ORGANIC CHEM

• structural isomers - compounds with the same molecular formula but different structural formula
• As branching increasing boiling point decreases as a result of reduced surfaced contact area this weakens london forces therefore less Energy is required to break London forces
• Homologous series - compounds containing the same functional group but each differing by successive CH2 group s
• Homolytic fission - breaking of a covalent bond , each bonding atom atom receives 1 electron from bonded pair . Produces a radicle
• Alcohols contain hydrogen bonds and London forces hydrogen bonds are the strongest intermolecular force
• free radical substitution can undergo multiple substitutions so produces many excess products . Has a higher atom economy
• E/Z isomerism is caused by limited rotation of the C=C double bond . EOPPOSITE AND ZAME

  
• chiral centre - where 4 different groups are attached to a central carbon atom
• Pi bonds - sideways overlap of p-orbitals above and below the carbon atoms

  
• Organic synthesis -organic solid . Recrystallisation - dissolve impure solid in minimum volume of hot water , cool solution and filter the solid , wash crystals with cold water
• Major product forms from most stable carbocation which is the secondary and tertiary carbocation
• C-C bonds are able to rotate easily compared to C=C bonds which has restricted rotation
• Alkanes - undergo combustion , free Radical substitution and cracking
• Alkenes - undergo electrophilic addition , hydration with concentrated H3PO4 , steam and hydrogen to form alcohols . Hydrogenation with H2 and nickel catalysts to form alkanes . To test for Alkenes we use bromine water . Should decolourise from orange to colourless
• Haloalkanes - involved in nucleophillic substitution with KCN and ethanol to form nitriles , they also do the same with NAOH to form alcohols and NH3 , R-Cl in ethanol to form a primary amine . To test we must use silver nitrate which will form halogen precipitates
• Alcohols - will undergo combustion , nucleophillic substitution with NaBr , NaI or Nacl in H2So4 acid to form haloalkanes , undergo dehydration with H3PO4 steam and Heat to form Alkenes . To test for alcohol we Use K2Cr2O7H+ will form a colour change from orange to green
• Radical - a species with an unpaired electron
• Low reactivity of alkanes due to high C-C Bond enthalpy
• environmental Impact of soot : can lead to cancer
• Whenever doing free radical substitution equations we always use H-X
• ways to dispose plastics : landfill , recycle combustion and electricity generation
• There is no E/Z isomerism if 1 carbon atom is attached to 2 groups whihc are identical
• Can-Ingold prolog rules : we use the atomic number
• Sources of nitrogen oxides in the stratosphere : thunderstorms and lightning
• ALWAYS MENTION IN HALOALKANE QUESTIONS : either the C-CL bond is stronger than the C-Br bond or the C-Br bond is stronger than the C-I bond
• Atom economy = product Mr ➗desired Mr of reactants
• Phenols are weak acids they will react with NAOH but will not react with any carbonates
• Phenol and bromine forms 2,4,6-tribromophenol
• 2,4,6-tribromophenol forms a white precipitate , smells of antiseptic and decolourises bromine water
• Benzene is resistant to halogenation and nitration due to delocalised ring of electrons containing pi bonds and requires halogen carriers catalysts and high temperatures in order to react
• Phenol contains a lone pair of electrons on the oxygen atom which increases electron density making it less table and more susceptible to attack from electrophiles due to this it does not require a catalyst or halogen carriers
• Electron donating groups such as OH and NH2 direct electrophiles to substitute at the 2 and 4 positions on the ring
• Electron withdrawing groups such as NO2 are 3 directing and direct electrophiles to substitute at the 3 regions on the ring
• with tollens reagent an aldehyde will form a silver mirror and then produce a carboxylic acid
• With tollens reagent ketones will go colourless
• Mobile phase : fluid allowing molecules to move through stationary phase
• Rf = distance moved by molecule ➗ distance moved by solvent
• Retention time : time taken for sample to travel from gas chromatogram
• Ways to check purity : TLC chromatography and gas chromatograms
• TLC : metal plate is coated in thin layer of silica solvent , substance separate and solvent front is created we then calculate RF value