CHEM1049A 2024 Organic Chemistry Past Paper PDF

1 CHEM1049A Organic Chemistry Dr. S. Chetty Email: [email protected] Acknowledgement of material: - Brown et al, Chemistry: The Central Office: C207, Humphrey Raikes Building -...

1 CHEM1049A Organic Chemistry Dr. S. Chetty Email: [email protected] Acknowledgement of material: - Brown et al, Chemistry: The Central Office: C207, Humphrey Raikes Building - Science, Global Edition, 15th Edition. Staff from the School of Chemistry @ Wits Compiled by Dr Shaeen Chetty - 2024  2 O.1: Why study organic chemistry? What is organic chemistry? O.2: Ways of representing organic molecules: Structural formula 2-D structural formula 3-D structural formula (perspective drawing) Line formula O.3: Trivial and IUPAC nomenclature used to name hydrocarbons (alkanes, alkenes, alkynes) O.4: Structural features of organic molecules: acyclic, cyclic, polycyclic, straight-chain, branched chain, saturated, unsaturated. Classification of organic compounds into one of four fundamental classes based on the presence or absence of unsaturation and/or heteroatoms O.5: Describe the structural and chemical features of benzene and explain why it does not behave like a typical unsaturated hydrocarbon. Compiled by Dr Shaeen Chetty - 2024  3 O.6: Recognition and naming of functional groups in a molecule: Alcohols and ethers Compounds with a carbonyl group Aldehydes Carboxylic acids Esters Amines and amides O.7: Isomerism, and why it is an important factor in accounting for the vast number of organic compounds Structural isomerism Stereoisomerism (conformational, geometric, enantiomers) Chirality examples and 3-D structural formulae or enantiomers O.7: Define the terms nucleophile and electrophile, and identify nucleophilic and electrophilic sites in molecules. O.8: Classify organic reactions as addition, elimination or substitution processes. Compiled by Dr Shaeen Chetty - 2024  4 O.9: Organic Reactions O.10: Modern materials. Reactions of alkanes - substitution Explain what a polymer means and classify different types of polymers. Combustion of hydrocarbons Explain the difference between Condensation reactions (esterification addition polymers and condensation and formation of amides) polymers and give equations to show Addition reactions of alkenes and the formation of different polymers of alkynes both types. Reactions of aromatic hydrocarbons The molecules of life: Explain how Reactions of alcohols α-amino acids link to give proteins Reactions of ethers and polypeptides. Oxidation and reduction of aldehydes and ketones Synthesis of carboxylic acids Reactions of carboxylic acids Reactions of amines Compiled by Dr Shaeen Chetty - 2024  5 Why study Organic Chemistry? Natural Products Synthetic Materials Compounds (Smart materials & (Dyes, Paints, Glue, Composites) Flavourings, Perfumes, Cosmetics) Organic Chemistry Chemical Biology Environmental (Understand the (Agrochemicals) chemical reactions within organisms) Medicine Energy (Fuels) (Drug Discovery & Pharmaceuticals) Compiled by Dr Shaeen Chetty - 2024  6 What is Organic Chemistry? Chemistry of compounds containing carbon & their reactions. Carbon is in group lV in the periodic table & can have a maximum of 4 bonds, often with a C-H bond. Hydrocarbons contains only C & H. Compounds can also contain O, N, S, P (heteroatoms). Compiled by Dr Shaeen Chetty - 2024  7 Hybridization Compiled by Dr Shaeen Chetty - 2024  8 Representing Organic Compounds Compiled by Dr Shaeen Chetty - 2024  9 Representing 3-D Organic Compounds Compiled by Dr Shaeen Chetty - 2024  10 Example: Draw the 2-D, 3-D & Line structures for the following 1. CH3CH3 2. CH3CH2CH2CH3 Compiled by Dr Shaeen Chetty - 2024  11 Condensed 2-D Structure 3-D Structure Line Structure Formula CH3CH3 CH3CH2CH2CH3 Compiled by Dr Shaeen Chetty - 2024  12 Hydrocarbons Hydrocarbons are compounds that contain only carbon and hydrogen. Three main classes: Alkanes Alkenes Alkynes Compiled by Dr Shaeen Chetty - 2024  13 Alkanes Have only single bonds. General formula: CnH2n+2 End in –ane Alkanes are known as saturated hydrocarbons, as they contain the maximum number of hydrogen atoms Compiled by Dr Shaeen Chetty - 2024  14 Alkenes & Alkynes Alkene Alkenes have a double bonds between carbons H H Alkenes are unsaturated General formula: CnH2n H C C H Alkyne Alkynes have a triple bonds between carbons General formula: CnH2n-2 Alkynes are unsaturated H C C H Compiled by Dr Shaeen Chetty - 2024  15 Naming Organic Compounds Trivial Names: a common name often based on historical origins (non-systematic) Systematic Names: - internationally accepted set of rules - International Union of Pure and Applied Chemistry (IUPAC) Trival Name: Acetic acid IUPAC Name: Ethanoic acid Derived from: Acetum which is Latin for vinegar Compiled by Dr Shaeen Chetty - 2024  16 Organic Nomenclature Three parts to a compound name: - Parent: Tells how many carbons are in the longest continuous chain. - Suffix: Tells what type of compound it is. - Prefix: Tells what groups are attached to chain. Prefix Parent Suffix Compiled by Dr Shaeen Chetty - 2024  17 Prefixes Group Name No. of Prefix same F Fluoro group Cl Chloro 2 di Br Bromo 3 tri 4 tetra I Iodo 5 penta NO2 Nitro NH2 Amino Compiled by Dr Shaeen Chetty - 2024  18 Parent Parent Number of Carbon atoms How many carbons in the Meth- 1 longest chain? Eth- 2 Homologous series Prop- 3 Consistent difference of CH2 But- 4 between family members Pent- 5 Similar chemical properties Hex- 6 Related physical properties Hept- 7 Oct- 8 Non- 9 Dec- 10 Compiled by Dr Shaeen Chetty - 2024  19 Naming Organic Compounds 1.Find the longest chain in the molecule. 2.Number the chain from the end nearest the first substituent encountered. 3.List the substituents as a prefix along with the number(s) of the carbon(s) to which they are attached. Compiled by Dr Shaeen Chetty - 2024  20 If there is more than one type of substituent in the molecule, list them alphabetically. Don’t include the prefixes di-, tri-, tetra-, etc. in alphabetising Compiled by Dr Shaeen Chetty - 2024  21 Example: Name the following compounds CH3 CH2CH3 CH CH H3C CH2CH3 Compiled by Dr Shaeen Chetty - 2024  22 Compiled by Dr Shaeen Chetty - 2024  23 Structural features of organic compounds – Ring Structures Alkanes that form rings or cycles. Possible with at least three C atoms, but sp3 hybridization requires 109.5° angles—not a very stable molecule. Four-C ring is also not very stable. Five-C and more have room for proper bond angle. Naming: add cyclo- as a prefix to alkane name. Compiled by Dr Shaeen Chetty - 2024  24 Example: Name the following compounds Compiled by Dr Shaeen Chetty - 2024  25 Terminology 1. Acyclic: Open chain compound with a linear structure. 2. Cyclic: Compounds that form a ring structure. 3. Polycyclic: Several cyclic structures linked together. 4. Straight Chain: Compounds that form a linear structure. 5. Branched Chain: Compounds that have alkyl side- chains. 6. Saturated: Consists of only single bonds. Compiled by Dr Shaeen Chetty - 2024  26 7. Unsaturated: Contains σ and π bonds within the compound. 8. Heteroatom: Any atom that is not a carbon or hydrogen. 9. Heterocycle: Ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring 10. Aromatics with heteroatom (heteroaromatic): Compound with a ring structure which is both heterocyclic and aromatic. 11. Aromatic hydrocarbon: Hydrocarbon compounds that contain a planar, cyclic arrangement of carbon atoms linked by both σ and delocalised π bonds. Compiled by Dr Shaeen Chetty - 2024  27 Isomerism Isomer: Leads to structural diversity and a vast number of compounds There are two classes of isomers: 1. Structural Isomers 2. Stereoisomers Compiled by Dr Shaeen Chetty - 2024  28 Structural Isomers Same molecular formula but a different arrangement of atoms. Different “connectivity” between atoms: sequence of bonds between atoms is different Different physical properties (and in some cases, different chemical properties) Compiled by Dr Shaeen Chetty - 2024  29 Examples: Draw all the possible structural isomers for C4H10 Compiled by Dr Shaeen Chetty - 2024  30 Stereoisomers Stereoisomer: Shape is important! We often need to use 3-D projection formulae 3 different classes of stereoisomers: 1. Conformational 2. Geometric 3. Enantiomers Compiled by Dr Shaeen Chetty - 2024  31 1. Conformational Isomers Require: σ bonds for free rotation about these bonds No bond is broken, energy barrier is low Two conformers: Compiled by Dr Shaeen Chetty - 2024  32 2. Geometric Isomers Require: a rigid unit about which rotation is NOT possible Example: a π bond or a ring Interconversion of isomers required Alkane Alkene All single or σ bond C=C bond – 1σ bond & 1π Fully saturated bond Rotation about C-C bond is Unsaturated possible Rotation about C=C bond is No geometric isomers not possible possible Geometric isomers possible Compiled by Dr Shaeen Chetty - 2024  33 Two types of isomers: 1. Cis – on the same side (also called Z) 2. Trans – on opposite sides (also called E) Different physical properties (similar chemical properties) Example: But-2-ene Compiled by Dr Shaeen Chetty - 2024  34 3. Enantiomers Require: saturated sp3 hybridised carbon (tetrahedral) with 4 different substituents These molecules are non-superimposable – but are mirror images of one another. Enantiomers are known as chiral compounds A carbon atom attached to four different atoms or groups is called a chiral carbon. Have virtually identical chemical properties Physical properties are identical EXCEPT: they interact with plane polarised light differently Compiled by Dr Shaeen Chetty - 2024  35 They have optical activity and are known as optical isomers Optical activity measured using a polarimeter Enantiomers rotate plane polarised light to the: Right – Dextrorotatory (+) Left – Laevorotatory (-) A mixture of 50% (+) and 50% (-) = Racemic mixture and the mixture is optically INACTIVE, but the individual molecules are still optically active. Compiled by Dr Shaeen Chetty - 2024  36 Remember: Molecules with one stereogenic centre exist as a pair of enantiomers. Many pharmaceuticals are chiral molecules. Thalidomide (S) Sedative, painkiller, antiemetic, antidepressant (R) Teratogen – intercalates DNA & affects limb & ear development Sold as a racemate (1957-62) Caused 10,000 birth defects Compiled by Dr Shaeen Chetty - 2024  37 Compiled by Dr Shaeen Chetty - 2024  38 Classification of Organic Molecules Saturated - C & H only - Single / σ bonds only Hydrocarbons Unsaturated - C & H only - Multiple (σ & π) bonds (C=C, C≡C) Organic Compounds Saturated - C,H and other atoms (O,S,N,P) - Single / σ bonds only Hydrocarbons + Heteroatoms Unsaturated - C, H and other atoms (O,P,N,S) - Multiple (σ & π) bonds (C=C, C≡C, C=O, C=N, C≡N) Compiled by Dr Shaeen Chetty - 2024  39 Addition Reactions of Alkenes & Alkynes Hydrogenation Halogenation Hydrogen Halide Water Compiled by Dr Shaeen Chetty - 2024  40 Hydrogenation Addition of hydrogen gas using a platinum or nickel catalyst and a temperature up to 500℃. Used to manufacture margarine Compiled by Dr Shaeen Chetty - 2024  41 Halogenation Addition of a halogen (Cl2 or Br2) with UV light as a catalyst Used as a test for unsaturation (double or triple bonds), the brown colour of bromine is decolourises. Compiled by Dr Shaeen Chetty - 2024  42 Hydrohalogenation Addition of a hydrogen halide (HCl, HBr, HI) to produce a haloalkane No catalyst required Compiled by Dr Shaeen Chetty - 2024  43 Hydration Addition of water using acid (usually H2SO4) as a catalyst producing an alcohol Compiled by Dr Shaeen Chetty - 2024  44 Alkynes The reactions will occur twice for alkynes Compiled by Dr Shaeen Chetty - 2024  45 Combustion of Hydrocarbons The C–C and C–H bonds are very strong. Therefore, alkanes are very unreactive At room temperature alkanes do not react with acids, bases, nor strong oxidizing agents Alkanes do combust in air (making them good fuels due to their stability): 2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(l) ΔH= -2855 kJ Complete combustion (excess oxygen) Incomplete combustion (limited oxygen) Compiled by Dr Shaeen Chetty - 2024  46 Functional Groups Definition: An atom, or group of atoms, that imparts characteristic chemical properties to an organic compound. Functional Groups (FGs) include hetero-atoms (not H or C) & multiple bonds FGs are the most reactive sites in a molecule Compiled by Dr Shaeen Chetty - 2024  47 Compiled by Dr Shaeen Chetty - 2024  48 Compiled by Dr Shaeen Chetty - 2024  49 Functional Group Priorities Rules for nomenclature: 1. The parent hydrocarbon is the longest continuous chain containing the highest priority functional group. 2. The chain is numbered in the direction that gives the highest priority functional group the lowest possible number. 3. If there is a functional group and a substituent the functional group gets the lowest possible number. 4. If the same number for the functional group is obtained in both directions, the chain is numbered in the direction that gives a substituent the lowest possible number. 5. If there is more than one substituent, the substituents are cited in alphabetical order. Compiled by Dr Shaeen Chetty - 2024  50 Example: Identify the functional groups in the following compounds Compiled by Dr Shaeen Chetty - 2024  51 Alcohol Suffix: -ol Note the position of the –OH group C OH H H H Parent: 3C – prop Single bonds between carbons – ane H C C C OH Carbon 1 has –OH group – 1-ol H H H Propan-1-ol or Propanol Compiled by Dr Shaeen Chetty - 2024  52 Primary (1°) Secondary (2°) Tertiary (3°) Primary alcohols Secondary Tertiary alcohols have the –OH alcohols have have the –OH group bonded a the –OH group group bonded a carbon bonded bonded a carbon carbon bonded to 1 other carbon bonded to 2 to 3 other directly. other carbons carbons directly. directly. Compiled by Dr Shaeen Chetty - 2024  53 Carboxylic Acids O Contain a –COOH group C OH Suffix = –oic acid Compiled by Dr Shaeen Chetty - 2024  54 Esters Esters are the products R' C O R'' of reactions between carboxylic acids and O alcohols. They are found in many fruits and perfumes. Naming: name the alcohol part as an alkyl name; separate word is the acid part as an -ate anion. Compiled by Dr Shaeen Chetty - 2024  55 Ether Suffix: -ether Polar molecule that is inert hence makes an excellent solvent. Compiled by Dr Shaeen Chetty - 2024  56 Aldehydes & Ketones Aldehyde Suffix: -al Ketone Suffix: -one Both groups have a carbonyl (C=O) Aldehydes are terminal Compiled by Dr Shaeen Chetty - 2024  57 Amines Suffix: -amine R-NH2 Compiled by Dr Shaeen Chetty - 2024  58 Amides O Suffix: -amide C N Compiled by Dr Shaeen Chetty - 2024  59 Condensation Reactions 1. Esterification - Between a carboxylic acid and an alcohol to produce an ester and water - Catalyst is heat and an acid (eg. H2SO4) Compiled by Dr Shaeen Chetty - 2024  60 2. Amide - Between a carboxylic acid and an amine to produce an amide - DCC (N,N'-Dicyclohexylcarbodiimide) is a catalyst Compiled by Dr Shaeen Chetty - 2024  61 Compiled by Dr Shaeen Chetty - 2024  62 Benzene A special type of unsaturated compound: C6H6 Molecule as a whole is PLANAR. Neither structure actually exists, which is the real structure? Auguste Kekule first realized that benzene has a ring structure when he dreamed of snakes biting their own tails. Compiled by Dr Shaeen Chetty - 2024  63 Evidence: Normal C-C single bond: 1.54 Å, normal C=C double bond: 1.34 Å Benzene bond lengths are all 1.38 Å: bond order between single and double Unlike alkenes and alkynes, π-electrons do not sit between two atoms. Not alternating single and double bonds. Electrons are delocalised; this stabilizes aromatic compounds. Compiled by Dr Shaeen Chetty - 2024  64 The benzene family includes all “aromatic compounds” or “arene” e.g. naphthalene, benzene etc. Many aromatic hydrocarbons are known by their common names. Compiled by Dr Shaeen Chetty - 2024  65 Modern Materials: Polymers Monomer: repeating structural units Polymer: Polymer is a term used to describe large molecules consisting of repeating structural units, or monomers, connected by covalent chemical bonds. Polymerisation: process of bonding monomers, or single units together through a variety of reaction mechanisms to form longer chains called polymers. Examples: virtually all plastics, rubber etc. Biopolymers: proteins, polysaccharides, nucleic acids Compiled by Dr Shaeen Chetty - 2024  66 Compiled by Dr Shaeen Chetty - 2024  67 Polymerization 1. Addition Polymerisation monomer molecules are added to a growing polymer chain one at a time. No small molecules are eliminated in the process. the monomer is an unsaturated compound which, after an addition reaction, becomes a saturated compound. There are three stages in the process of addition polymerisation. 1. Initiation refers to a chemical reaction that triggers off another reaction. 2. Chain propagation is the part where monomers are continually added to form a longer and longer polymer chain. 3. Termination refers to a chemical reaction that destroys the reactive part of the polymer chain so that propagation stops. Compiled by Dr Shaeen Chetty - 2024  68 Compiled by Dr Shaeen Chetty - 2024  69 Polyethene - When lots of ethene molecules bond together, polymer called polyethene (commonly called polyethylene) is formed. - Ethene is the monomer which, when joined to other ethene molecules, forms the polymer polyethene. - Polyethene is a cheap plastic that is used to make plastic bags and bottles. Compiled by Dr Shaeen Chetty - 2024  70 2. Condensation Polymerisation two monomer molecules form a covalent bond and a small molecule such as water is lost in the bonding process. a. Polyester Polyesters are synthetic materials formed from a repeating pattern of ester functional groups. While many types exist, the term "polyester" often refers specifically to polyethylene terephthalate (PET). PET is created by combining ethylene glycol (an alcohol) and terephthalic acid (a carboxylic acid). During this chemical reaction, a hydrogen atom from the alcohol and a hydroxyl group from the carboxylic acid join to form water, which is released. This process, known as condensation polymerization, results in the formation of a new bond between an oxygen atom and a carbon atom, called an ester linkage. Properties - resistant to stretching and shrinking, they are easily washed and dry quickly, and they are resistant to mildew - stretched out into fibres and can then be made into fabric and articles of clothing. Compiled by Dr Shaeen Chetty - 2024  71 Compiled by Dr Shaeen Chetty - 2024  72 b. Nylon Nylon is very strong and resistant, and is used in fishing line, shoes, toothbrush bristles, guitar strings and machine parts to name just a few. Nylon is formed from the reaction of an amine (1,6- diaminohexane) and an acid monomer (adipic acid) The bond that forms between the two monomers is called an amide linkage. An amide linkage forms between a nitrogen atom in the amine monomer and the carbonyl group in the carboxylic acid. Compiled by Dr Shaeen Chetty - 2024  73 The Molecules of Life Amino acids have amine and carboxylic acid functional groups. Proteins are polymers of α-amino acids. A condensation reaction between the amine end of one amino acid and the acid end of another produces a peptide bond, which is an amide linkage. Compiled by Dr Shaeen Chetty - 2024  74 Compiled by Dr Shaeen Chetty - 2024  75 Compiled by Dr Shaeen Chetty - 2024  76 Primary structure is the sequence of amino acids. Amide bonds form between amino acids. This is repeated MANY times for a polypeptide/protein. Compiled by Dr Shaeen Chetty - 2024  77 Classification of Organic Reactions 1. Addition (increases saturation at C) 2. Elimination (increases unsaturation at C) 3. Substitution (degree of saturation at C is not changed) Compiled by Dr Shaeen Chetty - 2024  78 Example: Identify the type of reaction in each of the following: Compiled by Dr Shaeen Chetty - 2024  79 Electrophiles & Nucleophiles Reagents and substrates can be classified according to how their electrons are arranged: 1) Unpaired electrons -Radicals (homolytic reactions) 2) Paired electrons (electron poor or electron rich species) (heterolytic/polar reactions) Compiled by Dr Shaeen Chetty - 2024  80 Compiled by Dr Shaeen Chetty - 2024  81 What are electrophiles & nucleophiles? Electrophile: - literally means “electron loving” - it is a fully or partially positively charged site - it is looking for electrons - It is Electron-poor Nucleophile: - literally means “nucleus loving” - it is a fully or partially negatively charged site - it has got electrons to give - It is Electron-rich Compiled by Dr Shaeen Chetty - 2024  82 Curly arrows are used to show movement of electrons in the reaction Compiled by Dr Shaeen Chetty - 2024  83 Predicting Organic Reactions - Reactions occur between sites of opposite polarity (i.e.+ or δ+ will react with – or δ-) Compiled by Dr Shaeen Chetty - 2024  84 Reactions of Alkanes Compiled by Dr Shaeen Chetty - 2024  85 Substitution Reactions OH- > F- > Cl- > Br- > I- If the anion is higher on the list, it will substitute for an anion lower on the list. CH3Cl + HF → CH3F + HCl CH3Cl + HBr → No Reaction Compiled by Dr Shaeen Chetty - 2024  86 Radical Reactions - These reactions don’t use nucleophiles or electrophiles, but instead they use “free radicals” which have unpaired electrons. - Both reactants donate one electron to form the new bond. - E.g. H Cl - Substitution: These reactions are difficult to control and therefore there are mixtures of products. Compiled by Dr Shaeen Chetty - 2024  87 Addition Reactions of Alkenes & Alkynes The typical reaction for unsaturated hydrocarbons is an addition reaction, where the π electrons from the double bond act as the nucleophile. The obvious reagent to react with an alkene in an addition reaction? An electrophile. Substitution and elimination reactions are less important for unsaturated systems. Compiled by Dr Shaeen Chetty - 2024  88 Compiled by Dr Shaeen Chetty - 2024  89 Alkynes Alkynes undergo many of the same reaction's alkenes do. As with alkenes, the impetus for the reaction is the replacement of π-bonds with σ-bonds. When there is a halogen already attached to the alkene, the 2nd halide ion will add to the same position (the side with fewer hydrogens). Compiled by Dr Shaeen Chetty - 2024  90 Markovnikov’s Rule In the addition of HX to an alkene, the hydrogen adds to the carbon atom of the double bond bearing the greater number of hydrogen atoms bonded directly to it. Compiled by Dr Shaeen Chetty - 2024  91 Hydrohalogenation Mechanism Compiled by Dr Shaeen Chetty - 2024  92 Reactions of Benzene Compiled by Dr Shaeen Chetty - 2024  93 2. Halogenation Compiled by Dr Shaeen Chetty - 2024  94 3. Alkylation (Friedel-Crafts) 4. Acylation (Friedel-Crafts) Compiled by Dr Shaeen Chetty - 2024  95 Reactions of Alcohols Compiled by Dr Shaeen Chetty - 2024  96 Reactions of Ethers Compiled by Dr Shaeen Chetty - 2024  97 Oxidation & Reduction of Aldehydes & Ketones Compiled by Dr Shaeen Chetty - 2024  98 Reduction Compiled by Dr Shaeen Chetty - 2024  99 Potassium Dichromate (K2Cr2O7) 1° Alcohol + K2Cr2O7 → Aldehyde + K2Cr2O7 → Carb. Acid 2° Alcohol + K2Cr2O7 → Ketone 3° Alcohol + K2Cr2O7 → No Reaction Compiled by Dr Shaeen Chetty - 2024  100 Ozonolysis This reaction cleaves the double bond in the alkene to form a carbonyl species i.e. a species containing the C=O group. The reaction can be summarised as shown below. The exact identity of the products of this reaction will depend upon the nature of the R groups. If for instance we start with the following alkene: Compiled by Dr Shaeen Chetty - 2024  101 Synthesis of Carboxylic Acids Compiled by Dr Shaeen Chetty - 2024  102 Reactions of Carboxylic Acids Compiled by Dr Shaeen Chetty - 2024  103 Compiled by Dr Shaeen Chetty - 2024  104 Reactions of Amines Carboxylic acid + Amine → Amide + Water Compiled by Dr Shaeen Chetty - 2024  105 Compiled by Dr Shaeen Chetty - 2024  106 Having studied this chapter, you should be able to: Represent an organic molecule using a structural formula, 2-D and 3-D structural formula, and line drawing. Name hydrocarbons. Recognise common structural features on organic molecules. Explain the meaning of isomerism; recognise structural and geometric stereoisomerism. Identify functional groups in organic molecules. Describe addition reactions and condensation reactions Describe the structural and chemical features of benzene and explain why it does not behave like a typical unsaturated hydrocarbon. Explain what is meant by a polymer and classify different types of polymers. Explain the difference between addition polymers and condensation polymers and give equations to show the formation of different polymers of both types. Explain how α-amino acids link to give proteins and polypeptides. Classify organic reactions as, addition, elimination or substitution processes. Define the terms nucleophile, and electrophile, and identify nucleophilic and electrophilic sites in molecules. Understand reactions of alkanes, alkenes, alcohols, ethers, aldehydes, ketones carboxylic acids and amines. Understand the reactions of organic molecules. Understand the concepts of chirality Compiled by Dr Shaeen Chetty - 2024