Question

Can anybody explain Nucleophilic Substitution Reaction?

Answer 1

Yes! So let's break down what the name is, since that'll help us understand how to distinguish it from an elimination reaction.

Nucleophilic - this just means Nucleus Loving, basically. the -philic part is the same as the phil- in philosophy (the love of knowledge) and pedophile (love of children). Nucleophiles are almost the same thing as bases, and a lot of time something can act as both a nucleophile or a base. The difference is, are the electrons being donated to the nucleus of a carbon, or to a proton?

Substitution - Just like the name says, we're substituting one for the other. If you have a substitute teacher, that means your original teacher must have left. Same idea here, you're going to lose one thing and gain another.

There are two kinds of substitution reactions, SN1 and SN2. SN1 involves something leaving on its own spontaneously, and then something comes in later to replace it. SN2 happens all at once, where a nucleophile comes in, attaches to the carbon and in doing so, the leaving group gets kicked off in the same step. Here's a picture of SN2 to give you an idea:



So here we see an SN2 reaction where the nucleophile (NU) kicks out the leaving group (LG) all in one step. I sort of drew it like if it were an animation, but all three of those are really part of one step.

I'll explain more if you like, it's sort of a large issue to talk about and would be easier if I knew what you do and don't understand first rather than just explain the whole subject.

Answer 2

http://en.wikipedia.org/wiki/Nucleophilic_substitution