[StevR]

Hi All,

I am taking organic chemistry II, as part of my chemical engineering program, and I am having a little bit of trouble knowing if this inference can be made.

I am given an unknown, solid compound, which I determined to be a phenol via IR spec. I did the bromine water test, and it was positive for a phenol, in that it accepted 60-drops of Br water solution and still did not retain the colour of the Br water reagent. I understand this much.

I am wondering if, since there was a white precipitate formed, and the textbook (shriner) tells me that a white precipitate forming is 2,4,6-tribromophenol, can I make the conclusion that my unknown compound is phenol itself? Or at least a phenol which is substituted only at the meta-positions. The book says that phenol will become brominated in the ortho and para positions due to the net hydroxyl 2,4-directing effect.

My question is essentially, will only phenol itself produce this white precipitate, or could the precipitate be formed even if one or more of the 2,4, or 6-positions are substituted already. And similarly, does this result then also mean that the meta positions are also only filled with hydrogen in the unknown, or could the result be 2,4,6-bromo-3,5-something-phenol.

Thanks, guys.

[AWK]

Each chemical test has a description that describes its scope of application in detail. Just read carefully your textbook or instruction.
There are also such descriptions on the internet.
Substituted phenols are usually less water-soluble then parent phenols themselves (there may be exceptions).
Phenol has limited water solubility up to 65°C, but much higher than needed to perform the test.
And besides, even if the bromine derivative was water-soluble, it is the second characteristic feature of the test
- discoloration.