so activators make the ring unstable right since they donate e- ?
and vice versa for deactivators ?
so....since activators donate e- the ring doesnt want e- making it a poor Lewis Acid ?
vice versa for deactivators ?
You seem very lost...have a seat. An activating group simply means the molecule is made more reactive. The stability of the molecule is NOT the factor,,,,but reaction rate is........ An activating group such as methoxy, hydroxy or amino simply makes the reaction go FASTER.
The usual mechanism is called Aromatic Electrophilic Substitution, and involves a carbocation intermediate called an Arenium ion. These groups donate electrons and thus STABILIZE the carbocation. Anytime we stabilize the intermediate, the reaction rate INCREASES. A group such as NO2 or COOH will withdraw electrons and therefore DESTABILIZE the carbocationic intermediate and slow the reaction down.
Lewis acids such as FeCl3 and AlCl3 are involved with the mechanism. They allow for the breaking of a carbon-halogen bond or halogen-halogen bond to become more facile. Consult any Organic chemistry book and have a look. For the DAT.....know which groups are activating and which groups are deactivating. I would also understand how to do reactions using these directors.
For example, Cyanobenzene when treated with Chlorine in FeCl3 gives meta isomer product, but the reaction rate is SLOWER.....than if we used Ethylbenzene. Ethylbenzene would have given you a faster rate, and ortho and para isomers mainly.
The Kaplan review book does a nice job to simplify the basics. I also love the Klein book for its clarity and simplicity.
Hope this helps.
Dr. Romano
