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Author Topic: Borohydride reduction,please advise..  (Read 2276 times)

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menime

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Borohydride reduction,please advise..
« on: September 03, 2003, 10:45:00 PM »
SWIM did his best with ketone,no one replied to my question-oh well.Seemed OK. Next SWIM followed LaBTop's procedure, with a little molar excess of NaBH4 and a little excess MeNH2,and all seemed to go OK.When doing the work up,SWIM has a not expected gray brown oily emulsion layer as well.SWIM could see oil drops in it, and has shaken with DCM to extract those freebase (hope!)oil drops .The DCM layer is a dark fleshy color on the bottom, then the "emulsion" floats on this, then a minor pinkish water layer on top of that....this water layer smells MeNH2-ish.Should swim throw it all in a flask and distill?Or distill off the DCM alone and see what's there? Thanks for tips...
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menime

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Part 2
« Reply #1 on: September 04, 2003, 03:13:00 AM »
SWIM started with 280g redistilled pale yellow suspected ketone,30g NaBH4,125g MeNH2 freebase in MeOH-stirred 36 hours.Distilled DCM layer to recover 205g browny oil with a touch of yellow.Doesn't smell at all like ketone.The emulsion layer is oily and weighs 10g....extracted the water/alcohol layer with lots of DCM,so probly none there.Sound OK? Thanks for any info...
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menime

  • Guest
Beware Evil Vacuum Leaks
« Reply #2 on: September 04, 2003, 05:23:00 AM »
Ketone was not ketone..a leak in the vacuum line raised the boiling point to the right temp and fooled me....after fixing the pinhole,saf and "ketone" have the same boiling point.Damdamdamdam...it looked and smelled so good.Anyways,recovered more of my "ketone"after putting the water/MeOH in the freezer.Mebbe the benzo wacker would be better...
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hest

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TLC
« Reply #3 on: September 04, 2003, 04:55:00 PM »
Atleast check your product with TLC all the time, will spare you a lot of trouble.
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Vitus_Verdegast

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I second that - always use TLC !
« Reply #4 on: September 04, 2003, 08:12:00 PM »
If your 'ketone' was actually safrole or isosafrole, then now after reducing with NaBH4 you will have dihydrosafrole (double bond reduced to alkane). This compound is pretty useless, unless you're into piperonyl butoxide analogues  :P .


Also, next time when you're confronted with a nasty emulsion, you might want to try vacuum filtering the whole lot. This will remove the crap that is causing the emulsion and will most of the time leave you with two nice, easy to separate layers.

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pooky

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Keep trying
« Reply #5 on: September 04, 2003, 08:59:00 PM »
Nice try on your attempt & don't give up after the first try.LaBTop says in his writeup check and double check your ketone...an understandable screw up happened.Maybe try the benzo wacker,apparently it's hard to have a complete disaster.
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pooky

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BTW
« Reply #6 on: September 04, 2003, 09:16:00 PM »
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Xicori

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thin layer chromatography, utfse to get ...
« Reply #7 on: September 04, 2003, 10:16:00 PM »
thin layer chromatography, utfse to get yourself informed!
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pooky

  • Guest
Lighten Up
« Reply #8 on: September 05, 2003, 12:45:00 AM »
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