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Topic: nBuli + H2O, and whether nBuli is a bronsted base?  (Read 567 times)

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Offline gavindor

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nBuli + H2O, and whether nBuli is a bronsted base?
« on: April 27, 2024, 10:27:41 AM »
nBuli + H2O, and whether nBuli is a bronsted base?

This reaction-

n-BuLi + H2O → nBuH + LiOH

I understand is

C4H9Li + H2O --> C4H10 + LiOH

And I understand that n-Buli(C4H9Li)  is in a solvent but is not forming solvated ions. It's a molecule, it's covalent.

What i'm wondering is whether or not it's a bronsted base.
 
The conjugate pairs don't quite work..

C4H9Li/C4H10   <-- The Li has gone..

H2O/LiOH <-- An Li has been gained.

And we can't cancel the Li out as a spectator ion, because it's part of the n-Buli(C4H9Li) molecule, it's not a spectator ion.

Thanks

Offline Babcock_Hall

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Re: nBuli + H2O, and whether nBuli is a bronsted base?
« Reply #1 on: April 27, 2024, 02:36:03 PM »
https://en.wikipedia.org/wiki/N-Butyllithium#:~:text=In%20the%20case%20of%20n,%5BCH2R%5D4.

I don't have specific thoughts regarding your question; I do, however, have a general comment.  Although we write nBuLi as if it were a simple, covalent compound, it aggregates in solution.

Offline Hunter2

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Re: nBuli + H2O, and whether nBuli is a bronsted base?
« Reply #2 on: April 27, 2024, 02:36:34 PM »
Butyllithium is a strong base pka 50 stronger as hydroxide pka 15.7.
The reaction with water is an exchange reaction of Li to H.


https://www.uwindsor.ca/people/jgreen/sites/uwindsor.ca.people.jgreen/files/pka_bases.pdf

Offline gavindor

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Re: nBuli + H2O, and whether nBuli is a bronsted base?
« Reply #3 on: May 05, 2024, 08:31:13 PM »
Butyllithium is a strong base pka 50 stronger as hydroxide pka 15.7.
The reaction with water is an exchange reaction of Li to H.


https://www.uwindsor.ca/people/jgreen/sites/uwindsor.ca.people.jgreen/files/pka_bases.pdf

Thanks.

From what I understand,  in an exchange reaction, https://open.oregonstate.education/aandp/chapter/2-3-chemical-reactions/ both symthesis and decomposition occur e.g. A+BC→AB+C.

But isn't that the case with any acid base reaction?  e.g. if a proton leaves the acid and goes to a base, then that's an exchange reaction?

Or did you just mean that it's a chemical reaction involving a proton exchange?

I'm wondering whether  you would call n-BuLi + H2O → nBuH + LiOH a bronsted lowry reaction?  Or not, because one can't identify conjugate pairs?

And i'm wondering where you would call it a neutralisation reaction, given that while some neutralisation took place, NaOH is still a strong base. so the product is far from neutralised?

Offline Hunter2

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Re: nBuli + H2O, and whether nBuli is a bronsted base?
« Reply #4 on: May 06, 2024, 12:52:50 AM »
Quote
But isn't that the case with any acid base reaction?  e.g. if a proton leaves the acid and goes to a base, then that's an exchange reaction?

Or did you just mean that it's a chemical reaction involving a proton exchange?

I would say the second one.

Quote
I'm wondering whether  you would call n-BuLi + H2O → nBuH + LiOH a bronsted lowry reaction?  Or not, because one can't identify conjugate pairs?

Can not identify  conjugate pairs.

Quote
And i'm wondering where you would call it a neutralisation reaction, given that while some neutralisation took place, NaOH is still a strong base. so the product is far from neutralised?

Neutralisation guides to the middle of pH scale, means  in aqueous solution pH 7. Here only a stronger base exchanged to a weaker one.



Offline gavindor

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Re: nBuli + H2O, and whether nBuli is a bronsted base?
« Reply #5 on: May 06, 2024, 01:39:31 PM »
Quote from: Hunter2
Neutralisation guides to the middle of pH scale, means  in aqueous solution pH 7. Here only a stronger base exchanged to a weaker one

Thanks, that makes sense

Quote from: gavindor
I'm wondering whether  you would call n-BuLi + H2O → nBuH + LiOH a bronsted lowry reaction?  Or not, because one can't identify conjugate pairs?


Quote from: Hunter2
Can not identify  conjugate pairs.

Thanks, I know for sure that we can't identify conjugate pairs.

But to clarify, would you say  n-BuLi + H2O → nBuH + LiOH is thus not a bronsted lowry reaction?



Offline Hunter2

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Re: nBuli + H2O, and whether nBuli is a bronsted base?
« Reply #6 on: May 06, 2024, 01:43:09 PM »
I would say so.

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