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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Sev on August 11, 2007, 01:43:15 AM

Title: Solubility of commercial aspirin
Post by: Sev on August 11, 2007, 01:43:15 AM

Hi,

In a recent practical I synthesized aspirin (from salicylic acid and ethanoic anhydride).  The aspirin precipitated out of solution after adding cold water.
Does anyone know how some commercially available aspirin tablets are soluble?

I suspect there are added ingredients in the tablet, but I'm not sure how these act to increase solubility.

Could someone kindly help.  Thanks.

Title: Re: Solubility of commercial aspirin
Post by: HP on August 11, 2007, 05:18:37 AM

The Solubility of Aspirin: One gram of aspirin dissolves in the following solvents:
300 mL water at 25oC
100 mL water at 37oC
5 mL ethyl alcohol
17 mL chloroform
10-15mL ether (less soluble in anhydrous ether)
The white precipitate in water is may be from the tablet additives like silica(SiO2), starch or talk or some else or too little water added :)

Title: Re: Solubility of commercial aspirin
Post by: Custos on August 13, 2007, 01:09:08 AM

Commercial aspirin is sold as the sodium salt or a mixture with sodium bicarb or sodium carbonate. The acid salt form of aspirin is quite a bit more soluble in water than the free acid.

Title: Re: Solubility of commercial aspirin
Post by: Mitch on August 14, 2007, 12:19:33 AM

Also, the human gut can be more acidic than normal cold water from the DI faucet.