aromatic (benzenes)

planar stable due to delocalisation of p electrons intermediate bond length cyclic

bond lengths are longer than c=c and shorter than c—c each c forms 3 bonds so 1 lone electron which gets delocalised as the p orbitals overlap to form a pi bond e cloud above and below the ring plane molecule is stable due to electron delocalisation

• bond lengths - C-C and C=C are different lengths. so this hypothetical molecule would be?? Impossible, less stable? • Doesn’t undergo addition reactions - doesn’t decolourise bromine water, doesnt readily undergo addition reactions because it disrupts the stability of the e ring by ruining it basc. • Enthalpies of hydrogenation - refers to the enthalpy change measures when different cyclic alkenes are hydrovenated to get to cycloalkanes. All db get hydrogen added across them - they increase for 1ene to diene from triene, indicating that it’s more exothermic to become cyclohexane - but the enthalpy of hydrogenation for benzene is less than triene, indicating it is more stable

Electrophilic substitution Electron density makes it attractive to electrophiles Addition would disrupt the delocalisation and therefore reduce stability but substitution only causes temporary disruption and preserves the delocalised system

Nitration with nitronium ions to form nitro benzenes Friedek crafts acylarion with acid anhydrides or acyl chlorides to form phenyl ketones (depends on r group)

Conc nitric acid Conc sulfuric acid 50 degrees Hno3 + h2so4 - > h2no3+ + hso4- H2no3+ - > no2+ + h2o

Nitronium ion attacks the ring Ring is disrupted and a C forms bond with N ion Horseshoe H on the C that is in that C-NO2 donates bond to ring forms nitrobenzene and proton could have successive reactions

Used as explosives Important step in organic synthesis of other molecules eg amines. Produces primary aromatic amines that are used in the manufacture of dyes

Anhydrous AlCl3 Both reagents have same group that is attached (molecule left after leaving group (different) goes): O II R-C+

ACYL CHLORIDES AlCl3 + RCClO -> RCO+ + AlCl4- AlCl4- + H+ (from benzene) -> AlCl3 + HCl ACID ANHYDRIDES RCOOCOR + AlCl3 - > [Cl3Al-OOCR] - + +COR ((the leaving group divide is RCO(|) OCOR)) [Cl3Al-OOCR] - + H+ - > AlCl3 + RCOOH

REDUCTION REACTIONS - Sn & HCl, heating, followed by NaOH - nitrobenzene + 6[H] - > phenylamine + 2water this phenylamine becomes - NH3+ Anion- because it acts as a base, then forms a salt. follow by NaOH to react to give the insoluble phenylamine CATALYTIC HYDROGENATION - nickel catalyst - nitrobenzene + 3H2 - > phenylamine + 2water (nickel catalyst reduction also for nitriles into (aliphatic) amines

products used as chemical feedstocks and synthetic intermediates. so they are necessary to make other useful chemicals

Is more covalent than ionic Al shows covalent character because small radius, high charge so high positive charge density So high electronegativity, or polarising effect. It attracts electrons towards itself, from the anion for ex Which distorts the E cloud introducing cov character to the bonds

Number - phenyl [carbon chain] - number - ol