fatchains - 13-7-2012 at 12:31
First let me apologize if I missed a post where this was answered, I spent sometime trying to find one but couldnt.
Ive made bromoform via haloform reaction, comparing KBr, NaBr, and LiBr. I got great results with LiBr and KBr but my NaBr bromoform came out quite
cloudy. All chemicals were old, but recrystallized, lab grade salts (Sigma, carolina, etc); they were not OTC.
I hesitated to distill it because it is sensitive to heat but when I did it, even with a [light] vaccuum (crappy pump), it seems that the material
became severely discolored sometime in to the distillation. Must have been too hot (about 100C, with vacuum).
A) what about the NaBr synth is being left behind making the solution cloudy (NaOH)?
B) is there a way to purify this material, without applying heat?
Thanks in advance
[Edited on 13-7-2012 by fatchains]
Hexavalent - 13-7-2012 at 12:41
1. Are you sure you used good stoichiometry with the NaBr?
2. What impurities could feasibly be in it? How was it stored?
3. Did you leave a fair amount of time for the layers to cleanly separate?
4. Did you try adding saturated NaCl or even adding the solid directly?
To purify, you could try washing with several batches of water, maybe even dilute saline, or even solvent extraction.
[Edited on 13-7-2012 by Hexavalent]
crazyboy - 13-7-2012 at 13:10
It could be dissolved water, have you tried drying it over sodium sulfate?
fatchains - 13-7-2012 at 17:54
wow, you guys are fast. Thanks!
Stoichiometry should be accurate (1M increments)
Impurities; couldnt tell you- the bottle wasnt airtight when I got it.
The time was consistent between runs but that may have been an issue (left about 1.5-2h).
Have not tried washing with NaCl. I will try that. I have not collected this solid.
If it were dissolved water, wouldnt that indicate the NaBr-derived CHBr3 was somehow different in its ability to take on water compared to the KBr- or
LiBr-derived CHBr3?
I think either the NaBr is impure or Na-salt side products are more soluble in CHBr3, possibly both. Im thinking that wash or two with water to grab
the poss contaminates then drying with sat. NaCl soln will solve the problem if it arises (I think I like KBr better and its not too much more
expensive).
Thanks for the advice.