[rodelero2]

Hey, it's my first post.

I work in a lab as an undergrad, my PI has given me a task to complete.

To monobrominate an activated toluene derivative.

my reagents are bromine and acetic acid.  

I evaporated my acetic acid and I am left with a dark almost purplish liquid. (my starting material was a liquid so no problems there)

However After evaporating all my bromine the liquid is still colored.

I can't seem to purify my compound. If it's Br2 then it should evaporate. Could it be a complex of my product and bromine or HBr?

There has to be a way to separate this.

EDIT: I did a mini workup on an eppendorf. I added water and DCM. My purple liquid sinks to the bottom and goes to DMC.

I'm still unsure on how to approach this.

[Doc Oc]

One thing to keep in mind, your compound is now brominated so it might be colored.  But in general it's hard to judge the purity of anything by color unless you already know for fact it should or shouldn't be a certain color.

I commonly get rid of excess bromine using sodium thiosulfate (Na2S2O3).  Procedures vary, some people use saturated solutions, others use 10-20% solutions.  I would try a 20% solution and stir it with your compound for 10-20 min and see if the color leaches out.  If some of it does but your product is still significantly brown or purple, do more washes until you see no more leaching of the color.

[pacifyer]

I agree with J-bone: once the reaction completes, eliminate excess bromine by a thiosulfate of bisulfate treatment, until reddish color vanishes...
Excess bromine is dangerous, AVOID any eye-skin contact, and if present, excess bromine will codistill with the solvent in the rotovap... that must be avoided...

[discodermolide]

Hey, it's my first post.

I work in a lab as an undergrad, my PI has given me a task to complete.

To monobrominate an activated toluene derivative.

my reagents are bromine and acetic acid.  

I evaporated my acetic acid and I am left with a dark almost purplish liquid. (my starting material was a liquid so no problems there)

However After evaporating all my bromine the liquid is still colored.

I can't seem to purify my compound. If it's Br2 then it should evaporate. Could it be a complex of my product and bromine or HBr?

There has to be a way to separate this.

EDIT: I did a mini workup on an eppendorf. I added water and DCM. My purple liquid sinks to the bottom and goes to DMC.

I'm still unsure on how to approach this.

Do a proper solvent extraction. After the reaction is complete dilute it with a solvent, say methyl tButyl ether, was out the excess acetic acid with bicarbonate (gas evolution) get rid of the excess bromine, as the other posters have suggested. Remove the solvent, crystallizse the product or distill it.

[PJGRAY]

As described above, you do need to carry out a proper aqueous work up incorporating both a base and thiosulfate wash. If colour still persits then perhaps consider a charcoal treatment.