organic chemistry

• organic chemistry -> study of carbon compounds extracted from living organisms
• Hydrocarbons -> class of organic compounds containing carbon and hydrogen - covalently bonded
• Alkanes -> saturated hydrocarbons
• Alkenes -> unsaturated hydrocarbons
• Alkanes are a family of organic compounds in which carbon atoms are single bonded to each other.
• functional group of alkanes -> C--C [single covalent bonds between carbon atoms]
• general formula of alkanes --> CnH2n+2
• A Homologous series is a family of organic compounds with the same general formula, same functional group, and same chemical properties
• Alkanes only undergo substitution reaction
• Substitution Reaction -> Hydrogen is replaced by monovalent atom
• when one hydrogen is removed from alkanes they become alkyls
• CHCl3 and CCl4 are organic solvents
• Organic solvents are volatile, flammable and have low boiling point
• Alkanes burn in excess oxygen to give carbon dioxide and water
• burning of alkanes produces large amounts of heat so they are used as fuels
• the main constituent of natural gas is methane
• Alkenes are a family of organic compounds in which there is a double bond between carbon atoms
• General Formula of Alkenes -> CnH2n
• Functional Group Of Alkenes -> C=C
• Alkenes undergo addition reactions
• Addition Reaction -> a reaction in which 2 monovalent atoms (radicals) are added to 2 adjacent carbon atoms carrying the double bond which will break down to give single bond forming saturated compound
• Types Of Addition Reactions -> Hydrogenation, Halogenation and Hydration
• Hydrogenation -> Alkene + H2 -> Alkane
• Hydrogenation occurs in presence of nickel catalyst and heat
• Halogenation -> adding halogens to alkenes to breakdown double bond between carbon to single bond and form haloalkane
• Hydration -> Alkene + Steam (H2O) -> Alkanol
• Hydration occurs in presence of phosphoric or tungstic acid (catalyst), high heat and pressure
• Alkanes undergo substitution reaction in which 2 products are given
• Alkenes undergo addition reactions in which only one product is given
• Tests for unsaturation [presence of double bond]:

  • using Aqueous Bromine/Bromine in CCl4 (orange) -> Alkane: no change Alkene: decolorization
  • using Acidified Potassium Manganate VII (purple) -> Alkane: no change Alkene: decolorization
• for alkane to react with Bromine, it must be used as liquid Br2 not dissolved in any solvent and reaction must be in presence of light
• Alkenes burn in good supply of oxygen to give CO2 and H2O and a large amount of heat so they can be used as fuels
• Ethene is not used as a fuel, because it is used for manufacturing industrial products like polyethene (plastic) and ethanol (alcoholic drinks)
• Isomers -> organic compounds with same molecular formula and different structural formula
• Crude Oil (Petroleum):

  • Complex mixture of saturated hydrocarbons (alkanes) of similar boiling points
  • Components can be separated by fractional distillation but each section is still a mixture of Alkanes
• Products Of Fractional DistillatIon Of Crude Oil:

  • Refinery Gas -> Heating and Cooking
  • Petrol (Gasoline) -> fuel for cars
  • Naptha -> Chemicals
  • Kerosine (paraffin) -> Jet fuel and stoves
  • Diesel Oil -> fuel for diesel engines
  • Fuel Oil -> fuel for ships and home heating systems
  • Lubricating Oil -> Lubricants, Waxes and Polishes
  • Bitumen -> Roads and Roofs
• Petroleum is a non renewable resource so to obtain more, the lonmg chain alkanes are broken down to small chain alkanes in a process called Cracking
• Cracking -> Breakdown of long chain alkanes to small chain alkanes
• Types Of Cracking:

  • Thermal -> requires high temperature and pressure
  • Catalytic -> requires catalyst
• Cracking of Alkanes can produce Alkenes and Hydrogen so it is considered an industrial process for the preparation of hydrogen like electrolysis