October 15, 2024, 12:13:39 AM
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Topic: Possible harm of an XS of base in Horner reactions  (Read 706 times)

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Offline Babcock_Hall

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Possible harm of an XS of base in Horner reactions
« on: September 07, 2024, 03:05:35 PM »
We must perform our next Horner Wadsworth Emmons reaction on a smaller scale than usual, owing to a limited amount of a sulfonyl phosphonate diester (perhaps 45 milligrams).  It will be challenging to control the stoichiometry.  Our usual base is DBU, and we use LiCl to promote this reaction.  If there is an excess of phosphonate over base (or if the reaction does not go to completion), the remaining sulfonyl phosphonate can be difficult to remove via silica gel chromatography (we have had this difficult more than once).  If there were an excess of base over sulfonyl phosphonate, could there be a side reaction or another undesirable effect?  Any suggestions are most welcome.

Offline rolnor

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Re: Possible harm of an XS of base in Horner reactions
« Reply #1 on: September 08, 2024, 10:25:50 AM »
You can make stock-solutions of base and other reactants, this way it is easier to control the amount you add sometimes. Use smaller syringes than usual, maybe a GC-syringe can be useful, they are very exact. You can have some Molecular Sieves in the stock solutions to keep it very dry if this is important.

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