question on nucleopilic substitution/elimination

[yahoogoogle]

to determine whether the reaction is Sn2 or E2(especially for secondary), we need to know the strength of the basicity of the attacking nucleophilic, which is quite abitrary. so what's the strategy to tackle this type of problems on dat?

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[lintydent]

to determine whether the reaction is Sn2 or E2(especially for secondary), we need to know the strength of the basicity of the attacking nucleophilic, which is quite abitrary. so what's the strategy to tackle this type of problems on dat?

If they give you the product, then one obvious way to determine between the two is that E2 will give you an alkene, Sn2 will not...and in addition, the E2 rxn is an "elimination" of the leaving group, while Sn2 is the "substitution" of a leaving group for a strong nucleophile.

 

[Yellow Snow]

to determine whether the reaction is Sn2 or E2(especially for secondary), we need to know the strength of the basicity of the attacking nucleophilic, which is quite abitrary. so what's the strategy to tackle this type of problems on dat?

I don't see how they can make it too specific because if you have a secondary w/ an ambiguous nu: the major product might barely dominate. I am hoping it will mostly be a bulky base leading me to E2 over Sn2.

Also, heat promotes E2 over Sn2? Not that I have seen any practice questions w/ heat.