12-22-01 11:48
No 249853
I have tried the 2C-H a la beaker and I have some trouble at the end of the third step:
Here is what I have done:
Nb: excuse my poor english
Step 1:
I have made the nitrostyrene with 5g 2,5dmb, 2ml CH3NO2, .6g NH4AC in 24ml hot IPA.
I stirred for 3h and let it cool and stay for one day aside.
An orange mass crashed out of the solution, it was filtered and washed with cold IPA to yield 5.6g of caoutchouc like orange fluo crystal. I recrystallised this mass in 16ml boiling IPA and got 4.8g of orange crystal of 2,5dms.
Step 2:
I dissolved the 2,5dms in 45ml THF and put this in a dry addition funnel with a drying tube attached.
I made a suspension of 3.5g NaBH4 in 4ml EtOH and mag stirred it while droping one drop at a time the THF solution. The NaBH4 sol is trouble (NABH4 not dissolved), and after each addition pass from orange to white(NABH4).
First mistake: after the first half of the nitro was added (45min) I put the second half by error in 5min!
-> maybe some dimer was formed. I let it stir for 20 min after that, the sol was a little yellow.
I added H20(45) and brine(15), some H2 appeared then I added dropwise !caution! 20ml glacial HAc
After a lot of H2 evolution I have a sol yellow with no more salt in it. Added brine and Et2O, decanted and dried the org layer with MgSO4, sol is yellow-orange. I evapored most of the Et2O on a hot plate(maybe to hot?) and then added to the residue (with 5-6ml of ether still in it) some MeOH. I got an orange sol.
Second mistake: maybe I have got some degradation here?
Step 3:
To the sol in 50 ml MeOH was added 250mg 50%wet 10% commercial PD/C and 6g AmmFormate. A piece of tubing was attached and submerged.
I refluxed this for 9h, some gas evolve during the process from the submerged tube.
Third mistake: someone cut the water at the 8 hours point and when I saw this one hour latter I reopened it and then got a suck back of maybe 400ml of water in my solution.
So I stopped it, filtered the PD/C and got an yellow trouble water when acidified (or no colour when neutral (but still trouble)). I extracted this with brine and several portion of Et2O at pH~10, the combined org layer was orange and the aq layer clear.
The org is dry with MgSO4 for 30min, filtered, put in a dry beaker, gassed with HCl gas made with NaCl and H2SO4.
When I gassed it I got after ~5sec a white trouble and the solution discolorized. After ~2min I got some nasty oily
orange layer formed at the bottom and The more HCl I add the worse it became. At no time I got a solid.
Maybe I screwed the gassing or maybe this is because my freebase is to impure or something like this, what do you think?
Note: I don't want to distill the freebase for purity, is it necessary?
So can anyone help me find where is the problem in this? Maybe sunlight or beaker or someone else who know well the method.
Some more question:
-when I added to much NaOH in the extraction of step3 I got some gelatin between the layers.
What is this? some hydroxide of a salt? When the pH was put back to ~10 with some Hcl The interlayer is clean.
-Maybe if I make the sulfate at the 3 step like sunlight it my work?
-How do I now that some dimer are formed without TLC? Does it do a change in colour or what?
-Why in the 2 step anhydrous condition must be respected? I have see NaBH4 reduction in water and EtOH is a protic solvant.
Because If its not that important I don't have to recristalise the 2,5dms in step 1. I have lost 800mg of it and it looked the same orange, the same purity but less wet.
-Is it dangerous to evaporate Et2O with a hotplate at step2, ie can I get some decomposition of the nitroethane? I haven't got a rotavap yet. Is it ok to let the Et2O, add MeOH and do the CTH?
-In step 2 do I have to put all the NaBH4 in solution or is a suspension ok?
-Is pH 10 OK to extract the amine or do I have to put it to 12 or more?
Thank you all
PoiX
(Daddy)
12-23-01 01:04
No 250024
fUCK, BROTHER POIX, SHIT the caps lock on, more problems! You have induced a severe headache to your beloved mod, only TWENTY questions, this is far tooo low, we do not answer usualy such a minor attack on our braincapacities, but I promise you to take a indept look into this nagging chain of events, after sobering up.
Shit, just drank PURE COKE, forgot to add the Glenfiddich! Look what youve done, this could be fatal at my age, please consider next time the ailing constitution of ALL participants at this fabulous board, there are too many victims lately fallen on the field of honor, or is it onor? Why that obnoxious H? No need for nonverbal characters, get rid of them.
What thefuck is that for a name, Poix? How the hell did you stumble over something like that? French??
C'est la vie, vive le president deGaulle, fuck, that was a fuckin long one. Or is it tall? What a nose! He walked like a brick, poor fella. Whatever, he's laying down now, no need to stay upright anymore, ehh?
Where were we? Ahhh, yep, lots of problems there! Will have to look into that later. LäBTöp/
PS: what the fuck poor english? ITS fluent!
WISDOMwillWIN
(Daddy)
12-23-01 01:08
No 250027
Ehh, where that funnyfellow Beaker btw? HEHHHH, beaker, wakeup, miss you funny guy!
(he sure could prolly save me a lot of time after the headacck!) LäBTöp/
WISDOMwillWIN
(Pioneer Researcher)
12-23-01 05:55
No 250059
Excuse my poor english as well. I've performed this rxn a few times, I'll try to help you. I haven't seen Beaker in the past months.
Step 1 is not from beaker, but if it works it si a very good new, aldehyde+am. acetate in hot IPA 3 hours (refluxing ?). It is not a documented synth, though probably yielded the nitrostyrene in good yield. I'll try it.
Let's suppose it was the nitrostyrene, though I don't understand your description, the nitro is orange.
Step 2, NaBH4 dioesn't dissolve, it's suspension, correct. Color changes from orange to white in 15 seconds or so, correct. 5 minutes of difference in the addition is not important. After final workup I've always get a deep orange residue, not light yellow, it is the nitrethane with some impuities, but enough good to be reduced. I'ts better to evaporate the ether in awarm/ hot water bath with the aspirator, but if the hotplate was not too hot, I don't think you could hurt too much your product.
Step 3, 8 hours are enough to complete a big part of the reaction, in fact with Beaker ratios the most part of rxn proceed in the first 6-10 hours. If rxn runs ok, initially there's a lot of gas bubbling in the glass with water were is the drain tube from the condensor, and when rxn works fine sometimes crystals are formed in the condensor and you have to check it time to time in order to avoid its obstruction, it is probably ammonium carbonate. In the beginning there is a continous strong bubbling At three hours the bubbles in the water glass are may be 30-60 /minute while and in the next hours it diminishes, at 10 hopurs you see 5 /minute or so. Anhydrous formate is a must. It seems that rxn went more or less ok.
You didn't make an acid wash to remove unreacted material, and honestly, my best yield was 64 % adn it was when I got Pd/C from Aldrich, using home made catalyst yield was 4 %, so you have som unreduced compounds and amine hydrochloride. I would add water and discard ether, basify and extrat again, dry the extracts and crystallize with HCl gas or if you check correcly the pH adding a mixture 1:10 sulfuric/IPA, yu will gat the sulfate and may be a bit of bisulfate, but xtallyzation is easier, and prdouct is perfect for next step.
-How do I now that some dimer are formed without TLC? Does it do a change in colour or what?
In the reference posted by Cyrax about nitrostyrene NaBH4 reduction tehy say CH2CL2 TLC is used to see the dimer (only CH2CL2?)
-Why in the 2 step anhydrous condition must be respected? I have see NaBH4 reduction in water and EtOH is a protic solvant.
Because If its not that important I don't have to recristalise the 2,5dms in step 1. I have lost 800mg of it and it looked the same orange, the same purity but less wet.
Water decomposes NaBH4, and water could interefe in rx as well, don't ask me why, but Beaker told to use dried nitro.
>>>>
-Is it dangerous to evaporate Et2O with a hotplate at step2, ie can I get some decomposition of the nitroethane? I haven't got a rotavap yet. Is it ok to let the Et2O, add MeOH and do the CTH?
I don't have a rotovap, put the ether in a flask connceted to the aspirator, inmmersed in a water bath over the hot plate, and turn on heat if necessarywhen ether doesn't evaporate more.
>>>>>>>>>>
-Is pH 10 OK to extract the amine or do I have to put it to 12 or more?
I suppose 10 is ok, but 12 or 14 wan't hurt. Better make an acid wash in the extraction, witth the 94 % yield of Beaker it is not necessary, but we don't know wich yiled we'll have and impurities are a problem in crystallization.
I hope this can help you.
(Stranger)
12-23-01 11:57
No 250100
Thanx sunlight, I'll retry it this week.
For the first step I tried it at first with excess CH3NO2 as solvant and NH4Ac, with vanillin as the aldehyde. The prob with this method was that I get a nasty deep red solution and I must recrystallise the nitro to get it yellow. I've tried this on 2,5dmb, after the recrystallisation the nitro was dark orange and colour of the sol in NaBH4 turned red. So with my second run I switched of method and inspired by the file edda.html on rhodium site but not having the EDDA I tested it with NH4Ac in the same ratio that in this text for IPA, 2,5 and CH3NO2 but with my old ratio (0.6g NH4AC/5g 2,5dmb) for the catalyst.
I added at first the NH4Ac to the IPA, stired it and warm it to let it dissolve. Then I added the 2,5 dmb and when it was in solution I added the nitro. The IPA was hot, not refluxing because I've done it in a small beaker for easy retrieval of the crystals (you will have difficult to take them out of a RBF). I adjusted the temp so that the IPA was the hotter possible but not evaporating to much. After one hour of stiring (but not warming) the sol was still yellow so I turned the heat on. At the second hour it was orange and at the third hour I thought that it was a deep orange like in the text with EDDA. I took the beaker out of the hot plate and let it aside. In the next 10 min all the IPA was a mass of orange xtal. I let it a day aside but I don't think it's necessary. Then I put it in a freezer for 15min, vaccuum filtered it and washed it with a little IPA.
The problem in this method is that the cristals are agglomerated, like plastic and that's why I say they were caoutchouc like. The recrystallisation of these gave me crystals a little more separated but not much otherwise they were the same with or without recrystallisation.
At this time I'm trying to do it like in the text EDDA.html: I have put all in sol (same as before) with heating but I will let them aside for 36h, and not warm them like I did, maybe if crystals form they will be more crystallised and not mass precipitated.
One hour after this: some yellow crystal are formed in a yellow sol. I will let it stand for one or two day then I will say if it worked.
Two and an half hour after: I've got a suspension of yellow crystals, stop stirring, let it aside.
STEP2:
"5 minutes of difference in the addition is not important"
No, I have added the second half of my THF sol in 5 min instead of 45 min, but I will not do that again, I'll watch it.
"After final workup I've always get a deep orange residue, not light yellow"
Ok, my sol was yellow but after some of the solvant was evaporated it turned orange. I thought it was decomposition so I stopped the evap there and let some Et2O with it. I will try to evap the Et2O next time under reduced pressure at water pump on a water bath. Do I have to put some boiling stone ( altough I have read that it doesn't work for reduced pressure distillation) or a capillary to reduce bumping?
STEP3
I assume that to this point all is more or less Ok and that I have the nitroethane as I believe it.
The reaction is like you say, with gas bubbling etc... The first time I've done it there was some residue in the condensor like you say but not this time. One mistake I have done is that in the first hour the tube was not put correctly and there was a leak in it, so some O2 may have entered in the reaction but I think it's not too bad because in the file cth.txt on rhodium's site they say that argon atmosphere is not needed.
My Amform was done like this: I mixed some 20% NH4OH and some 85% ac formic in a beaker until pH was 6-7, put the heat on with a ventilator and evaporated the water. At a time I got some heavy fume, I stopped it here, it crystalized, I scrapped the crystals, vacuum filtered them and washed them with plenty acetone. I put them for a night in vacuum, I think that they are dry enough.
I used 250mg 10% commercial Pd/C 50% wet, so 125mg of Pd/C for ~4g of nitroethane, I think this is not a too low amount, how much have you used?
I haven't put boiling stone or magnetic bar in my RBF, because at reflux I think that there is enough movement of the Pd/C in all the solution. Do you think I must put stones or mag stir it?
What is the colour of the sol after the filtration of the Pd/C and before the work up?
"...and impurities are a problem in crystallization"
So maybe my worst mistake was not to do the acid wash. I'm disgusted of gassing and next time I will do your sulfate with IPA.
I will do this workup: filter Pd/C, evap MeOH (colour of the residue?), add Et2O, extract with aqueous acid 3x, basify the water layer, extract with Et2O 3x, extract the org sol with brine 2x, dry org sol over MgSO4, filter, add IPA and 95%H2SO4 10:1 until ph 4 (is it ok?), filter if I have got some crystal and dry them in vacuo for the next step.
Another thing: what can be the gelatin like emulsion at the interlayer when the pH is too high? any idea?
Thank you much sunlight. I will let you now with the nitro in 2 days.
LabTop:
"Why that obnoxious H? No need for nonverbal characters, get rid of them.": I don't understand that one.
My name was poix because half of my keyboard was broken after that some rain fell on it, so the letters at the right and the extreme left was ok but not the letters in the center. When I had to choose an user name I hit the key at the right in decreasing order namely P O I and then I choose one letter at the left for the balance. Maybe POIQ was better? I know it is not a name as cool as Labtop but voila keske tu veux.
PoiX
(Pioneer Researcher)
12-23-01 16:11
No 250125
May be I'll check your nitrostyrene method, it's atractive but it's not good to use and untested method if you are trying a new rxn, if it doesn't work you don't know the step that failed.
About 2,5 DMNS, 1:1.1:0.06 aldehyde:nitromethane:cycloehxylamine 24 hours give a 50-60 % of nitrostyrene, but 1:1.1:0.2 about a 100% of a mixture of aldehyde and other compund, deep orange, almost red, amorphous, not very soluble in IPA. 1:1.1:0.06 in methanol gave nitrostyrene, but TLC showed a little spot of a impurity. Better use an known method for this first attempt. This nitro is orange.
I think that you got some amine, the change of color during the addition to the NaBH4 is ok, and the rest of rxn seems to had worked ok, probably you have amine and other byproducts that have interfered in the xtallyzation, so you should add water, discard the ether, basify and extract again, dry and xtallize.
>>>>>.
Ok, my sol was yellow but after some of the solvant was evaporated it turned orange. I thought it was decomposition so I stopped the evap there and let some Et2O with it. I will try to evap the Et2O next time under reduced pressure at water pump on a water bath. Do I have to put some boiling stone ( altough I have read that it doesn't work for reduced pressure distillation) or a capillary to reduce bumping?
>>>>>
Probably there's some decomposition, or are impurities of the nitro. I've done the rxn exactly like described by Beaker, and the nitroethane after evaporation of ether with the aspirator was a brownish yellow, sometimes more dark or less, or more orange. You can use magnetic stirring to evaporate the ether, but sometimes I've evaporated it without stirring and without capillary, but of course it is a good idea.
.>>>>>
The reaction is like you say, with gas bubbling etc... The first time I've done it there was some residue in the condensor like you say but not this time. One mistake I have done is that in the first hour the tube was not put correctly and there was a leak in it, so some O2 may have entered in the reaction but I think it's not too bad because in the file cth.txt on rhodium's site they say that argon atmosphere is not needed.
>>>>>>
If methanol is boiling no 02 can enter in the rxn, but I guess it won't interfere anyway. I've used the stirrer but I think like you it is not stricly necessary because the boiling methanol mix everything completely.
>>>>>
My Amform was done like this: I mixed some 20% NH4OH and some 85% ac formic in a beaker until pH was 6-7, put the heat on with a ventilator and evaporated the water. At a time I got some heavy fume, I stopped it here, it crystalized, I scrapped the crystals, vacuum filtered them and washed them with plenty acetone. I put them for a night in vacuum, I think that they are dry enough.
>>>>>
You made a good work to do it.
>>>>>>
I used 250mg 10% commercial Pd/C 50% wet, so 125mg of Pd/C for ~4g of nitroethane, I think this is not a too low amount, how much have you used?
>>>>>>
I think it's ok , but with this amoutn acording with beaker will be better to keep the rxn refluxing 24 hours. Sometimes I've used more Pd/C to make the rxn shorter.
>>>>>>
What is the colour of the sol after the filtration of the Pd/C and before the work up?
>>>>>>
Slightly yellow, almost colorless.
>>>>>
I'm disgusted of gassing and next time I will do your sulfate with IPA.
>>>>>
I prefer to make the sulfate with this amine, it's ok for the next step.
My workup has been filter, evaporate methanol, residue was brownish, add water, wash with dcm, basify, extract with ether/toluene, dry and make the salt. With H2SO4 try to keep pH in 6, although if it is lower the only problem is that you can get more bisulfate.
>>>>>>
Another thing: what can be the gelatin like emulsion at the interlayer when the pH is too high? any idea?
>>>>>
Don't worry, for us are byproducts, discard them.
If you are working with a few grams you can considere the option of reduce the nitro with Zn/HCl, it's one step and very easy. It uses a lot of solvent in the workup, but it's almost the same with beaker procedure.
Good luck and be patient.
(Stranger)
01-02-02 00:47
No 251928
Sorry for the long time..
I retried it two times, and now it seems to me obvious that my nitrostyrene method does not work at all.
The first time it was with my nitro and at the end of the third step I cannot recrystalise.
The second time it was with a nitro prepared in excess CH3NO2 as solvent, amm acetate as catalyst and reflux for 4h, then I pourred the hot solution in boiling IPA (as dr S method in #32 of his bible) (when I did with cold IPA as beaker I do no had nice crystals but instead some impure product)
As the black-red mixture of hot IPA/hot CH3NO2 returned to room temperature nice fluffy orange crystals appeared spontaneously, they were washed with cold IPA to remove the adsorbed CH3NO2 and were of a good purity.
The beaker method worked nice with these crystals and some 2C-H was collected at the end of the third step.
Sunlight: have you tried this method on escaline or 3C-E? Or another 3,4,5 trisubstituted benzaldehyde?
Sorry about posting method wich does not work
Happy 2002 to all the hive /PoiX
(Pioneer Researcher)
01-02-02 03:28
No 251958
No, but it should worrk.