Random things to know cuh

Question 1

Explain the resistance of bromination/chlorination of a benzene ring compared with normal Double bond

Answer 1

Electrons are delocalised in Benzene ring

In double bond, electron density is higher so more susceptible for attack

Double bond polarises electrophile more

Question 2

Similarities between kekule and delocalised model

Answer 2

Similarity:
Side ways P orbital overlap
Pi bonds above and below

Differences:
Kekule has 3 alternating Pi bonds, delocalised has a Pi system

Question 3

evidence to support delocalised model?

Answer 3

C-C bond length is the same
DeltaH less exothermic than predicted
Benzene is less reactive than alkenes

Question 4

Why does Phenol react more readily than benzene

Answer 4

Greater electron density than Benzene
Phenol polarises electrophile more
Lone pair on OH gets partially delocalised into Pi system

Question 5

How to purify something

Answer 5

Dissolve in minimum amount of hot solvent
Cool solution and filter solid
Wash with cool solvent and dry

Question 6

Why is something biodegradable

Answer 6

Able to undergo hydrolysis

Question 7

What is a stereoisomer?

Answer 7

compounds with the same structural formula, different arrangement in space

Question 8

What is an optical isomer

Answer 8

non super imposable images about a chiral centre