laoqianxiu - 13-3-2007 at 00:09
Beilstein 1(2)463
CAS 3344-77-2
I ran a search in Google got 1 hit:
[PDF] Synthesis of deuterated fatty acids to investigate the ...文件格式: PDF/Adobe Acrobat
12-Bromo-1-dodecanol (1). To a solution of 1,12-dodecan-. diol (4.04 g, 20 mmol) in 50 mL of toluene cooled to 0°C was. added 28 mL of HBr (48%, 240
mmol), and the mixture was re-. fluxed in the dark for 5 h (TLC monitoring). ...
www.springerlink.com/index/L417GQ22313R432P.pdf - 类似网页
12-Bromo-1-dodecanol (1). To a solution of 1,12-dodecan-
diol (4.04 g, 20 mmol) in 50 mL of toluene cooled to 0°C was
added 28 mL of HBr (48%, 240 mmol), and the mixture was re-fluxed in the dark for 5 h (TLC monitoring). The reaction was allowed to cool to room
temperature, and 50 mL of brine was then added. The mixture was extracted with hexane, dried, fil-tered, and concentrated at reduced pressure.
How could I get rid of the byproduct that is still in the product?
i do this product in term of front ,is right?
Does anybody have experience with the synthesis 12-Bromo-1-dodecanol
Sauron - 13-3-2007 at 01:03
I can think of two alternatives for the bromination.
1. PBr3
2. TCT/DMF complex + KBr
Is the 1,12-diol commercially available or will you need to build it?
I suppose it ought to be readily available by reduction of the saturated C12 dicarboxylic acid.
In workup you will have unreacted acid, your product and maybe a little 1,12 dibromo compound if you exceeded 1 mol eq. reagent to substrate. Prep LC
is probably your best bet for isolation. Pain in the neck but will give you purest unambiguous product. Otherwise is the product solid or liquid?
That will dictate purification. Even if solid it might be distilled at low enough pressure without heating so much as to decompose.
----------------------
Aldrich 224677 99% also sold by Fluka
1 bromo 12 dodecanol
mp 34-36 C
bp 155 C/4mm
Sold in 1 and 5 g glass bottles.
Can't blame you though, Aldrich is too expensive!
Anyway there's your answer, you can distill it with a good two stage pump and a half decent column. So you won't need the prep LC.
[Edited on 13-3-2007 by Sauron]
Shaddy - 13-3-2007 at 01:23
How could I get rid of the byproduct that is still in the product? - all organic stuff you can have is diol, desired monoalcohol and dibromide. It
schould be great difference in terms of water/hexane solubility, Rf in chromat. and boiling points between all of them. Diol and inorganic rest you
will wash with water . Most certain way to get out of dibromide will be small column in hexane or petrol ether. then distillation (UPD: bp 155/4
Kugelrohr or just skip it ).
PS: Aldrich is expensive, but comprehensive.
[Edited on 13-3-2007 by Shaddy]
Sauron - 13-3-2007 at 02:26
Agreed, but I wish they packaged a product like this in something more than 5 g.
I didn't bother looking up the glycol (diol) once I saw the target product. Maybe Acros or Merck has it too, they are sometimes easier to deal with
then Aldrich (at least from my location. NB: neither one has the bromide or diol but Aldrich does see below.))
Synonym Dodecamethylene glycol
Molecular FormulaHO(CH2)12OH
Molecular Weight202.33
CAS Number5675-51-4
Beilstein Registry Number 1742760
EG/EC Number 2271339
MDL number MFCD00004755
Aldric D221309 100 ml poly bottle
There's a more reasonable amount. The monobromide will gain mass so as long as yield is high, and it ought to be, he ought to end up with c150 g at
least.
bp 189 C/12 mm
mp 79-81 C
[Edited on 13-3-2007 by Sauron]
[Edited on 13-3-2007 by Sauron]
benzbenz - 14-3-2007 at 09:41
this question was preveilling in last century. how to get rid of side-product? just diol reacts completly. then make phase separated. it should be OK