Organic chemistry

• Crude oil is a finite resource found in rocks
• Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud
• Mixture


  2 or more elements that are not chemically combined
• The chemical properties of each substance in the mixture are unchanged
• Separating substances in the crude oil mixture

  Physical methods including distillation
• Alkenes


  Hydrocarbons with at least one carbon-carbon double bond, making them unsaturated

  
• Most of the compounds in crude oil consist of molecules made up of hydrogen and carbon only (hydrocarbons)
• Most of these saturated hydrocarbons are alkanes
• Addition polymerisation


  1. Alkenes can be used to make polymers such as poly(ethene) and poly(propene)

  2. Many small molecules (monomers) join together to create very large molecules (polymers)
• First 4 alkenes


  • Ethene
  • Propene
  • Butene
  • Pentene

  
• Hydrocarbons


  Have the general formula: CnH2n+2
• Repeat unit


  Has the same atoms as the monomer because no other molecule is formed in the reaction
• Unsaturated carbons


  • Can be represented in the following forms:
• First 4 alkanes


  • Methane
  • Ethane
  • Propane
  • Butane

  
• When drawing a polymer, remember to draw the bonds coming off the Cs out the brackets and the little 'n' (means there are large numbers of these molecules joined together)
• Reactions of alkenes


  Alkenes react with oxygen in combustion reactions, hydrogen, water and halogens by the addition of atoms across the carbon-carbon double bond

  
• Reactions of alkenes


  1. C=C bond is broken to form a C-C bond

  2. The compound added splits into two groups and the two groups are added to the 2 different carbons in the C=C bond (each group can be added to either carbon)

  3. H2 splits into 2 H's, H2O splits into a H and an OH, Br2 splits into 2 Br's (same for Cl2 or I2)

  
• Condensation polymerisation


  1. Involves monomers with two functional groups

  2. When they react, they join together, usually losing small molecules such as water, and so the reactions are called condensation reactions

  3. Simplest polymers are produced from two different monomers with two of the same functional groups on each monomer
• Alcohols


  Contain the functional group -OH
• Fractional distillation


  Oil is heated in the fractionating column and the oil evaporates and condenses at different temperatures
• First 4 alcohols


  • Methanol
  • Ethanol
  • Propanol
  • Butanol

  
• Polyester


  • 1 monomer with 2 carboxylic acid functional groups and 1 monomer with 2 alcohol functional groups
• The many hydrocarbons in crude oil can be separated into fractions each of which contains molecules with a similar number of carbon atoms
• Reactions of alcohols


  They burn in air, dissolve in water to form a neutral solution, react with sodium to produce hydrogen and a salt, and react with oxidising agents to form carboxylic acids

  
• The fractionating column works continuously, with heated crude oil piped in at the bottom
• The various fractions are constantly tapped off at the different levels where they condense
• Fuels produced from crude oil fractions

  • Petrol
  • Diesel oil
  • Kerosene
  • Heavy fuel oil
  • Liquefied petroleum gases
• Amino acids


  • They have two different functional groups in a molecule (an amine group and a carboxylic acid group)
  • They react by condensation polymerisation to produce polypeptides
  • Different amino acids can be combined in the same chain to produce proteins
• DNA (deoxyribonucleic acid)


  • A large molecule essential for life- it encodes genetic instructions for the development and functioning of living organisms and viruses
  • Most molecules are two polymer chains, made from four different monomers called nucleotides, in the form of a double helix
• Uses of alcohols


  • Methanol: chemical feedstock, in anti-freeze, to make biodiesel
  • Ethanol: the main alcohol in alcoholic drinks, used as a solvent and fuel
  • All 4: can be used as fuels

  
• Materials produced by the petrochemical industry

  • Solvents
  • Lubricants
  • Polymers
  • Detergents
• The vast array of natural and synthetic carbon compounds occur due to the ability of carbon atoms to form families of similar compounds
• Producing ethanol


  1. Ethanol can be produced by fermentation of sugar with yeast, using renewable sources

  2. Conditions: about 35°C, anaerobic (without oxygen) and yeast enzyme catalyst

  3. Sugar → ethanol + carbon dioxide
• Other naturally occurring polymers important for life

  • Proteins (monomer = amino acid)
  • Starch (monomer = glucose)
  • Cellulose (monomer = glucose)
• Carboxylic acids


  Have the functional group -COOH
• First 4 carboxylic acids

  • Methanoic acid
  • Ethanoic acid
  • Propanoic acid
  • Butanoic acid

  
• Reactions of carboxylic acids

  They dissolve in water to produce acidic solutions, react with metal carbonates to produce carbon dioxide, a salt and water, and react with alcohols in the presence of an acid catalyst to produce esters
• Carboxylic acids do not ionise completely in solutions, so do not release many H+ ions, making them weak acids
• This means carboxylic acids have a higher pH (less acidic) than solutions of strong acids of the same concentration
• Viscosity


  How runny a hydrocarbon is