Test tube containing small portion of aspirin

[stanton]

I had an experiment. A test tube containing small portion of aspirin was prepared. NaOH was added to the solution, and then HCl was added. when I mixed FeCl3 with the solution, the solution turned intense purple.
This result is the positive test for phenols.

And why does this result proves that the aspirin is active in intestine? I cannot understand. I thought the aspirin is most active in stomach, because I though the acid converts aspirin to salicylic acid?

 

[chemisttree]

What is the pH of the stomach? How about lower down in the intestines?

 

[stanton]

stomach has lower ph than the intestine(acidic). intestine is basic, right?

 

[chemisttree]

Yes. The stomach is acidic and the intestines are somewhat basic. This means that aspirin is not ionized in the stomach and is ionized further down the intestines. How might this affect solubility? Absorption?

 

[stanton]

If the ASA is ionized in intestine, it might mean the ASA is dissolved. So intestine can absorb this ASA. Then the ASA is very active in intestine. And NaOH in my experiment converted the ASA to sali acid(Test tube with NaOH is similar to the environment of intestine). And although the HCl was added lastly, the ASA is not very affected, so it showed phenol test to be positive. (salicylic acid is a substituted phenol) I think I am getting it. :) Thank you!