[silentelysium]

Why is a dry solvent and glassware required for sulfonamide synthesis?

I've been trying to find out why this is so and some reference also. Can anyone help?

Also, in our method we added K2CO3 also. I know it makes the reaction environment basic but why does this help with the synthesis of sulfonamide?

[Doc Oc]

Without knowing more about your synthesis I will need to make some assumptions.

I'm guessing that you're starting with a sulfonyl chloride and an amine.  If you don't use dry solvent or glassware the water can react with the sulfonyl chloride to give sulfonic acid.  The base is there to scavenge the proton off of the amine after it displaces the chloride.

[tamim83]

I am pretty familiar with this synthesis as it is one of the synthesis projects in the organic lab course that I have taught. 

I don't know how you are sulfonating the benzene ring but we used chlorosolfonic acid.  This acid is really nasty (causes very painful burns, etc.) and reacts very violently with water.  If you are using this, you definitely want dry glassware.  If you need a reference, check the MSDS for chlorosulfonic acid. 

Also, in our synthesis, we converted aniline to acetanilide to direct the sulfonyl chloride  group to the para position.  Then, in the last step we used an acid catalyzed amide hydrolysis to remove the acetyl group.  This leaves a protonated sulfanilamide.  To get sulfanilamide, you need to deprotonate, so you can add a weak base.  A carbonate does the job well we used sodium bicarbonate, which also works well.  Look up acid catalyzed amide hydrolysis in your organic text, that would be a handy reference. 

Hope this helps some. 

[silentelysium]

I don't know how you are sulfonating the benzene ring but we used chlorosolfonic acid.  This acid is really nasty (causes very painful burns, etc.) and reacts very violently with water.  If you are using this, you definitely want dry glassware.  If you need a reference, check the MSDS for chlorosulfonic acid.  

Also, in our synthesis, we converted aniline to acetanilide to direct the sulfonyl chloride  group to the para position.  Then, in the last step we used an acid catalyzed amide hydrolysis to remove the acetyl group.  This leaves a protonated sulfanilamide.  To get sulfanilamide, you need to deprotonate, so you can add a weak base.  A carbonate does the job well we used sodium bicarbonate, which also works well.  Look up acid catalyzed amide hydrolysis in your organic text, that would be a handy reference.  

In our actual lab, the technicians already supplied the product produced after the use of chlorosulfonic acid. Our product was 4-acetamidobenzene-sulfonylchloride and using acetonitrile as a solvent, 2-aminothiazole was added also to form the intermediate. I understand that you need to use dry solvent and glassware to produce 4-acetamidobenzene-sulfonylchloride but why do we need dry acetonitrile and glassware in the preparation of sulfathiazole? 4-acetamidobenzene-sulfonylchloride was practically in a glass jar and they didn't tell us to keep it closed all the time to prevent moisture out I hope I'm not pointing out bad protocol in our lab but I just thought it's not necessary to have these measures addressed.

[Doc Oc]

Well, odds are that some of your sulfonyl chloride is hydrolyzed, but how much is hydrolyzed depends on how long it was left open and how often this happened.  If it was a significant amount of time and you are having trouble with this synthesis, that could be part of the difficulty.

The reason you keep the sulfathiazole dry is for the same reasons we spoke of earlier.  If you take precautions to keep the sulfonyl chloride dry but then use wet reagents and glassware for the other reagent then you're still introducing water, just later in the reaction.  So all stages of it should be dry to minimize the hydrolysis of the sulfonyl chloride.