2) As per rhodiums synthesis of NBS:
1.62mol (160g) succinimide is dissolved in a mixture of 1.60mol (64g) NaOH, 300g crushed ice and 400ml water. Cool the mixture in an ice bath, and add
85ml (1.65 mol, 264g) Br2 at once while stirring violently. Stir for two more minutes, then filter the precipitated product and wash with ice water.
Dry in a desiccator. Yield 75-81%.
Would this work?
Thanks.
-rlrMephisto - 9-2-2005 at 04:31
Yes, you're right. You can also heat succinic acid with urea to 175 °C to get your succinimide. In Gattermann 'Die Praxis des Organischen
Chemikers' (don't know if it’s translated) there are preparations of succinimide from succinic acid and ammonia and succinic acid and
formamide. The NBS-synthesis is described there too.
Does anybody tried to substitute NBS with OTC pool brominators? It might even work better than NBS, like the example of NCS and TCCA
(for water-disinfection) shows. It only depends from what those pool brominators are made of. Because they giving bromine very slowly away, I am
optimistic, that they might be as selective as NBS.
OTC brominating agents
Mephisto - 9-2-2005 at 05:41
Common OTC pool brominators consists either of BCDMH (1-Bromo-3-chloro-5,5-dimethylhydantoine => product: Aquabrome) or DBDMH
(1,3-Dibromo-5,5-dimethylhydantoine => product: Albrom).
DBDMH:
BCDMH reacts with water to form both hypochlorous and hypobromous acids. DBDMH forms only the hypobromous acid and should be sufficient for
bromination. As I am in hurry, I would be glad if someone could check DBDMHs ability as brominating agent.
I think, this gives a good summary of possible OTC brominating agents.
~Mephistoenima - 9-2-2005 at 08:20
Yup, it can brominate. Works well only on activated rings..
Tetradehdron Letters, Vol. 38. No. 25 pp. 4415-4416, 1997
anisole is brominated with a 85% yield (18 hours)
1,3-dimethoxybenzene is brominated with a 98% yield, (18 hours).
2-methylphenol is dibrominated.
Anisaldehyde, toluene and 2-picoline fails bromination.
there are plenty of rhodium mirrors around, search for them and you can easily find the page you want...
-rlr
A U2U to another
UpNatom - 23-2-2005 at 13:52
.,.member at this board has prompted me to post what I should have included earlier. Euroscientists...where you see oxone, insert virkon.
Caffinehog - 5-3-2005 at 17:47
Just remember that this stuff is good for radical reactions, too.sparkgap - 6-3-2005 at 04:26
Quote:
Just remember that this stuff is good for radical reactions, too.
Truly. For the times peroxides and AIBN are inaccessible...
sparky (^_^)
[Edited on 6-3-2005 by sparkgap]Mephisto - 14-3-2005 at 12:11
This idea of brominating with DBDMH was just a fast thought. However, in very rare cases DBDMH is even more efficient then NBS. For example to
dibrominate piperonylic acid (as I said, these cases are very rare). As I scanned two articles about DBDMH-bromating to inform myself about its
possibilities, I can also share these articles:
[color=darkred]Tetrahedron Letters, Vol. 34, No. 6, pp. 931-934 (1993)[/color]
Title: N-Bromosuccinimide, Dibromodimethylhydantoin in Aqueous Base: A Practical Method for the Bromination of Activated Benzoic Acids Abstract: A new bromination method employing NBS or dibromodimethylhydantoin in aqueous base is described for the synthesis of
3-bromo-2,6-dimcthoxybenzoic acid (1) and other monobrominated alkoxy benzoic acids.
[color=darkred]Tetrahedron Letters, Vol. 38, No. 25, pp. 4415-4416 (1997)[/color] - found by enima Title:1,3-Dibromo-5,5-Dimethylhydantoin, a useful Reagent for Aromatic Bromination Abstract: 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) is a useful and easy to handle reagent for bromination of various aromatic
derivatives substituted with electron donating groups. In the presence of trimethylsilyltrifluoromethanesulfonate, DBDMH showed increased reactivity,
and in one case, the reaction followed another pathway, suggesting an alternative mechanism.
BTW: Has anybody seen DBDMH containing products in Europe? It seems that the Albemarle products 'XtraBrom' and 'Albrom' are only
available on the US-market.
****
Both articles are attached.
Attachment: Both.Articles.rar (207kB) This file has been downloaded 850 times
enima - 15-3-2005 at 00:11
Nice find Mephiso. I wonder how well the DBDHM would work on activated aldehyde groups. Those are very nice yields for the bromination of benzoic
acids. I must say very impressive.UpNatom - 15-3-2005 at 11:59
Quote:
BTW: Has anybody seen DBDMH containing products in Europe? It seems that the Albemarle products 'XtraBrom' and 'Albrom' are only
available on the US-market
Yes indeedy...Maxibrom and Allbrom are what you're looking for (possibly other brands as well but I don't have time to
check). Btw the first hit on google UK for either of those two products gives a company which also sells an item called "Shock II" which you
may find interesting/useful Mephisto - 16-3-2005 at 03:18
UpNatom: I searched for the Dibromdimethylhydantoine, while Allbrom and Maxibrom contain Bromochlorodimethylhydantoine. There
is a chance that the bromochloro-mix works too, as Br is a better substituent than Cl, but to be on the safe side I am looking only for the chlorine
free substance.UpNatom - 16-3-2005 at 13:04
My apologies Mephisto, you are correct in that Maxibrom contains Bromochlorodimethylhydantoin as well as the dibromo compound however allbrom
(according to the manufacturers MSDS) contains only the dibromo compound.
