03-19-03 22:09
No 419153
2,5-dimethoxyphenyl-2-nitropropene was reduced in the usual way with Fe/HCl. After vacuum filtration of the rxn mixture, product was xtracted w/DCM, the DCM extracts washed thoroughly w/5% NaOH, then aq. NaCl, dried w/MgSO4, and the DCM evaporated... to leave a colourless-to-red xtalline mass! These xtals were insoluble in H2O, but soluble in DCM.
I was expecting 2,5-dmp2p to bee an oil... any ideas what the product I have is? oxime?
Thanx
(Hive Addict)
03-19-03 22:40
No 419166
Use sodium bisulfite to make adduct, or run a tlc chromatogram, or test melting point or index of refraction, there are a myriad of ways to find out what you have.
(Stranger)
03-19-03 23:17
No 419174
Thanks, yes I was aware of that, but as I am pressed for time I wondered if anyone could give suggest the most likely to be correct answer.
(Chief Bee)
03-19-03 23:44
No 419180
2,5-MeO-P2P & its oxime are kind of acid sensitive, and may cyclize to a furan-like structure. I don't know if that is what you got or not. I know there has been a post about this, but I don't remember when or by whom.
Are you following any literature reference when performing the reduction in question?
(Stranger)
03-20-03 01:14
No 419200
Thanks Rhodium, I thought it may be something like that... I didn't follow a lit.ref., but I have performed this rxn a couple of times before successfully giving ~65% of a ketone that was confirmed to be the desired one. This time it just doesn't seem to have worked the same
(Chief Bee)
03-20-03 01:21
No 419202
How have you processed the resulting ketone further to anything interesting? Any procedure to share which is not on my page?
(Hive Bee)
03-28-03 06:05
No 421900
consider trying the Steel/AcOH nitropropene -> ketone synth rhodium posted?
75% yield of 2,4,5-tmp2p was acheived, i think, a good sign...
(Hive Addict)
03-29-03 19:47
No 422312
Add the acid slower so there is not excess around to react with the formed ketone. Mabyee that will help. Can anyone help me with Crystalization of DMA.
20gms 2,5DMP2NP was taken up in 400ml of reagent THF. 12gms NaBH$ was dissolved in 200ml IPA(dried with MGSO4) in an ice bath.12gms silica gel was then added. The nitropropene/THF was added in 50mlportions waiting till the color dissappeared each time before the next addition.. when the rxn was complete, as noted by the amazingly clear liquid. the silica was filtered off and the hydride destroyed by addittion of AA the solvents removed over 20 mins on the rotovap. before the removal of the solvents the color was crystal clear. after there was left a pale yellow orange oil. to this was aded 700ml of MeOH and 76gms of GAA. 45gms of Al was amalgamated and added in two portions 1 hr apart. the rxn was hot to the touch. the final rxn mix was very dark. Usually with a failed rxn the color is more of a lighter grey. after basification the mix was black. this was extracted with 2x400ml of toulene. this toulene went through the usual washes then was dried over MGSO4. to this point everything has seemed textbook. when the toluene was gassed no crystals formed. however the mix got very cloudy. you could not see more than 1 cm into the solvent. . This has happened to swim before. when it happened before swim merely added H2O and reaped the benifits of an HP. Strange thing is this time when swim added the H2O everything went white. the bottom water layer was white and tasted like amine. in between the two layers were some amorphous crystals and the top was like a white semi gelli almost. The H2O layers were vapped to give an amine tasting oil that would not crystalize in IPA MEOH EtOH THF OR GAA.. WHat is going on here. DOes any one have anything besides MP&BP for this compound. what are the solubilities?????
VL_
Start thinking more like a chemist and less like a criminal
(I'm Yust a Typo)
03-29-03 21:53
No 422333
Did you do a proper A/B wash? I don't see you dumping the whole shebang into dilute HCl.
BTW: using DCM is not an option?
(Hive Addict)
03-30-03 12:15
No 422467
Make sure the gassed toluene solution is slightly acidic (about pH 5). Strip off the solvent in a rotovap and dissolve the residue in water. Filter the solution if necessary, and optional, add some active carbon to remove some crap. Basify the aqueous solution and extract the free base. Since I assum some form of halogenation is to be performed why don't you make the acetate right away?
To a solution of the free base in toluene add GAA until pH 5. Remove any water by azotropical distillation in the rotovap. Example: 200 ml wet toluene is slowly distilled at 140 mbar and 40-44°C (vapour temperature). When the vapour temperature climbs to >48°C the solution is pratically dry. Then lower the pressure to 80 mbar and remove almost all of the toluene. To the in most cases oily residue, add 15-20 volumes dry EtOAc and distill off half the volume of solvent. This removes the last traces of water which might inhibit the crystallisation. Let the solution cool to room temperature while scratching the walls now and then with a glass rod. If crystalisation has not begun when the solution has reached room temp, remove about one third of the remaining solvent and repeat the cooling and scratching.
This method works every time for me. It can also be used to make salts with sulphuric acid, oxalic acid (use MeOH or IPA), fumaric acid (use MeOH or IPA), hydrochloric acid and so on. Remember that there are other solvents too. If you encounter problems with toluene, then try IPA alone or IPA/EtOAc for example. Don't be afraid to try different solvents. The amine won't be destroyed. It's happily protonated and couldn't care less.
Freaky
(Hive Addict)
03-30-03 23:33
No 422583
DOes It seem like i have good product to you though. WIll the toulene get cloudy like that?? Do i even need to isolate the DMA as a salt before BrominATION. Could i just rotovap off the toulene before gassing or anything and take the base up in MeOH for a NaBr/Oxone bromination?
Start thinking more like a chemist and less like a criminal
(I'm Yust a Typo)
03-30-03 23:48
No 422587
Don't know. Maybe. Nope. Yup.
03-31-03 12:23
(Rated as: insignificant)