Chemistry AS OCR Organic Mechanisms
- Created by: Waqas Mahmood
- Created on: 23-07-13 10:38
Organic Mechanisms at AS Level – a summary
A mechanism shows the steps by which the reactants turn into the products. A mechanism will always show
· bond breaking in the reactants
· any intermediates
· bond making in the products
Bond breaking – a covalent bond can break in two ways:
1. Heterolytic fission
If both electrons in a covalent bond between X and Ymove on to Y, this produces IONS:
X:Y → X+ + :Y-
We show the movement of a pair of electrons with a curly arrow:
2. Homolytic fission
If atoms X and Y take one each of the electrons in the covalent bond between them, this produces FREE RADICALS:
Free radicals have no charge but they are highly reactive because they have anunpaired electron, shown by the dot( . ).
In these mechanisms, there are three types of particle which attack the organic molecules:
definition
examples
free radical
a neutral particle with an unpaired electron
Cl. Br. CH3.
electrophile
a particle which is attracted to a region of negative charge – an electron pair acceptor
Br+ or polarised molecule
nucleophile
a particle which is…
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