Organic Chemistry

• Catalytic Cracking

  • Long chain hydrocarbons are heated until they vaporise.
  • They are past over a hot, powdered aluminum oxide catalyst
  • This breaks the long chain alkanes into a shorter chain alkane and an alkene
• Steam Cracking

  The same as catalytic cracking except the vaporised long chain alkane is mixed with steam at very high temperatures
• What two molecules does cracking always produce

  An alkane and an alkene
• What molecules are saturated and unsaturated

  Alkenes are unsaturated

  Alkanes are saturated
• Bromine Water Test

  Bromine water is orange

  When mixed with alkenes, all of the bromine will react and so the solution loses its orange colour and turns colourless

  If alkanes are mixed with bromine water, they are not reactive enough to react with bromine water so the solution will stay orange.
• Reacting an alkene with hydrogen gas and a catalyst will produce an alkane
• Reacting an alkene with water at a high temperature and with a catalyst will produce an alcohol
• Reacting an alkene and a halogen will produce a halogenoalkane
• Only alkenes undergo addition polymerisation
• General Formula for Alcohol- CnH2n+1OH
• Properties of Alcohols

  • They can be oxidised to carboxylic acids
  • They are flammable
  • They are soluble
• Alcohol Uses

  Solvent in industry

  Fuels

  Alcoholic Drinks
• Ethanol Uses

  Chemical Feedstock

  Biofuel

  Alcoholic Drinks
• Ethene reacts with water at a high temperature and with a catalyst to produce ethanol.

  Conditions- High temperature of 309 degrees. High pressure of 60-70 atm. Phosphoric acid catalyst.
• The reaction of ethene with water is an addition reaction.

  The reaction is cheap and efficient.
• Ethene is made from crude oil which is a finite resource
• Ethanol can be produced by fermentation

  Glucose forms ethanol and carbon dioxide

  Fermentation is the anaerobic respiration by yeast cells to produce ethanol and carbon dioxide
• Fermentation Conditions

  Carried out in fermentation tanks

  Requires yeast cells

  Temperatures of 30-40 degrees

  Must be anaerobic conditions
• Glucose is a renewable resource so cannot run out

  Fermentation is slow and the ethanol produced is not pure
• Carboxylic acids are weak acids

  • They do not fully ionise in water, they do not release all their hydrogen ions
  • The ionisation of carboxylic acids in water is a reversible reaction
  • It is the H+ attached to the OH group that ionises
• Carboxylic acids partially dissociate in water to produce a negative ion and a hydrogen ion.

  The negative ion has an ending of 'anoate ion'
• Carboxylic acids react like any other acids

  • Carboxylic acid + metal → salt + water
  • Carboxylic acid + metal oxide → salt + water
  • Carboxylic acid + metal hydroxide → salt + water
  • Carboxylic acid + metal carbonate → salt + water + carbon dioxide
• Carboxylic acids are made from oxidising an alcohol with an oxidising agent
• Carboxylic acids have the functional group of COOH

  O double bond to C

  OH bond to C

  C to another C/H on other side
• General Formula for carboxylic acids- CnH2n+1COOH
• Esters have a sweet smell
• Esters are volatile
• Esters are used in food flavourings and in perfumes
• An ester is made by reacting a carboxylic acid and an alcohol in the presence of an acid catalyst
• In an ester reaction, the carboxylic acid loses its OH group and the alcohol loses the H from its OH group.

  These combine to form water.
• Ester Group/Link/Bond- COO

  One O is double bonded
• Ethanoic Acid + Ethanol → Ethyl Ethanoate
• A diol has two alcohol functional groups.

  A dicarboxylic acid has two carboxylic acid functional groups.
• To make a polyester, the monomers need to have two carboxylic acid and alcohol groups to form a continuous chain
• Condensation polymers and not addition polymers are biodegradable

  Ester links can be broken down by microorganisms
• An amino acid has three functional groups

  An amino group NH2

  A carboxylic acid group COOH

  An 'R' group The rest of the molecule
• In an amino acid, the Carboxyl group and the amino group are joined by a carbon which also has the R group and a hydrogen connected
• Amino acid group and carboxyl group allows the molecules to react together in a condensation polymer reaction which also produces water.

  The bond is called an amide bond/link or peptide bond
• In amino acid polymerisation, a H from the Amine group is lost and so is the OH from the carboxyl group
• Starch cellulose and glycogen are polymers of glucose