From: Ravi Orugunty (rorugunty$##$oragenics.com)
Date: Wed Feb 15 2006 - 13:26:07 EST
Suppose you want to weigh 500 mg of KH, you do it as follows. Take a
clean dry flask with a stopper. Tare the flask and the stopper. KH is a
50% mixture with mineral oil weigh about 1.0-1.2 g of this material and
quickly trasfer it into the flask. Flush with nitrogen or argon and place
the stopper on the flask. Now add about 10mL of dry hexanes place a dry
stopper and stir for about 5 mins. Stop stirring and let the KH powder
settle. Open the stopper have a gentle current of argon blowing on the top.
with the help of a syring remove the hexanes. add another 10 ml of hexanes
and stirr for 5 mins and repeat this process atleast 3-4 times and this
should give you clean KH without any mineral oil. After the last wash place
the contents of the flask on a vacuum/schlenk line for about 30 mins and you
should have 0.5-0.6 g of pure dry KH.
Having said that the next question to ask is do you really need to do all
that to do a wittig reaction? I have routinely used potassium t-Butoxide
(conia dauben conditions for wittig reactions, KOtBu is much easier to
handle) in DMSO and have gotten very good results. Good luck with the
chemistry.
With reagards to C=O to CH2 reduction i need more information on the
compound. are you trying to reduce the carbonyl of an amide or a carboxylic
acid or a ketone or an aldehyde. Please send a chemdraw file of the
transformation to rorugunty$##$yahoo.com and i will try to provide some help
best regards
ravi
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Today's Topics:
1. wittig reaction (Sunil Silvary)
2. C=O to CH2 Reduction (shrent)
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Message: 1
Date: Tue, 14 Feb 2006 17:23:11 -0500
From: Sunil Silvary <sunil.silvary$##$gmail.com>
Subject: ORGLIST: wittig reaction
To: everybody$##$orglist.net
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<fc97303a0602141423v6a7ccf74q3605c0d5aae6eacb$##$mail.gmail.com>
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Hi,
I am doing wittig reaction in the lab and I am using KH and DMSO for
the reaction but the problem that i am facing is weighing KH. How to weigh
it ? as it ignites once exposed to air and it is present in mineral oil.
Please let me know the correct procedure for handling this chemical.
Thanking you,
sunil
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Message: 2
Date: 15 Feb 2006 14:10:24 -0000
From: "shrent" <shrent$##$rediffmail.com>
Subject: ORGLIST: C=O to CH2 Reduction
To: everybody$##$orglist.net
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I'm trying to reduce an amino acid derivative having C=O group to CH2.
I have references in which mostly it is being reduced by Pd/C. But is not
being economical for me with this reagent.
Can I get your suggetions about this reduction with some economical
process/reagents ?
Thanks in advance,
shrent
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