Tuesday, December 24, 2013

Reaction Types - Fool Proof Guide

Ever wondered how to work out which reaction are electrophilic, nucleophilic, substitutions, additions?

There is a fairly fool proof way to work it out.

Electrophilic - This needs electrons to be attacked. So will happen to benzene (cloud of them), alkenes (double bond full of them)

Nucleophilic - This needs a very electronegative element to pull the electrons away and create a delta positive carbon - so alcohols, aldehydes/ketones, halogenoalkanes are the main culprits.

Addition - If you are going to add on an extra atom you need some space to add some extra bonds, (i.e a double bond) so that means alkenes with almost anything (electrophilic) and aldehydes and ketones with HCN (nucleophilic)

Substitution - There are two reasons why you would get substitution reactions...

1. The molecule is stable as it is and adding anything would disrupt that stability (i.e. benzene)
2. The carbon being attacked doesn't have space for extra atoms so if something is coming in,
    something else has to leave  - like a one in one out policy (i.e. alcohols, halogenoalkanes).

There we have it. Four different types of reactions. A (relatively) fool proof way to tell them apart.




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