aromatics benzene Flashcards
describe benzene
bonding:
alternating bonds
each carbon has 3 covalent bonds
spare orbitals overlap leads to delocalisation
shape:
planar shape
120 degrees bond angle
bonds in benzene are intermediate length between C-C and C=C
stability:
expected ^H is -360kjmol-1
^H of benzene is 152 less exothermic than expected of…
benzene is more stable due to delocalisation
suggest a value for ^H and justify why (in context)
alternating binds C-C and C=C
spare electrons overlap
leads to delocalisation
reformation of catalyst (friedel crafts acylation)
AlCl4- + H+ —> AlCl3 + HCl
Wat does a higher carbocation mean and definition
more stability as there is more positive inductive effect:
ability of an alkyl group to release electron density through a covalent bond
formation of nitrate
conc H2SO4 + conc HNO3 —> HSO4- + NO2+ + H2O
definition of electronegativity
Ability of an atom to attract a pair of e- within a covalent bond
formation of acyl chloride
RCOCl + AlCl3 —> RC+O + AlCl4-
C6H14 + Cl2 —> C6H13Cl + HCl
suggest a suitable hazard warning
corrosive
C-C bond length in benzene
lies in between a single and double bond
why arenes (compounds with benzene attached) undergo electrophilic substation
benzene has a high electronegativity because it has a delocalised ring of electrons which makes it attractive to electrophiles (electron loving substances)
what conditions/apparatus used for friedel crafts acylation
reflux
uses of nitrations benzene
allows to make dues for clothing
explosives
explain another piece of evidence that suggests kekules structure of benzene is incorrect
all the bonds in benzene are the same length
if benzene has alternating single and double bonds it would leave some long bonds and short bonds
kekules structure of benzene de colourises bromine water whereas actual structure doesn’t or de colourises
bromine water remains orange
why does C6H5Cl not react with ammonia
electron each benzene ring repels nucleophile / ammonia
