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All 21 posts Subject: 3,4,5-TMBA to TMA or M question Please login to post Down

Blind_Angel
(Hive Bee)
08-07-04 21:10
No 524126
User Picture       3,4,5-TMBA to TMA or M question

Swim just fell of a cliff a found a bit of 3,4,5-TMBA near a tree, so he wondered how could it be reduced to a safest chemical (3,4,5-TMBA is very unstable, it has the habit to degrade rapidly wink ). After a quick UTFSE he found that a good way would be to reduce it to the nitrostyrene using MeNO2/EtNO2 "а la Shulgin" (with cyclohexamine and GAA) then reduce it with NaBH4, using Post 465461 (Bandil: "Proof of concept!", Novel Discourse) as reference. Swim question would be: is the formic acid really necessary or can it be replace with GAA, which is already owned by the guy?
Also any comment on this method would be interesting.

/}/_//\//) /-|/\//¬/=/_

Rhodium
(Chief Bee)
08-08-04 01:44
No 524191
User Picture       The formic acid is acting as a reducing agent...

The formic acid is acting as a reducing agent together with the Zinc, so that would not be a good idea.

^{The Hive - Clandestine Chemists Without Borders}

Vaaguh
(Hive Bee)
08-08-04 13:59
No 524248
User Picture       reduction

For reducing 3,4,5-trimethoxy-beta-nitrostyrene with NaBH4 it is advised to use a 4 molar equivalent of NaBH4, using less will often result in a lot of dimer byproducts.

The Zinc/Formic acid method seems to give very poor yields for reducing the nitro group of 3,4,5-trimethoxy-2-nitroethene.

Reducing 3,4,5-trimethoxy-2-nitroethene with Pd/C gives good yields.

Hippler

Blind_Angel
(Hive Bee)
08-08-04 17:36
No 524267
User Picture       Nice, i found Post 499607 I'll ask for Pd/C if

Nice, i found Post 499607 (armageddon: "different routes starting from nitropropenes", Methods Discourse)
I'll ask for Pd/C if none available i'll use Zn
By reading Post 382254 (Barium: "A great CTH method", Novel Discourse), i've wondered if the IPA (or alcohol used) need to be anhydrous?

/}/_//\//) /-|/\//¬/=/_

armageddon
(Hive Bee)
08-08-04 18:47
No 524280
User Picture       LAH

As trimethoxy compounds are a bit sensitive and therefore somewhat tricky to handle, you could perhaps try to get hold of some LiAlH₄ (LAH) - it is capable of reducing nitrostyrenes to their corresponding amines directly - less steps to perform, meaning less product loss on the way...

(but LAH reduction requires *thoroughly* dried THF as solvent, water causes a violent runaway reaction... wink )

If you can get LAH, I would suggest you use that to "protect" your 3,4,5-TMBA! laugh

Greetz A

Pleased to meet you hope you get my name.
But whats puzzlin you is the nature of my game!

SpicyBrown
(Hive Bee)
08-09-04 16:01
No 524443
      Recently, an experiment was conducted in which

Recently, an experiment was conducted in which ~4.2g of 3,4,5-TMBA was reduced to M in ~47% yield using Al/Hg following the method reported in this document. (https://www.rhodium.ws/chemistry/nitrostyrene.reduction.alhg.html)

-SpicyBrown

moo
(Hive Addict)
08-09-04 16:46
No 524446
      Is that the yield for the reduction of the...

Is that the yield for the reduction of the nitrostyrene or the overall yield starting from the benzaldehyde? If the latter, could you please tell the yields for the two steps?

_{fear fear hate hate}

L42L
(Newbee)
08-09-04 21:02
No 524471
      yes yes, kiss and tell

and what nitration conditions (amine cat.?)
all the details please (time yeild TLC?)
thank you

SpicyBrown
(Hive Bee)
08-10-04 02:35
No 524534
      Re: Is that the yield for the reduction of the

Is that the yield for the reduction of the nitrostyrene or the overall yield starting from the benzaldehyde? If the latter, could you please tell the yields for the two steps?

Ahh, that's only the yield for the reduction. The nitrostyrene was made by treating a solution of 3,4,5-TMBA and nitromethane with methanolic KOH at a low temperature, then treating with acid to accomplish the dehydration. The yield was never calculated, but it SUCKED. It's believed a botched recrystalization attempt actually destroyed some of the material: initially, a nice yellow clumpy solid was obtained from the condensation. This was "dissolved" in boiling isopropyl alcohol. What really seemed to happen was the nitrostyrene oiled out during this process, and formed a separate layer which slowly turned red. This pissed off the chemist royally. Eventually the oil formed a solid which was recrystalized twice more, this time from boiling methanol which worked much better. The final nitrostyrene was around 4.2 grams, from a starting 15 grams of the 3,4,5-TMBA. The final material formed nice platelett-like crystals, but was always a slightly darker color than would be expected. This suggests some remaining impurity, and that the reduction yields might be boostable with more pure material.

Next time, the nitrostyrene will be made with n-butylamine as the catalyst, just because the chemist likes n-butylamine. It was considered sort of ironic that the "easy" part of the synthesis in this case was the reduction and not the condensation..

-SpicyBrown

hest
(Hive Adickt)
08-10-04 08:01
No 524592
      Read this

Post 419399 (Barium: "High-yielding nitrostyrene catalyst", Methods Discourse)

armageddon
(Hive Bee)
08-10-04 20:15
No 524668
User Picture       or this..

Post 523841 (psyloxy: "nBuNH2 in Henry rxn on 25DMB / 345TMB - 1h, 84-88%", Chemistry Discourse)

(slightly lower yields, but FAST!)

Greetz, A

Pleased to meet you hope you get my name.
But whats puzzlin you is the nature of my game!

L42L
(Newbee)
08-11-04 20:51
No 524886
      yea but, read this

but further down in the same thread (barium's):

"
Sunlight
(Pioneer Researcher)
07-08-03 18:40
No 445732
   Test with 3,4,5 TMB failure   Bookmark Reply

Acording with Barium's instructions, 5 gr of 3,4,5 TMB was mixed with repective amounts of aqueous methylamine and nitromethane in 20 ml of methanol, and it was kept at 50 C for 1 hour. Then it was put in the freezer, and filtered. The filtrate was a yellow and amorphous solid, and a TLC showed three spots, one on the bottom line, other in the place of the aldehyde an the third one in the place ot the nitrostyrene.
I tried to recrystallize a sample of 1.9 grams in ethanol. It was posted a reference it the Hive in wich this recrystallization was done using 7:1 of ethanol, but this substance refused to dissolve even in 18:1 boiling ethanol. I filtered it immediatly and recovered about 1.2 grams of the product, a sample of that couldn't be dissolved even in a large excess of boiling acetone, while a sample of the nitrostyrene made with Shulgin's procedure (one spot TLC) was easily dissolved in a bit of acetone at room temperature. The procedure yield a mixture in wich the main part corresponds to this not soluble product, that appears in the bottom line in the TLC because it is in suspension. I got the same product when I tried to make 3,4,5 TMNS with cyclohexylamine in methanol at room temp as I've said before, then I was confused thinking it was the styrene, because it has a yellowish aspect.
So I don't recommend this method if you want to get this particular nitrostyrene. It probably will work fine with some aldehydes, but others will produce byproducts, as in this case and in the others tested in the paper in Rhodium's page. (Link above).
I guess Barium didn't verified that the product he got in his test was the desired product.

By the way, I guess there is a typo in PIHKAL in the entry of mescaline, the nitrostyrene is recrystallized using 15 ml/g but in fact 5 ml it's enough, I've done it. There's another one in the dose, the amount of the sulfate and the hydrochloride doesn't match.
"

still looking for the most promising 3,4,5 cat.!

SpicyBrown
(Hive Bee)
08-12-04 01:33
No 524940
      Well the NaOH/HCl method in Post 505399 does...

Well the NaOH/HCl method in Post 505399 (imp: "Just do it this way!!", Newbee Forum) does work, it's just absolutely imperative that you keep it cold and stirring quite vigorously. If it's not kept cold enough, you'll get a shitty tar and a bad yield of impure material. I had problems keeping it cold enough with a normal water ice bath, if you could rig your stirrer in the freezer however... Hell, just use a dry ice/CH₃CN and it'll probably work great.

-SpicyBrown

hest
(Hive Adickt)
08-12-04 05:42
No 524979
      KOH

In the same Post 516547 (KidCurry: "Crappy yield", Newbee Forum) from the Post 505324 (KidCurry: "3,4,5-TMBA -> 3,4,5-TMNS", Newbee Forum)KidCurry claims 30-40% yeald with this KOH method (21 gstyrene from 50g aldehyde)

KidCurry
(Hive Bee)
08-12-04 10:04
No 525032
      SWIM has verified the method again, with ...

SWIM has verified the method again, with better cooling (could be even better though), and yield was much better (19g from 25g aldehyde. As SpicyBrown sais, keeping it cold is the key to getting good yields. Also hard stirring during the dehydration step is absolutely necessary, go for a overhead stirrer as a normal stirrer plate is too weak.

If you want a simple and completely OTC method of reducing the nitrostyrene, go for the Zn/HCl method as described here: https://www.rhodium.ws/chemistry/leminger.html

Gives yields around 50%, and is very simple (altough a bit tedious and takes a while).

jorypl
(Stranger)
08-21-04 18:17
No 526610
      345TMNS is needles?, and other M synth. questions

SWIM make 345TMNS and this is pale yellow needles, not plates. its ok ? (make with NH4Ac/nitromethane/AcOH 3h reflux).

when SWIM make 345TMBA from syringaldehyde (Na2CO3, syring, DMS all in DMF - 2h stirring in room temp. like hest) he get only 40% yields (white powder, m.p. <<100C). Whats wrong ?
And last - when SWIM make syringaldehyde (sodium methanolate, CuCl, DMF, 3h reflux) he get brownish mixture and afetr add some HCl it create brownish percipate (maybe it is Cu?) and yield is 40%.... why it reduce CuCl to Cu(0) ? Maybe in methanol is too much water and SWIM must destilate it ?

AND very last ;-). When SWIM make amine by AlHg reduction he get yellow IPA solution, and afet addition some HCl it changes to red (most red colour go to DCM after extraction). Why? What is wrong ?

Sorry but I never talk in english and this is my first post here. Best regards :)

armageddon
(Hive Bee)
08-22-04 04:25
No 526725
User Picture       red=ketone

The red color is unreacted ketone that becomes fucked up by the acid. But if you do a DCM wash, the unreacted ketone is removed - so it is no problem, at least if you remove every red color before basifying.

At least if your Al/Hg was done on a ketone...

A

Pleased to meet you hope you get my name.
But whats puzzlin you is the nature of my game!

hypo
(Quasiquerumodo)
08-22-04 15:16
No 526775
      FTIR-eyes?

> The red color is unreacted ketone that becomes fucked up by the acid.

do you have analytic equipment or are you guessing?
how do you explain the fact that lots of the red crap goes through A/B?

He always lied while on the earth and now he's lying in it

jorypl
(Stranger)
08-22-04 15:17
No 526776
      thanks

maybe in kitchen foil is some Fe (who reduce nitrostyrene to ketone), maybe...

I washed acidify solution twice with DCM, next add some NaOH and extracted with DCM. When I slowly add H2SO4 to twis solution it slowly create red colour. After evaporate DCM I get reddish tar.

And when I try bubble it with HCl(g) (from CaCl2+HCl) nothing is creating :(.

thanks for reply :)

armageddon
(Hive Bee)
08-22-04 23:49
No 526841
User Picture       pure experience

Neither guessing nor having access to advanced analytical methods - just plain knowledge about arylketones becoming pink/red upon treatment with strong mineral acids and further having the tendency to polymerize when treated with strong alkalimetal hydroxides.

And this especially the case with (substituted) phenylacetones and H2SO4 (or HCl). Ever steam distilled any phenylacetone from acidic solutions? Or vacuum distilled such a ketone over solid NaOH? Then you would know what I mean.

Of course it could always still be something else!

- but as old organic chemistry textbooks state that said ketones can cause this kind of color under said circumstances, I simply thought this could one possible reason for the coloration and decided "throw in all info you have".

Will you again start throwing with dirt because I did so, hypo? smile

But anyway, your red stuff indeed doesn't behave like ketone - and if the talked about rxn was a direct nitrostyrene reduction, I doubt that there would be still any ketone present after 2 DCM washes - the amount should be very small if any and DCM is quite effective in removing this kind of gunk...

Did I get this right: we talk about a nitrostyrene red.amination with Al/Hg on 3,4,5-TriMeO-NS? Maybe you should try to acidify with dilute HCl *very* carefully, as unreacted nitrostyrene tends to polymerize even quicker than ketones. Or perhaps you should consider other reduction methods, or at least try a different workup!? Maybe do several hydrogencarbonate/bicarb/brine/whatever washes before attempting to acidify it would help (just an idea)?

Because your main problem seems to be getting your product free from side products causing this nasty tar...

Greetz, A

Pleased to meet you hope you get my name.
But whats puzzlin you is the nature of my game!

SpicyBrown
(Hive Bee)
08-23-04 05:56
No 526913
      Ahh yes, the DCM washes.

It's technically just a reduction, not a reductive amination, since the nitrogen is already present in the nitrostyrene as a nitro group.

I've seen this red stuff as well, and it's always boggled me. I've done this Al/Hg reduction on several substrates now, and always do the CH₂Cl₂ wash immediately after the acidification. Different substrates have yielded different colors... When reducing 3,4,5-TMNS, the CH₂Cl₂ layer was very light red. After sitting overnight however, it became very dark red, to the point that you could no longer see through it. I've always wondered just what's in that CH₂Cl₂ layer and what's happening to it over time.

When reducing 2,5-dimethoxy phenyl-2-nitrropropene, the post-acidification CH₂Cl₂ wash yielded a yellow/orange solution. After sitting overnight it turned olive green. I'm mystified, and just consider it a good thing CH₂Cl₂ is so effective at washing out whatever those byproducts are.

-SpicyBrown

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	All 21 posts		Subject: 3,4,5-TMBA to TMA or M question		Please login to post		Down


		Blind_Angel (Hive Bee) 08-07-04 21:10 No 524126				3,4,5-TMBA to TMA or M question
						Swim just fell of a cliff a found a bit of 3,4,5-TMBA near a tree, so he wondered how could it be reduced to a safest chemical (3,4,5-TMBA is very unstable, it has the habit to degrade rapidly ). After a quick UTFSE he found that a good way would be to reduce it to the nitrostyrene using MeNO2/EtNO2 "а la Shulgin" (with cyclohexamine and GAA) then reduce it with NaBH4, using Post 465461 (Bandil: "Proof of concept!", Novel Discourse) as reference. Swim question would be: is the formic acid really necessary or can it be replace with GAA, which is already owned by the guy? Also any comment on this method would be interesting. /}/_//\//) /-\|/\//¬/=/_



		Rhodium (Chief Bee) 08-08-04 01:44 No 524191				The formic acid is acting as a reducing agent...
						The formic acid is acting as a reducing agent together with the Zinc, so that would not be a good idea. ^{The Hive - Clandestine Chemists Without Borders}



		Vaaguh (Hive Bee) 08-08-04 13:59 No 524248				reduction
						For reducing 3,4,5-trimethoxy-beta-nitrostyrene with NaBH4 it is advised to use a 4 molar equivalent of NaBH4, using less will often result in a lot of dimer byproducts. The Zinc/Formic acid method seems to give very poor yields for reducing the nitro group of 3,4,5-trimethoxy-2-nitroethene. Reducing 3,4,5-trimethoxy-2-nitroethene with Pd/C gives good yields. Hippler



		Blind_Angel (Hive Bee) 08-08-04 17:36 No 524267				Nice, i found Post 499607 I'll ask for Pd/C if
						Nice, i found Post 499607 (armageddon: "different routes starting from nitropropenes", Methods Discourse) I'll ask for Pd/C if none available i'll use Zn By reading Post 382254 (Barium: "A great CTH method", Novel Discourse), i've wondered if the IPA (or alcohol used) need to be anhydrous? /}/_//\//) /-\|/\//¬/=/_



		armageddon (Hive Bee) 08-08-04 18:47 No 524280				LAH
						As trimethoxy compounds are a bit sensitive and therefore somewhat tricky to handle, you could perhaps try to get hold of some LiAlH₄ (LAH) - it is capable of reducing nitrostyrenes to their corresponding amines directly - less steps to perform, meaning less product loss on the way... (but LAH reduction requires thoroughly dried THF as solvent, water causes a violent runaway reaction...) If you can get LAH, I would suggest you use that to "protect" your 3,4,5-TMBA! Greetz A Pleased to meet you hope you get my name. But whats puzzlin you is the nature of my game!



		SpicyBrown (Hive Bee) 08-09-04 16:01 No 524443				Recently, an experiment was conducted in which
						Recently, an experiment was conducted in which ~4.2g of 3,4,5-TMBA was reduced to M in ~47% yield using Al/Hg following the method reported in this document. (https://www.rhodium.ws/chemistry/nitrostyrene.reduction.alhg.html) -SpicyBrown



		moo (Hive Addict) 08-09-04 16:46 No 524446				Is that the yield for the reduction of the...
						Is that the yield for the reduction of the nitrostyrene or the overall yield starting from the benzaldehyde? If the latter, could you please tell the yields for the two steps? _{fear fear hate hate}



		L42L (Newbee) 08-09-04 21:02 No 524471				yes yes, kiss and tell
						and what nitration conditions (amine cat.?) all the details please (time yeild TLC?) thank you



		SpicyBrown (Hive Bee) 08-10-04 02:35 No 524534				Re: Is that the yield for the reduction of the
						Is that the yield for the reduction of the nitrostyrene or the overall yield starting from the benzaldehyde? If the latter, could you please tell the yields for the two steps? Ahh, that's only the yield for the reduction. The nitrostyrene was made by treating a solution of 3,4,5-TMBA and nitromethane with methanolic KOH at a low temperature, then treating with acid to accomplish the dehydration. The yield was never calculated, but it SUCKED. It's believed a botched recrystalization attempt actually destroyed some of the material: initially, a nice yellow clumpy solid was obtained from the condensation. This was "dissolved" in boiling isopropyl alcohol. What really seemed to happen was the nitrostyrene oiled out during this process, and formed a separate layer which slowly turned red. This pissed off the chemist royally. Eventually the oil formed a solid which was recrystalized twice more, this time from boiling methanol which worked much better. The final nitrostyrene was around 4.2 grams, from a starting 15 grams of the 3,4,5-TMBA. The final material formed nice platelett-like crystals, but was always a slightly darker color than would be expected. This suggests some remaining impurity, and that the reduction yields might be boostable with more pure material. Next time, the nitrostyrene will be made with n-butylamine as the catalyst, just because the chemist likes n-butylamine. It was considered sort of ironic that the "easy" part of the synthesis in this case was the reduction and not the condensation.. -SpicyBrown



		hest (Hive Adickt) 08-10-04 08:01 No 524592				Read this
						Post 419399 (Barium: "High-yielding nitrostyrene catalyst", Methods Discourse)



		armageddon (Hive Bee) 08-10-04 20:15 No 524668				or this..
						Post 523841 (psyloxy: "nBuNH2 in Henry rxn on 25DMB / 345TMB - 1h, 84-88%", Chemistry Discourse) (slightly lower yields, but FAST!) Greetz, A Pleased to meet you hope you get my name. But whats puzzlin you is the nature of my game!



		L42L (Newbee) 08-11-04 20:51 No 524886				yea but, read this
						but further down in the same thread (barium's): " Sunlight (Pioneer Researcher) 07-08-03 18:40 No 445732 Test with 3,4,5 TMB failure Bookmark Reply Acording with Barium's instructions, 5 gr of 3,4,5 TMB was mixed with repective amounts of aqueous methylamine and nitromethane in 20 ml of methanol, and it was kept at 50 C for 1 hour. Then it was put in the freezer, and filtered. The filtrate was a yellow and amorphous solid, and a TLC showed three spots, one on the bottom line, other in the place of the aldehyde an the third one in the place ot the nitrostyrene. I tried to recrystallize a sample of 1.9 grams in ethanol. It was posted a reference it the Hive in wich this recrystallization was done using 7:1 of ethanol, but this substance refused to dissolve even in 18:1 boiling ethanol. I filtered it immediatly and recovered about 1.2 grams of the product, a sample of that couldn't be dissolved even in a large excess of boiling acetone, while a sample of the nitrostyrene made with Shulgin's procedure (one spot TLC) was easily dissolved in a bit of acetone at room temperature. The procedure yield a mixture in wich the main part corresponds to this not soluble product, that appears in the bottom line in the TLC because it is in suspension. I got the same product when I tried to make 3,4,5 TMNS with cyclohexylamine in methanol at room temp as I've said before, then I was confused thinking it was the styrene, because it has a yellowish aspect. So I don't recommend this method if you want to get this particular nitrostyrene. It probably will work fine with some aldehydes, but others will produce byproducts, as in this case and in the others tested in the paper in Rhodium's page. (Link above). I guess Barium didn't verified that the product he got in his test was the desired product. By the way, I guess there is a typo in PIHKAL in the entry of mescaline, the nitrostyrene is recrystallized using 15 ml/g but in fact 5 ml it's enough, I've done it. There's another one in the dose, the amount of the sulfate and the hydrochloride doesn't match. " still looking for the most promising 3,4,5 cat.!



		SpicyBrown (Hive Bee) 08-12-04 01:33 No 524940				Well the NaOH/HCl method in Post 505399 does...
						Well the NaOH/HCl method in Post 505399 (imp: "Just do it this way!!", Newbee Forum) does work, it's just absolutely imperative that you keep it cold and stirring quite vigorously. If it's not kept cold enough, you'll get a shitty tar and a bad yield of impure material. I had problems keeping it cold enough with a normal water ice bath, if you could rig your stirrer in the freezer however... Hell, just use a dry ice/CH₃CN and it'll probably work great. -SpicyBrown



		hest (Hive Adickt) 08-12-04 05:42 No 524979				KOH
						In the same Post 516547 (KidCurry: "Crappy yield", Newbee Forum) from the Post 505324 (KidCurry: "3,4,5-TMBA -> 3,4,5-TMNS", Newbee Forum)KidCurry claims 30-40% yeald with this KOH method (21 gstyrene from 50g aldehyde)



		KidCurry (Hive Bee) 08-12-04 10:04 No 525032				SWIM has verified the method again, with ...
						SWIM has verified the method again, with better cooling (could be even better though), and yield was much better (19g from 25g aldehyde. As SpicyBrown sais, keeping it cold is the key to getting good yields. Also hard stirring during the dehydration step is absolutely necessary, go for a overhead stirrer as a normal stirrer plate is too weak. If you want a simple and completely OTC method of reducing the nitrostyrene, go for the Zn/HCl method as described here: https://www.rhodium.ws/chemistry/leminger.html Gives yields around 50%, and is very simple (altough a bit tedious and takes a while).



		jorypl (Stranger) 08-21-04 18:17 No 526610				345TMNS is needles?, and other M synth. questions
						SWIM make 345TMNS and this is pale yellow needles, not plates. its ok ? (make with NH4Ac/nitromethane/AcOH 3h reflux). when SWIM make 345TMBA from syringaldehyde (Na2CO3, syring, DMS all in DMF - 2h stirring in room temp. like hest) he get only 40% yields (white powder, m.p. <<100C). Whats wrong ? And last - when SWIM make syringaldehyde (sodium methanolate, CuCl, DMF, 3h reflux) he get brownish mixture and afetr add some HCl it create brownish percipate (maybe it is Cu?) and yield is 40%.... why it reduce CuCl to Cu(0) ? Maybe in methanol is too much water and SWIM must destilate it ? AND very last ;-). When SWIM make amine by AlHg reduction he get yellow IPA solution, and afet addition some HCl it changes to red (most red colour go to DCM after extraction). Why? What is wrong ? Sorry but I never talk in english and this is my first post here. Best regards :)



		armageddon (Hive Bee) 08-22-04 04:25 No 526725				red=ketone
						The red color is unreacted ketone that becomes fucked up by the acid. But if you do a DCM wash, the unreacted ketone is removed - so it is no problem, at least if you remove every red color before basifying. At least if your Al/Hg was done on a ketone... A Pleased to meet you hope you get my name. But whats puzzlin you is the nature of my game!



		hypo (Quasiquerumodo) 08-22-04 15:16 No 526775				FTIR-eyes?
						> The red color is unreacted ketone that becomes fucked up by the acid. do you have analytic equipment or are you guessing? how do you explain the fact that lots of the red crap goes through A/B? He always lied while on the earth and now he's lying in it



		jorypl (Stranger) 08-22-04 15:17 No 526776				thanks
						maybe in kitchen foil is some Fe (who reduce nitrostyrene to ketone), maybe... I washed acidify solution twice with DCM, next add some NaOH and extracted with DCM. When I slowly add H2SO4 to twis solution it slowly create red colour. After evaporate DCM I get reddish tar. And when I try bubble it with HCl(g) (from CaCl2+HCl) nothing is creating :(. thanks for reply :)



		armageddon (Hive Bee) 08-22-04 23:49 No 526841				pure experience
						Neither guessing nor having access to advanced analytical methods - just plain knowledge about arylketones becoming pink/red upon treatment with strong mineral acids and further having the tendency to polymerize when treated with strong alkalimetal hydroxides. And this especially the case with (substituted) phenylacetones and H2SO4 (or HCl). Ever steam distilled any phenylacetone from acidic solutions? Or vacuum distilled such a ketone over solid NaOH? Then you would know what I mean. Of course it could always still be something else! - but as old organic chemistry textbooks state that said ketones can cause this kind of color under said circumstances, I simply thought this could one possible reason for the coloration and decided "throw in all info you have". Will you again start throwing with dirt because I did so, hypo? But anyway, your red stuff indeed doesn't behave like ketone - and if the talked about rxn was a direct nitrostyrene reduction, I doubt that there would be still any ketone present after 2 DCM washes - the amount should be very small if any and DCM is quite effective in removing this kind of gunk... Did I get this right: we talk about a nitrostyrene red.amination with Al/Hg on 3,4,5-TriMeO-NS? Maybe you should try to acidify with dilute HCl very carefully, as unreacted nitrostyrene tends to polymerize even quicker than ketones. Or perhaps you should consider other reduction methods, or at least try a different workup!? Maybe do several hydrogencarbonate/bicarb/brine/whatever washes before attempting to acidify it would help (just an idea)? Because your main problem seems to be getting your product free from side products causing this nasty tar... Greetz, A Pleased to meet you hope you get my name. But whats puzzlin you is the nature of my game!



		SpicyBrown (Hive Bee) 08-23-04 05:56 No 526913				Ahh yes, the DCM washes.
						It's technically just a reduction, not a reductive amination, since the nitrogen is already present in the nitrostyrene as a nitro group. I've seen this red stuff as well, and it's always boggled me. I've done this Al/Hg reduction on several substrates now, and always do the CH₂Cl₂ wash immediately after the acidification. Different substrates have yielded different colors... When reducing 3,4,5-TMNS, the CH₂Cl₂ layer was very light red. After sitting overnight however, it became very dark red, to the point that you could no longer see through it. I've always wondered just what's in that CH₂Cl₂ layer and what's happening to it over time. When reducing 2,5-dimethoxy phenyl-2-nitrropropene, the post-acidification CH₂Cl₂ wash yielded a yellow/orange solution. After sitting overnight it turned olive green. I'm mystified, and just consider it a good thing CH₂Cl₂ is so effective at washing out whatever those byproducts are. -SpicyBrown

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