makfc - 21-4-2006 at 06:13
I done an acetylation reaction of 3-hydroxy benzldehyde very well using acetyl chloride as acetylating agent and iodine was used as a powerful
catalyst in this solvent-free reaction.
But after the reaction completion, in work-up, what should I do to remove both these reagents ? I read that Sodium thiosulfate can be used for iodine
but also read that it may also react with my aldehyde.
Pls suggest something............
makfc
[Edited on 21-4-2006 by makfc]
kclo4 - 21-4-2006 at 13:00
would distilltion work?
i know nothing of 3-hydroxy benzldehyde, what are you using it for?
makfc - 21-4-2006 at 20:20
i don't get the simple distillation as a solution for this......
i have to find out something more as I'm developing this on plant scale.
by the way, i'm synthesizing m-acetoxybenzaldhyde from the hydroxyaldehyde to use it as a fine chemical for a company.
The_Davster - 21-4-2006 at 21:13
Well water will destroy acetyl chloride leaving you with a pretty acidic solution. This could end up hydrolysing the ester. Perhaps crashing the
reaction mix into an aqueous solution of a weak base perhaps bicarbonate, pyridine or another amine would work.
Is this stuff a solid or a liquid? I'm guessing a solid. Filtration after crashing into the weak base would leave you with the m-acetoxybenzaldhyde
with slight iodine contamination, the water will have dissolved some of the iodine. A recrystalization could then be done on the m-acetylbenzaldehyde
with a good non polar solvent, perhaps hexane? Most of the iodine should be gone now. Keeping the m-acetylbenzaldhyde at 100C or so for a while
afterwards should sublimate any remaining iodine.
trilobite - 23-4-2006 at 13:36
I don't know about the method, so in case you are using a large excess of acetyl chloride, recover most of it off first by distillation. Then simply
dilute with water/ice, add a little thiosulfate or bisulfate to get rid of the iodine, extract with a suitable solvent, wash the extract with dilute
NaOH (removes phenolics also), dry the solvent and evaporate.
I don't think acidic or basic hydrolysis is going to give you any trouble. Any starting material will end up in the NaOH washes. If you really want to
recover them do a few NaHCO3 washes before the NaOH wash to remove the acetic acid.
[Edited on 23-4-2006 by trilobite]
makfc - 25-4-2006 at 05:51
Acetyl chloride is removed !
But still I'm there for iodine. Thiosulfate reacts with my acetoxybenzaldehyde making a decomposition like solid product. (My acetoxybenzaldehyde is
LIQUID).
So I have to find something more for this............