chapter 25 Flashcards
what is the formula for benzene?
C6H6
what is benzene?
simplest arene
what are the properties of benzene?
colourless
smells sweet
highly flammable liquid
carcinogenic
what is Kekule’s model?
hexagon with 3 double bonds
what are 3 pieces of evidence that disprove Kekule’s model?
benzene does not decolourise bromine under normal conditions (does not undergo electrophilic addition reactions)
all carbon-carbon bond lengths in benzene are equal and inbetween length of C-C and C=C bonds
benzene has a less exothermic enthalpy change of hydrogenation than expected (more stable structure than theoretical model)
why does benzene have extra stability?
enthalpy changes of hydrogenation show extra stability due to electron delocalisation
what is the delocalised model of benzene?
planar, cyclic, hexagonal hydrocarbon
each carbon has 1 less electron in p-orbital at right angles to plane of bonded carbon and hydrogen atoms
adjacent p-orbitals overlap sideways above and below plane of carbon atom to form ring of electron density
overlapping p-orbitals create pi bonds
how is the ring of electron density in benzene formed?
adjacent p-orbitals overlap sideways above and below plane of carbon atom
how do you name benzene with a methyl, chloro or nitro group?
methylbenzene
chlorobenzene
nitrobenzene
how do you name benzene with an alkene chain attched?
2-phenylbutane
how do you name benzene with an aldehyde group attached?
benzaldehyde
how do you name benzene with a ketone group attached?
phenylethanone
how do you name benzene with a carboxylic acid group attached?
benzoic acid
how do you name benzene with an amine group attached?
phenylamine
how do you name benzene with a alcohol group attached?
phenol
what is it called when two benzene rings are attached?
napthalene
what is it called when 3 benzene rings are attached?
anthracene
