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Topic: Amide hydrolysis  (Read 7627 times)

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Offline kriggy

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Re: Amide hydrolysis
« Reply #15 on: January 19, 2018, 02:57:30 AM »
Looks scary :D

im not saying the silylation at the sulphonate will happen but I like to consider all possibilities.

Offline Sonic Hedgehog

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Re: Amide hydrolysis
« Reply #16 on: January 20, 2018, 06:42:40 AM »
@kriggy I found this (http://onlinelibrary.wiley.com/doi/10.1002/047084289X.rb381.pub2/abstract)

tert-Butyldimethylsilyl Trifluoromethanesulfonate

Quote
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Handling, Storage, and Precautions: the material should be stored under argon at 0 °C. The compound has an unpleasant odor and reacts rapidly with water and other protic solvents.

Would it be completely necessary to store under an inert gas?

https://www.cerilliant.com/shoponline/Item_Details.aspx?itemno=c3130131-d64a-4844-b8cd-ed1bacaeaa2f&item=M-108

This reagent^ is surprisingly cheap, has anyone used it before?  Does it work as well as TBDMS-Cl?

Offline rolnor

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Re: Amide hydrolysis
« Reply #17 on: January 20, 2018, 08:37:57 AM »
No, I have used it, you dont need inert gas for storage although it keeps fresch longer.
Its similar to TBDMS-Cl, just more reactive.

Offline Sonic Hedgehog

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Re: Amide hydrolysis
« Reply #18 on: January 20, 2018, 04:05:27 PM »
No, I have used it, you dont need inert gas for storage although it keeps fresch longer.
Its similar to TBDMS-Cl, just more reactive.
I hoped that was the case haha

After the derivatization I plan on adding an equal volume of water to the derivatization mix (50:50 water/organic mix)- that wouldn't cause an issue would it?  I've read the TBDMS ethers are >100 times more stable to hydrolysis compared to TMS ethers, so hopefully it's ok.

Offline Sonic Hedgehog

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Re: Amide hydrolysis
« Reply #19 on: January 20, 2018, 07:19:08 PM »
"A silylation derivatisaion using N-methyl-N-t-butyldimethylsilyltrifluoroacetamide (MTBSTFA) replaces the active hydrogen with tert-Butyldimethylsilyl (t-BDMS) group. The tert-Butyldimethylsilyl derivatives which are more resistant to hydrolysis and can be up to 10,000 times more stable than TMS derivatives. N-methyl-N-t- butyldimethylsilyltrifluoroacetamide will target sulfonic and phosphoric groups if present"

I just found this- it looks like this reagent will react with sulfonic acid groups, which I really want to avoid :(.  TBDMS-Cl might be the better option...

Offline rolnor

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Re: Amide hydrolysis
« Reply #20 on: January 21, 2018, 10:19:23 AM »
MTBSTFA is probably more selektive for sulphonat and phosphate then hydroxyl-groups, I beleive this silylation is catalyzed by acid when it attacks these groups. TBDMS-groups ar stable to water under neutral conditions so your work-up should be OK. If you get silylation on the suphonat this will be more sensitive to hydrolysis and maby can be cleaved during work-up.

Offline wildfyr

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Re: Amide hydrolysis
« Reply #21 on: January 21, 2018, 01:36:14 PM »
Sorry, didn't mean to sidetrack this discussion. You should use tbdms-Cl.  my post about the trifluoromethane sulfonate was just sharing some info with kriggy since the topic came up.

MTBATFA is an interesting piece of Chemistry to find (thanks! It's new to me) but I don't think you want to deal with it in this case. The simple way is best. If you want a literature procedure I'll be happy to direct you to one (probably plug one of my papers haha).

Offline Sonic Hedgehog

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Re: Amide hydrolysis
« Reply #22 on: January 21, 2018, 06:09:00 PM »
Sorry, didn't mean to sidetrack this discussion. You should use tbdms-Cl.  my post about the trifluoromethane sulfonate was just sharing some info with kriggy since the topic came up.

MTBATFA is an interesting piece of Chemistry to find (thanks! It's new to me) but I don't think you want to deal with it in this case. The simple way is best. If you want a literature procedure I'll be happy to direct you to one (probably plug one of my papers haha).

Yeah if you have a few references to methods I'd really appreciate it :)

Offline wildfyr

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Re: Amide hydrolysis
« Reply #23 on: January 22, 2018, 01:07:40 PM »
Its in the supporting info of this paper (http://onlinelibrary.wiley.com/doi/10.1002/anie.201506253/abstract) or the main body of this one (http://pubs.acs.org/doi/full/10.1021/acs.macromol.7b02372). Mine are in DCM or DMF, but any moderately polar aprotic solvent has worked fine in my hands as long as its dry. Looking back, I should have added that I dried the organic layer with MgSO4 in my first reference.

You mentioned you're not a chemist, so I would think about going to one of the organic labs at your university and asking an experienced grad student there to run it for you in exchange for an authorship credit or mention in the acknowledgements. It should be a pretty trivial reaction taking only one or two attempts and an afternoon's work. I did add some nitty gritty details in that reddit post you should show them.

Doing this with no synthesis bench experience is not the end of the world, but you're not likely to have good success right away or the right materials/glassware/setup like an organic lab would. And you never know when some technical issues could crop up. For instance, since you will have a charged species (sulfonate salt) it may be necessary to force the product into the organic layer with brine.

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