Module 4 – Core organic chemistry Archives

Synthetic Routes

Heat/ reflux is a condition for most of the reactions, so mention both, as well any acid catalysts. • AS Mechanisms- radical substitution, nucleophilic substitution and electrophilic addition.

Mass Spectrometer: Sample is placed, vaporised and ionised to form positive ions. Ions are accelerated. Heavier ions move slowly and more difficult to deflect than lighter ions, so ions of each isotope separated. In vacuum so no interference with other molecules. •...

Infrared Spectroscopy

Covalent Bonds: Covalent bonds can absorb infrared radiation, which makes the bonds vibratebonds bend or stretch more. Stretch and bend are two types of vibration. Bonds have energy normally and vibrate. • Wavenumber: Wavenumber is proportional to frequency and used...

Combining Questions

Empirical and Molecular Formula: • Do elemental analysis by using percentage composition data to determine empirical formula and then molecular formula. • Sometimes volumetric analysis given, use Mr Moles to work out Mr. • If empirical formula and molecular formula...

Chemical Reactions of Alkanes

Unreactive: C-C bonds non- polar. C- H non- polar as electronegativity of C and H similar. • Complete Combustion: Alkanes burn completely with plentiful supply of oxygen to produce carbon dioxide and water to give out heat. C gives CO2 and half of H gives H2O. •...

Properties of Alkenes

• Three Sigma Bonds: For each carbon atom in double bond, three of the four electrons are used in three σ- bond/ sigma bond. • One Pi Bond: One electron left in p- orbital. Sideways overlap of two p orbitals on each carbon atom forms π-bond above and below plane of...

Stereoisomerism

Stereoisomers: Compounds with same structural formula but different arrangement of atoms in space. So chemically different. • If asks what type of stereoisomerism- E/Z. • Why E/Z Isomerism: Stereoisomerism arises because… - Must have double bond as rotation around...

Reactions of Alkenes

Reactivity: Alkenes more reactive than alkanes as the π- electrons are more exposed than σ- bond electrons. The π- bond is weaker than σ- bond. • Addition Reactions: Each of these reactions involves addition of molecule across double bond, causing π- bond (double...

Electrophilic Addition in Alkenes

• Electrophilic Addition: A reaction mechanism. • Electrophile: It is a species that is attracted to an electron- rich centre, where it accepts a pair of electrons to form a covalent bond. Usually a positive ion or contains δ+ charge. It can be something like HBr-...

Polymerisation in Alkenes

• Addition Polymerisation: Polymers are named as poly- (alkene monomer). • All alkene reactions in this topic are addition reaction so 100% atom economy- no waste products. • Remember n, should be on correct side and correct posiiton. • Repeat Unit: Repeat unit is...

Properties of Alcohols

Alcohols: Contain hydroxyl group. Simplest alcohol is methanol- CH3OH and it’s used as fuel, chemical feedstocks and solvents. Next in alcohol homologous series is ethanol and used in alcoholic drinks, fuel and solvent. • If make methanol using carbon monoxide it’s...

Chemical Reactions of Alcohols

Combustion of Alcohols: Alcohols burn completely in plentiful supply of oxygen to produce carbon dioxide and water, like alkanes. • Oxidising Agent: It is a solution of potassium dichromate, acidified with dilute sulfuric acid. Acidified potassium dichromate + reflux....

Chemistry of Haloalkanes

Naming Haloalkanes: If two+ halogen present, listed in alphabetical order. Like alcohols, haloalkanes classed as primary, secondary and tertiary. • Nucleophiles: An atom or group of atoms that is attracted to an electron- deficient carbon atom, where it donates a pair...

Organohalogen Compounds in the Environment

Organohalogen: Contain at least one halogen atom joined to carbon chain. Used in pesticides, polymers and refrigerators. • Ozone Layer: Ozone layer in the outer edge of the stratosphere. Only a fraction of gases making up ozone layer is ozone. Ozone absorbs the...

Practical Techniques in Organic Chemistry – Need to be able to draw all this.

Preparing a Sample of Organic Liquid: Will need Quickfit apparatus- 1) pearshaped/ round bottom flask, 2) receiver, 3) screw- tap adapter, 4) condenser and 5) still head. • Reflux: The continual boiling and condensing of a reaction mixture back to the original...

Nomenclature of Organic Compounds

IUPAC- international organisation to standardise names. • 3 Types of Hydrocarbons: Aliphatic- containing carbon atoms joined in straight chain, branched chains or non- aromatic rings. Alicyclic- an aliphatic compound containing carbon atoms joining together in a non-...

Representing Formula of Organic Compounds

General Formula: Alcohols is CnH2n+2O but molecular formula for alcohol is CnH2n+2O. Carboxylic acid is CnH2nO2. Ketones is CnH2nO. Cycloalkane is CnH2n. If asks for molecular formula, can’t have OH on the end. • Structural Formula: Usually CH3 at either ends. CH2 in...

Isomerism

Structural Isomers: Compounds with the same molecular formula but different structural formula. Can also have isomers with different functional groups- aldehydes and ketones. - The functional groups and side chains are in different positions along first half of carbon...

Reaction Mechanisms

Covalent Bonds: Their bonds can be broken by homolytic fission or hetrolytic fission. • Homolytic Fission: Breaking of bond. Each of the bonded atoms takes one of the shared pair of electrons from the bond. Now both atoms are radicals- species with a single unpaired...

Properties of Alkanes

Alkane Use: Components of natural gas and crude oil. • Sigma Bond: The type of covalent bonds in alkanes are called sigma bond- It is overlapping of two orbitals, one from each bonding atom. Positioned on line directly between bonding atoms. Each carbon atom in alkane...

Exam Technique- organic

If given unknown compound, identify what functional groups and the reactions and properties related to that. Use any hints in question about compound. First draw displayed formula if just given structural formula. • Pay most attention to the ‘weird’ stuff question...

Organic Chemistry

Organic is when it contains the element carbon. • Hydrocarbon: A compound containing hydrogen and carbon only. • Saturated: Contains single C—C bonds only. Unsaturated: Contains multiple carbon to carbon bond such as C=C bond. • Homologous Series: It is a series of...

4.2.1 Alcohols

Properties of alcohols - alcohols are polar due to the electronegative hydroxyl group(-OH) which pulls the electrons away from the carbon atom in the C-OH bond. The electronegative oxygen in a polar hydroxyl group draws electron density away from the hydrogen in the...

Haloalkanes

Substitution reactions of haloaklanes: When a haloalkane is reacted with hot aqueous alkali, a nucleophilic substitution occurs. It must be refluxed. To test for the rate of hydrolysis of C-halogen bonds: 1. Add water, to react with the haloalkane to form an alcohol....

4.1.3 Alkenes

Alkenes Unsaturated hydrocarbon containing a σ bond (overlap of orbitals directly between the bonding atoms) and a π bond (sideways overlap of adjacent p-orbitals above and below the bonding C atoms) overlapping. Shape of alkenes - Trigonal planar shape with 120˚ bond...

4.1.2 Alkanes

Alkanes - saturated hydrocarbons containing single C-C and C-H bonds as σ-bonds with free rotation of the σ-bonds. Shape of Alkanes - tetrahedral with bond angle 109°. Electron pairs repel. lone pairs repel more than bonded pairs. Boiling points of alkanes - longer...

4.1.1 Basic Concepts of Organic Chemistry

No. of carbons: meth- 1, eth- 2, prop- 3, but- 4, pent- 5, hex- 6, hept- 7, oct- 8, non- 9, dec- 10 Nomenclature IUPAC rules for naming organic compounds; count carbons on longest carbon chain use functional groups as prefixes or suffixes other side chains are...