[Elias Jeryes]

Good evening everyone,
I am new to this forum and I registered to seek help, so I hope it will be hopefull,

note : I study organic chemostry according to this book : Organic Chemistry by Brown 4th edition.

In chapter 7 (haloalkanes), i learned about sn1 and sn2 and e1 and e2 mechanisms, and i learned that the mechanisms e2 and sn2 are competing but the confusing phrase was : the greater the nucleophilicity of the attaching reagent, the greater the sn2 to e2 ratio. conversly, the greater the basicity of the attacking reagent the greater the e2 to sn2 ratio.
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can anyone please explain how a reagent is more nucleophile or more basic ?
what i know is all the bases are nucleophiles, until that phrase shown up
please help me i have midterm exam tomorrow
and thank you a lot
 

[Dan]

A good starting point:

http://www.masterorganicchemistry.com/2012/06/06/nucleophilicity-vs-basicity/