Carboxylic acids, iodine + NaHCO3

What exactly does that do?
No description
23 Replies
iTeachChem Helper
iTeachChem Helper•2w ago
@Dexter
iTeachChem Helper
iTeachChem Helper•2w ago
Note for OP
+solved @user1 @user2... to close the thread when your doubt is solved. Mention the users who helped you solve the doubt. This will be added to their stats.
Nimboi [ping if answering]
i looked up iodolactonization online but didn't exactly get how it works
Nimboi [ping if answering]
Answer
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trin
trin•2w ago
i2 forms a triangle intermediate i think
Opt
Opt•2w ago
I remember doing this. Cyclic iodinium ion by iodine insertion on the C=C double bond. Bicarbonate removes acidic proton, so COO(-) acts as nucleophile and opens up the ring. Pyridine (base) and heat eliminates iodine to form double bond. Wait a sec, are you sure that's the answer?
Opt
Opt•2w ago
Elimination should be preferred on the other side imo. Resonance stabilised product
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trin
trin•2w ago
there will be E2 elimination right so there will be a negative charge when we remove the acidic hydrogen and then it removes the iodine hence double bond there. we can do it that way too right?
Opt
Opt•2w ago
Yeah, i suppose acidic proton logic works better here
trin
trin•2w ago
did it this way
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Opt
Opt•2w ago
Yup
Nimboi [ping if answering]
that does indeed show as the answer wait so how do we know whether to use resonance logic or acidic proton logic :sweaty: cuz both are in the options thank u this makes sense
Opt
Opt•2w ago
Acidic proton is going to be one step ahead so that
Nimboi [ping if answering]
one step ahead as in? compared to resonance, its just faster?
Opt
Opt•2w ago
Any acid-base reaction such as proton abstraction is faster than an electrophile-nucleophile reaction.
Nimboi [ping if answering]
ahhh oke i remember now
Opt
Opt•2w ago
Yeah
Nimboi [ping if answering]
@Opt related doubt
No description
Nimboi [ping if answering]
why is (3) the answer (none of the other options are cyclic 🤷) mechanism is the same (cyclic bromonium) i'd have expected for it to attack the far end and form a 6 membered ring rather than a 5 membered one
Opt
Opt•2w ago
Ehhhh it might be cus six members rings don't enjoy being both substituted and planar. Maybe look at a 3D model to see which is closer?
trin
trin•2w ago
i think its also because NCC is formed there right, at the other end theres no cation stabilization, theres +I effect which stabilises the carbocation and hence we attack there?
Nimboi [ping if answering]
hm probably that that makes sense thanks yall +solved @Opt @trin
iTeachChem Helper
iTeachChem Helper•2w ago
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