StephAmanda
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Recently carried out a lab which involved the synthesis of sulfapyridine from p-acetamidobenzenesulfonyl and pyridine, using dichloromethane followed by conc HCl and saturated sodium bicarb.

My question is I know this produces a low yield due to solubility issues - would a mechanism involving KOH or NaOH with acetone be more effective.

Secondly why is p-Acetamidobenzenesulfonyl specifically used in this reaction mechanism?

Any help whatsoever would be greatly appreciated even if it mildly touches on something.

Thank you,

Steph
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illusionz
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(Original post by StephAmanda)
My question is I know this produces a low yield due to solubility issues - would a mechanism involving KOH or NaOH with acetone be more effective.
Base in acetone leads to enolisation, self condensation of your solvent and all sorts of side reactions. Bad idea. There are other, less reactive but equally as polar solvents which might help.

Secondly why is p-Acetamidobenzenesulfonyl specifically used in this reaction mechanism?
Sulfonyl what? You get sulfonyl chlorides, solfonyl azides etc not simply sulfonyl.
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StephAmanda
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Thanks for your help regarding this.

Do you have any examples of polar solvents that I can use instead then? The issue here is pure regarding solubility so reagants which increase the solubility better than HCl and pyridine do is what I am looking for?


(Original post by illusionz)
Base in acetone leads to enolisation, self condensation of your solvent and all sorts of side reactions. Bad idea. There are other, less reactive but equally as polar solvents which might help.



Sulfonyl what? You get sulfonyl chlorides, solfonyl azides etc not simply sulfonyl.
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illusionz
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(Original post by StephAmanda)
Thanks for your help regarding this.

Do you have any examples of polar solvents that I can use instead then? The issue here is pure regarding solubility so reagants which increase the solubility better than HCl and pyridine do is what I am looking for?
You seem confused as to which reagent is playing what part. Your solvent is DCM.

Also you didn't answer my question regarding the sulfonyl X. Was it a sulfonyl azide?
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StephAmanda
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I think that is my whole problem.

We have been asked to find an alternative synthesis mechanism from the one I have already explained that increases solubility....

As far as the sulfonyl X I don't understand what you mean - forget about that my main problem is the alternative synthesis.

(Original post by illusionz)
You seem confused as to which reagent is playing what part. Your solvent is DCM.

Also you didn't answer my question regarding the sulfonyl X. Was it a sulfonyl azide?
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username913907
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(Original post by StephAmanda)
I think that is my whole problem.

We have been asked to find an alternative synthesis mechanism from the one I have already explained that increases solubility....

As far as the sulfonyl X I don't understand what you mean - forget about that my main problem is the alternative synthesis.
The X is needed as otherwise it is an incomplete compound and doesn't exist in real life... therefore it is difficult to give definite answer of how will this react....
It's like saying I'm going to react water with a methyl group... You can't have a bottle of Methyl groups. You can however have a bottle of Me-X (eg. MeBr) and this will react with water to give methanol.
You are probably looking for the sulfonyl chloride as these are good electrophiles and you can easily 'click' the two components together.

Another polar solvent... DMSO.

Also, is the target compound really the one on the wikipedia page as your reagents wouldn't give that compound. You would need 2-aminopyridine rather than pyridine? Maybe somebody will say I'm wrong?
Besides, 2-aminopyridine can be made from pyridine in one step(ish).
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illusionz
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(Original post by JMaydom)
The X is needed as otherwise it is an incomplete compound and doesn't exist in real life... therefore it is difficult to give definite answer of how will this react....
It's like saying I'm going to react water with a methyl group... You can't have a bottle of Methyl groups. You can however have a bottle of Me-X (eg. MeBr) and this will react with water to give methanol.
You are probably looking for the sulfonyl chloride as these are good electrophiles and you can easily 'click' the two components together.

Another polar solvent... DMSO.

Also, is the target compound really the one on the wikipedia page as your reagents wouldn't give that compound. You would need 2-aminopyridine rather than pyridine? Maybe somebody will say I'm wrong?
Besides, 2-aminopyridine can be made from pyridine in one step(ish).
I was wondering if the reaction could have used the sulfonyl azide (which was the first result when I googled the incomplete name), with loss of N2 and nucleophilic attack through carbon. Not sure how the mechanism would work but no idea how else it could occur with the reagents given...

I would also never run a reaction in DMSO as you'll have a devil's job getting it out of your product. It also reacts pretty violently with acyl chlorides - don't know if the same thing happens with sulfonyl chlorides.

She also hasn't told us what compound wasn't soluble in DCM which isn't very helpful as we don't know what to try and avoid...

Personally I'd use
NaNH2 + pyridine to give 2-aminopyridine
React with the sulfonyl chloride
Done.
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username913907
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(Original post by illusionz)
I was wondering if the reaction could have used the sulfonyl azide (which was the first result when I googled the incomplete name), with loss of N2 and nucleophilic attack through carbon. Not sure how the mechanism would work but no idea how else it could occur with the reagents given...

I would also never run a reaction in DMSO as you'll have a devil's job getting it out of your product. It also reacts pretty violently with acyl chlorides - don't know if the same thing happens with sulfonyl chlorides.

She also hasn't told us what compound wasn't soluble in DCM which isn't very helpful as we don't know what to try and avoid...

Personally I'd use
NaNH2 + pyridine to give 2-aminopyridine
React with the sulfonyl chloride
Done.
The downsides of a theoretical chemistry degree showing there! Didn't know that about DMSO, suppose it's obvious come to think of it.
That's the reaction to generate 2-aminopyridine i was thinking of... Sulfonyl azide would be just as good, maybe even better?
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illusionz
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(Original post by JMaydom)
The downsides of a theoretical chemistry degree showing there! Didn't know that about DMSO, suppose it's obvious come to think of it.
That's the reaction to generate 2-aminopyridine i was thinking of... Sulfonyl azide would be just as good, maybe even better?
hehe I wouldn't have known until I started doing a lot of proper lab work. It's got a stupidly high boiling point.

Have you come across the swern oxidation? That's the fairly violent reaction.
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username913907
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(Original post by illusionz)
hehe I wouldn't have known until I started doing a lot of proper lab work. It's got a stupidly high boiling point.

Have you come across the swern oxidation? That's the fairly violent reaction.
Why of course, but only on paper
We never do anything in labs. Hardly a bad thing as we all hate them, but the whole of my next year will be in research labs, so I might get round to doing some actual practical chemistry!
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StephAmanda
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My apologies. The X = Chloride

P- Acetamidobenzenesulfonyl chloride

Hope this helps
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illusionz
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(Original post by StephAmanda)
My apologies. The X = Chloride

P- Acetamidobenzenesulfonyl chloride

Hope this helps
In which case you are missing a reagent, as those given will not lead to the product you want. Are you sure it was just pyridine?
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popnit
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(Original post by StephAmanda)
Recently carried out a lab which involved the synthesis of sulfapyridine from p-acetamidobenzenesulfonyl and pyridine, using dichloromethane followed by conc HCl and saturated sodium bicarb.

My question is I know this produces a low yield due to solubility issues - would a mechanism involving KOH or NaOH with acetone be more effective.

Secondly why is p-Acetamidobenzenesulfonyl specifically used in this reaction mechanism?

Any help whatsoever would be greatly appreciated even if it mildly touches on something.

Thank you,

Steph
What do you study?

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StephAmanda
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it was 2-aminopyridine...

But why would P- Acetamidobenzenesulfonyl chloride over other reagants be used?

(Original post by illusionz)
In which case you are missing a reagent, as those given will not lead to the product you want. Are you sure it was just pyridine?
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illusionz
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(Original post by StephAmanda)
it was 2-aminopyridine...

But why would P- Acetamidobenzenesulfonyl chloride over other reagants be used?
What other reagent are you suggesting? It's reactive so the reaction will be simple to carry out, and it has the structure you want...
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