Quote: Originally posted by SplendidAcylation |
Is there any particular reason you recrystallized the benzoic acid from acetone?
I've always had good results using boiling water.
I'm pretty sure it didn't have any smell, though, maybe a slight smell resembling benzoic acid?
Would you say the smell is substantially different from that of benzoic acid?
I would urge caution regarding the ammonium benzoate to benzamide idea.
Unlike the analogous reaction using ammonium acetate to form acetamide, this reaction doesn't seem to be feasible in an open vessel, as the loss of
ammonia is favoured over the loss of water, so you just end up with benzoic acid, all the ammonia having escaped...
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I was testing solubility of polar vs. non-polar compounds. Sodium benzoate and ammonium benzoate are polar, so they dissolve in water but not in
acetone, whereas benzoic acid is non-polar so it dissolves in acetone but not in water. I wanted to see this for myself. I also thought that if
there was any trapped sodium chloride in the benzoic acid precipitate, it would not dissolve in the acetone and I could filter it out. I did filter
the acetone, but didn't see anything left behind so apparently it was already fairly pure just from multiple washings with water.
I note almost no smell from sodium benzoate. Benzoic acid to me smells just like some sort of soda I used to drink years ago as a child. It must
have been loaded with benzoic acid as a preservative. I only noted the rubbery smell in addition with ammonium benzoate, not benzoic acid. It is
possible that this may be due to impurities in the acetone though. The acetone container says it contains denatonium benzoate, apparently to prevent
consumption. I'm sure the amounts are very small, but may be enough to change the smell.
Here is one of the few YouTube videos I have found that mention ammonium benzoate.
https://www.youtube.com/watch?v=lzw2qbmYivg
The author heats a test tube containing ammonium benzoate and a thick vapor escapes. Author concludes (not sure why) that benzamide was formed based
on this.
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