MHB Electrophiles vs. Nucleophiles

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$C{H}_{3}Cl$ primarily acts as an electrophile due to the positive polarization of chlorine when bonded to the methyl group, despite the chlorine's ability to attract electrons. The chlorine atom is negatively polarized near the carbon but positively polarized on the opposite side, making the entire molecule electrophilic. If chlorine were to lose an electron, it would form a $\ce{Cl-}$ ion, which would then act as a nucleophile. Chlorine typically does not exist as a standalone atom; it is usually found as a $\ce{Cl2}$ molecule, which is also electrophilic, or as a $\ce{Cl-}$ ion. Overall, the discussions clarify that while chlorine can exhibit nucleophilic behavior when ionized, in the context of $C{H}_{3}Cl$, it functions as an electrophile.
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Stupid question here, but why wouldn't it be possible for $C{H}_{3}Cl$ to act as a nucleophile also since it has a nucleophilic site at the chlorine due to it being negatively-polarized when attached to methyl group?
 
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MermaidWonders said:
Stupid question here, but why wouldn't it be possible for $C{H}_{3}Cl$ to act as a nucleophile also since it has a nucleophilic site at the chlorine due to it being negatively-polarized when attached to methyl group?

With the chlorine bound to the methyl group, it's single valence electron is near the methyl group.
Consequently, on the outside of the molecule, the chlorine is slightly positive charged, and attracts an electron.
It makes the molecule as a whole an electrophile.

If the chlorine atom would actually bind a lose electron, it would detach itself and form a $\ce{Cl-}$ ion, which is a nucleophile.
 
I like Serena said:
With the chlorine bound to the methyl group, it's single valence electron is near the methyl group.
Consequently, on the outside of the molecule, the chlorine is slightly positive charged, and attracts an electron.
It makes the molecule as a whole an electrophile.

If the chlorine atom would actually bind a lose electron, it would detach itself and form a $\ce Cl^-$ ion, which is a nucleophile.

Wait... doesn't the polar bond between C and Cl result in Cl being negatively-polarized?
 
MermaidWonders said:
Wait... doesn't the polar bond between C and Cl result in Cl being negatively-polarized?

A $\ce{Cl}$ atom on its own is neutrally charged.
When it bonds to $\ce C$, the electron in its outer shell moves to the $\ce C$ atom.
So it's indeed negatively polarized near the $\ce C$-atom, but at the same time it is positively polarized on the other side, which is the outside of the molecule.
Attractions to other particles happen on the outside of the molecule.
 
I like Serena said:
A $\ce Cl$ atom on its own is neutrally charged.
When it bonds to $\ce C$, the electron in its outer shell moves to the $\ce C$ atom.
So it's indeed negatively polarized near the $\ce C$-atom, but at the same time it is positively polarized on the other side, which is the outside of the molecule.
Attractions to other particles happen on the outside of the molecule.

Ah, I see now. :) So if the whole molecule is an electrophile overall, is there a case where the Cl atom serves as the electrophilic site? It's just that with the problems I've encountered so far, I'm used to seeing the C atom acting as the electrophilic site and Cl the nucleophilic site but never the Cl atom yet...
 
MermaidWonders said:
Ah, I see now. :) So if the whole molecule is an electrophile overall, is there a case where the Cl atom serves as the electrophilic site? It's just that with the problems I've encountered so far, I'm used to seeing the C atom acting as the electrophilic site and Cl the nucleophilic site but never the Cl atom yet...

A $\ce{Cl}$ atom doesn't (normally) occur on its own. If it does we call it a radical, meaning it will immediately react with anything that comes nearby.

Instead we'll either have a $\ce{Cl2}$ molecule, which is electrophilic.
Or we'll have a $\ce{Cl-}$ ion, which is nucleophilic.
 
I like Serena said:
A $\ce{Cl}$ atom doesn't (normally) occur on its own. If it does we call it a radical meaning it will immediately react with anything that comes nearby.

Instead we'll either have a $\ce{Cl2}$ molecule, which is electrophilic.
Or we'll have a $\ce{Cl-}$ ion, which is nucleophilic.

Yeah, OK, got it. Thanks!
 
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