Author Topic: Reductions...  (Read 3639 times)

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spectralmagic

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Reductions...
« on: September 11, 2002, 10:09:00 AM »
I haven't strayed too far from the Couch for several months so I'm a little out of practice...  SWISM has a question I can't answer.

If a synthesis calls for NaBH4, could another reduction scheme, such as Al/Hg, be used instead?  In SWISM's dreams lower yields are not a nightmare...  but if it isn't possible at all, he might bite the bullet and dream of obtaining NaBH4...  in this particular case he's dreaming of reducing a ketone to an alcohol, in an OTC manner.

TFSE suggests that it might be possible...  lots of examples of NaBH4 being used instead of Al/Hg, but nothing that I could find going the other way.

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foxy2

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You better bee specific.
« Reply #1 on: September 11, 2002, 12:54:00 PM »
You better bee specific.

I think LiAlH4 will usually work in place of NaBH4  ;)

Read and Listen!!! 

http://www.zmag.org/chomsky/index.cfm


spectralmagic

  • Guest
LAH, eh? Right, I'm sure SWISM will jump all over ...
« Reply #2 on: September 11, 2002, 08:33:00 PM »
LAH, eh?  Right, I'm sure SWISM will jump all over that one  ::)

To bee specific, he's wondering about reducing cathinone to PPA.

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Kinetic

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PPA to amphetamine?
« Reply #3 on: September 11, 2002, 09:14:00 PM »
So is this PPA going to then be reduced to amphetamine? SWIK is also interested in a very similar idea if so (see

Post 355271

(Kinetic: "How does this sound?", Novel Discourse)
), and was hoping the usual iodine/red phosphorus reduction would do the trick from cathinone straight to amphetamine. I can't see any reason why not, since a ketone is much easier to reduce than an alcohol, and iodine/RP (or is it HI/RP?) is a powerful reducing agent.

Sorry if this is not the intention you had in mind for your PPA, but I can't think of much else that can be done with it, unless you have a blocked nose maybe... :)

spectralmagic

  • Guest
PPA is fairly useful
« Reply #4 on: September 11, 2002, 10:31:00 PM »
PPA is a direct precursor to 4-methylaminorex (U4Euh), but I'm sure that's not what SWISM has in mind...

So, reducing PPA further yields amphetamine... that would not make SWISM happy...  I wonder how easily that happens... now, if ketones reduce easily, and alcohols do not, I suppose a decent yield can be achieved through timing and/or choice of reducing agent.  Hence the original question...  my gut tells me SWISM is going to think about Al/Hg anyway in his dreams.

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hest

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Kinetic, dont think so. In the red off eph.
« Reply #5 on: September 11, 2002, 11:11:00 PM »
Kinetic, dont think so. In the red off eph. with I2 you make an substitution(sn1/sn2) of the alcohol to the iodide and then reduce the iodide(werry easye). You can't sub. the ketone with iodine.

Kinetic

  • Guest
Thankyou
« Reply #6 on: September 11, 2002, 11:48:00 PM »
hest, you saved me a lot of time and money trying! I posted this as a suggestion because I wanted to try it and hoped it would work, but wanted input from other bees more knowledgeable than I (most of you then :-[ ) as to whether it would work before I did so. Thankyou!

spectralmagic

  • Guest
Re: reducing PPA further yields amphetamine Hold ...
« Reply #7 on: September 12, 2002, 01:51:00 AM »

reducing PPA further yields amphetamine



Hold on a minute, that can't be right.

Amphetamine is based around phenyl-2-propanone, PPA is based around phenyl-1-propanone (well, propanol perhaps), or am I missing something?  Grrr... maybe SWISM should just dream about it and see where it goes...


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PrimoPyro

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It is right
« Reply #8 on: September 12, 2002, 02:11:00 AM »
Neither are based around either except in your mind. We make the associations, the chemistry couldn't care less what X is related to what Y or Z, etc.

Reducing PPA's hydroxyl does indeed yield amphetamine. You can make amphetamine from P2P as well, but the processes are completely different. I think you should look at the structures of these three chemicals and you will understand.

PrimoPyro

Will perform sexual favors for females in exchange for 1,2-dimethylaziridine. PM for details.

spectralmagic

  • Guest
[Homer]Doh![/Homer]
« Reply #9 on: September 12, 2002, 06:16:00 AM »
[Homer]Doh![/Homer]

Yes, I see it now.  Scratch the previous post.  But still no definitive answer on the substitution...  I guess he'll find out himself.

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spectralmagic

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OK, after some research, how about this: Reduce ...
« Reply #10 on: September 18, 2002, 08:31:00 AM »
OK, after some research, how about this:

Reduce phenyl-2-nitropropanol to phenylpropanolamine using Urushibara (sp?) nickel?

And does anyone know how much nickel is actually in nickels (the currency), particularly in Canada?  I'm currently dissolving some nickels in HCl, the solution seems to be turning the right colour... 

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Organikum

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Nickel catalyst needs some pressure...
« Reply #11 on: September 18, 2002, 08:54:00 AM »

Nickel catalyst needs some pressure...

Starts at +60bar and up to +250bar and more. I read that it might be possible to do these reactions on a very small scale at atmospheric pressure by using a very huge amount of catalyst, but if somebody did do it is unknown to me.

Sorry for the bad news.
There have been rumors about urushibara Ni working in CTH/microwave setups. But nothing I would bet on.

ORGY

~ Love is the law, love under will. ~

spectralmagic

  • Guest
Perhaps pressure is not an issue?
« Reply #12 on: September 18, 2002, 09:24:00 AM »
Well, I got the idea from

https://www.thevespiary.org/rhodium/Rhodium/chemistry/amph.urushibara.html

, seemed like a nice OTC way of going about what I want (the goal is a theoretical path from toluene to 4-MAR completely OTC, lots of labour involved though).

An observation on the nickels: Canadian nickels from 1994 and prior are reacting with the HCl nicely, the 2001 I threw in there is barely even touched - either they changed the type of metal in use, or there's some sort of coating that hasn't rubbed off yet.  I didn't have any nickels from 1995-2000, or 2002, so can't comment on them.

Edit: Further examination reveals that the 2001 nickel responds strongly to a magnet, whereas the others respond very weakly if at all (placed the beaker on a magnetic stirrer, the only nickel to jump around was the 2001).  Clipping a piece off of the 2001 reveals what looks like a copper core, the a 1994 is uniform throughout.

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cilliersb

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NaBH4/AL/Hg
« Reply #13 on: September 18, 2002, 10:27:00 AM »
Swim ran NaBH4/AL/Hg on the weekend on 2,5-DMP2NP.

The reaction (unlike some warnings on Rhod's page) with NaBH4 ran fine in MeOH (anhydrous!!) (I also thought this was odd as MeOH is meant to be to reactive toward NaBH4.) 5g 2,5-DMP2NP was added to Methanol 250ml (the reaction mixture became very light yellow color within 15 mins of adding 2g NaBH4 (mag stirring on fast!). Some HCl 30ml and HgCl2 200mg was added after around 40 mins followed by shredded Al 10.5g. The temp rose for a while to around 50C and slowly returned to around 35C where it sat for hours. I put the hotplate on very low (40C)

Stirred at 40C over night (16H). Not all the Al reacted!! Solution was basified, vac filtered and extracted with Toluene 150ml, 100ml, 80ml. The toluene was vac distilled off at 37-40C. After this the dist setup was allowed to reach 60C before distillation was discontinued which left swim with around 2.5ml of a light yellow oil. To this was added 5ml AcOH followed by 2.5g Br2 in 5ml AcOH. My 2C-B.HBr is busy cryst. and so far looks around 1.5g.

This synth is easy and cheap as hell. I will post my final yeild ASAP. At least we know this works bees!! The original writeup can be found at Rhod's page.

Personally I feel that this synth can be done a hell of a lot better than swim did it as my lab technique sucks to say the least.

The only thing that went down strange here is that the 2C-B took 24 hours to start cryst. out of the AcOH/Br2 sol. Every mornings there are more and larger crystals. This doesn't seem to always happen as quickly as it has before. Maybe my 2C-H base was still quite dirty, who knows.

Barium

  • Guest
Hmm!
« Reply #14 on: September 18, 2002, 11:30:00 AM »
You said that you started with 2,5-DMP2NP (I assume you mean 1-[2,5-dimethoxyphenyl]-2-nitropropene). Then you said you in the end made 2C-B. This means you started with 1-(2,5-dimethoxyphenyl)-2-nitroethene. There is a huge diffrence in how the nitropropene and the nitroethene behave when reduced by NaBH4 in MeOH. Beaker and myself have never said it is impossible to reduce the nitroethene in MeOH with NaBH4, just that the yields really sucks. Therefore we gave you the methods to get the good yields.

cilliersb

  • Guest
Sorry for the typo!!
« Reply #15 on: September 18, 2002, 01:00:00 PM »
You're right Barium.

I reduced the Nitrostyrene not the Nitropropene. It is 2C-B and not DOB I'm talking about. Yeilds are not great as you stated as well. I merely posted this to confirm the functionality of that synth as stated on Rhodium's page.

I tried an LAH reduction once before and screwed it up properly with my super wet THF. Swim will post yields for this in a week or so and also of my current project which reduces the nitrostyrene with Red-AL.

Just trying to be of help to bees wondering about the validity of things they read. Sorry, I did not mean to mislead anyone. :-[

Barium

  • Guest
Hmm again!
« Reply #16 on: September 18, 2002, 01:48:00 PM »
I saw that you didn´t perform an acid wash of the amine after you was done with the Al/Hg reduction. This means that god-knows-what might be in there, especially since you added the bromine directly to the isolated unwashed product. If I were you I would definetly distill the 2C-B freebase. I can guarantee you that the reason for the slow crystallisation is because the product is immensly dirty. I wouldn´t taste it for my life!

Rhodium

  • Guest
Good 2C-H bromination writeup: ...
« Reply #17 on: September 18, 2002, 01:55:00 PM »
Good 2C-H bromination writeup:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/2cb.bromination.html



Only apply to vacuum distilled 2C-H freebase!

cilliersb

  • Guest
Right again
« Reply #18 on: September 18, 2002, 02:13:00 PM »
Yip, sooo Right dude!

Swim was thinking of washing 2C-B freebase while converting to 2C-B.HCl

Basify, solvent extract, wash, wash, wash, crystallize. Hope this will clean up enough.

Antoncho

  • Guest
a QUESTION...
« Reply #19 on: September 18, 2002, 07:18:00 PM »
Dear Rhodi!

Pray, tell!

Why it is always distilled 2C-H freebase that is used in bromination?

What will happen with the non-distilled base?

Is there any other suitable substitute (e.g., steam-distillation) for it?





Antoncho

Rhodium

  • Guest
The reduction of 2C-B is generally very ...
« Reply #20 on: September 18, 2002, 08:39:00 PM »
The reduction of 2C-B is generally very low-yielding, due to dimer formation and other side-reactions. Without distillation you have no idea how much 2C-H you have in the oil you want to brominate. And purification after the bromination is even more tedious than doing it before (as well as the usual lowered yield), and you have to purify it by distillation (or possible column chromatography) at SOME point in the process, or you will never get a pure product.

Tricky

  • Guest
Why, why, why?!
« Reply #21 on: September 18, 2002, 09:00:00 PM »
Question about distillation is alarmin' me too.
Is it possible to treat w/o it?
Here

https://www.thevespiary.org/rhodium/Rhodium/chemistry/2cb-lah.html

is write-up of purification w/o distilling, as far as I unerstand. Realy it's wrong?  :(

Quote: "Then 20ml 4N NaOH was added slowly. Each portion was allowed to react before the next was added. 60ml water was added and the reaction mixture stirred for an hour or so until it was almost white and granular. The mixture was filtered through a porcelain filter and the filter cake was extracted twice with 50 ml portions of THF in a separate beaker. The organic solvents was combined and evaporated under vacuum. The residue was dissolved in water/HCl (pH=1). The aqueous phase was washed with 3x50 ml CH2Cl2. The organic phase was re-extracted with 50ml HCl/water. Then the combined aqueous phase was made basic with NaOH (pH=14) and extracted with 4x50ml CH2Cl2. The organic phase was dried with K2CO3 and evaporated. The residue (2C-H) was only slightly colored and weighed 16.98g (75%).

A bit more cost effective then earlier methods using LAH I dare say!

According to the original JMC article it is also possible to directly dry the THF solution after filtering off the inorganic lithium/aluminum salts, evaporate the solvent and distill directly to get the freebase. About the same amount of work, and you'll get an even cleaner product."
Pliz calm me. It's very urgent problem to me just now. And I hate vacuum distilling.

Wanna make laugh the GOD? - Tell him about your plans.

Rhodium

  • Guest
Personally, I think that either the 2C-H freebase ...
« Reply #22 on: September 18, 2002, 09:34:00 PM »
Personally, I think that either the 2C-H freebase should be distilled at that point, or the freebase 2C-B should be after the bromination. If you would do a TLC of that 2C-H, I don't think it would show a single spot, rather 3:1 2C-H/dimer or something. I'd be very glad if you could prove me wrong here.

You won't die off from impure 2C-B, but I don't understand people going through a whole synthesis like that, and then skimp on the purification, ingesting a tan product of unknown purity - you will never know what the compound really should be like if you would have made it properly. And giving an impure product to other people, that is outright nasty.

Tricky

  • Guest
Thanx
« Reply #23 on: September 18, 2002, 09:50:00 PM »
Thanx for advise, Rhod, I don't skimp on the purification, but vacuum distilling is really serious problem for me, so thought that simply acid/base/DCM purification of 2CH will give me product with valid purify to other synthetic steps and finally 2CB will not be very revolting... 

Wanna make laugh the GOD? - Tell him about your plans.

Rhodium

  • Guest
Make the HBr salt, it can at least be ...
« Reply #24 on: September 18, 2002, 09:55:00 PM »
Make the HBr salt, it can at least be recrystallized to aid in your vacuum distillation-free purification.

Tricky

  • Guest
Thanx one more.
« Reply #25 on: September 18, 2002, 10:02:00 PM »
Subj.  :)

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scram

  • Guest
Lith Al Hyd in situ Al for al/hg
« Reply #26 on: September 19, 2002, 12:35:00 AM »
"I think LiAlH4 will usually work in place of NaBH4"

What would be the molar amounts of LiAlH4 to Ketone in place of Al? Does MeOH pose any oxidizing threat to this reducing agent?

Osmium

  • Guest
> Does MeOH pose any oxidizing threat to this ...
« Reply #27 on: September 19, 2002, 12:42:00 AM »
> Does MeOH pose any oxidizing threat to this reducing agent?

Yes, that's another way to express it  ;D

LAH + MeOH = Boom!


I'm not fat just horizontally disproportionate.

spectralmagic

  • Guest
Where, oh where has my little thread gone?
« Reply #28 on: September 19, 2002, 04:40:00 AM »
As fascinating as all this has been...  I'm still confused about the P2NPol -> PPA thing...  will I get amphetamine instead, or does that outcome not pose a risk with the reducing agents I've mentioned?

I tells ya, it's enough to drive one mad!

Perhaps in a few weeks I'll report on SWISM's results using various methods...  he doesn't have the theory (or knowledge of first principles) to work from, so all he's got is brute force (try, try again).  So, brute force it is then!

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