at least 5 of the C 4 H 8 O compounds (not the cyclic ones)

13. Main Menu Key Points  Organic chemistry is the chemistry of carbon containing compounds  A homologous series is a family of organic compounds differing only by the length of their carbon chains  The melting and boiling point increases as you go down a homologous series  Displayed formulas show the unambiguous arrangement of atoms in a compound

14. Main Menu Lesson 2 Isomers

15. Main Menu Refresh  List two characteristics of a homologous series. Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

16. Main Menu We Are Here

17. Main Menu Lesson 2: Isomers  Objectives:  Describe the term structural isomer  Draw a name the non-cyclic alkanes  Draw and name the straight-chain alkenes

18. Main Menu Isomers  Compounds with the same molecular formula but different structural formula  The 20 different C 4 H 8 O compounds from last lesson are isomers of each other  These are all structural isomers  Same number of each atom, but bonded in a different order  You would have even more if you included geometric and optical isomers

19. Main Menu Structural Isomers of the Alkanes  The (non-cyclic) alkanes have the general formula C n H 2n+2  Draw full and condensed structural formulas for every isomer of every one of the alkanes up to n = 6  If you finish early, draw each as a skeletal formula

20. Main Menu Did you get them all?

21. Main Menu And skeletally

22. Main Menu Naming Straight-chain alkanes  Suffix:  Tells us the functional group of the molecule  For alkanes it is ‘-ane’  Prefix:  Tells us the length of the longest carbon chain:  1 carbon: meth-  2 carbons: eth-  3 carbons: prop-  4 carbons: but-  5 carbons: pent-  6 carbons: hex-  Example 1: ethane  Example 2: butane:  Task: write in the names of the 4 straight chain alkanes next to your diagrams from last slide

23. Main Menu Naming branched-chain alkanes  Start by naming the longest chain  Add extras to say the size of a branch, its position and how many of that branch  Branch Size:  1 carbon: methyl-  2 carbons: ethyl-  3 carbons: propyl-  Position:  Number the carbons in the longest chain  Choose numbers to minimise the total numbers used  Number of same branches  One branch – nothing  Two branches – di-  Three branches – tri-  Four branches – tetra-  Example 1: 2-methylpropane  Example 2: 2,3-dimethylbutane  Task: name the remaining alkanes

24. Main Menu The straight-chain alkenes  Alkenes are the same as alkanes but have one C=C double bond.  The suffix for the alkene homologous series is ‘-ene’  Task: draw full structural and skeletal formulas for each of the straight-chain alkenes up to C6 and name them.  Do the branched ones as well if you have time  Hint: you need to state the position of the double bond, but only if there is the possibility of multiple isomers:  i.e. ‘but-2-ene’ or ‘hex-1-ene’ but only ‘ethene’ not ‘eth-1-ene’

25. Main Menu Did you get them?

26. Main Menu Key Points  Structural isomers have the same number of each atom but they are connected differently  When naming compounds  The longest carbon chain forms the prefix  The functional group tells you the suffix  Sometimes numbers need to be used to tell you where this functional group is  Side chains and other groups are named according to what they are, how many there are and their position

27. Main Menu Lesson 3 Meet the Families

28. Main Menu We Are Here

29. Main Menu Lesson 3: Meet the Families  Objectives:  Meet and learn to recognise the 7 functional groups required for the SL course  Produce a mind-map summarising each of the homologous series

30. Main Menu Functional Groups Table (landscape)  You need to research and produce a mind- map summarising the following functional groups:  Alkane  Alkene  Alcohol  Aldehyde  Ketone  Carboxylic acid  Halide/Halogenoalkane  Your table should have four columns including:  Name of functional group  General structural formula (use ‘R’ to signify a carbon chain)  Rules for naming them (including the position where relevant)  A named example  Relative volatility  Relative solubility in water  For alcohols and halides you should include a branch to explain the difference between 1 o, 2 o and 3 o  You should also have a branch called ‘Other Functional Groups’ that just allows you to recognise the groups:  Amine  Ester  Benzene  If HL you should leave space for four more functional groups

31. Main Menu Building Organic Compounds  Use molecular models to make any of the compounds mentioned in your mind-map:  Draw it (structural and skeletal)  Name it  Give it to a friend and challenge them to do the same  Only go up to 6 carbons  Only include branched-chains for the alkanes

32. Main Menu Review  You should know and be able to recognize the functional groups and their naming conventions

33. Main Menu Key Points  There are 7 functional groups we need to know in detail and 3 extra we need to be able to recognise  We will look at each in detail over the rest of the unit

34. Main Menu Lesson 4 Alkanes

35. Main Menu Refresh  The following is a computer-generated representation of the molecule, methyl 2- hydroxy benzoate, better known as oil of wintergreen. a) 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. b) Name all the functional groups present in the molecule. H H H H H H H H C C C C C C C C O O O Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

36. Main Menu We Are Here

37. Main Menu Lesson 4: Alkanes  Objectives:  Explain the stability of the alkanes  Observe the combustion of alkanes  Describe the free-radical substitution reactions of alkanes and its mechanism  Observe the free-radical substitution of hexane

38. Main Menu Combustion of Alkanes (5 mins)  The alkanes really don’t do much  Combustion is of one of two notable reactions (this is why we use them for fuels)  Complete combustion:  alkane + oxygen  carbon dioxide + water  Incomplete combustion:  Alkane + oxygen  carbon + carbon monoxide + carbon dioxide + water  The amounts of C, CO and CO 2 will vary depending on conditions  Task: Observe the combustion of the gas from the gas taps (propane/butane mix) and of a small amount hexane (in spirit burners). Hold the end of a clean boiling tube just over the flame for 15 seconds, this will collect soot from the flame.  Record all observations clearly and try to account for them  Include balanced equations to describe the (complete) combustion

39. Main Menu Why Good Fuels?  To do:  Use Table 12 in the data booklet to help you determine the trend in energy released per gram by combustion of the alkanes.  Use bond enthalpies to help you explain the trend noted above.  What do you think should be the characteristics of a good fuel?  Use the above to decide and explain which out of methane and octane is a better fuel.

40. Main Menu Why so boring stable?  There are at least two reasons why alkanes are so unreactive  Task: Think back to your knowledge of molecular structure, and look at the tables of bond-enthalpies in the data booklet to see if you can work out why.

41. Main Menu Halogenation  Alkanes will undergo halogenation if reacted with a halide in the presence of u.v. light.  For example:  C 2 H 6 (g) + Cl 2 (g) CH 3 CH 2 Cl(g) + HCl(g) ethane chloroethane  This reaction is an example of free radical substitution u.v.

42. Main Menu Radicals  Radicals are species with unpaired electrons  They are crazy reactive  Halogens form radicals when hit by uv light of the right frequency:  Cl 2 2 Cl  The dot after the Cl represents the unpaired electron and tells us we have a radical  This process is called homolytic fission – the bond breaks equally with one electron going to each chlorine  Task: draw Lewis structures for the Cl 2 molecule and each of the Cl radicals u.v.

43. Main Menu Reaction Mechanism: Free Radical Substitution  Cl 2 2 Cl  Cl + C 2 H 6  C 2 H 5 + HCl  C 2 H 5 + Cl 2  C 2 H 5 Cl + Cl  Cl + Cl  Cl 2  Cl + C 2 H 5  C 2 H 5 Cl  C 2 H 5 + C 2 H 5  C 4 H 10  Initiation  Radicals formed by homolytic fission  Propagation  These steps feed each other the radicals needed to continue  Termination  Any two radicals can combine to terminate the reaction  Concentration of radicals is low so this is a rare event  A single radical can cause thousands of cycles of the propagation stage before it reaches termination  This same mechanism applies to all of the halogens  The alkane can be substituted multiple times, until every H has been replaced u.v.

44. Main Menu Try it Yourself  Place approx 1 cm 3 of hexane into two test tubes  Add roughly 1 cm 3 of bromine water to each and stopper them, then give them a good shake.  Leave one test-tube in the classroom but take the other outside and shake it in direct sunlight.  Record and explain all observations  Write equations showing the mechanism of the reaction  Draw full structural and skeletal formulas of at least 6 possible products, and name each one.

45. Main Menu Extension:  Research the role of free radical reactions in the depletion of the ozone layer

46. Main Menu Key Points  Alkanes are pretty unreactive  They release a lot of energy on combustion, and are easy to handle which makes them good fuels  Undergo free radical substitution to form halogenoalkanes and a hydrogen halide in the presence of UV light

47. Main Menu Lesson 5 Alkenes

48. Main Menu Refresh  Write an equation for the reaction between methane and chlorine to form chloromethane.  Explain this reaction in terms of a free- radical mechanism. Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

49. Main Menu We Are Here

50. Main Menu Lesson 5: Alkenes  Objectives:  Describe the main addition reactions of the alkenes  Extract an alkene from a citrus fruit

51. Main Menu Reactivity of Alkenes  Alkenes are considerably more reactive than alkanes and are a major industrial feedstock  The reactivity is due to the double bond:  The double bond contains 4 electrons  This is a significant amount of charge which:  Makes it attractive to electrophiles  Enables it to polarise approaching molecules  Most reactions of alkenes are addition reactions where two molecules come together to make one new one

52. Main Menu Alkenes and hydrogen  Alkene + hydrogen  alkane  Reaction conditions:  Hot  Ni catalyst  This is an addition reaction, in which the hydrogen adds across the double bond

53. Main Menu Alkenes and hydrogen halides  Alkene + hydrogen halide  halogenoalkane  Reaction conditions:  This reaction occurs very readily and needs no special conditions  This is an addition reaction, in which the hydrogen halide adds across the double bond

54. Main Menu Alkenes and halogens  Alkene + halogen  dihalogenoalkane  Reaction conditions:  This reaction occurs very readily and needs no special conditions  If the halogen used is an aqueous solution of bromine (bromine water), the orange-brown colour of bromine solution is decolourised.  This is the standard test for alkenes.

55. Main Menu Alkenes and water  Alkene + water  alcohol  Reaction conditions:  Water must be steam  Phosphoric or sulphuric acid catalyst  This is the process used to make industrial ethanol  Fermentation from sugar would be far too expensive!

56. Main Menu Polymerisation  Under the right conditions, alkene molecules will add to each other creating a polymer  In this case, 1-bromo-2-fluoroethene polymerises to form poly-1- bromo-2-fluroethene  Conditions:  Vary from alkene to alkene but often include high pressure, temperature and a catalyst  The carbons in the C=C double bonds form the carbon chain, everything else hangs off this chain

57. Main Menu Drawing polymers  Draw three-monomer lengths of the polymers formed by:  Propene  Styrene  Pent-2-ene

58. Main Menu Homework  Research the economic importance of alkenes including:  Manufacture of margarine  Manufacture of ethanol  Polymerisation

59. Main Menu Key Points  Alkenes undergo addition reactions with:  Hydrogen  Hydrogen halides  Halogens  Water (steam)  Alkenes undergo addition polymerisation  Alkenes are very economically important due to the range of products they can make

60. Main Menu Lesson 6 Alcohols

61. Main Menu Refresh  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 Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

62. Main Menu We Are Here

63. Main Menu Lesson 6: Alcohols  Objectives:  Explain the relative ease of combustion of the alcohols  Describe the oxidation reactions of the alcohols  Investigate the oxidation reactions of the alcohols

64. Main Menu Alcohols as Fuels  Alcohols combust more readily than equivalent alkanes but release less energy since they are already partially oxidised Alcohol + oxygen  carbon dioxide + water  Alcohols are used as fuels:  As a fuel for cars – either pure or blended with petrol  Methanol as fuel for competitive motorsports including dragsters and monster trucks  Much fuel ethanol is fermented from crops…crops that could otherwise be eaten, forcing up food prices. Is this ok?

65. Main Menu Oxidation of alcohols  The most important reactions of the alcohols are their oxidations  A range of compounds will oxidise them so the oxidiser is often represented as [O]  One oxidising agent you need to know is potassium dichromate, K 2 Cr 2 O 7.  When using this, orange Cr (VI) is reduced to green Cr (III)  More on what this means in the oxidation and reduction unit  See next slide for details

66. Main Menu Oxidation reaction scheme

67. Main Menu Key Points  Alcohols are highly combustible  Primary alcohols oxidise to form aldehydes, which oxidise to form carboxylic acids  Secondary alcohols oxidise to form ketones  Tertiary do not oxidise due to the 3 strong C-C bonds surrounding the –OH carbon

68. Main Menu Lesson 7 Halogenoalkanes

69. Main Menu Refresh a) Draw four structural isomers of molecular formula C 4 H 10 O which contain the –OH group. b) On reaction with acidified potassium dichromate(VII), two of the isomers are oxidized in two steps to produce different products. Draw the structural formula of the two products formed from one of the isomers. Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

70. Main Menu We Are Here

71. Main Menu Lesson 7: Halogenoalkanes  Objectives:  Describe the substitution reactions of halogenoalkanes with a strong base  Understand the S N 1 and S N 2 mechanisms for nucleophilic substitution  Produce an animation showing the two different mechanisms

72. Main Menu Nucleophilic Substitution  One of the most important reactions undergone by halogenoalkanes is nucleophilic substitution  A nucleophile is a ‘nucleus-loving’ species that is attracted to positive charges.  Nucleophiles have either full negative charges or delta-negative charges  Water and hydroxide are both nucleophiles  In this case we can also call the reaction ‘hydrolysis’  The carbon in the carbon-halogen bond has a  + charge due to the greater electronegativity of the halogen  This makes it susceptible to attack by nucleophiles

73. Main Menu Halogenoalkanes and strong bases  A substitution reaction takes place, where the halogen atom is displaced by the hydroxide ion halogenoalkane + sodium hydroxide  alcohol + sodium chloride  Conditions:  Aqueous base  Gently warmed (can at room temperature, but may be quite slow)  This is a nuclephilic substitution.  The C attached to the halogen is  + due to the high electronegativity of the halogen  The OH - ion (our nucleophile) is attracted to the  + carbon  A nucleophile is a species with a negative charge or a lone pair that is attracted to positive/delta-positive atoms

74. Main Menu S N 1 – Unimolecular nucleophilic substitution – animation hereanimation here  Unimolecular because only one molecule is involved in the rate determining step  The rate determining step involves the spontaneous breaking of the carbon-halogen bond and is a heterolytic fission, forming a halide ion and a carbocation intermediate  The stability of the carbocation intermediate is a key factor in S N 1  The attack by the nucleophile (OH - ) is very fast, but does need the carbocation to be formed first  The rate is only dependent on the concentration of the halogenoalkane:  Rate = k[halogenoalkane] Note: the curly arrows show the movement of pairs of electrons

75. Main Menu S N 2 – Bimolecular nucleophilic substitution – animation hereanimation here  Bimolecular because two molecules are involved in the rate determining step  In the rate determining step, the nucleophile (OH - ) attacks at the same time as the carbon-halogen bond breaks.  The reaction passes through a negative transition state where the carbon has a ‘half-bond’ to both the –OH and the –Br with an overall negative charge  The rate is dependent on both the concentration of the halogenoalkane and the nucleophile  Rate = k[halogenoalkane][nucleophile]

76. Main Menu S N 1 or S N 2?  1 o halogenoalkanes predominantly undergo S N 2  2 o halogenoalkanes undergo a mix of S N 1 and S N 2  3 o halogenoalkanes predominantly undergo S N 1  You do not need to know why at SL, but will find out more at HL

77. Main Menu Understanding Check  Write balanced equations, using condensed structural formulas, and name the products of the reactions of the following with dilute sodium hydroxide:  Bromoethane  1-chloro-2-iodopropane  3-chloro-3-ethylhexane  Name and draw the mechanism for the first and third one.

78. Main Menu Refresh  Halogenoalkanes undergo substitution with strong bases to form alcohols  The reaction has two possible mechanisms:  S N 1: the C-X bond breaks and then the nucleophile attacks  S N 2: the nucleophile attacks at the same time as the C-X bond breaks  The mechanism depends on the halogenoalkane:  1 o - S N 2  2 o - S N 1 and S N 2  3 o - S N 1

79. Main Menu Refresh  Predict the mechanism (S N 1 or S N 2) expected for the reaction of the following halogenoalkanes with aqueous KOH. 1-chlorobutane to form butan-1-ol 2-chloro-2-methylpropane to form 2 methylpropan-2-ol.  Describe the mechanism for one of the above reactions using diagrams with curly arrows to show electron movements.

80. Main Menu Lesson 8 Reaction Pathways

81. Main Menu We Are Here

82. Main Menu Key Points  Inter-converting between organic compounds is the bread and butter of an organic chemist  Reaction pathways are the map that help you navigate from your point of origin to your destination

83. Main Menu Reaction Pathways  Review all the reactions covered to date  Produce a diagram summarising all of the reactions in one place including:  Reactants and products for reactions (use general names)  Reaction conditions  It will look something like the diagram right  Leave space for more if you are HL

84. Main Menu Some Challenges  Use your reaction pathways diagrams to help you solve the following problems  Give the reactants and conditions to produce butan-2-one from a halogenoalkane in two steps.

85. Main Menu Lesson 9 Meet the Families Part 2 – The Revenge of Father-in-Law

86. Main Menu Refresh  Propene is converted to propanone in a two stage process. Propene → X → Propanone  What is the formula of compound X? A. CH 3 CHBrCH 3 B. CH 3 CH 2 CH 2 Br C. CH 3 CHOHCH 3 D. CH 3 CH 2 CH 2 OH Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

87. Main Menu We Are Here

88. Main Menu Lesson 9: Meet the Families….again  Objectives:  Learn to recognise and name a further 4 functional groups

89. Main Menu Functional Groups Mind map  You need to be able to recognize these functional groups :  Amide  Amine  Nitrile (R-C triple bonded to N)  Ester – with the full detail now  For each one you should include:  General structural formula  Rules for naming them (including the position where relevant)  With an example  Relative volatility and solubility in water  For amines you should include a branch to explain the difference between 1 o, 2 o and 3 o

90. Main Menu Lesson 10 S N 1 and S N 2 Revisited

91. Main Menu Refresh  What is the IUPAC name of the compound CH 3 CH 2 COOCH 2 CH 3 ? A. Ethyl ethanoate B. Propyl ethanoate C. Ethyl propanoate D. Pentyl propanoate Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

92. Main Menu We Are Here

93. Main Menu Lesson 10: S N 1 and S N 2 Revisited  Objectives:  Understand why the nature of the halogenoalkane affects the mechanism of nucleophilic substitution reactions  Understand why OH - is a better nucleophile than H 2 O  Understand the effect of the halogen on the rate of nuclephilic substitution reactions

94. Main Menu S N 1 and S N 2 Recap

95. Main Menu S N 1 and the carbocation  The carbocation is an unstable species, and will often immediately attract the halide ion straight back  Alkyl groups surrounding the carbocation donate electron charge to it and stabilise it  In this diagram, the arrows on the bonds represent the charge donated by the surrounding alkyl groups  3 o carbocations have most surrounding alkyl groups and therefore are most stable, thus S N 1 is preferred for 3 o halogenoalkanes

96. Main Menu Mechanism and rate  For S N 1:rate = k[halogenoalkane]  For S N 2:rate = k[halogenoalkane][nucleophile]  Since S N 1 only depends on one reactant, it tends to be faster (all else being equal) than S N 2  Therefore, if we consider the rates of hydrolysis / substitution, as a rule of thumb: Tertiary > Secondary > Primary

97. Main Menu S N 2 and steric hindrance  Alkyl groups are physically bulky, and make it difficult for a nucleophile to attack the carbon: this is called steric hindrance  1 o halogenoalkanes only have one surrounding alkyl group so steric hindrance is low and SN2 is favourable  3 o halogenoalkanes have three surrounding alkyl groups so steric hindrance is high and SN2 is unfavourable  The black arrows on the diagram are supposed to show possible avenues of approach by the nucleophile, red crosses show where they are blocked

98. Main Menu Changing the Nucleophile  Water can act as our nucleophile:  Halogenoalkane + water  alcohol + hydrogen halide  However, hydroxide is much better. Why?  Explain why using ideas from the bonding unit

99. Main Menu Changing the Halogen  The rate of substitution / hydrolysis varies greatly depending on the halogen atom  As a rule, with all else being equal, the rate changes as follows: Iodine > Bromine > Chlorine  Explain why using ideas from the bonding unit

100. Main Menu Key Points  The substitution mechanism followed depends on:  Stabilisation of the carbocation by surrounding alkyl groups  Steric hindrance of the carbocation by surrounding alkyl groups  Hydroxide ions are better nucleophiles than water due to their strong negative charge  Iodoalkanes react faster than chloroalkanes due to the C-I bond being weaker than the C-Cl bond

101. Main Menu Lesson 11 More Nucleophiles

102. Main Menu Refresh Which statements about substitution reactions are correct? I. The reaction between sodium hydroxide and 1-chloropentane predominantly follows an S N 2 mechanism. II. The reaction between sodium hydroxide and 2-chloro-2-methylbutane predominantly follows an S N 2 mechanism. III. The reaction of sodium hydroxide with 1- chloropentane occurs at a slower rate than with 1-bromopentane. A. I and II only B. I and III only C. II and III only D. I, II and III Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

103. Main Menu We Are Here

104. Main Menu Lesson 11: More Nucleophiles  Objectives:  Understand the reaction of halogenoalkanes with ammonia  Understand the reaction of halogenoalkanes with potassium cyanide  Describe and explain the reduction of nitriles

105. Main Menu More nucleophiles  So far we have met two nucleophiles:  Hydroxide  Water  This lesson we meet two more:  Ammonia, NH3  Cyanide, - CN  Draw the Lewis structure of cyanide  These undergo participate in nucleophilic substitution in exactly the same way as hydroxide and water.

106. Main Menu Key Points  Halogenoalkanes react with:  Ammonia to form primary amines  Further reactions can for secondary and tertiary amines and quaternary ammonium salts  Potassium cyanide to form a nitrile  This is useful as it creates a new C-C bond…no mean feat!  The nitrile can be reduced to an amine by reaction with H 2 and Ni catalyst

107. Main Menu Lesson 12 Elimination Reactions

108. Main Menu Refresh  What is the product of the following reaction? CH 3 CH 2 CH 2 CN + H 2 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 Ni. cat Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

109. Main Menu We Are Here

110. Main Menu Lesson 12: Elimination Reactions  Objectives:  Describe with equations the elimination reactions of halogenoalkanes  Describe the mechanism of elimination reactions  Complete an experiment investigating elimination reactions

111. Main Menu Complete the equation  1-bromobutane + sodium hydroxide 

112. Main Menu The Correct Answer  What are the conditions?

113. Main Menu Elimination  With warm, aqueous sodium hydroxide, halogenoalkanes undergo substitution  With hot, ethanolic sodium hydroxide an elimination reaction will take place: halogenoalkane + sodium hydroxide  alkene + water + sodium halide

114. Main Menu The mechanism  Similar to substitution, there are unimolecular (E1) and bimolecular (E2) mechanisms:  They work in a similar way to S N 1/2 and are affected by similar factors:  E1:  E2:  You only need remember one (go with E2…shorter), and do not need to know the same level of detail as for substitution

115. Main Menu Key Points  Halogenoalkanes will undergo elimination on reaction with sodium hydroxide if:  It is dissolved in ethanol  Hot  The elimination proceeds by both bimolecular and unimolecular mechanisms

116. Main Menu Lesson 13 Condensation Reactions

117. Main Menu Refresh  But-1-ene can be prepared from 1- bromobutane. a) State the equation (using structural formulas) and the necessary reagents and conditions for the preparation of but-1-ene from 1-bromobutane. b) Identify the type of reaction and explain the mechanism for the preparation of but-1-ene from 1-bromobutane using curly arrows to represent the movement of electron pairs. Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

118. Main Menu We Are Here

119. Main Menu Lesson 13: Condensation Reactions  Objectives:  Describe with equations the reaction of alcohols with carboxylic acids  Describe with equations the reaction of amines with carboxylic acids  Complete a lovely-smelling esters experiment

120. Main Menu Condensation Reactions  A reaction in which two molecules join together, and produce a molecule of water as a by-product.  Nuff said

121. Main Menu Esterification – the reaction of alcohols and carboxylic acids  Carboxylic acids react with alcohols to make esters:  The ester linkage is outline in red  Carboxylic acid + alcohol ester + water  You may need to review your mind-map for details on naming esters…basically the alcohol gives the ‘-yl’ part and the acid the ‘- oate’ part H + cat

122. Main Menu Amides – the reaction of amines and carboxylic acids  Carboxylic acids react with amines to make amides:  The amide linkage is outlined in red  Carboxylic acid + amine amide + water  You may need to review your mind-map for details on naming esters  The amine gives the ‘-yl’ part and the acid the ‘-anamide’ part, the N- signifies that the alkyl group is attached to the nitrogen  Note the similarity to esterification

123. Main Menu Draw and name the products of the following reactions:  Ethanoic acid with ethanol  Methanoic acid with butylamine  Pentanoic acid with phenol (C 6 H 5 OH)  Propanoic acid with methylamine

124. Main Menu Key Points  Carboxylic acid + alcohol  ester + water  Carboxylic acid + amine  amide + water

125. Main Menu Lesson 14 Condensation Polymerisation

126. Main Menu Refresh  What is the IUPAC name of CH 3 CH 2 CONH 2 ? A. Aminopropanal B. Ethanamide C. Propylamine D. Propanamide Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

127. Main Menu We Are Here

128. Main Menu Lesson 14: Condensation Reactions  Objectives:  Describe with equations the condensation reactions of diacids with diols  Describe with equations the condensation reactions of diacids with diamides  Perform the nylon rope-trick

129. Main Menu Polyesters  Polyesters form from monomers containing two functional groups  For example dicarboxylic acids and dialcohols  Each end of each molecule forms an ester linkage, allowing for long chains to build up

130. Main Menu Polyamides  Similar to polyesters, polyamides form from monomers containing two functional groups  For example dicarboxylic acids and diamines  Each end of each molecule forms an amide linkage, allowing for long chains to build up

131. Main Menu A quick note  You can also get condensation polymerisation from monomers containing one of each of the functional groups.  The best example is amino acids and proteins:

132. Main Menu Key Points  Polyesters form from monomers containing two acid and two alcohol groups  Polyamides form from monomers containing two acid and two amine groups

133. Main Menu Lesson 15 Geometrical Isomerism

134. Main Menu Refresh Which formula represents a polyamide? A. ( CH 2 –CHCl ) n B. ( NH–(CH 2 ) 6 –NH–CO–(CH 3 ) 4 – CO ) n C. ( CF 2 –CF 2 ) n D. ( O–(CH 2 ) 2 –O–CO–--–CO ) n Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

135. Main Menu We Are Here

136. Main Menu Lesson 15: Geometrical Isomerism  Objectives:  Understand the term stereoisomerism  Understand and identify geometrical isomerism  Understand the chemical significance of cis-trans isomerism

137. Main Menu Molecular Modelling  Make a molecule of but-2-ene  Compare your model with your neighbours

138. Main Menu Stereoisomerism  Stereoisomers are compounds with the same structural formula but different 3D arrangement of atoms  There are two types of stereoisomerism:  Geometrical isomerism  Optical isomerism

139. Main Menu Geometrical (cis-trans isomerism)  It happens because double bonds are not free to rotate  Each C=C carbon must have two different groups attached to it.  In the trans isomer, the substituents (the –CH 3 groups) are on opposite sides of the double bond  In the cis isomer, the substituents are on the same side of the double bond  Geometric isomerism involves the arrangement of groups around a double bond  Or a single bond that can’t rotate freely such as in a cyclic compound

140. Main Menu Properties  Chemical and physical properties will often be similar but there can be important differences as you are about to see….

141. Main Menu To do (individually, not pairs):  Build, draw and label the cis and trans isomers of:  Pent-2-ene  2,3-dichloro-but-2-ene  1,2-dichlorocyclopropane  1,2-dichlorocyclobutane  Research the melting/boiling points of cis/trans but-2-ene, hex- 3-ene and oct-4-ene. What pattern do you notice between the cis and trans isomers? Why do you think this happens?  Draw the cis and trans isomers of 1,2-dichloroethene. Predict, with a reason, which you think will have the higher boiling points. Research online to determine whether you were right and think of a reason if you were wrong.

142. Main Menu Chemical properties of geometric isomers  Can be different  For example:  Why do you think this happens?  Hint: think about the previous couple of lessons

143. Main Menu Research  Research online the importance of geometrical isomerism  Find three examples of commercial compounds (medicines, plastics etc) where geometrical isomerism plays a key role in their properties

144. Main Menu Key Points  Cis isomers: the substituents are on the same side  Trans isomers: the substituents are on opposite sides  Cis alkenes have lower mp/bp than trans due to ‘rounder’ shape  Cis halogenoalkenes have higher mp/bp due to polarity  Chemical properties can be different where cis brings groups close enough to react

145. Main Menu Lesson 16 Optical Isomerism

146. Main Menu Refresh  The molecular formula, C 3 H 4 Cl 2 represents several isomeric compounds. Some isomers are cyclic and some are unsaturated. a) 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 (4 structures needed). Reviewing Your Notes You should spend 60 seconds reviewing your notes from last lesson before attempting this. Your notes and mind-map must be ready for me to inspect.

147. Main Menu We Are Here

148. Main Menu Lesson 16: Optical Isomerism  Objectives:  Understand and identify optical isomerism  Understand the chemical significance of optical isomerism

149. Main Menu Modelling  Build a model of 2-methylbutan-2-ol  Compare your model with your neighbours  Have you all made the same thing?

150. Main Menu Optical Isomerism  Optical isomerism occurs when you have at four different groups all bonded to a central atom.  For example: amino acids  Build these for yourself to see that they are different

151. Main Menu Some terminology  The central carbon is referred to as ‘chiral’  You will see books refer to the ‘chiral carbon’ or ‘chiral centre’  You may see books talking about the ‘chirality’ of a molecule  A molecule might be described as ‘chiral’ if it has a ‘chiral centre’  A carbon must have 4 different groups to be chiral  The two optical isomers are referred to as enantiomers  A racemic mixture is a one with a 50:50 mix of the two enantiomers  Enantiomers can be referred to as right or left handed  If you see ‘R-’ or ‘L-’ in a name, this is what they are referring to  There is a standard way to work this out but we don’t need it!

152. Main Menu Properties of optical isomers  Enantiomers share virtually identical chemical and physical properties  However:  Two enantiomers will rotate plane- polarised light in opposite directions…hence the term ‘optical isomerism’  More on the next slide  Chemical properties differ significantly in chemical systems where 3D-shape is important, particularly biochemistry  The image above right shows an enzyme, these are sensitive to the exact shape of a molecule

153. Main Menu Rotation of plane-polarised light  Light normally vibrates in many different directions  Plane-polarised light only vibrates in one direction  Pure solutions of enantiomers rotate the plane-polarised light in opposite directions  A racemic mixture will not rotate light as the rotations from each enantiomer cancel each other out  This rotation can be detected using a polarimeter

154. Main Menu To do:  Assess whether or not the following compounds display optical isomerism. If they do, draw each of the two enantiomers in 3D and place a * next to the chiral carbon. Build them from molecular models if it helps:  2-chloropropane  2-chlorobutane  2-chloropropanal  chlorocyclopropane  1,2-dichlorocyclobutane  Research the importance of optical isomerism in biochemistry. Give details of two important examples.  Draw a Venn diagram summarising geometrical and optical isomerism

155. Main Menu Key Points  Optical isomers (enantiomers) rotate plane-polarised light in opposite directions  To display optical activity, a compound must have at least four different groups attached to the same atom  The central atom is referred to as chiral