Electron Withdrawing

[the truth]

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Is electron withdrawing/donating based solely on an atom's electronegativity (high electronegativity = withdrawing and vice versa)? If so, what's the cut-off that dictates this?

Unrelated: can someone clarify what exactly acetylcholinesterase is/does -- I assume its an enzyme related to acetylcholine and synapses...

 

[DieselPetrolGrl]

acetylcholinesterase degrades actych from synapse..think of it as the cleanup sponge that removes it before the next Ap is triggers another synaptic release

 

[DieselPetrolGrl]

well kindof ..like u know halides are E rich and so are carbonyl groups so u can say they are electron withdrawing..but at the same time phenyls are e rich and they are electron donating ....

 

[BisMuOxo]

Acetylcholineesterase hydrolyzes the ester bond in acetylcholine. As a general rule of thumb, you should memorize the electron donating/withdrawing groups. Alkyl, alkoxy, amino groups are electron donating. Halides, amides, carbonyl, nitro groups are all electron withdrawing.

 

[liverotcod]

Even more generally, a nitrogen or oxygen atom (except nitrate) attached directly is electron donating, because they have free lone pairs. Aminos and hydroxys are good example. But if they are attached via a carbon atom, they are electron withdrawing, as in carbonyl and amides.

Even nitrate fits the scheme, because in nitrate, the two oxygens attached to the nitrogen make it equivalent to the carbon in, say, carbonyl.

Halides are electron withdrawing based on electronegativity alone - they want to complete their octets.

 

[Jon Davis]

Guys, I dont think that electron withdrawing/donating stuff is on the MCAT orgo anymore. I just checked the orgo topics list, and theres NO mention of that stuff relating to electrophilic addiction to aromatics. Correct me if I'm wrong!!!!!!!!
thanks.

 

[imsotired]

That may well be but it comes in very handy sometimes to know the electron withdrawing and electron donating groups. It won't hurt you at all....I think it would probably hurt you NOT to know them.

edit: and it doesn't only apply to aromatic compounds.