25.1 introducing benzene Flashcards
1
Q
evidence that disproves kekule model
A
- Bond length different from (short) C=C and (long) C–C
- enthalpy change of hydrogenation less exothermic than expected when compared to the enthalpy change of hydrogenation for cyclohexene
- Only reacts with Br2 at high temp or in presence of a halogen carrier
2
Q
delocalised model of benzene
A
- p-orbitals overlap to form pi bonds
- pi-bonds are delocalised
- 6 delocalised electrons
3
Q
draw benzoic acid
A
page 435
4
Q
draw phenylamine
A
page 435
5
Q
draw benzaldhyde
A
page 435
6
Q
draw ethylbenzene
A
page 435
7
Q
draw chlorobenzene
A
page 435
8
Q
draw nitrobenzene
A
page 435
9
Q
draw phenylethanone
A
page 435
10
Q
draw 2-phenyloctane
A
page 435
11
Q
explain why the delocalised model of benzene accounts for the observed stability of benzene better than the kekule model
A
- the delocalised model has the pi- bond electron density spread out rather than having concentrated areas of electron density from separate double bonds as in the kekule structure
- compounds containing delocalised electrons are more stable than those that do not have delocalised electrons
12
Q
what is the empirical formula of benzene
A
CH
13
Q
kekule model of benzene
A
- p-orbitals overlap to form pi bonds
- pi-bonds are localised between two carbons
