Flashcards
Topic 17: 17.4 (key terms)
Flashcards do conjunto (15)
- 1formula of benzeneC6H6
- 2basic structure of benzene-6 carbon atoms in a hexagonal ring with one H atom bonded to each C atom
-planar molecule where all the bonds are the same length
-made of P-orbitals which overlap to form pi bonds - 3benzene's electrons-there's one unused electron on each C atom
-which creates a ring of negative charge above and below the plane of the ring
-the electrons are delocalised and can move throughout the pi system - 4problems (1 and 2) with the Kekule structure for benzene1. substitution reaction with bromine water rather than the addition one that is expected
2. there should be 4 isomers of dibromo benzene but there are only 3 - 5problems (3 and 4) with the Kekule structure for benzene3. the c-c bond lengths in benzene were very similar to the c=c bonds in cyclohexene
4. the data about enthalpy changes of hydrogenation shows that benzene has a much lower value than the value a structure with 3 c=c bonds would be expected to have - 6aromaticdelocalised electrons forming Pi bonding in a hydrogen ring
- 7hydrogenation of benzene-produces cyclohexane
-process: mix benzene with hydrogen and heat under pressure with a nickel catalyst - 8combustion of benzene-produces carbon dioxide and water
-benzene burns in air with a smoky flame - 9bromination of benzene-produces bromobenzene and hydrogen bromide
-addition reaction
process: heated under reflux in the presence of a catalyst (halogen carrier) - 10nitration of benzene-produces nitrobenzene and water
-substitution of a hydrogen atom by a nitro group (NO2)
-warmed benzene with a mix of conc. nitric acid and sulfuric acid (catalyst) - 11friedel-crafts alkylation-produces alkylbenzene and hydrogen chloride
-substitution of one of the hydrogen atoms by an alkyl group - 12friedel-crafts acylation-produces phenylethanone
-the substitution of a hydrogen atom by an acyl group - 13phenolan aromatic compound with an aliphatic (non-aromatic) hydroxyl group
- 14bromination of phenol-occurs at room temp with no catalyst
-substitution reaction occurs 3 tmes
-bromine water is decolourised and a white, organic precipitate forms - 15why does bromination occur more readily in phenol than benzene?-the OH has lone pairs of electrons
-they merge with the delocalised pi system
-electron density will increase (activation)
-bromine is polarised until the Br-Br bond breaks
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- A level Chemistry 2 (Topic 17&18: further organic chemistry) FlashCards sobre Topic 17: 17.4 (key terms), criado por Laura Merifield em 08-02-2022.
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- Laura Merifield
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