SunriseSunset - 25-9-2015 at 03:01
Would it be possible to fractionally distill bromoacetones without applying vacuum, using only standard atmospheric pressure?
I understand that bromoacetones will begin decomposition shortly after being produced (if left un-stabilized) and so it is common to quickly proceed
use into whatever is next.
If I used the procedure way low below, would it be possible to actually separate the polybromoacetones to isolate pure monobromoacetone? Because those
boiling point fractions look way too close to one another, and in the procedure he/she tried two fractional distillations. Shouldn't I be worried that
it would decompose. I assume that is why they used a vacuum, but would it be possible to fractionally distill bromoacetones without vacuum?
PROCEDURE
A 5-l., three-necked, round-bottomed flask is provided with an efficient mechanical stirrer, a 48-cm. Allihn reflux condenser, a thermometer, and a
500-cc. separatory funnel, the stem of which reaches nearly to the bottom of the flask (Note 1).
Through the separatory funnel are introduced 1.6 l. of water, 500 cc. of c. p. acetone, and 372 cc. of glacial acetic acid. The stirrer is started and
the temperature of the water bath is raised to 70–80°, so that the mixture in the flask is at about 65° (Note 2). Then 354 cc. (7.3 moles) of
bromine is carefully added through the separatory funnel. The addition, which requires one to two hours, is so regulated as to prevent the
accumulation of unreacted bromine (Note 3). As a rule the solution is decolorized in about twenty minutes after the bromine has been added. When the
solution is decolorized, it is diluted with 800 cc. of cold water, cooled to 10°, made neutral to Congo red with about 1 kg. of solid anhydrous
sodium carbonate, and the oil which separates is collected in a separatory funnel and dried with 80 g. of anhydrous calcium chloride. After drying,
the oil is fractionated and the fraction boiling at 38–48°/13 mm. is collected. The yield is 470–480 g. (50–51 per cent of the theoretical
amount). It may be used without further purification for the preparation of acetol (p. 5); but, if a purer product is desired, the above product is
refractionated and the fraction boiling at 40–42°/13 mm. is collected. The yield is 400–410 g. (43–44 per cent of the theoretical amount).
The higher-boiling fraction contains a mixture of isomeric dibromoacetones.
CITE
Org. Synth. 1930, 10, 12
DOI: 10.15227/orgsyn.010.0012
SunriseSunset - 25-9-2015 at 04:09
Probably a dumb question but what the hell, worth finding an answer.
CuReUS - 25-9-2015 at 04:24
see this video from 7:00 ,he makes chloracetone and distills it without a vacuum or even a frac column,but there is significant loss of product
https://www.youtube.com/watch?v=DDqIzxTGc78
Metacelsus - 25-9-2015 at 04:47
You would do much better with vacuum. The lower boiling temperature will slow down decomposition.
Have you ever made any haloacetones before? Be sure you know what you're getting into. They're serious lachrymators, even at low concentration
(bromoacetone was used in World War I).
SunriseSunset - 25-9-2015 at 04:52
Very cool! I like the test he used for a color change from NaOH to verify the presence of chloroacetone. That's good to know
SunriseSunset - 25-9-2015 at 04:57
Never ever delt with any specific haloacetones before, but I did deal with a halogenated phenyl ketone twice in the past and that alone (for a solid)
was pretty damn close to tear gas, in my own opinion lol.
Pretty aware of the impact that a small amount can cause. In the future, it would be smart to have a pre-made-neutralization-solution to neutralize
any and all waste, and to clean the glassware with a before attempting to further clean. And thanks!
The main reason why I wondered about the requirement for vacuum is because I don't have any fume hood. Without a fume hood, even distilling a
micro-scale amount, I'm sure the fumes would vent through the vacuum and make it worst. during the entire distillation
[Edited on 25-9-2015 by SunriseSunset]
macckone - 25-9-2015 at 06:19
Chloroacetone doesn't decompose like bromoacetone.
It will form all kinds of nasties if unstabilized though.
Condensation products of unstabilized chloroacetone
may explode due to the formation of peroxides.
Bromoacetone probably requires vacuum to keep the
temperature low enough to prevent decomposition and
forming the same kind of nasties that chloroacetone does.
Serious warning: If you are going to mess with these compounds
then you need to do it outside with a gas mask or inside a very
good fume hood (and a gas mask is still recommended).
Know what you are messing with:
http://www.sigmaaldrich.com/MSDS/MSDS/DisplayMSDSPage.do?cou...
One whiff of chloroacetone laid me out for several days.