Sciencemadness Discussion Board

Reduction of substituted 2-phenylnitroethenes to 2-phenylnitroethanes with NaBH4 - Maybe the greatest way to make tar

Bottle - 15-2-2018 at 13:07

Hi!
I need some input
I'm currently trying to make 2,5-dimethoxy-phenylnitroethane from the 2,5-dimethoxyphenylnitroethene (2,5DMNS) counterpart

I tried several systems found on the net:

Quote:

In a two-neck 250ml rb flask with a egg shaped stirbar containing 40ml EtOAc and 10ml denaturated EtOH(1), 3.63g (95mmol) commercial NaBH4 is added in one portion. The flask is immersed in a 10°C cooling bath. A 4-bulb Allihn condenser(2), with cold tap water running through it, is inserted in the central neck and a thermometer in the side neck. Let the temperature drop to 15°C and start add 5g (24mmol) 2,5-dimethoxy-beta-nitrostyrene in 0.5g portions to the borohydride suspension. Keep the temperature between 20-30°C during the addition, which takes some 15 minutes. When all nitrostyrene has been added allow the reaction mixture stir for another 20 minutes.Add 50ml cold water to the reaction mixture and stir for a couple of minutes. Transfer the mixture to a 500ml separation funnel and remove the bottom aquoeous layer(3). Add another 50ml portion of cold water, shake, allow to separate and remove bottom layer. Add a third portion of 25ml cold water and dropwise 50% aq. acetic acid untill gas evolution ceases. One might need to shake it now and then to bring the aqueous layer in contact with some borohydride still remaining on the walls. When no more gas is evolved add 50ml brine, shake, let separate and remove the bottom layer. Now you will have a bright yellow solution of the phenylnitroalkane in some wet EtOAc, dry with some MgSO4 and strip off the solvent to give a yellow oil. Yield 4.94g (98%) 1-(2,5-dimethoxyphenyl)-2-nitroethane, purity 97% (HPLC).

Source: https://erowid.org/archive/rhodium/chemistry/nitrostyrene.na...

I perfomed it in a 400mL beaker instead of a flask, except that I followed the instructions very carefully, but ending up with a slightly dark reddish oil at the end.
Shortpath-destillation in good aspirator vacuum and a 130°C oil bath yielded within a few minutes only a miniscule amount of condensate (a few mgs) of a colorless imho pleasent sligthly nitromethane- and desifectant like smelling colorless oil in the collecting flask and a violently fast decomposing of the oi which began to turn into sticky black tar within a very few minutes so destillation was discontinued


Quote:

10,5 g (50 mmol) 2,5-dimethoxy-beta-nitrostyrene was added during 5 minutes to a solution of 2,4 g (63 mmol, 1,25 mol eq.) sodium borohydride in 50 ml IPA and 20 ml water. The temperature rose from 20 to 50°C while the orange color faded to a slightly yellow. 2N HCl was then carefully2 added until pH 4 was reached followed by enough solid NaCl to cause the IPA to form a separate layer containing the product. Two volumes of water was added to the isolated IPA layer which caused 2-nitro-1-(2,5-dimethoxyphenyl)ethane to separate as a clear yellow oil and was isolated by extraction with 2x15 ml toluene. The organic phase dried over MgSO4 and the solvent removed under vacuum leaving the product as a clear yellow oil. Yield 9,7 g (46 mmol, 92%) 2-nitro-1-(2,5-dimethoxyphenyl)ethane.

Mirror: https://chemistry.mdma.ch/hiveboard/novel/000426052.html
I used ~30% HOAc instead of HCl to bring the pH to 4.00 and used a 300ml erlenmeyerflask with ice-bath-cooling instead of RT to avoid dimeric sideproducts (maybe a mistake?)

In my case the isolated sligthly yellow IPA-layer precipitated around 1g of a grey-greenish very fine solid in the IPA layer while washing it the second time with sat. aq. NaCl-solution. I filtered and washed the cake with cold IPA and removed some IPA using mild heat from waterbath and an aspirator pump. I wanted to see if even more will precipitate when cooling but upon cooling in the fridge to my suprise another sideproduct was formed - 1-2mL of a very viscous deep orange-red oil which is heavier than brine crashed out, causing a beautyful 3-layer system in the s.funnel with a clear bright yellow upper layer, a clear colorloess brine center and a clear deep orange red bottom-layer
Not gone any further yet, don't know if it's worth a try

I used 99.98% IPA, home-destilled water, high quality 99% anhydrous EtOH with 1% MEK, 99.8% EtOAc, food-grade glacial acetic acid, technical borohydride. The nitrostyrene was made with catalytic amount of EDDA in hot IPA and then recristallized twice from EtOAc which caused up to 2cm long needles which had to be grinded for further use. Except the technical grade borohydride all chemicals were from exceptional quality, so I doubt that would be the problem.

Now a few questions?
-What are these impurities I was able to isolate?
-What causes them, especially what causes tar when heating slightly? Air? Impurities in technical borohydride? Does EDDA interfer even in trace amounts? Reactions with the solvent?
Has anyone any clue about that?
-Might I have sepperated ALL the impurities due their insoloubility in IPA?
-Has anyone here had success or know someone personally who had success to produce a acceptable yield of a product of a usable quality?
-I can't find a literature boiling point of the desired product, is a good aspirator vacuum-pump good enough to destill it if it's pure?
The impurity seems to have almost catalytic-self-destruction impact on the substrate, the oil I recieved from the first procedure produces tar already at very moderate temperatures around 50-70°C.

(Side-Question: Is there a way to get the aldoxime from the NS without the usage of exotic homogenous Rhodium- or Gold/TiO2-Catalysts or tons of acid in acceptable yield (I have Pd/C!)? Would be a nice bypass!? I know it's possible with longer chained phenylnitroalkanes, but is it possible with phenylnitroethanes aswell?


[Edited on 15-2-2018 by Bottle]

Chemi Pharma - 16-2-2018 at 03:56

Do you intend to make 2C-H ( 2,5-DIMETHOXYPHENETHYLAMINE) as your final goal?

Pihkal say that's a no psychoative amine at all.

If so, read the paper attached about reduction of nitrostyrenes with Zn and HCl at 0ºC.

I hope it helps.







Attachment: phpmeHwOU.pdf (1.1MB)
This file has been downloaded 1135 times

zed - 16-2-2018 at 17:44

First try? Don't improvise. Follow instructions exactly. If they say HCl, use HCl.

Hard enough to get good results, when conditions are followed exactly.

Just because someone said the procedure works, doesn't mean it does.


Bottle - 19-2-2018 at 19:49

That paper looks rather unsexy to me, as workup is hard.

It's not my first try, it's actually already my third try using this substrate. I've done it on other substrates with success, though this one is a bitch.
I used acetic acid instead of HCl to avoid Nef-reaction side products as I only got dirt on the very first try when using HCl and I guess it might by caused by Nef-reaction (substrate seems very sensitive towards this). Acidfication only has to be made to release product from their nitronate salts and thus a weak acid can be used for sure, avoiding Nef-reaction

I made a TLC (PE:EToAC: DCM:Ethylenediame) on the yellow IPA layer, it shows one big spot along with a tiny one (hopefully no the regarded product) and no traces of the educt.
Evaporation of the IPA yielded only 30% of theory of a yellow-to-orange oil
CTH Reduction with Ra-Ni+Formic-Acid (5mmol substrate;3mL formic, 3mL EtOH and one spatula of Ra-Ni heated to ~50°C similar to this ref: http://eprints.uni-mysore.ac.in/4673/1/00397910008087439.pdf) is currently running - at least some kind of reaction is taking place, as CO2 bubbles are beeing formed
Though I know that 2C-H and educt almost have the same retention times for eluents like mine, so TLC will be hard on this one



[Edited on 20-2-2018 by Bottle]

Melgar - 19-2-2018 at 22:15

Acetic acid should work too, I've seen this procedure use both. I don't think that's the problem.

How soluble is the nitrostyrene in isopropanol? What was going on at the bottom of the flask? How finely divided was your nitrostyrene?

Come to think of it, did you even have any nitrostyrene? Are you sure you didn't just recrystallize your benzaldehyde? I have to ask dumb questions too, after all. I'm assuming you used this procedure?

https://erowid.org/archive/rhodium/chemistry/edda.html

Was it a vivid orange color? Were there a lot of bubbles when you added the nitrostyrene? Did you have stirring?

Also, if your sodium borohydride is exposed to air for a long time, it'll turn into borax. However if that were the case there would be no reaction.

Bottle - 27-2-2018 at 16:04

In the 1g batch of inpure phenylnitroethan (from IPA-route) I got only about 230mg 2C-H-base-carbamate (tested via TLC) with the Ra-Ni/Formic method and a lot of side products (tar!) making workup horrible so I'm still not happy with the quality of the phenylnitroethane
Quote: Originally posted by Melgar  

How soluble is the nitrostyrene in isopropanol? What was going on at the bottom of the flask? How finely divided was your nitrostyrene?

The NS is only sparingly soluoble in IPA
The NS was not very finley divided prior usage (maybe the problem?)

Quote:

Come to think of it, did you even have any nitrostyrene? Are you sure you didn't just recrystallize your benzaldehyde? I have to ask dumb questions too, after all. I'm assuming you used this procedure? Was it a vivid orange color? Were there a lot of bubbles when you added the nitrostyrene? Did you have stirring?

NS was recristallised twice and it fits literature melting points and is clean by TLC, no doubt it's the correct stuff. It has a very vivid deep orange color. There were only tiny bubbles while adding the NS. I had very strong magnetic stirring.

Quote:

Also, if your sodium borohydride is exposed to air for a long time, it'll turn into borax. However if that were the case there would be no reaction.

Yes my borohydride hasn't been used since a few years and might have lost a lot of quality. I will get some new stuff




[Edited on 28-2-2018 by Bottle]

cubalibre - 2-3-2018 at 12:04

On addition the reduction is normally vigorous and very exothermic which is the only reason this NS goes into solution in that IPA/H2O compared to EtOAc/EtOH system.

You will see a fast color change from orange to white/clear/cream color on addition of the substrate.

Did you notice this and H2 production on quenching with GAA?

[Edited on 2-3-2018 by cubalibre]

clearly_not_atara - 2-3-2018 at 22:38

The nitrostyrene precursor reacts with the nitroalkane product in a Michael addition. So if the reduction is incomplete you will get a dimer upon distillation. That is the main pitfall of this procedure. So if your borohydride is bad it can muck up the whole thing.

Maybe a nitroalkene scavenger could be used if you think borohydride is too expensive to use in excess. I'm not sure what would be suitable; perhaps sodium phenolate would work.

Alternatively the Zn/HCl reduction suggested by Chemi Pharma is preferred for this substrate. I highly recommend it if you want to make a phenethylamine.

Corrosive Joeseph - 3-3-2018 at 02:15

I have previously uploaded an excellent review on the reduction of nitrostyrene using the Zn/HCl system in the link below......

'Optimizing Henry reaction conditions (substituted benzaldehydes + nitromethane)'
https://www.sciencemadness.org/whisper/viewthread.php?tid=76...


/CJ


Bottle - 11-3-2018 at 13:34

I think I have found the reason(s)
--->The nitrostyrene was rextallised a fourth(!) time, but this from EtOH/HOAc 1:1 using a lot active charcoal and filtration, which didn't improve the melting point but did remove a lot of orange color, which made the nitrostyrene brighter orange, almost yellow! Using this system also produces less loss that rextallisation from EtOAc<---
I guess the EDDA-way-made nitrostyrene is directly only usable for LAH reduction without heavy cleaning.

Then I used 5g nitrostyren to 4g freshly bought NaBH4, dissolved the NS in a lot (~100mL) EtOAc and added it over 2h drop by drop to the fresh NaBH4 suspended in 40mL ahydrous EtOH in a 200mL beaker. I don't know the yield as I had an overboiling during acidification (next time I would use ice-cubes), though this time the product seems MUCH cleaner, as it had a different less pleasent smell and almost no tar formed :)
I will post again if it's still not pure enough for decent yielding CTH reduction with Formic/Raney etc.

Thx guys, especially to Melgar!

[Edited on 11-3-2018 by Bottle]

Chemi Pharma - 12-3-2018 at 09:33

Man, I could tell you a better way to use your NaBH4 in addition to NiCl2 to perform your synthesis withouth any tar formation and with high yields, but you are a newbie here and came, at your first time, just asking how to perform a nitroalkene reduction drugs related.

Don't you think it's a little suspect? A lot of other members read this thread but nobody until now, with a few exceptions, didn't say a word, cause I suspect they feel this thread is very suspicious too, I guess!

Search across Sciencemadness about my nickname and I'm sure you will find threads about NaBH4 couple that will help you, certainly, with your synthesis.

It's not tolerated by moderators spoonfeeding here at the forum, neither I want to do it so for you.

FireLion3 - 12-3-2018 at 12:38

I have to agree with Chemi Pharma. While discussing the theory and synthesis of restricted compounds isn't totally frowned upon on this forum, doing so for simple cookery is. It would be a totally different matter if OP was a genuine researcher exploring subtle chemical dynamics for academic/research or whatever, but this isn't the case. It's pretty clear OP is a beginner attempting to make a psychoactive drug (one that is illegal in most countries), who hasn't been studying chemistry for very long - no offense OP. Especially using words like "rextallised" and "rextallisation"

Melgar - 14-3-2018 at 16:43

Eh, it was borderline, and fairly benign. We don't even know where he is to know if he's breaking the law. And he seemed to be more interested in the chemistry than how fucked up he's going to get, so that's a point in his favor. As long as he learned something about chemistry, and as long as he's not going to just forget it as soon as he's done with this reaction, I have no problem with asking and answering these types of chemistry questions.

Corrosive Joeseph - 14-3-2018 at 16:51

I don't see a problem here

I am much impressed by the characterization and the tenacity to keep going despite alternative suggestions by members

This is far above the many shitty cookery posts by first time members.

Target compound isn't even active


/CJ

[EDIT 2] - I won't post again, so I'll drop it here.
Can we stop spamming an otherwise decent thread......?

[Edited on 15-3-2018 by Corrosive Joeseph]

[Edited on 15-3-2018 by Corrosive Joeseph]

Vosoryx - 14-3-2018 at 16:53

It isn't active, so I think this is allowed.

"I was up to a 1+ with 80 milligrams of the hydrochloride, and since it appeared to be totally a physical trip with tremors and some cardiovascular push and nothing of a sensory nature, I chose to explore it no further." - Alexander Shulgin (PiHKAL)

Edit:
My reply was very similar to CJ's... which I only saw after posting. I'm not copying you, I swear!

[Edited on 15-3-2018 by Vosoryx]

Chemi Pharma - 14-3-2018 at 18:01

I don't know, I'm still felling something smelling bad here.

Don't forget guys 2C-H is easy brominated to afford 2C-B, a banished, psychedelic and aphrodisiac drug, with efects similar to Exctasy (MDMA).

See what Pihkal say about the easy bromination:

"To a well-stirred solution of 24.8 g 2,5-dimethoxyphenethylamine in 40 mL glacial acetic acid, there was added 22 g elemental bromine dissolved in 40 mL acetic acid. After a couple of min there was the formation of solids and the simultaneous evolution of considerable heat. The reaction mixture was allowed to return to room temperature, filtered, and the olids washed sparingly with cold acetic acid. This was the hydrobromide salt. "

Even 12-24 mg is enough for an efetive dosage and to fell its effects.


Bottle - 14-3-2018 at 19:03

Neither 2C-H or my target are illegal where I live.
It's not against the forum-rules.
If we start talking like "but you could easily do xxx with it" we could directly ban all kind of chemistry and chemistry-related knowledge! :mad:

Back to topic
Experiment still was unsuccessful.
Everything I got from the last try (check my last post) was an oil which was much denser than water but didn't reduce to the desired product with Pd/C+H2@10bar until hydrogen uptake ceased plus some additional hource. A/B-Extraction after H2/Pd/C yielded only a lot of a viscous heavy oil in the from the washes of the acidic media and a tiny amount of some alkaline plastic-like soft but not liquid material (maybe the reduced dimer), the desired product was only visible by TLC. My latest guess is that some styrene-->polystyrene-alike oligomerisation takes place when the solvent is evaporated, maybe catalysed by an inpurity.
Original sources used a rotovap, while I was only using a hot water bath and water-jet-vacuum.
Though anyway there must be much more going on than only Micheal-addition to a dimer, as almost zero yield is produced which can't be explained easily. Any ideas?

I might try it again without solvent removal, using the intermediate in solution as-is. Or Maybe with dioxane/silica like in the original sources. Is a acidic workup / neutralisation of the intermediate necessary as with hydroboration/oxymercuration etc.? I can't find enough information about the mechanism.

@ChemiPharma
Quote:
Man, I could tell you a better way to use your NaBH4 in addition to NiCl2 to perform your synthesis withouth any tar formation and with high yields, but you are a newbie here and came, at your first time...

I was already thinking of using NaBH4 or KBH4+Raney-Nickel (as potassium borohydride is a better hydrogen donor for CTH
as far as I know http://www.arkat-usa.org/get-file/23388.html) as one-pot reaction which should be almost exactly the same way as your NaBH4+NiCl2 which produces nano-nickel on nickel-boride in-situ as active catalyst, making it a very similar CTH-mechanism for the nitro-reduction aswell. Though I don't know if there might be any side-reaction as there might be some kind of a hydroborate-complex forming with the double-bond, especially under alkaline conditions, which might react to a saturated nitroalcohol(-->aminoalcohol) and more complex sideproducts.
So, have you ever tried it (maybe with a similar substrate) or why are you telling that there's s high yield and no tar produced?

Can anyone here explain the mechanism how the nitro- activated (conjugated) double-bond is actually reduced? Is it more 1,4-addition-alike funky or more hydroboration-alike or something completly different?

[Edited on 15-3-2018 by Bottle]

clearly_not_atara - 14-3-2018 at 20:29

Quote: Originally posted by Chemi Pharma  
I don't know, I'm still felling something smelling bad here.

[PiHKAL]
Even 12-24 mg is enough for an
We're not the police, it's hardly our job to speculate about what people might be doing. We had a sticky on 2,5-dimethoxybenzaldehyde at one time and everyone knows what that's for (not to mention the crucial role of acetic anhydride in making heroin!). Our concern is with what they tell us they're doing and, more importantly, with what we're doing, which is to spread the understanding of chemistry, but not to promote or in any way encourage drug manufacturing. That chemistry makes drug manufacturing possible is hardly something we can hope to avoid; in fact the chemical restrictions we now fight so hard against came from the idea that the government could ban only drug chemistry, which as we all know turned into a ban on all chemistry.

Frankly I think it's worse to post quotes and links from PiHKAL than to answer questions about reducing nitrostyrenes. We don't need to give him any more help making drugs; if someone posts repeated queries about each step in the 2C-B manufacturing process, we can cross that bridge when we come to it, and ignore or ban them with good justification.

Also, 2C-B may be active, but it was hardly popular last I checked, which suggests that at least OP is not going to make any money -- and commercial production is the real problem, anyway.

[Edited on 15-3-2018 by clearly_not_atara]

JJay - 14-3-2018 at 21:17

2C-H is a precursor to other designer phenethylamines and these days is a controlled substance like lysergic acid.

Chemi Pharma - 15-3-2018 at 04:20

Since some members here think that's nothing wrong, we're not the police and forum's moderators did nothing about this thread until now, I feel free to expose my ideas and reply @bottle question, although, in my opinion, I still thinking this discussion obviously are drugs related:

Quote: Originally posted by Bottle  
@ChemiPharma
Quote:
Man, I could tell you a better way to use your NaBH4 in addition to NiCl2 to perform your synthesis withouth any tar formation and with high yields, but you are a newbie here and came, at your first time...

I was already thinking of using NaBH4 or KBH4+Raney-Nickel (as potassium borohydride is a better hydrogen donor for CTH
as far as I know http://www.arkat-usa.org/get-file/23388.html) as one-pot reaction which should be almost exactly the same way as your NaBH4+NiCl2 which produces nano-nickel on nickel-boride in-situ as active catalyst, making it a very similar CTH-mechanism for the nitro-reduction aswell. Though I don't know if there might be any side-reaction as there might be some kind of a hydroborate-complex forming with the double-bond, especially under alkaline conditions, which might react to a saturated nitroalcohol(-->aminoalcohol) and more complex sideproducts.
So, have you ever tried it (maybe with a similar substrate) or why are you telling that there's s high yield and no tar produced?


Yes I did nitroalkenes reduction reaction using NaBH4 and NiCl2 in methanol a few times, just for cientific purposes. And I'm the major defensor of this technique of reduction here at the forum, instead using expensive Pd/C, Raney nickel and surpassed techniques like urushibara nickel, Al/Ni+2 and Hg/Al amalgam, that some members here still defending.

You can follow the directions given by the papers I attached below to have high yields getting your 2C-H with no tar at all. Remember tar is intimately related with room temperatures reaction mix and above. However the papers didn't say a word about temperature factor, try to do the reactions at near 0ºC:



Attachment: sodium borohydride-nicl2-reduction of nitro compounds.pdf (399kB)
This file has been downloaded 1117 times

Attachment: amphetamine synthesis from phenylnitropropene - NaBH4 + NICL2.doc.doc (189kB)
This file has been downloaded 1758 times

[Edited on 15-3-2018 by Chemi Pharma]

Corrosive Joeseph - 15-3-2018 at 10:11

Quote: Originally posted by Bottle  

Can anyone here explain the mechanism how the nitro- activated (conjugated) double-bond is actually reduced?


Check Hudlicky's for an excellent review on nitro and nitro conjugated double bond reductions and mechanisms.
Maybe you know it already...... Pages 69 thru to 75
The whole book really is a must-read anyway.

'Reductions in Organic Chemistry' - Milos Hudlicky
http://cnqzu.com/library/Anarchy%20Folder/Chemistry/Crystali...

Also attaching Nitro to Amine SET mechanism - taken from
http://www.ch.ic.ac.uk/widdowson/teach_files/nitrogen/dw1.ht...

And you might like this -
'Catalytic Transfer Hydrogenation of Nitroalkenes to Primary Amine'
Attached -
It has a proposed hydride transfer mechanism on beta-Nitrostyrene deep in there somewhere.

And this for a chaser -
'Selective Reduction of Conjugated NitroOlefins' - https://etd.ohiolink.edu/!etd.send_file?accession=osu1448465...

I'm sure I have more but that'll do for now.....

Very interested in your Ni/Formic Acid. I sometimes wonder if a Nickel nanoparticle CTH could replace Ra-Ni which is not so OTC but your results with that don't look so promising.

Hope this helps


/CJ

Nitro To Amine Mechanism - The Chemistry of Nitrogen Compounds.gif - 7kB

Attachment: Catalytic Transfer Hydrogenation of Nitroalkenes to Primary Amine.pdf (1.4MB)
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Bottle - 15-3-2018 at 20:20

Quote: Originally posted by Chemi Pharma  

Yes I did nitroalkenes reduction reaction using NaBH4 and NiCl2 in methanol a few times, just for cientific purposes. And I'm the major defensor of this technique of reduction here at the forum, instead using expensive Pd/C, Raney nickel and surpassed techniques like urushibara nickel, Al/Ni+2 and Hg/Al amalgam, that some members here still defending.

You can follow the directions given by the papers I attached below to have high yields getting your 2C-H with no tar at all. Remember tar is intimately related with room temperatures reaction mix and above. However the papers didn't say a word about temperature factor, try to do the reactions at near 0ºC:

[Edited on 15-3-2018 by Chemi Pharma]

Thank you very much!
But have you also tried it on nitrostyrenes or only on a-methyl-nitrostyrenes? They behave quite different; a-alkyllnitrostyrenes are generally very easy to reduce with NaBH4 to their nitroalkanes while the nitroethenes tend to produces crap!

[Edited on 16-3-2018 by Bottle]

Bottle - 15-3-2018 at 20:29

Quote: Originally posted by Corrosive Joeseph  

...
Very interested in your Ni/Formic Acid. I sometimes wonder if a Nickel nanoparticle CTH could replace Ra-Ni which is not so OTC but your results with that don't look so promising.

I've used Ra-Ni/Formic a few times times on completly different substrates for nitro reductions in EtOH, usually always got good (70-90%) yields, the 30% yield is most likes caused by very impure educt.
It's imho as good as Pd/C+Formate in MeOH, maybe a bit smoother and workup is sometimes crappy as a little Ni can dissolve (though not so much when using formate instead of formic acid).
I bet CTH will work with NiNP and nickel boride aswell.
Most likely even with Ni2+ and heat, producing nanoparticles in-situ, though of course with limited usage

edit j_sum1
fixed formatting issue



[Edited on 17-3-2018 by j_sum1]

Chemi Pharma - 15-3-2018 at 22:24

Quote: Originally posted by Bottle  
Thank you very much!
But have you also tried it on nitrostyrenes or only on a-methyl-nitrostyrenes? They behave quite different; a-alkyllnitrostyrenes are generally very easy to reduce with NaBH4 to their nitroalkanes while the nitroethenes tend to produces crap!


To reduce methyl nytrostyrenes and nitropropenes you'd better use nickel boride instead NaBH4/CH3OH couple alone, while reducing nitrostyrenes itself, I'd rather use Zn and HCl at 0ºC, as I've told before in this thread.

Don't make sense to me reducing nitroalkenes to nitroalkanes intermediates if the target are the amines and I can do it directly, in just one step.

Melgar - 16-3-2018 at 11:58

I'm posting here just to fix the formatting glitch that XMB seems to be having right now.

edit: Bottle, or a moderator: please edit that post, and replace the curly bracket with a square bracket for the rquote tag, ok?

[Edited on 3/16/18 by Melgar]

[Edit j_sum1]
Thanks for that Melgar.
Done.

[Edited on 17-3-2018 by j_sum1]

Bottle - 23-4-2018 at 20:53

Finally a great success to share:
A suspension of 5g substrate in a solvent-mixture composed of IPA and DCM (sry I didn't remember ratios and can't find the paper anymore the idea came from which used chloroform+IPA) and a huge excess (~maybe 40g if I remember correctly) of silical gel (made from silica gel* cat litter!!! which was finely powdered using an electric coffee grinder and kitchen metal sieve) was added in small portions to a suspensions of a teaspoon of homemade homemade "Raney-Ni T-4" to about 10g very old NaBH4 (catalyst and especially NaBH4 were used in extreme excess, the amount of NaBH4 should be a MASSIVE OVERKILL, a fraction could be used for sure) in little cold absolute EtOH. Everything was stirred using a magnetinc stirrer. Reaction was cooled slightly using an water bath and a few ice cubes - reaction at this scale was very smooth, it didn't get a very warm, cooling might be actually optional.

After addition the reaction stirrend for another one or two hours, the catalyst+silica gel were filtered off by suction filtration and washed with EtOH.

-->Don't don't destroy the NaBH4 as long as Ra-Ni is present, as it will yield into a very voluminous sludge which is very hard to filtrate and wash (and dangerous due the massive hydrogen evolutin and the pyrophoric nature of Ra-Ni).

The excess of NaBH4 was extracted two times with 40% aq. NaOH (--->maybe aq. potassium carbonate might be better but I'm not sure as 2C's do react rapidly with CO2 and maybe aswell with carbonates to form carbmates(!?), maybe someone has an idea to this point?<---), the organic phase was dried using fused and powdered MgSO4 (choosed it instead of waterfree Na2SO4, as it could partially neutralise traces of remaing NaOH which might hydrolyse the a part of the product during the destillation process), decanted from the drying agent and drying agent was washed three more times with EtOH, solvents were destilled and evaporated under aspirator vakuum using a boiling water bath as it source, the water bath was switched to an ~160°C oil bath, the revieving flask was switched to an 25mL oven-dried RBF and pump was switched to a two-stage rotary vane pump -->

The remaining oil was destilled** using the two strage rotary vane pump with a cold trap to yield 83%(!!!!) of theory of completly colorless 2C-H which was successfully identified by TLC and by making the HCl salt (by HCl-gas made from fusing NaCl and pre dried NaHSO4 in a flask on a hotplate , gassing the HCl into a little toluene+base, yielding 79% of constant dried very pure 2CH*HCl, directly hitting the literature metling point without further recristallsation)

Without the silica gel and absolute EtOH as only solvent the yield drops to about 50-60% "only" (still better than everything else tried except LAH).

*the silica gel acts as a weak proton donor to improve yield of the in-situ produced phenylnitroethane and avoid micheal-addition side product

**also tried A/B extraction with DCM, but DCM tends to form emulsions and you need very huge amounts (at least four extractions with a lot solvent) to get a similar yield with lower purity, so direct destillation is prefered

Discussion:
-Cat litter silica gel seems to be a usable source of cheap silica gel which is pure enough for this purpose, it can be easily grinded using a electric coffee grinder. There's no need of using expensive chromatography-grade silica gel.

-The idea to this was developed after 10+ more or less unsessful tries (mostly based on the writeups from "Barium", using EtOAc or IPA as only solvent an isolating the intermediate) but got only very bad yields due side products forming - but now finally a good yield was reached mixing several methods - The reaction isn't optimized yet, I'm almost sure the yield can reach 90%+ using the perfect conditions and solvents, as already with such a sloppy work a ~80% yield was reached. Phenyl-2-nitropropenes maybe even reach 95%+ as they should produce even less side products!

-Reusage of the Ra-Ni + silica gel sludge wasn't tried but should be possible a few times.

-Most likely Ni2+ (as nickel acetate or NiCl2) precipitated onto the silica gel in MeOH or EtOH as solvent with NaBH4 directly onto the silica gel matrix and then using DCM/IPA as solvent system should work just as well as Raney-Nickel T4, maybe It's giving even giving higher yields as the intermediate should react faster. And this specialised catalyst might be reusable several times aswell.
Though "even better yields" are only speculation so far.

[Edited on 24-4-2018 by Bottle]

Chemi Pharma - 24-4-2018 at 01:24

Congratulations @Bottle. Finally my point of view was proved. Nickel Boride made "in situ" from raney nickel or nickel salts and NaBH4 is far superior than other methods to realize a low cost and high yielding hydrogenation.

The surprise for me was the usage of silica gel as you've proposed and DCM/IPA as a solvent media. Very interesting. I will try this kind of optimization next time.

Well done. Nice job!

[Edited on 24-4-2018 by Chemi Pharma]

S.C. Wack - 24-4-2018 at 17:55

Quote: Originally posted by Bottle  
2N HCl was then carefully2 added until pH 4 was reached followed by enough solid NaCl to cause the IPA to form a separate layer containing the product.

...

I used ~30% HOAc instead of HCl to bring the pH to 4.00 and used a 300ml erlenmeyerflask with ice-bath-cooling instead of RT to avoid dimeric sideproducts (maybe a mistake?)


A bit late reading the thread just now...BTW there was something posted as an attachment somewhere at the-hive saying "This document presents a writeup of his final work on the topic. Some modifications of the original procedure has been included in this document."...it's a Rhodium page (Easy borohydride reduction of beta-nitroalkenes to nitroalkanes) but it isn't in Rhodium and wasn't then AFAIK and after 14 years I forget what's up with that, but notice how acetic acid appears and somehow everything before and after is the same.

Dilute 80% acetic acid was added untill no more fizzing from the remaining borohydride occured. This is followed by addtion of enough solid NaCl to cause the IPA to form a separate upper layer containing the product. The mixture was suction filterd and rinsed with a little IPA.

...

General Procedure

Use the following amounts of reagents:

1 mole eq. of any arylnitrostyrene
1,25 mol eq. potassium or sodium borohydride1
Approximately 5*wt. of the nitrostyrene in mL's of IPA (i.e. 10 g P2NP would require 50 mL IPA)
2/5 the vol of IPA used of dH2O

Mix the IPA and water in a sufficiently large beaker. Add the borohydride in one portion and commence stirring. Begin adding the nitrostyrene in small portions after a minute or two. This will cause a rise in temperature and moderate hydrogen evolution. Add the substrate in small portions to avoid any nasty volcano reactions. The rate of addition should be such that a lively evolution of hydrogen can be observed in the beaker, but slow enough to avoid the reaction shooting out of the flask.

Once all of the substrate has been added, keep stirring the mixture for 30 mins. The colour of the mixture should be alot more pale than that of the nitrostyrene2. Add dilute (32-80%) acetic acid drop wise untill fizzing stops. Add solid non-iodized table salt while stirring heavily, untill no more dissolves. Suction filter the mixture, to remove any remaining salt and borates. Rinse the filter cake with a little fresh IPA. The IPA layer, containing the product will float on top of the water. Isolate the IPA layer, and discard the water.

At this point the reaction is over, and the IPA layer contains a product which is sufficiently pure for a CTH, Zn/Formate, SnCl2 nitro reduction or whatever your preference might be. So simply use this IPA direcly.

...

[1]The larger the scale of the reaction is, the larger molar eq. of boroydride is required. From emperical knowledge potassium borohydride requires a larger molar eq. Perhaps KBH4 decomposes faster in the IPA/water environment.

[2]Please use as pure nitrostyrene as possible in this reduction. If there are too many coloured impurities left, it is very hard to tell if the compound has been reduced properly, once the reaction is over.


[Edited on 25-4-2018 by S.C. Wack]

Chemi Pharma - 30-4-2018 at 07:07

The discussion is over, I guess, although @S.C. Wack oppinion.

The thread is exhausted. The two papers I brought to the topic teaching how to reduce nitrostyrenes with zinc and HCl at 0ºC to phenylethylamines and phenyl-2-nitropropenes to amphetamines with nickel boride made in situ with nickel salts (or the more expensive raney nickel) and NaBH4 is enough in my oppinion.

@bottle testimony above proved what I've been saying all time long about the better techniques to do this kind of reductions with satisfactory yields.

[Edited on 30-4-2018 by Chemi Pharma]

stoichiometric_steve - 12-10-2018 at 15:25

Quote: Originally posted by Chemi Pharma  
The discussion is over...The thread is exhausted.


So one single guy used your methods and apparently succeeded...wow. You've successfully helped someone make a drug precursor. I guess you're still jerking off to that, aren't you?

I don't think this thread is over, since the initial problem of the claimed procedure (using plain NaBH4 without additives) failing still persists.

Chemi Pharma - 19-10-2018 at 04:42

@stoichiometric_steve, don't you have anything better to do besides criticizes other members?

Not just one person used the method I preach, but dozen of researchers, and I brought to this thread a lot of papers proving it.

Although you, a few other members and the ass hole named @clearly not atara insists in depreciate my efforts with Nickel boride as the better and cleanner hydrogenation agent to reduce nitro groups and double bonds, I'm shitting for your oppinion at all.

I have alerted the moderators and other members that this thread were intimately related with drugs, cause I warned all members in this thread that @bottle really intended to produce 2C-B and not only 2C-H, like he said, but no one listened me and no one did nothing respect this. Than, screw up you all guys. Don't come now to blame me at all.

You and other ass holes in this Forum are really pissing me off, and cause of people like you I'm really disgusted to post anything else here anymore.



[Edited on 19-10-2018 by Chemi Pharma]

j_sum1 - 24-10-2018 at 22:19

Please dial it back a little Chemi Pharma. This is not the time to make it personal. Ditto stoichiometric_steve. Your comment could be interpreted as snarkiness.

Sure the topic is intimately related with drugs. That much is obvious from the title alone. But there are unresolved questions of a chemical nature which is why the forum allows such discussion topics.

CP'sproposed method using nickel boride may be better (I am not experienced enough to make a judgement call one way or the other on that). But since the discussion initiated around a different procedure, that point is somewhat moot.

[/mod comment]

Chemi Pharma - 31-10-2018 at 06:30

Ok, I apologize for the bad language J_sum1.

But I'm tired reading @Clearly_not_atara and other few members posts, mocking and messing me when I expose my posts, papers and theory about nickel boride as the better, higher yielding and cleanner hydrogenation agent to reduce nitro groups, double bonds, aminoacids, etc.

Nickel boride is enough efficient as a reducting agent like LiAlH4 with more selectivity, low cost and safe handle. I have brought to this Forum a dozen of papers of researchers proven it, spreaded at too many threads, along the last years. Only a dumb can't see this.

But this kind of guys insists in depreciate me, my efforts and my theories, with a lack of education that's awful to read.

I think this Forum exists to change ideas beetwen it's members about the best methodology to produce chemicals, the best work up and the best theories to achieve the best yields. But some members here seems too much full of yourselves and arrogant enough to ever criticize other members that desagree with their ideas. It's really awful and denies to this Forum to be a democratic space to discuss about chemistry.

I still thinking this thread is OVER! NaBH4 alone it's know as ineffective to reduce nitro groups. It reduces only double bonds alone. Everyone here knows that or should know about it. Borohydrides only works as an effective hydrogenation reducing agent if coupled with transition metals like cooper, cobalt or nickel.

Oh man! Do a research and learn more about this! I brought to this Forum so many papers dealing with this. Go, research, learn and stop to tell me bulshits. May be after this I reconsider post again in this Forum!

[Edited on 31-10-2018 by Chemi Pharma]

clearly_not_atara - 31-10-2018 at 12:27

Sciencemadness does not support "pinging"; there is no effect when you type @clearly_not_atara or @Melgar or @Boffis or whatever. I think this is a good thing.
Quote: Originally posted by stoichiometric_steve  
I guess you're still jerking off to that, aren't you?

Pretty sure you're the one who revived the thread!
Quote: Originally posted by stoichiometric_steve  
since the initial problem of the claimed procedure (using plain NaBH4 without additives) failing still persists.

Some work done elsewhere has revealed that in order for the reaction to succeed, a large excess of NaBH4 is necessary, since this "kinetically overpowers" the nitroalkene+nitroalkane Michael dimerization which is responsible for the tar formation. However, this generally implies that the procedure is impractical.

Using the Hantzsch ester may achieve better yields, since it forms an intermediate which may impede dimerization. There are AFAIK no amateur reports using the Hantzsch ester method for nitroalkene->alkane conversion. The original paper reports high yields from a simple procedure, and is here:
Attachment: 5659-hantzsch-ester-olefin-reduction7bb1.pdf (84kB)
This file has been downloaded 478 times
Quote: Originally posted by Chemi Pharma  
@clearly not atara insists in depreciate my efforts with Nickel boride as the better and cleanner hydrogenation agent to reduce nitro groups and double bonds

I did not post about nickel-assisted borohydride reduction in this thread, either for or against. Our only interaction involved me explaining why I did not think this thread ran afoul of the rules, and I was generally correct in that Bottle did not go on to start other threads about making 2C-B.

Overall, you seem to have a bit of a persecution complex.

I will say, though, that CuCl2 seems to be just as effective as NiCl2 in catalysing this reduction, with high yields for nitroalkene -> amine with NaBH4/CuCl2. This may be useful as the copper powder produced is likely to be less flammable than that obtained with nickel.

EDIT: Post #1234! I declare thumb war!

[Edited on 31-10-2018 by clearly_not_atara]

Chemi Pharma - 4-11-2018 at 04:28

Quote: Originally posted by Chemi Pharma  
@clearly not atara insists in depreciate my efforts with Nickel boride as the better and cleanner hydrogenation agent to reduce nitro groups and double bonds


Quote: Originally posted by clearly_not_atara  
I did not post about nickel-assisted borohydride reduction in this thread, either for or against. Our only interaction involved me explaining why I did not think this thread ran afoul of the rules, and I was generally correct in that Bottle did not go on to start other threads about making 2C-B. Overall, you seem to have a bit of a persecution complex.


Really? You've wrote posts attacking me every opportunity I defend my point about Nickel Boride usage. it's enough reading your answers to my posts in your posts below in other threads, always mocking and messing up with me:

http://www.sciencemadness.org/talk/viewthread.php?tid=78639&...

Quote: Originally posted by clearly_not_atara  
Of course this is very silly, anyone who is familiar with the literature on these compounds knows that catalytic hydrogenation tends to attack the C=C double bond whereas hydride reagents attack the carbonyl. It's not surprising that someone who only pays attention to hydrides would be misled.


http://www.sciencemadness.org/talk/viewthread.php?tid=65915&...

Quote: Originally posted by clearly_not_atara  
Is this one of those cases where I'm arguing with someone who's *really* bad at understanding how meaning derives from context, or do you just intentionally misinterpret things in ways that you think might make you sound intelligent? Do you see *any* examples using Ni2B as a reducing agent on its own?


I don't want to discuss with people like you. I gave you a time ago an opportunity to call me at U2U to tell what's your real problem with me. You didn't do that. Now is late! I just have blocked you. Do me a favor, don't ever reply my posts and I will never reply yours. Pretend I do not exist, cause I will do the same with you, ok?


stoichiometric_steve - 5-11-2018 at 09:16

Quote: Originally posted by clearly_not_atara  

Using the Hantzsch ester may achieve better yields


I have a strong feeling that at least one of those Nitroalkenes has an mp. above 100 deg. C and thus the method smells strongly of bullshit, as is just so terribly often the case with indian publications.

Especially since the Hantzsch ester only melts at 170+ deg. C.

zed - 6-11-2018 at 13:48

Well, now that we got to talking about Hantzsch Esters. They seem to work, and.....I can make 'em myself.

Got a high molecular wt., which matters quite a bit, but then as stated....I can make them myself.

https://www.youtube.com/watch?v=4SkftlNhxKQ

Thank you, clearly_not_atara. Something I didn't know about.

stoichiometric_steve - 7-11-2018 at 02:58

Quote: Originally posted by Chemi Pharma  
Nickel Boride made "in situ" from raney nickel or nickel salts and NaBH4 is far superior than other methods to realize a low cost and high yielding hydrogenation.


First of all, he didn't make it in situ. Adding NaBH4 to metallic Nickel powder does not reduce it to anything other than it already is.

Quote: Originally posted by Chemi Pharma  

The surprise for me was the usage of silica gel


Which is actually an old method known to work and providing good yields, just the amounts of solvent are too damn high.

The added Nickel did absolutely NOTHING here, just the NaBH4.

I highly doubt that you can provide any legitimate reference where your Nickel Boride method is applied to 2-Nitrovinylbenzenes.

Chemi Pharma - 7-11-2018 at 12:07

Quote: Originally posted by stoichiometric_steve  
Quote: Originally posted by Chemi Pharma  
Nickel Boride made "in situ" from raney nickel or nickel salts and NaBH4 is far superior than other methods to realize a low cost and high yielding hydrogenation.


First of all, he didn't make it in situ. Adding NaBH4 to metallic Nickel powder does not reduce it to anything other than it already is.

Quote: Originally posted by Chemi Pharma  

The surprise for me was the usage of silica gel


Which is actually an old method known to work and providing good yields, just the amounts of solvent are too damn high.

The added Nickel did absolutely NOTHING here, just the NaBH4.

I highly doubt that you can provide any legitimate reference where your Nickel Boride method is applied to 2-Nitrovinylbenzenes.


Raney nickel in fact don't react with borohydride. Borohydride reacts with metanol giving methoxyborohydride and nascent hydrogen. In the case of nickel salts in methanol, borohydride reacts forming nickel boride, methoxyborohydride and nascent hydrogen also.

Either raney nickel and nickel boride acts as a catalyser, absorbing this nascent hydrogen and giving it to the reaction promoting the hydrogenation. You're completely wrong thinking nickel does nothing in the reaction and seems never have read any of the papers I brought to this forum. NaBH4 alone in methanol has a reduced power to hydrogenate something, just reducing ketones and aldehydes to alcohol and double bonds to saturated compounds.

In the other way, nickel/borohidride/methanol couple can reduce acids, ketones and aldehydes groups to alcohols; nitro, nitroso, cyanide and oxime groups to amines and double bonds to saturated chains, and other things I don't remember now.

You can find a dozen of papers I brought to this forum in the last two years to prove what I'm saying, spread around a lot of threads. Just do a search for my nickname to find those papers talking about reduction of nitro groups and you will find the legitimated references you're looking for the reduction of Beta nitrostyrene (aka 2-nitrovinylbenzene) with nickel boride in methanol to phenethylamine.


clearly_not_atara - 8-11-2018 at 00:13

Quote:
You've wrote posts attacking me every opportunity I defend my point about Nickel Boride usage. it's enough reading your answers to my posts in your posts below in other threads, always mocking and messing up with me:

In neither case did I argue that NiBx is not an effective hydrogenation catalyst (although, it is not a stoichiometric compound). Rather, in the one case, you gave a totally wrong interpretation of alkene reduction, and in the other, you misunderstood the way Wikipedia used the term "reducing agent". Also, in the second case, you were attempting to derail a thread that I started.

Frankly, it's kind of nuts to be archiving old arguments like this. I suggest getting some fresh air.

Quote:
I highly doubt that you can provide any legitimate reference where your Nickel Boride method is applied to 2-Nitrovinylbenzenes.

A number of people I know have reported success with NaBH4/CuCl2. The paper which introduced it notes that it is a variant of the NaBH4/NiCl2 method:
https://www.researchgate.net/publication/267961413_TRANSITIO...
Ironically, the original paper does not actually test any aliphatic nitro compounds. It simply happened that somebody misread it, tried it, and it worked. Papers aren't everything.

Quote:
I have a strong feeling that at least one of those Nitroalkenes has an mp. above 100 deg. C and thus the method smells strongly of bullshit, as is just so terribly often the case with indian publications.

3,4-dimethoxynitrostyrene melts at 140 C, which would seem to be an issue for performing a reaction at 100 C, but perhaps not if they're soft goopy solids and you stir them. Take a look at the procedure:

"To a preheated 10 mL round-bottomed flask 1 mmol of nitroolefin and 1.1 mmol of hantzsch ester were added. The reaction mixture was stirred at 100 C..."

stoichiometric_steve - 8-11-2018 at 08:54

Quote: Originally posted by clearly_not_atara  

A number of people I know have reported success with NaBH4/CuCl2.


Would it be possible for that number of people to come forward and post some experimental details of their attempts?

That would be greatly appreciated. I have been researching reactions concerning those compounds extensively and would love to compile them for quick reference.

Guys like Barium of former hive fame have been posting a great deal of highly dubious procedures previously.
Going back to those posts where others requested experimental details or product characterization, conversations quickly derailed into made up excuses for not providing any such thing, which also reminds me a bit of the tantrums our fellow chemipharma is throwing here. I wonder what that's all about? Someone needs to realize that earning internet points for being right isn't quite what we do here.

Chemi Pharma - 8-11-2018 at 10:15

Quote: Originally posted by stoichiometric_steve  
Going back to those posts where others requested experimental details or product characterization, conversations quickly derailed into made up excuses for not providing any such thing, which also reminds me a bit of the tantrums our fellow chemipharma is throwing here. I wonder what that's all about? Someone needs to realize that earning internet points for being right isn't quite what we do here.


@stoichiometric_steve it's not a question of "a bit of tantrums" like you've said, I guess is more a question of a lack of education at home some members here suffer. You said we all are fellows. Well I think fellows must treat other fellows with a minimum of education, don't you think that?

I really felt offended with your expression "jerking off". It's not a good way to iniciate a fellowship, isn't it? I think your post were our first meeting here at the forum and do you start a dialog this way? The same with @Clearly_not_atara. In one example the guy replies my post saying "Of course this is very silly!". Well, I think he's calling me a fool, isn't it? Like if I know nothing about chemistry and can't make any mistake. I think he is extremely rude in his posts with other fellows that desagree with him. He needs to try be more polite, apologize for his rudeness and not come to ask me to take fresh air and forget about his past rudeness like nothing had happened. This kind of things is really annoying.

Since you are complaining about the lack of information and seems you like spoon feeding, I'm posting again all the papers about nickel boride reductions, not only nitro groups reductions, below. Enjoy it. They are very instrutive about the study of hydrogenations using borohydride coupled with transition metals, not only nickel, but also cobalt and copper, like @clearly_not_atara said.


Attachment: Sodium Borohydride-Nickel Chloride-reduction of dienes and cleavage of allyl esters.pdf (279kB)
This file has been downloaded 562 times

Attachment: Amino acids reduction with borohydride-nickel chloride.pdf (93kB)
This file has been downloaded 686 times

Attachment: Reduction Of Aliphatic Nitro Compounds To Amines Using NaBH4_NiCl2 and Ultrasound.pdf (157kB)
This file has been downloaded 459 times

Attachment: nitrile-2boc-amine.nabh4-nicl2.pdf (198kB)
This file has been downloaded 534 times

Attachment: Nitriles to Amines with NaBH4 + NICL2- Nickel Boride.pdf (39kB)
This file has been downloaded 625 times

Attachment: amphetamine synthesis from phenylnitropropene - NaBH4 + NICL2.doc.doc (189kB)
This file has been downloaded 596 times

Attachment: nickel boride hydrogenations.pdf (482kB)
This file has been downloaded 418 times

Attachment: nitro aromatics to amines with nickel boride.pdf (459kB)
This file has been downloaded 431 times

Attachment: sodium borohydride-nicl2-reduction of nitro compounds.pdf (399kB)
This file has been downloaded 487 times


laserlisa - 8-11-2018 at 11:22

Quote: Originally posted by stoichiometric_steve  
Quote: Originally posted by clearly_not_atara  

A number of people I know have reported success with NaBH4/CuCl2.


Would it be possible for that number of people to come forward and post some experimental details of their attempts?

That would be greatly appreciated. I have been researching reactions concerning those compounds extensively and would love to compile them for quick reference.

Guys like Barium of former hive fame have been posting a great deal of highly dubious procedures previously.
Going back to those posts where others requested experimental details or product characterization, conversations quickly derailed into made up excuses for not providing any such thing, which also reminds me a bit of the tantrums our fellow chemipharma is throwing here. I wonder what that's all about? Someone needs to realize that earning internet points for being right isn't quite what we do here.

Relevant thread: http://www.sciencemadness.org/talk/viewthread.php?tid=84596

clearly_not_atara - 8-11-2018 at 11:53

Quote:
Guys like Barium of former hive fame have been posting


Barium has been posting? I thought he vanished into the aether years ago.
Quote:
The same with @Clearly_not_atara. In one example the guy replies my post saying "Of course this is very silly!". Well, I think he's calling me a fool, isn't it? Like if I know nothing about chemistry and can't make any mistake.

The post you made was very silly. You insisted on a wrong claim, people disagreed, and you continued to insist and insult them. To the extent I have been rude to you, it was only when you were already being rude. For example, in that thread where I said you were being silly, you insulted Loptr for no good reason, and were wrong while doing it:

"If so, you deserve an article at chemical periodic bulletins, cause to reduce the double bond of insatured [sic] carbonyl compounds without affect the carbonyl group deserve a honor medal."

You think you are being mistreated, but in reality you pick fights whenever anyone disagrees with you and are extremely defensive about your own knowledge of chemistry. You need to stop interpreting rebuttals as personal attacks.
Quote:
Would it be possible for that number of people to come forward and post some experimental details of their attempts?


Eh, why the hell not. The following work belongs to someone else, who probably prefers not to be named:

"With vigorous stirring, to 5ml of IPA / 1g of P2NP and 0.4 times volume of H2O in RBF was dumped 6 mol eq. of NaBH4.
Recrystallized P2NP was washed with sodium bisulfite solution, then with and water and it was then added in small portions to the mixture to minimize frothing. No external cooling applied. After all substrate was added and near-colourless solution is obtained, the solution left stirring for 30 minutes. Claisen adapter was fitted to the rbf with reflux setup and addition funnel. With one portion, 10%-mol equivalent (for the nitroalkene) of CuCl2.2H2O dissolved in IPA was added to the solution via the funnel. It was refluxed for 30 minutes. After which the remaining NaBH4 was destroyed by adding about 50% acetic acid untill the fizzing stopped and the solution was fairly acidic. With the claisen adapter still attaced, short path distillation setup was rigged and everything below 100'C was stripped.
Then the solution was made basic dripping strong NaOH solution to the reaction flask and steam distilled. Additional very dilute NaOH solution was added through the addition funnel every now and then. The distillate was then made slightly acidic with H2SO4 and evaporated.
Total yield after recrystallization: 80% mol wise from the P2NP due to very sloppy work"

Chemi Pharma - 9-11-2018 at 02:51

Quote:
Quote: Originally posted by clearly_not_atara  
Quote:
The same with @Clearly_not_atara. In one example the guy replies my post saying "Of course this is very silly!". Well, I think he's calling me a fool, isn't it? Like if I know nothing about chemistry and can't make any mistake.

The post you made was very silly. You insisted on a wrong claim, people disagreed, and you continued to insist and insult them. To the extent I have been rude to you, it was only when you were already being rude. For example, in that thread where I said you were being silly, you insulted Loptr for no good reason, and were wrong while doing it:

"If so, you deserve an article at chemical periodic bulletins, cause to reduce the double bond of insatured [sic] carbonyl compounds without affect the carbonyl group deserve a honor medal."

You think you are being mistreated, but in reality you pick fights whenever anyone disagrees with you and are extremely defensive about your own knowledge of chemistry. You need to stop interpreting rebuttals as personal attacks.


And who are you to tell if someone is right or wrong? you're an arrogant bastard who wants to get the last word on everything. @Loptr does not need a stupid parent or healer like you to defend his interests. He and I talked through U2U and I got into his topic because he asked me to do that. He is a thousand times more educated than you, who looks like a spoiled boy who does not admit to be annoyed. You did not like about what I've posted because I posted that your methods are outdated, and you're wrong. Urushibara nickel is an outdated method, just like you, a brat wanting to appear in this forum with your arrogance and idiocy. Who always looks for a fight and begins the rudeness here is always you.

It is not possible to reduce a double bond of an aliphatic chain without reducing it's carbonyl group attached, like with the compound @Loptr had indicated. Everything you've posted is stupid and only works in theory. No surprising, cause your brain always work in theoretical mode. In practical chemistry you are a zero on the left. You does not know anything and still has the poker face to say that the others are wrong.

Before I forget, you are a brat, not a man. What you write it's like a dog barking for me. If you still messing up with my posts I will call a forum moderator and ask him to suspend your account at this Forum!

With your last posts you just proved to all members of this forum what I've being saying: that you are really a rude person and a perfect asshole!


[Edited on 9-11-2018 by Chemi Pharma]

stoichiometric_steve - 9-11-2018 at 13:42

Quote: Originally posted by clearly_not_atara  

Eh, why the hell not. The following work belongs to someone else, who probably prefers not to be named:

"With vigorous stirring, to 5ml of IPA / 1g of P2NP


A ha! Now we're getting somewhere. It is an undisputed fact that phenylnitropropenes are quite easy to reduce using such methods, but this threads topic specifically relates to 2-nitrovinylbenzenes, which are quite a different story.

Most people with proper knowledge of this class of compounds should probably be aware that the double bond reduction of phenylnitropropenes has been extensively discussed and for instance, a method using NaBH4 along with a phase transfer catalyst like Trioctylmethylammonium chloride can provide fairly high yields of the corresponding phenylnitropropanes.

That is one of the very, very few methods that Barium can get credit for bringing attention to that actually works, and beautifully so.

On the other hand, despite my efforts to dig up a similarly high yielding and yet procedurally easy method applying to nitrovinylbenzenes, i've been shit outta luck so far.

I was thinking that maybe some sort of flow chemistry setup with a bed of silica gel, providing the needed weak acidity to inhibit formation of intermediate-substrate dimers, where separate solutions of aqueous borohydride and an organic solution of the nitroalkene substrate and a phase transfer catalyst are contacted in a static mixer just before hitting the solid bed.

Now obviously this creates another set of obstacles like diverging affinity of the reagents used to the silica gel bed, producing chromatography-like differences in elution, but that should be quite possible to solve.

Anybody else here with a soft spot for flow chemistry?

Quote: Originally posted by Chemi Pharma  
you're an arrogant bastard who wants to get the last word on everything.


You, sir, need to calm the fuck down and stop accusing people of what you're actually doing yourself. Cut the red hot latino cojones crap and focus on science, if there really and actually is anything that you can contribute. That would be beautiful.

Like i said, your Nickel-whatever stuff does not apply to 2-nitrovinylbenzenes and all the things you posted refs to do not change that one bit.

[Edited on 9-11-2018 by stoichiometric_steve]

clearly_not_atara - 9-11-2018 at 14:11

Quote:
It is not possible to reduce a double bond of an aliphatic chain without reducing it's carbonyl group attached, like with the compound @Loptr had indicated.

https://pubs.acs.org/doi/abs/10.1021/ja00209a048?journalCode...
It's amazing that you're still unable to admit you're so obviously wrong about this simple question. Stop writing poorly-formatted rants and learn to Google.

Quote:
On the other hand, despite my efforts to dig up a similarly high yielding and yet procedurally easy method applying to nitrovinylbenzenes, i've been shit outta luck so far.

You've got me there. I hadn't bothered to check but everyone is just using this for P2NP. Most people use dissolving iron or zinc for nitrostyrenes. Actually several people reported failures with borohydride/CuCl2 for nitrostyrenes (d'oh!).

However, the thread linked above by laserlisa seems to indicate success at least with 4-trifluoromethyl-2,5-dimethoxynitrostyrene (although only 71% yield under ideal conditions).

Nitrostyrenes are reduced to aldoximes in >90% yield by electroreduction at about 0.15 volts (Wessling et al 1991, attached). I'm not sure what the highest-yielding reduction of the aldoxime would be, but the method seems very promising. Further electroreduction generates amines in ~60% yield which is comparable to the Leminger. But speculation regarding oxime reduction is clearly outside the scope of this thread.

Attachment: wessling1991.pdf (419kB)
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stoichiometric_steve - 9-11-2018 at 14:39

Quote: Originally posted by clearly_not_atara  
However, the thread linked above by laserlisa seems to indicate success

Which is not actually surprising if you consider the rather extreme measure of using an almost eightfold equivalent of BH4- which prevents some, but still not all of the dimerization side reaction, otherwise yields would have been quite stellar.

Admittedly, some of that excess BH4- goes on to reduce the Nitro group, so i guess we'll pop some bottles now?

stoichiometric_steve - 9-11-2018 at 15:17

Quote: Originally posted by stoichiometric_steve  

I was thinking that maybe some sort of flow chemistry setup with a bed of silica gel


Scratch that. A bed of BH4- on some support, either resin or inert filler would probably be best.

For 29 years, it has been hiding in plain sight. Sigh...

Now it should only be a few final steps, imagine the possibilities!

stoichiometric_steve - 9-11-2018 at 23:33

Quote: Originally posted by Chemi Pharma  

I will call a forum moderator and ask him to suspend your account at this Forum


You have now clearly proven to everyone that you desperately need a time out.

I hereby request the mods to consider revoking your posting rights for an appropriate amount of time. And since you also admit to insulting other members via U2U, those rights should be suspended as well.

laserlisa - 10-11-2018 at 02:19

Quote: Originally posted by clearly_not_atara  
...

However, the thread linked above by laserlisa seems to indicate success at least with 4-trifluoromethyl-2,5-dimethoxynitrostyrene (although only 71% yield under ideal conditions).

...


The thesis includes a few more substrates. I would be interesting to see if people can reproduce these results. Perhaps the conditions can be tweaked to improve the yields further.



[Edited on 10-11-2018 by laserlisa]

stoichiometric_steve - 1-12-2019 at 03:13

Since i've played around quite a bit with biphasic PTC reductions, e.g. toluene/water/Aliquat 336, i'd like to see if this concept can be extended to incorporate the Cu(2+) reduction step in a one-pot reaction.

The PTC/NaBH4 reduction works exceptionally well for phenyl-2-nitropropenes to phenyl-2-nitropropanes, with yields in the high 80s to 90s, but i've yet to try it out with phenyl-2-nitroethenes.

The latter substrates always carry the risk of dimerization, and that wouldn't change when working with this biphasic system, since the substrate is added as a solution in toluene and the PTC might just carry the increasing amounts of negatively charged phenyl-2-nitropropane-BH4(-) adduct to the toluene phase with the substrate instead of the decreasing amounts of BH4-.

That's where flow chemistry would come in handy - all it would take (lol) is determining the optimal amounts of each reagent injected together in a static mixer of sufficient length, then inject the effluent into a second static mixer together with an aqueous solution of Cu(2+). Inject that effluent in a third static mixer along with some acid, and drip-drip-drip, got your amine salt in the aqueous phase and unreacted organics in the toluene phase.