3 - The Delocalised Model Of Benzene Flashcards
What types of bonds are the C-C, C-C, C-H bonds? What plane are they in?
They’re sigma bonds - all in the same plane. There’s 3 sigma bonds bonding to the C and H. There’s 1 of the 4 electrons left over. These are SP2 orbitals.
What shape is benzene? How is the molecule bonded?
Benzene is cyclic, with 6 carbons and hydrogens. It’s a planar hexagonal ring, with bond angels of 120.
What happens to the 4th electron? What orbitals does this involve?
4th outer shell electron in a p-orbital. This is above and below the plane of the carbon atoms. The adjacent P orbitals overlap forming a delocalised electron ring, above and below the plane of the carbon atom.
What bonds are in a delocalised electron ring?
There are Pi bonds, which overlap sideways. The overlap is of P orbitals.
What reactions does benzene struggle to take part in?
It struggles to take part in typical alkene reactions (such as addition). These typical reactions involve Pi bonds.
What does benzene do?
It doesn’t take part in addiction reactions, react with HCl or halogens. As it doesn’t take part in addition reactions, it doesn’t decolourise bromine water.
Why do addition reactions not take place?
The product is less stale than benzene. This means the reaction is energetically less favourable. In order for this reaction to take place it would have to disrupt the delocalised ring.
What reactions does benzene take place in?
Substitution reactions.
