Question about Dat Destroyer Ochem #118 2013 version

[bluesolic]

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Which is the best nucleophile

and the answer is CH3SH out of H2O, AlCl3, C2H5OH, CH3SH

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it says that S is larger but I understood that it has more boundary area so it may be the answer but the thing is that is there anybody who has better answer?


and also, if there options are all ion versions, then , with - chaged on the Os, and S , the the S is the least nuc ???

 

[supergenius310]

Nucleophilicity trend I believe...for protic solvent it goes left and down...so that's why it is the best nucleophile in protic (H attached to the S)...and besides AlCl3 is an acid. 🙂...and for aprotic solvent it is left and up (same as basicity).

 

[Minion]

If we take all the H's out, the S becomes negative. The less electronegative, then the electrons are holding less tightly as in they are ready to attack. Also the larger they are, the electrons are not holding as tightly because the attraction to the nucleus, which contains protons and neutrons.

Other than that. Just remember your nucleophile trend.

 

[NewBee12]

S is large, not very electronegative. And therefore the electrons are more "loosely held" and could be used for attacking purposes!!

 

[Dotoday]

Electronegativity decreases going down the group and to the left of the period. That would mean stronger nucleophilicity.

Sent from my SPH-L710 using Tapatalk

 

[ikulu]

I have a quick question.
Does the question have to specify if the nucleophile is under protic environment or aprotic environment? Because the strength of the nucleophile depends if they're in aprotic/protic solvent.

Thanks

 

[shulace]

It is not defined whether or not it is under protic or aprotic conditions in the question. On the E2/SN2 page of chad's handout, he gives several examples of common, 1. strong bases and strong nucleophiles, 2. strong nucleophiles but weak bases, and 3. weak bases but strong nucleophiles.

R-S^- is listed as a common strong nucleophile but weak base.