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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: zilalti on October 30, 2005, 04:43:28 PM

Title: Aspirin sythesis bi product
Post by: zilalti on October 30, 2005, 04:43:28 PM

I recently synthesised aspirin by refluxing 2-hydroxybenzoic acid with ethanoic anhydride. Then filtering and recrystalizating with HCl I obtained about 1 or 2 grams of the impure aspirin.
Hears my question, when i dried the crystals in the dessicator on filter paper it burnt a hole right through. I know ethanoic acids is a biproduct but surely its not responsible. Anyone know what happened??.
     

Title: Re:Aspirin sythesis bi product
Post by: movies on October 30, 2005, 05:02:48 PM

Sounds like residual HCl to me.

Title: Re:Aspirin sythesis bi product
Post by: zilalti on October 30, 2005, 05:35:50 PM

hmm i suppose but it was a charred hole almost like it had ignited, i would have thought HCl corrosion would look different.

Title: Re:Aspirin sythesis bi product
Post by: movies on October 30, 2005, 07:55:36 PM

Depends on how it happened.  Have you ever seen the demonstration where sulfuric acid is added to table sugar resulting in a column of charcoal?  It looks just like you had burned something, but there isn't any burning, just dehydration of the hydrocarbons.

Title: Re:Aspirin sythesis bi product
Post by: Mitch on October 30, 2005, 08:05:26 PM

Quote from: movies on October 30, 2005, 07:55:36 PM

isn't any burning, just dehydration of the hydrocarbons.

Specifically oxidation of hydrocarbons for those purest physical organic chemists.

Title: Re:Aspirin sythesis bi product
Post by: movies on October 31, 2005, 01:37:04 AM

Ah!  Bested by Mitch once again!  ;)