Re: ORGLIST: purification of crude 4'-Bromo-4-Chlorobutyrophenone

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From: Darren Rhodes (darren.rhodes$##$gmail.com)
Date: Thu Apr 06 2006 - 10:09:28 EDT

It may be a consequence of how you're doing the distillation
(prolonged heating due to bigger scale).
It may be a consequence of a differing purity profile as a consequence
of scale up.

Try short path distillation (wiped film evaporation). Pics on here
aren't that good
http://www.reactorvessels.demon.co.uk/Short_Path_Distillation/short_path_distillation.html
but it will give you an idea.

Develop a continuous flow process for next time so that there isn't
any scaling up; instead it is scaling out or numbering up.

Darren.

On 4/6/06, paul joshua <pauljoshua_in$##$yahoo.com> wrote:
>
>
> Dear All,
> Ive been having a problem in final stage purification of my crude product on
> up-scaling.
> Ive synthesised (Crude) 4'- bromo-4-chlorobutyrophenone by friedel crafts
> rxn using bromo benzene and 4 chlorobutyryl chloride taking EDC as solvent .
> After the normal work-up the product 4' Bromo-4-Chlorobutyrophenone
> distilled at 135 -139 C (0.3 torr) at a lab scale succesfully . But on
> upscaling,while trying to distill ,the vaccum keeps dropping drastically
> and we are not able to distll the same.We have tried distilling at 3
> different facilities and at all the facilities the same problem was
> encountered.
>
> Could somebody help me with suggestions to purify the crude or bettering the
> procedure.
> Thanks in advance
>
> Paul
>
>
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