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Topic: Synthesis of stannane compound  (Read 9752 times)

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Offline rolnor

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Re: Synthesis of stannane compound
« Reply #15 on: December 17, 2019, 11:59:47 PM »
One good way to quench this time of sample is to mix it with a dropp of acetone, RF should go down if the lithiation is successfull.
after quenching with acetone, will  I see the spot of R-Li? If I don't quench, which kind of spot will I see? Because in this case, after lithiation I see a new spot with lower Rf to compare with starting material (5-octylthiophene)
If you quench with acetone, you get the tertiary alcohol from addition to the carbonyl in acetone, this product will be much more polar then the starting material. If you dont quench you will see the compound with a hydrogen instead of a bromo because the lithio-compound will be hydrolyzed on contact with moisture and silica on the tlc-plate. This compound will also be a little more polar then the startingmaterial.
I think you are doing everything right, its surprising it does not work.

Offline Hachiko

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Re: Synthesis of stannane compound
« Reply #16 on: December 18, 2019, 02:09:47 AM »
One good way to quench this time of sample is to mix it with a dropp of acetone, RF should go down if the lithiation is successfull.
after quenching with acetone, will  I see the spot of R-Li? If I don't quench, which kind of spot will I see? Because in this case, after lithiation I see a new spot with lower Rf to compare with starting material (5-octylthiophene)
If you quench with acetone, you get the tertiary alcohol from addition to the carbonyl in acetone, this product will be much more polar then the starting material. If you dont quench you will see the compound with a hydrogen instead of a bromo because the lithio-compound will be hydrolyzed on contact with moisture and silica on the tlc-plate. This compound will also be a little more polar then the startingmaterial.
I think you are doing everything right, its surprising it does not work.
Thank you for your sharing.

Offline Hachiko

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Re: Synthesis of stannane compound
« Reply #17 on: December 22, 2019, 07:58:24 PM »
Are there any methods for me to treat Bu3SnCl to reuse it?

Offline rolnor

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Re: Synthesis of stannane compound
« Reply #18 on: December 22, 2019, 11:22:05 PM »
Do you mean purify it? Distillation.

Offline Hachiko

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Re: Synthesis of stannane compound
« Reply #19 on: December 23, 2019, 02:24:59 AM »
Do you mean purify it? Distillation.
Thank you!

Offline Hachiko

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Re: Synthesis of stannane compound
« Reply #20 on: December 23, 2019, 02:32:22 AM »
Do you mean purify it? Distillation.
Distillation seems a little bit dangerous because it's toxic. Could I use the molecular sieve to remove water inside? Because I think the problem may come from the moisture.

Offline rolnor

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Re: Synthesis of stannane compound
« Reply #21 on: December 23, 2019, 06:08:17 AM »
No, if you get moisture it will react very fast, you get the tributyltinoxide.
« Last Edit: December 23, 2019, 06:38:21 AM by rolnor »

Offline Hachiko

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Re: Synthesis of stannane compound
« Reply #22 on: December 23, 2019, 06:43:54 AM »
No, if you get moisture it will react very fast, you get the tributyltinoxide.
You means moisture will react with Bu3SnCl to form tributyltinoxide. So could it be the reason why Bu3SnCl doesn't work? I doubt that problem come from Bu3SnCl.

Offline kriggy

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Re: Synthesis of stannane compound
« Reply #23 on: December 25, 2019, 02:13:29 PM »
I would check the purity of the stannane, NMR works fine for it. If your bottle is old, get a new one its not that expensive.
Im not sure exactly about your procedure but I would use different base because BuLi can react with tributyltinCl to form tetrabutyl tin. Try LDA or tBuLi.
Quench the organoLi with water before TLC to get the dehalogenated aryl (if you have TLC of that) you can also use DMF to get the aldehyde and stain it with DMP.
Also, the reaction might need some time and temperature, maybe warm it to room temperature after the addition is complete. The organotin reagents are super nonpolar, be sure to check with suitable mobile phases (we used pure hexanes for that).

Maybe check this procedure
http://orgsyn.org/demo.aspx?prep=CV8P0268


Offline rolnor

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Re: Synthesis of stannane compound
« Reply #24 on: December 25, 2019, 04:36:14 PM »
I would check the purity of the stannane, NMR works fine for it. If your bottle is old, get a new one its not that expensive.
Im not sure exactly about your procedure but I would use different base because BuLi can react with tributyltinCl to form tetrabutyl tin. Try LDA or tBuLi.
Quench the organoLi with water before TLC to get the dehalogenated aryl (if you have TLC of that) you can also use DMF to get the aldehyde and stain it with DMP.
Also, the reaction might need some time and temperature, maybe warm it to room temperature after the addition is complete. The organotin reagents are super nonpolar, be sure to check with suitable mobile phases (we used pure hexanes for that).

You can not use LDA if you want metal-halogen excange as in this case. N-BuLi works fine is my experience. You will get quench automaticaly if you put the lithiated material on a TLC-plate.

Maybe check this procedure
http://orgsyn.org/demo.aspx?prep=CV8P0268

Offline kriggy

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Re: Synthesis of stannane compound
« Reply #25 on: December 26, 2019, 04:28:36 AM »
Yeah youre right, LDA doesnt exchange, I mixed that up with procedure we used (Bu3SnH + LDA then quench with electrophile)

Offline rolnor

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Re: Synthesis of stannane compound
« Reply #26 on: December 26, 2019, 03:52:37 PM »
Yea kriggy, thats an interesting reagent, Bu3SnLi, I have used it too. Its a "lithiated metal".

Offline Hachiko

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Re: Synthesis of stannane compound
« Reply #27 on: December 27, 2019, 09:02:59 PM »
Thank you all for your valuable advice.

Offline Hachiko

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Re: Synthesis of stannane compound
« Reply #28 on: July 08, 2021, 10:51:40 AM »
I have already known my problem for a time but I'm so busy. Now I think that someone may need to know the reason. The reason I'm failed with reaction is that I don't use 2 equiv of n-BuLi.
For lithium halogen exchange, to be certain you should use 2 equivalents of t-BuLi at -78 degrees, generally takes about an hour.
The first equivalent undergoes Li-halogen exchange and the second equivalent of t-BuLi causes E2 elimination of the t-BuBr side product to produce unreactive isobutylene. If you don't use two equivalents the desired thiophenyllithium may cause the E2 elimination giving you thiophene.

Offline rolnor

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Re: Synthesis of stannane compound
« Reply #29 on: July 08, 2021, 03:21:15 PM »
Do you use t-BuLi or n-BuLi? n-BuLi does not give elimination. With t-BuLi its important sometimes to use 2equi. like you say.
If you do lithium-halogen exchange with n-BuLi you get n-BuBr and this can react with you lithio-thiophene but generally the tin chloride reacts faster.

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