Why No Clemmensen Reduction on Carboxylic acid
i was wandering, why clemmensen reagent can't reduce carboxylic acid, isn't it just about giving H+ from HCl and electron by Zn-Hg, what i'm missing
45 Replies
@Dexter
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.carbonyl double bond O does not act the same as carboxylic acid double bond O
the characteristic feature of a carboxylic acid is that the =O is in resonance with its own -OH group
which is what give it its properties, like insane acidity
it does not act like a normal carbonyl
if ur asking the mechanism of clemmensen then no clue
so we can't reduce it directly how about using amine with heat to create amide then do hydrolysis
you want to remove the double bond O from carboxylic acid right
does LAH do that?
It's actually not confirmed. Like Cannizarro rxn
COOH to OH
Yup
oh tf? we were taught a mechanism for cannizarro
oh i remember even H2/Ni with heat can do it
LAH would reduce hydrogen if it could, ngl
directly
It's just a proposed mechanism
lmao
huh ok
how do they confirm mechanisms
if its in dispute
But iirc the most common proposed mechanism for clemmensen starts with protonation of carbonyl O
Which will not happen in COOH
So there you go, that logic works
very cool
They figure out a compound A that would give a certain result if Mechanism X were correct. Prepare A, perform reaction on A, see if required result is observed.
ahh
bro but what about about Aac1 mechanism
we added HCl it will for H2O(+)-C(=O)-R
can't we do it like that?
So, by this mechanism, Clemmen redn can't reduce COOH because it's actually going to be a resonance hybrid of COO(-)
The what mechanism now?
Aac1 is about acyl bond
that is what defines carboxylic acids right, makes them something more than just a carbonyl and an alcohol
also i am very bad at mechanism names
it's not a mechanism for mains
it's for (tough category) advanced and olympiads normally
ah
@Opt apparently its this
small picture my bad
do it come in mains?
yeah talking about this mechanism
its not in ncert so no
never even seen that before wtf is that
triple bonded oxygen cursed af
The heck the what now?
Huh
"stable cation"? the oxygen is triple bonded
the O X Y G E N
how is this real
that's coz OH took H+ then + was stable at C
due to benzene
and attacking is bit easy
ok we both have no clue you might need to ask a separate doubt
for this
that's just equilibrium thing double triple
nothing much
i'm asking why clemmensen can't do
still
acha
the mechanism i told you was all i was talking about to inform you that OH can take H+
I sent it up there a bit back
Protonation won't occur on carboxylic oxygen
^^
the resonance in COOH affects things
if Aac1 can happen
that it should too
isn't it?
Yeah, but why is Clemmensen going to take place by Aac1 is my question?
It's experimental
And apparently, it doesn't occur by Aac1
this isnt very answerable because scientists dont know the confirmed mechanism of clemmensen lol
the one Opt sent is just a theory
hmm, fir toh maan ke hi chalna padega
the curiosity is commendable
keep it up
thanks
+solved @Nimboi @Opt
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