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Author Topic: Sulfonamide  (Read 4550 times)

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technologist

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Sulfonamide
« on: May 01, 2009, 01:31:17 AM »

A company is producing 2-chloro-4-amino sulfonamide.

They start with meta chloro aniline & do chlorosulfonation with CSA (chlorosulfonic acid) followed by SOCl2 (Sulfonyl chloride) & then amination using ammonia.

When I referred Vogel, I found that

R-H + ClSO3H = R-HSO3 + HCl
R-H + 2 ClSO3H = R-SO2Cl + HCl + H2SO4

Where R - is aromatic benzene ring.

Since Company is already using 8 times of theoretical value why they are using sulfonyl chloride.

The product is formed like this

R1-SO2Cl + NH3 = R1-SO2NH2 +HCl

Where R1 - is meta chloro aniline radical kind of structure.

Can anyone help me.
Can I use any other starting material for this product
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ns9908

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Re: Sulfonamide
« Reply #1 on: May 02, 2009, 07:09:33 PM »

Having done sulfonation with CSA and then converted the acid to the acid chloride with an excess of the same reagent, I think that you're absolutely right. The thionyl chloride was likely used for pedagogical purposes, but industrially it would definitely be avoided. One problem with this overall reaction is the formation of the ortho isomer when you sulfonate your product. From firsthand experience, the reaction of CSA with N-phenyl acetamide forms almost exclusively the para isomer at 10 degrees Celsius. One problem you will have is that your CSA will react with your free amine and you'll make the sulfonamide--but in reverse. The solution is to protect your amine; I did this with Ac2O.

So you're on the right track, but in order to fulfill the dual goal of getting better regioselectivity and preventing reaction of your aniline with your CSA (think of it as an acid chloride, it's best kept away from amines) you'll need to form some sort of amide first.

On a more industrial note, you could nitrate benzene, halogenate to yield m-chloro nitrobenzene, and then reduce to get to your starting material, which is how the compound is produced industrially.
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technologist

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Re: Sulfonamide
« Reply #2 on: May 02, 2009, 09:36:52 PM »

Thanks ns9908
I could not fully understand your answer. Can U pls explain with some chemistry equations also.

Further, the company is first using 8 times of stoichiometric amount of CSA then using 4 times of SO2cl amount. Is it necessary?

They are not converting it to amide first. MCA is directly sulfonated using CSA which is giving para derivative to amino group then SO2Cl is used to make Sulfonyl chloride at the same para position and then amination is done to convert SO2Cl into SO2NH2 (sulfonamide) at the same para position.

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