nucleophile

[datdat]

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from kbb p.288

nucleophilic strength

in protic solvent, I-> Br-> Cl->F-

but in aprotic solvent, I-< Br-< Cl-<F-

why is that and how do i apply this knowledge in real DAT?

 

[Valigator00]

from kbb p.288

nucleophilic strength

in protic solvent, I-> Br-> Cl->F-

but in aprotic solvent, I-< Br-< Cl-<F-

why is that and how do i apply this knowledge in real DAT?

Sn2->aprotic solvent-> needs strong nucleophile such as F- or Cl- so it can cause leaving group to leave
Sn1->protic solvent->proceeds with a weaker nucleophile I- and Br-. strong nucelophile is not needed, because leaving group leaves before the nucleophile attacks it

That is how I understood nucleophiles. hope it helps. 😀

 

[suhshi]

Think about it this way,

for Sn2, nucleophilicity increases going down the periodic table a large anion (I) will react fastest bc theres not that many solvent molecules surrounding the anion, as opposed to F, which is very small, so there are alot of interacting solvents around it.
In General, solvation weakens the nucleophile and smaller anions are more tightly solvate than larger ones.
Thats why you have aprotic solvent in Sn2

For Sn1, polar solvents accelerate the reaction bc the polar solvent stabilizes the transition state, leading to formation of carbocation.

So SN2: aprotic (nucleophile)

SN1: protic (carbocation formation)

someone please correct me if theres a misunderstanding

 

[peerless218]

from kbb p.288

nucleophilic strength

in protic solvent, I-> Br-> Cl->F-

but in aprotic solvent, I-< Br-< Cl-<F-

why is that and how do i apply this knowledge in real DAT?

omg..I guess after the DAT, you DO forget everything you've ever learned!! I used to know this...now I couldn't remember what nucleophile is if my life's depending on it.

 

[datdat]

omg..I guess after the DAT, you DO forget everything you've ever learned!! I used to know this...now I couldn't remember what nucleophile is if my life's depending on it.

the only thing is i'm "before" the DAT and you are "after" the DAT... I'll be in your case soon ^-