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Aspirin Industrial Production


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#1 guest_68

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Posted 04 May 2018 - 11:59 AM

Hi,

 

I would like to know why acetylsalicylic acid (active ingredient of Aspirin) is not produced using acetic acid (instead of acetic anhydride) in industry?

I know using acetic acid generates water and the reaction can go in reverse direction, hence minimizing the yield. 

But I want to know if that is the reason that it is not used in industry? or are there other contributing factors?



#2 MrShorty

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Posted 04 May 2018 - 02:39 PM

I don't claim any special knowledge on this. I put "esterification using acid versus using anhydride" into my favorite internet search engine. Among the top results was this Q & A from quora: https://www.quora.co...carboxylic-acid

The anydride consumes the water that is formed as part of the esterification reaction, improving the favorability of the forward reaction, and inhibiting the backward hydrolysis of the ester. That reasoning seems as good as anything I could have come up with on my own.



#3 guest_68

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Posted 04 May 2018 - 03:59 PM

I don't claim any special knowledge on this. I put "esterification using acid versus using anhydride" into my favorite internet search engine. Among the top results was this Q & A from quora: https://www.quora.co...carboxylic-acid

The anydride consumes the water that is formed as part of the esterification reaction, improving the favorability of the forward reaction, and inhibiting the backward hydrolysis of the ester. That reasoning seems as good as anything I could have come up with on my own.

 

THanks for your help.

 

I was just wondering if in industry there is a way to remove the water generated as a side product when using acetic acid? or maybe it is too costly?



#4 MrShorty

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Posted 04 May 2018 - 04:52 PM

I am pretty sure there are other methods for removing water from a reaction like this, so I expect it is all about cost/efficiency like you say. In this case, one of your two main reactants is not only a big part of creating the desired product, it is also your water scavenger for removing the water of reaction to encourage the reaction to go forward. I suspect that the simplicity of having one reactant serve as both reactant and water scavenger makes this approach advantageous compared to adding (and later removing) a separate water scavenger or removing the water by other means.



#5 breizh

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Posted 05 May 2018 - 01:27 AM

Hi ,

I've been producing Acetyl salicylic acid for 5 years . As explained , very simple route from salicylic acid + Acetic anhydride . simple process ( reaction/crystalization/centrifugation/drying )

 

Breizh   


Edited by breizh, 05 May 2018 - 01:30 AM.


#6 Peggy

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Posted 08 May 2018 - 03:24 AM

Production process:

Acetylation of salicylic acid: add acetic anhydride (feeding ratio is 0.7889 times of the total salicylic acid) in reaction vessel, and then add two thirds of salicylic acid, stir it and temperature rises. React 40-60min in 81-82℃. Cool it to 81-82 ℃ and keep the temperature for 2h. When free salicylic acid is qualified, cool it to 13 ℃, precipitation crystallization, rejection filter, dry it in 65-70℃ air flow, then we get acetylsalicylic acid.(Source: http://www.chemicalb...5114818_EN.htm)






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