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SN2 - Coggle Diagram
SN2
substrate dependance
the more substituted the substrate is/ more hindered the substrate is, the harder it is for the nucleophile to attack the LG at 180 degree and so the less likely the reaction will occur via SN2 mechanism.
more statically bulked the substrate is, the higher the activation energy will therefore be for the SN2 reaction.
therefore, primary substituted substrates are the best substrate for SN2.
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rate law
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as SN2 reactions rate law contains both the nucleophile and the substrate, a good nucleophile is therefore required for the reaction to occur. this in turn refers to larger molecules with a negative charge eg I-, RS-, R2N-, NC- as they are able to readily donate their lone pair of electrons
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sterochemistry
inversion of stergonic centres- nucleophile needs to be at 180 degrees to the leaving group in order to provide sufficient overlap of the orbitals. kit
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solvents
polar aprotic solvents. Polar means contains dipoles, but aprotic means no H-heteratom bonds and therefore, cannot form hydrogen bonding with the substrate.
examples include dimethylsulfoxide, DMF and acetonitrile.
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nucleophilic bimolecular substitution (substrate and nucleophile present in the RDS and thus rate law so one step process involving 2 curly arrows)