orgo help

[kumar28]

could someone please tell me how to distinguish the better nucleophilicity of two molecules. These are the things I know so far but I feel like I'm missing something.

Greater Electronegativity=Lower Nucleophilicity

And

Anions are usually better nucleophiles

But what if we were given two molecules and asked to tell which one was more nucleophillic.

Any help would be appreciated. Thanks

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[freakazoid]

From my Orgo book this is what I could gather:

Nucleophilicity increases:

1) w/ increasing negative charge: NH2(-1) > NH3
2) going from right to left across the periodic table NH2(-1) > OH(-1)
3) going from top to bottom across the period table I(-1) > Br(-1)
4) w/ increasing polarizability (explains 3)
5) when it is less sterically hindered (not as bulky)

Hope this helps. Good luck.

 

[Mr. Z]

I thought nucleophilicity increases from right to left and top to bottom?

 

[freakazoid]

Good call Z. Edited previous post.