Author Topic: 2,5-DMNS rectrystallization w/toluene  (Read 5008 times)

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starlight

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2,5-DMNS rectrystallization w/toluene
« on: December 15, 2003, 01:56:00 PM »
I know that IPA or IPA/EtOAc are recommended as recrystallization solvents for this compound.

When an attempt was made to reduce this nitrostyrene with Red-Al it was noticed how poorly the substrate dissolved in toluene at 5 deg. C.

The reduction was abandoned and it was decided to test the suitability of the solvent for recrystallizing the substrate.

21g of 2,5DMNS was dissolved in 500ml of toluene which was warmed to dissolve all of the material. It only needed to be warmed to perhaps 45C so a smaller volume could be used.

The toluene solution was allowed to cool to room temperature and then put into the fridge and then into the freezer. It was then vacuum filtered to afford beautiful, long, glittering orange colored needles. Air was drawn through the buchner filter for a while to dry the crystals, which were then air dryed to a constant weight of 18g. The crystalline material was almost like glass wool.

The starting material was certainly impure as a different portion of it afforded a terribly impure product after a borohydride reduction.

The yields from this recrystallization could obviously be improved by reducing the volume of solvent and heating it to a higher temperature.

Although there may be other suitable solvents this one certainly gives a beautiful result and may be appropriate depending upon your solvent supplies.

starlight

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25dmba/nm
« Reply #1 on: December 20, 2003, 02:24:00 AM »
condensation of 2.5DMBA with Nitromethane. Catalysed by alcoholic MeNH2