Arenes - OCR

Revision notes on arenes (Chains, Rings and Spec. module) for A2 chemistry.

HideShow resource information
Preview of Arenes - OCR

First 194 words of the document:

Benzene an its compounds
Benzene has s Molecular formula of C6H6
Kekule's Structure of Benzene
In theory this is correct but has been disproven by many tests
Bromine test can check for the presence of C=C
o When Br2 was added the solution wasn't de-colourised
CycloHexa-1,3,5-triene = C6H6 Benzene = C6H6
The enthalpy for the hydrogenation of Cyclohexene -120 KJ mol­1,
so the expected enthalpy for Cyclohexa-1,3,5-triene would be -360 KJ mol­1
but the enthalpy for benzene is -208 KJ mol­1
o The enthalpy is less than expected
X-ray defraction can check the distance between 2 nuclei
o Distance between C­C is 154 nm [2e­] (Single Bond - long)
o Distance between C=C is 134 nm [4e­] (Double Bond - short)
o But in Benzene C­/­C are 144 nm [3e­] (Single Bond and Bond ­ in between)
The electrons in the p-orbitals can overlap sideways with adjacent p-orbitals
o All the 6 p-electrons are free to move around the ring (above and below the plane)
Written By [email protected]

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

The electrons are said to be `delocalised'
Normally benzene is drawn as
The delocalised ring makes benzene stable
o not very reactive
Carcinogenic - Induces cancer
Benzene only undergoes an `Electrophilic substitution' reaction
Electrophile ­ An electron pair acceptor which forms a covalent bond
Common electrophiles include H+, Na+
The 4 reactions of Benzene include:
Nitration of Benzene
Written By [email protected]…read more

Page 3

Preview of page 3

Here's a taster:

Halogenation of Benzene
Alkylation of Benzene
Written By [email protected]…read more

Page 4

Preview of page 4

Here's a taster:

Acylation of Benzene
Written By [email protected]…read more


No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all resources »