Organic chemistry

• Homolytic fission occurs when each atom in a covalent bond gets one electron, producing free radicals.
• Heterolytic fission occurs when one atom gets both electrons when a covalent bond is broken, producing free radicals.
• Free radicals are reactive species which possess an unpaired electron.
• The type of reaction that occurs between a halogen and an alkene is Free Radical substitution.
• The conditions for Halogenation are UV light, Alkane + halogen (eg Br2), and the three stages of Halogenation are initiation reactions, propagation reactions, and termination reactions.
• A double bond is made up of a sigma-bond and a pi-bond.
• Alkenes are more reactive due to the pi-bond in the double bond, which is formed from the overlap of p-orbitals.
• The pi-bonds in alkenes are much weaker than sigma-bonds due to the spread of electron density above and below the molecule, making it more likely to be attacked by electrophiles.
• An electrophile is an electron-pair acceptor.
• The type of reactions alkenes go through are Electrophilic addition reactions.
• Markownikoff's rule states that H adds to the carbon with the most H atoms already attached as this is the more stable carbocation.
• The more alkyl groups on a carbocation, the more stable it is because the alkyl groups are electron-releasing and reduce the charge on the positive carbon atom, stabilising it.
• The test for a C=C double bond is to shake the alkene with orange bromine water, and if it goes colourless, it indicates the presence of a double bond.
• The production of alkanes from alkenes involves reagents such as Alkene + Hydrogen, Ni catalyst, 150 degrees Celsius, and the reaction taking place is Hydrogenation.
• The formation of alcohol from an alkene involves reagents such as alkene and steam, at 300 degrees Celsius, 60-70 atm, and the reaction taking place is Hydration.
• The products of complete combustion of alcohols are carbon dioxide and water.
• The formation of haloalkanes from alcohols involves reagents such as alcohol and halide ion, acid catalyst (H2SO4), and the reaction taking place is Halogenation.
• Dehydration of alcohols involves reagents such as alcohol and conc H2SO4, and the reaction taking place is Elimination reaction.
• The oxidation of Primary Alcohols involves reagents such as alcohol and potassium dichromate solution [O], distillation for aldehyde, reflux for carboxylic acid, and the observation is the reduction of the orange dichromate(VI) ion to the green chromium(III) ion, Cr3+.
• The oxidation of Secondary Alcohols involves reagents such as alcohol and potassium dichromate solution [O], distillation for ketone, and the observation is the reduction of the orange dichromate(VI) ion to the green chromium(III) ion, Cr3+.
• The oxidation of Tertiary Alcohols cannot be oxidised.
• A haloalkane is an alkane with halogen atoms.
• A nucleophile is an electron-pair donator.
• Halogens are much more electronegative than C, so the C-X bond in haloalkanes is polar.
• The delta+ C in haloalkanes is electron deficient, so attracts nucleophiles to undergo nucleophilic substitution reactions.
• Aromatic compounds contain a benzene ring.
• In benzene, electrons are delocalised, while in alkenes, they are localised between two carbon atoms.
• Benzene is more stable than alkenes because it has a lower electron density.
• In benzene, electrons are delocalised, while in alkenes, they are localised between two carbon atoms.</flashcard
• Benzene is a delocalised system made up of two rings of delocalised electrons above and below the plane of the molecule.
• All C-C bonds in benzene are 140pm, which is different from the normal length of 154pm for C-C bonds and 134pm for C=C bonds.
• Benzene is unwilling to undergo addition reactions because it is too stable.
• Benzene is more stable than alkenes because in benzene, electrons are delocalised, while in alkenes, they are localised between two carbon atoms.
• The enthalpy change of hydrogenation for cyclohexene is -120 kJ/mol, which is less exothermic than expected.
• Benzene has a lower electron density than alkenes, so it is unwilling to undergo addition reactions because it is too stable.
• Radical substitution in alkanes results in the conversion of an alkane into a haloalkane, with halogen (X 2 ) as the reagent and UV radiation as the condition.
• Hydrogenation in alkenes results in the conversion of an alkene into an alkane, with hydrogen (H 2(g) ) as the reagent and a Ni catalyst (at 423 K) as the condition.
• Dihalogenation in alkenes results in the conversion of an alkene into a dihaloalkane, with halogen (X 2 ) as the reagent and no conditions specified.
• Halogenation in alkenes results in the conversion of an alkene into a haloalkane, with hydrogen halide (HX) as the reagent and no conditions specified.
• The general equation for nitrile reduction is RCN + 2H2 → RCCH2NH2.