BRAINCAKEBenzene
Revision notes for Benzene in OCR Chemistry A (H432). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.
- BenzeneArenes are aromatic (ring) hydrocarbons that contain at least one benzene ring.
- Benzene StructureBenzene is less reactive than alkenes such as cyclohexene.
- Electrophilic Substitution ReactionsThe high electron density of the delocalised system attracts electrophiles.
- Nitration of BenzeneOne of the hydrogen atoms on the benzene ring can be replaced by a nitro- group (NO2).
- Halogenation of BenzeneBenzene will react with halogens in the presence of a halogen carrier.
- PhenolPhenols have a hydroxyl group attached directly to the benzene ring.
- Halogen CarriersBenzene reacts with halogens only in the presence of a catalyst called a halogen carrier.
- Friedel-Crafts AlkylationFriedel-Crafts reactions form a new carbon-carbon bond to a benzene ring.
- Friedel-Crafts AcylationIn Friedel-Crafts acylation, benzene reacts with an acyl chloride in the presence of a halogen carrier such as AlCl3, under anhydrous conditions.
- Reactivity of PhenolIn phenol, C6H5OH, an -OH group is bonded directly to the benzene ring.
- Phenol as a Weak AcidPhenol is a weak acid.
- Bromination of PhenolPhenol reacts with bromine water at room temperature, without a halogen carrier.
- Nitration of PhenolPhenol is nitrated much more easily than benzene.
- Directing Effects in Aromatic SubstitutionWhen a benzene ring that already has one substituent undergoes electrophilic substitution, the existing group affects where the new group goes.
- 2- and 4-Directing GroupsGroups that donate electron density to the benzene ring, such as -OH and -NH2, are 2- and 4-directing.
- 3-Directing GroupsGroups that withdraw electron density from the benzene ring, such as the nitro group, -NO2, are 3-directing.