Bandil
(Hive Bee) 02-04-03 03:19 No 404335 |
Dean Stark trap with nitropropene/styrene prep. | Bookmark | ||||||
Some time ago, swim enquired about the preparation of relative pure 2,5-dimethoxy-betanitropropene. I believe Rhodium suggested the use of a dean stark trap, if the nitroethane was not 100% anhydrous. According to the original preparation of the nitropropene: A solution of 10.0 g 2,5-dimethoxybenzaldehyde in 50 mL glacial acetic acid was treated with 6.8 g of nitroethane and 4.0 g of anhydrous ammonium acetate. AFAIK a Dean stark trap works by separating the water that is distilled azetropically with the solvent. But, in this case the water is soluble in the solvent acetic acid. How could a DS trap be used here? Even with nitroethane as the solvent, it could not work, as the nitroethane has a weigth of 1.05 g/mL and would thus form the lower layer... Any ideas on how to get this scheme to work? regards Bandil |
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Xicori (Newbee) 02-04-03 03:21 No 404336 |
it should work to just substitute the GAA with | Bookmark | ||||||
it should work to just substitute the GAA with Toluene or Benzene - but i´m not completely sure on that, but it works with P2NP... lg xicori |
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Bandil (Hive Bee) 02-04-03 03:48 No 404341 |
Do you have any references on that reaction? | Bookmark | ||||||
Do you have any refernces on that reaction? |
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Antoncho (Official Hive Translator) 02-04-03 06:07 No 404363 |
Do it in toluene. | Bookmark | ||||||
There's a proc on Rh's for o-methoxy-P2P. Also TFSE will give you Barium's excellent proc for hard-to-make nitropropenes and nitrobutenes. Antoncho |
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Rhodium (Chief Bee) 02-04-03 13:00 No 404459 |
ethylenediamine diacetate | Bookmark | ||||||
I suggested the use of 0.1 equiv. ethylenediamine diacetate in IPA at RT for 24h, gives 50% yield of pure nitropropene, the same yield as the ammonium acetate procedure in Pihkal but with less work. Directions can be found in edda.html at my page. |
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hest (Hive Adickt) 02-05-03 13:16 No 404808 |
Henry | Bookmark | ||||||
Use benzene as solven and KF/ethylenediamine diacetate /Am.Formiat/cyclohexylamin/ect. as the catalyst then let the DeanStarc work 24houers. Byt the synt of 2,5-dimetho... in a mw. works so nice, why bother onyething else. For some off the other aldehydes it's a different history. |
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