TheOrbit
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Phenacyl bromide synthesis using bromine water
new method for preparing phenacyl bromide without bromine liquid
To a stirred solution of acetophenone ( 5 mmol) in
aqueous (1:1) methanol (10 mL), the sodium bromide–sodium bromate
(2:1) (1 g, 5 mmol available Br2) was added, followed by
dropwise addition of dilute HCl (1 N, 10 mL). The reaction
mixture was stirred for 1.5 h . The mixture was then
extracted with Et2O (3 6 10 mL) and the extract was washed
with an aqueous solution of Na2S2O3 and brine, and dried
with(Na2SO4). Evaporation of solvent left the crude product,
crystalize from methanol
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panziandi
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Is it just me or do other people hate the naming of phenylhaloacetones as phenacyl halides, they are technically not acyl halides...
What was your yield of crude product and purified product out of curiosity? I don't think this is a "new" method?
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The_Davster
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They are not phenylhaloacetones. Bromination of this:
to give the alpha brominated ketone.
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DJF90
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I dont like the naming either, regardless of whether its based on acetone or not, because it is not an acyl halide as panziandi states, and thus
misleading. I think panziandi got confused with the acetone but because the molecule is called bromoacetophenone; I make these simple mistakes
sometimes, and we've all added or lost a carbon magically when we arent thinking straight  And I really dont think this is a new method either; the acid catalysed halogenation of carbonyls has been known for years!
[Edited on 28-6-2009 by DJF90]
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Sauron
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Interesting.
We just got rid of an obnoxious troll who wanted to make cgloroacetone "to ptotect hos family".
I always figured he rea;;y meant cgloroacetophenone.
And now we have a bewbie who wants to make bromoacetophenone, how coincidental.
I see nothing by way of technical elegance in substituting bromine water for btomine. All this accomplishes is creation of a large waste stream of
coaminated water. bromoacetophenone is more toxic than CN which is why LE does not use it despite higher lachrimatort effects.
And no I will not elaborate on better ways to make this CW agent. Those are well knoen to snyone who knows how to read.
[Edited on 29-6-2009 by Sauron]
Sic gorgeamus a los subjectatus nunc.
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kclo4
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Here is Orgsyn's phenacyl bromide synthesis for contrast.
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV2...
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Sauron
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Why spoonfeed?
People should go to the obvious and freely available sources before opening a thread not after. The forum library. Org.Syn. etc etc.
[Edited on 29-6-2009 by Sauron]
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The_Davster
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Compared to orgsyn this procedure does seem more convenient, as it negates the inconvenient starting materials or bromine and aluminum chloride. Of
course I would like to know if this procedure is reproduced from somewhere or if is theorbit's original procedure.
The theorbit has been a member since before we had an issue with that guy Sauron.
[Edited on 29-6-09 by The_Davster]
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Sauron
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In order to have bromine water you need bromine, in the first place.
There's no free lunch.
There are water treatment chenicals avaikable to cunsumers otc in small qty, that are convenient Br sources either for generating Br2 as needed or in
this instance for effecting the alpha bromination themselves. I am sure any chemist reading this will know what I mean. No AlCl3 reqd.
[Edited on 29-6-2009 by Sauron]
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The_Davster
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Of course Sauron, but in-situ synthesis with bromate and bromide is much less of
a hassle than dealing with the liquid.
EDIT: I assume you mean the bromo analogues of the chlorination agent used in another thread for the alpha chlorination of another ketone producing
another lachramatory agent
[Edited on 29-6-09 by The_Davster]
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Nicodem
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Quote: Originally posted by TheOrbit  | new method for preparing phenacyl bromide without bromine liquid
To a stirred solution of acetophenone ( 5 mmol) in
aqueous (1:1) methanol (10 mL), the sodium bromide–sodium bromate
(2:1) (1 g, 5 mmol available Br2) was added, followed by
dropwise addition of dilute HCl (1 N, 10 mL). The reaction
mixture was stirred for 1.5 h . The mixture was then
extracted with Et2O (3 6 10 mL) and the extract was washed
with an aqueous solution of Na2S2O3 and brine, and dried
with(Na2SO4). Evaporation of solvent left the crude product,
crystalize from methanol
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How about providing some reference or additional explanation? Obviously nobody (including me) understood whether this was an experiment, a copy/paste
from an unreferenced source or just some fantasy work. It is better to prevent misunderstanding in the first place.
PS: "Phenacyl" is an well established name for the PhCOCH2- group. It has nothing to do with acetone.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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panziandi
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Indeed what I meant was HALOACETOPHENONE, close.. but no cigar, to phenylhaloacetone, but as DJF90 pointed out we all make a mistake or two when not
thinking straight But all I meant was that the term Phenacyl for PhCOCH2' is just
a hangover from an old era and actually isn't very good since it's misleading, of course nothing to do with acetone, it was a typo.
It is of course an old method, the only "new" thing about it is formation of in situ bromine water, which in my opinion is a waste of time and waste
of bromate. But alas some people would rather not toy with liquid bromine (when they or IF they get it )
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