organic chem

• functional group


  pair of molecules which determines how it reacts with similar chemical properties
• homologous series


  same functional group but each successive member has additional CH2
• saturated


  single bond
• unsaturated


  double or triple bond
• molecular formula


  elements in a molecules and number of atoms in an element
• empirical formula


  simplest whole number ratio of the atoms of each element in a compound
• general formula


  simplest algebraic formula for a member of a homologous series
• structural isomers


  same molecular formula but different structural formulae
• stereoisomerism


  same structural formulae but different arrangement of atoms in space
• geometric isomers

  • single covalent bonds are fully rotational
  • double covalent bonds retrict rotation
• conditions of cis/trans and E/Z

  • carbon atom on double bond must be attached to two different groups
  • at least one of those groups must be same on both carbon atoms on double bond
• E/Z

  • can be used to name molecule thats attached to 4 different groups
  • the element with the greatest atomic number is given higher priority
• alkanes

  • CnH2n+2
  • forms tetrahedral with bond angle 109.5
  • only sigma bonds formed
  • non polar as C-H have similar electronegativity
  • insoluble in water as they have no permanent dipoles so they cant form hydrogen bonds
  • unreactive
  • as length of carbon chain increases, boiling point increases
  • increases strength of london forces
  • more electrons than shorter chain
  • greater surface area
  • branching reduces boiling point as it prevents them from being close together and london forces are strongest over short distances
• separation of alkanes by fractional distillation

  1. crude oil is heated in furnace
  2. crude oil vapours and liquid pass into fractionating column. Hot at bottom, Cool at top
  3. crude oil vapours make way up the column - tray has bubble caps to allow vapours to pass up
  4. at some point it will reach a temp which is cooler than its boiling point
  5. alkanes condenses back to liquid and passes out of column
  6. shorter chain is collected near the top
  7. longer chain is collected near the bottom
  8. very long chains form bitumen which is collected from very bottom
  9. very short are collected from very top as gases
• thermal cracking

  • high temperature 450-900
  • high pressure 70atm

  when covalent bond splits, both intermediate molecules have one unpaired electron
• catalytical cracking

  • high temperature 450
  • zeolite catalyst which has large surface area so makes it an effective catalyst
  • products are often branched which is useful for petrol
• alkenes

  • CnH2n
  • unsaturated
  • trigonal planar with bond angle 120
  • when double bond forms, one sigma and one pi bond is made
  • pi bonds cannot rotate unlike sigma and rotation reduces overlap of p orbitals so stereoisomers are formed
  • highly reactive due to double bond
  • bond enthalpy of pi bond is less than sigma so pi bonds are easier to break
  • double bond contains a pair of electrons in sigma and pi so double bond is a region of high density
• halogen halide

  primary carbocation

  • if positive carbon is bonded to one alkyl group

  secondary carbocation

  • if positive carbon is bonded to two alkyl groups

  tertiary carbocation

  • if positive carbon is bonded to three alkyl groups
  • more stable so it exists for a longer period of time
  • major product
• markownikoff’s rule


  when hydrogen halide reacts with asymmetrical alkene, the hydrogen atom of hydrogen halide is more likely to bond to the carbon atom which is attached to greater number of hydrogen atoms
• electrophilic addition

  • heterolytic fission

  adding halogen

  • induced dipoles
  • forms one product

  adding hydrogen halide

  • permanent dipoles
  • forms major and minor product
• reaction with halogen to test for presence of unsaturated molecule

  1. add drops of bromine water to substance
  2. bromine water is orange/brown
  3. gently shake test tube

  • if substance is unsaturated, bromine will add across the double bond and will appear colourless
  • if substance is saturated, bromine water will remain orange as theres no reaction
• hydration of alkenes


  alkene+h20 ->alcohol

  <-

  • phosphoric acid catalyst
  • high temp
  • heterolytic fission
• hydrogenation of alkenes


  alkene+H2 ->alkane

  <-

  • nickel catalyst
  • 150C
  • no electrophilic addition
  • molecules in vegetable oil contain fatty acids which are unsaturated
  • low melting point so its liquid at room temp
  • hydrogenating unsaturated fatty acids can increase melting point, converting from liquid to solid margarine
  • more double bonds hydrogenated, higher melting point of product
• addition polymers

  • requires high temp, high pressure, catalyst
  • alkanes
  • non polar and strong bonds which makes them difficult to break
  • unreactive
• environmental effects of addition polymer

  • lack of reactivity makes them useful for food containers
  • non-biodegradable so it can pollute environment for decades
  • use of crude oil which is non renewable
  • crude oil needs to be transported and refined which requires energy
  • occupy alot of space in landfills
• reduce environmental effects of addition polymer

  • instead of sending waste polymers to landfill, it can be combusted, generating energy but can release harmful chemicals
  • example: PVC contains cl atoms. when PVC combusted, HCl is produced which is corrosive so it needs to be removed from any waste gas before released
  • polymer waste can be sorted into different polymers and recycled into new products, reducing use of crude oil and amount of waste in landfills
  • feedstock recycling so waste polymers don’t need sorting
• alcohol

  • polar molecule due to uneven distribution of charge and difference of electronegativity
  • form london and hydrogen bonds which is strong so requires alot of energy to break
  • less volatile than alkanes
  • highly soluble in water as they form hydrogen bonds with water molecules
  • increasing length of carbon chain decreases solubility of alcohols
• oxidation of primary alcohols

  alcohol -> aldehyde + H2O

  • k2Cr2O7/H+
  • gentle heating and distillation
  • orange to green
  • aldehyde have low boiling points as they cant form hydrogen bonds
  • heating alcohol and oxidising agent produces aldehyde
  • aldehyde evaporated and passes into condenser where it condenses back to liquid and is removed
• aldehyde further oxidising to carboxylic acid

  alcohol -> aldehyde -> carboxylic acid + H2O

  • heat reaction under reflux
  • any volatile product condenses and returns to reaction mix
  • heat chemical until reaction is completed and makes carboxylic acid
  • carboxylic acids have higher boiling points than aldehydes so forms hydrogen bonds
  • at the end use distillation to separate carboxylic acid from reaction mixture
• oxidation of secondary alcohols

  alcohol -> ketone + H2O

  • K2Cr2O7/H+
  • orange to green
  • in primary, once aldehyde is formed, theres still another hydrogen bonded to carbon atom to oxygen so oxidises further
  • in secondary, when ketone is formed, carbon atom bonded to oxygen doesn't have another hydrogen
  • heat under reflux
  • ketone and water are formed as products but also unreacted alcohol and oxidising agent so use distillation to separate ketone from mixture
  • ketones have low boiling point and volatile so cant form hydrogen bond
• oxidation of tertiary alcohols

  • carbon atom bonded to alcohol is not bonded to any hydrogens so not easily oxidised
  • if its heated with acidified potassium dichromate, then theres no reaction
  • oxidising agent remains orange
• dehydration of alcohols


  alcohol -> alkene + H2O

  • H3PO4/H2SO4
  • reflux
  • forms two products
• formation of haloalkane

  1. NaBr(s)+ H2SO4(aq) -> HBr(aq)+ NaHSO4 (aq)
  2. alcohol + HBr -> haloalkane + H2O

  • volatile
  • distillation
• complete combustion


  ? + O2 -> CO2 + H2O
• structure of haloalkanes

  • when theres more than one halogen in a hydrocarbon, list them alphabetically
  • primary haloalkane: halogen thats bonded to a carbon is bonded to one carbon
  • secondary haloalkane: halogen thats bonded to carbon is bonded to two carbons
  • tertiary haloalkane: halogen thats bonded to carbon is bonded to three carbons
  • C to Halogen bond is polar
• properties of haloalkanes

  • Haloalkanes have higher boiling point than alkanes
  • Permanent dipole dipole because of the polarity of carbon to halogen bond
  • Permanent dipole have stronger forces than London, so require a lot of energy to break
  • As you go down group 7 boiling point of haloalkanes increases so strength of london forces increase as theres more electrons
  • Insoluble in water, so they can’t form hydrogen bonds
  • However, they are soluble in nonpolar solvent such as cyclohexane
• rate of hydrolysis of haloalkane

  1. three test tubes with 1 cm³ ethanol
  2. Add 0.1 cm³ haloalkane (1 chloro,bromo,iodopentane)
  3. 60°C water bath
  4. Add silver nitrate in separate test tube and place in same water bath
  5. Leave for 10 minutes
  6. Add the 1 cm³ silver nitrate to each tube and time it
  7. water molecule reacts with haloalkane by nucleophilic substitution and hydrolysis happens

  Cl-(aq) + Ag+ -> AgCl(s)white precipitate and very slow

  Br-(aq) + Ag+(aq) -> AgBr(s)cream precipitate and slow

  I-(aq) + Ag+(aq) -> AgI(s)yellow precipitate and rapid due to low bond enthalpy so not alot of energy required
• elimination


  haloalkane + KOH -> alkene + K(halogen) + H2O

  KOH dissolved in ethanol
• ozone

  • contains high concentration of chemical ozone
  • symbol O3
  • ozone layer absorbs great deal of UV radiation from sun before reaching earths surface
  • protects living organisms from excessive UV exposure
  • O=O -> O + O
  • O2 -> 2O
  • O + O2 -> O3

  < -
• CFC

  • cause ozone in ozone layer to be broken
  • haloalkane
  • very stable so have high bond enthalpy between C-halogen bond
  • non-toxic