05-29-03 12:26
No 436293
Is there any hurt to the 2,5-dimethoxyphenylnitropropane / nitroethane if one want to boil off the toluene from it?
thanks !
(Hive Addict)
05-29-03 14:08
No 436313
Such low temperature should not harm them. But why don't you use a water aspirator and a closed system. Then you can distill of toluene at about 40°C @ 80 mbar.
Freaky
(Stranger)
05-29-03 19:53
No 436366
Pardon me, but the boiling point for toluene is approx. 110 degree C, doesn't it hurt the products ? By the way, what is the bp for the 1-(2,5-dimethoxyphenyl)-2-nitropropane and 1-(2,5-dimethoxyphenyl)-2-nitroethane ?
(Chief Bee)
06-05-03 03:47
No 437864
No nitrostyrenes have boiling points at atmospheric pressure, they all decompose before boiling. Most melt between 50-100°C.
I beg to disagree with Barium here - personally I would never suggest to boil off toluene from nitrostyrenes without vacuum. There are even instances where recrystallization from boiling IPA (82°C) partly decompose such compounds, and ether/pentane had to be used instead. Add to this that recrystallization only involves short heating, while solvent removal is an extended process.
(Hive Addict)
06-05-03 11:11
No 437933
He asked for the bp of the nitroalkanes not the nitroalkenes
But I think he was a little confused.Most of the nitrostyrenes can actually be distilled, but there will be losses due to decomposition. If purification or beautification is desired EtOAC (ethyl acetate) is the best solvent. The crystals are so beautiful. The best option beside recrystallisation is high-vacuum sublimation. This is very efficient for nitrostyrenes.
The nitroalkanes can be distilled, and with regular high vacuum the boiling points are between 140-180°C. If they survive that why shouldn't they survive a measly 110°C when distilling off toluene at STP? In Post 352950 (Barium: "Get that double bond without borohydride", Novel Discourse) the authors recommend distillation at large scale production. The PBI reduction takes place in refluxing n-BuOH (bp 117-118°C) and the yields are good to excellent. No harm from that temp there either.
Freaky
(Chief Bee)
06-05-03 20:21
No 438026
The nitroalkanes can be distilled, and with regular high vacuum the boiling points are between 140-180°C. If they survive that why shouldn't they survive a measly 110°C when distilling off toluene at STP?
I haven't discussed the saturated nitroalkanes, only the unsaturated nitrostyrenes. Have you tried to distill nitrostyrenes? If so, what temp/pressure/yield, and which nitrostyrene was it?
(Hive Addict)
06-05-03 20:38
No 438034
I haven't discussed the saturated nitroalkanes, only the unsaturated nitrostyrenes.
Well not you perhaps, but the rest of us seems to have done just that in this thread
I haven't personally distilled nitrostyrenes but a close friend has on a few occasions. I never asked for the pressure and temp, but he told me that the yield was about 75%. The reason that he distilled them was that some impurities just refused to loose the grip of the nitrostyrenes. If I remember correct it was 4-bromo-beta-nitrostyrene, 3,4-dihydroxy-beta-nitrostyrene and 3,4,5-trihydroxy-beta-nitrostyrene.
Freaky