October 04, 2022, 07:27:09 PM
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Topic: Pd Eluting Down Silica Column  (Read 775 times)

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Offline SateliteX

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Pd Eluting Down Silica Column
« on: February 15, 2022, 02:24:31 PM »
I did a Suzuki coupling using Pd(PPh3)4 with a solvent system of 10:1 THF & water. After l-l extraction with ethyl acetate and water, the organic fraction was dried over MgSO4, reduced and fused to silica. The crude was loaded onto a silica column and purified with 7:3 EtOAc:Hex, which was alright except for some brown stuff coeluting with my product - which was probably some of the dead Pd catalyst?

I tried to redissolve my Pd-contaminated product with toluene and filter through celite, didn't work out. Also tried to remove Pd with charcoal, also didn't work out. I am one step away from ordering Pd scavenger. Could someone offer any advice on how to get rid of the brown contaminant?

Thanks in advance.

Offline Guitarmaniac86

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Re: Pd Eluting Down Silica Column
« Reply #1 on: February 15, 2022, 02:35:21 PM »
Are you certain it is palladium? What were the starting materials and what is the expected product? Anything with nitrogens or nitro groups in them? These can give brown colours.

I would be very surprised to see palladium come through at 30% EtOAc. Have you TLC'd it to see if there is more than one product in there? Have you tried to run a slow gradient starting from 0% EtOAc and moving up to 30% EtOAc to see if you can remove the potential impurity that way?
Don't believe atoms, they make up everything!

Offline SateliteX

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Re: Pd Eluting Down Silica Column
« Reply #2 on: February 15, 2022, 05:29:07 PM »
Hi, the fractions are pure by TLC, and the EtOAc are 70% so I'm not sure if that's the reason

Offline wildfyr

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Re: Pd Eluting Down Silica Column
« Reply #3 on: February 19, 2022, 02:22:42 PM »
Stir with activated carbon?

Offline rolnor

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Re: Pd Eluting Down Silica Column
« Reply #4 on: February 20, 2022, 01:04:20 AM »
Does it matter? Is the product OK on NMR?

Offline phth

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Re: Pd Eluting Down Silica Column
« Reply #5 on: February 20, 2022, 03:07:56 AM »
Be careful; palladium nanoparticles pass through nitrile gloves and typical filtrations easily.

Offline rolnor

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Re: Pd Eluting Down Silica Column
« Reply #6 on: February 20, 2022, 05:07:56 AM »
Its not Palladium, its something else I think.

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