starlight
(Hive Bee)
09-02-02 04:46
No 351780
      Anyone heard of this Nitro reduction?
(Rated as: excellent)
 Bookmark   

It looks too good to be true!

Zinc-catalyzed ammonium formate reductions: rapid and selective reduction of aliphatic and aromatic nitro compounds. Gowda, D. Channe; Mahesh, B.; Gowda, Shankare. Department of studides in Chemistry, University of Mysore, Mysore, India. Indian Journal of Chemistry, Section B: Organic Chemistry Including Medicinal Chemistry (2001), 40B(1), 75-77. Journal written in English.

Abstract
Aliphatic and aromatic nitro compounds are selectively and rapidly reduced to their corresponding amino derivatives in good yields using Ammonium Formate and com. Zinc dust. This system is found to be compatible with several sensitive functionalities including halogens, -OH, -OCH3, -CHO, -COCH3, COC6H5, -COOH, -CO2C6H5, -CONH2, -CN, -CH:CHCOOH, -NHCOCH3. The reduction can be carried out not only with HCOONH4 but also with HCOOH.

 
 
 
 
    starlight
(Hive Bee)
09-02-02 08:19
No 351813
      my library does not carry this journal  Bookmark   

Does anybody else's? I would be most grateful if someone could get hold of it / scan it in.
 
 
 
 
    Barium
(Hive Bee)
09-02-02 08:22
No 351815
      Looks nice  Bookmark   

IŽll try to find it ASAP
 
 
 
 
    foxy2
(Distinctive Doe)
09-02-02 12:40
No 351892
      Reduction of nitro groups w. Zinc/Ammonium formate
(Rated as: excellent)
 Bookmark   

Zinc-catalyzed ammonium formate reductions: rapid and selective reduction of aliphatic and aromatic nitro compounds
Gowda, D. Channe; Mahesh, B.; Gowda, Shankare.
Indian Journal of Chemistry, Section B: Organic Chemistry (2001), 40B(1), 75-77.

Abstract
Aliphatic and aromatic nitro compounds are selectively and rapidly reduced to their corresponding amino derivatives in good yields using Ammonium Formate and commetrial Zinc dust. This system is found to be compatible with several sensitive functionalities including halogens, -OH, -OCH3, -CHO, -COCH3, COC6H5, -COOH, -CO2C6H5, -CONH2, -CN, -CH:CHCOOH, -NHCOCH3. The reduction can be carried out not only with HCOONH4 but also with HCOOH.


In this communication we wish to report a selective, rapid and simple reduction of aliphatic and aromatic nitro compounds to the corresponding amino derivatives using commertial zinc dust and ammonium formate at room temperature.  This new system reduced a wide variety of nitro compounds directly to the corresponding amines and many functional groups can bee tolerated.  When ammonium formate is replace by formic acid the reduction proceeds effectively and the products were obtained in almost comparable yeilds.

The reduction of nitro group in the presence of activated zinc (pretreated with HCl and throughly washed with water and ether prior to use) and HCOONH4 or HCOOH was complete in 2 - 10 min.  The course of this reaction was monitored by TLC and IR.  The work-up and isolation of the products were easy.  Thus all compounds reduced (Table 1) by this system were obtained in good yeild (90-95%).  All products were characterized by comparison of their TLC, IR and melting points with authentic samples. 

Typical Procedure
A suspension of an appropriate nitro compound (5 mmol) and Zn dust (6 mmol) in methanol or in any suitable solvent (5 ml) was stirred with ammonium formate (0.5 g) or 90% HCOOH (2.5 ml) at room temperature.  After completion of the reaction (monitored by TLC), the mixture was filtered off.  The organic layer was evaporated and the residue dissolved in CHCl3 or ether and washed with saturated NaCl to remove ammonium formate.  The organic layer upon evaporation gave the desired amino derivatives.

Thus the reduction of nitro compounds can bee accomplished with commertial zinc dust instead of expensive Pt, Pd ect., without affecting the reduction of any reducible substituents includeing halogen and carbonyl compounds.  The yeilds were virtually quantitative and analytically pure.

The obvious advantages of the proposed method over previous methods are: (i) selective reduction of nitro compounds in the presence of other reducible groups includeing halogen and carbonyl compounds, (ii) ready availabilty and easy to operate, (iii) rapid reaction, (iv) high yeilds of substituted anilines, (v) avoids strong acid media, (vi) no requirement for pressure apparatus, and (vii) LESS EXPENSIVE.  This procedure will be of general use espically in cases where rapid, mild and selective reuction are required.


Table 1.  Zinc catalyzed reduction of nitro compounds.
============================================================
-------------------------- Reaction Time in Min ---------Yeild (a)---
Nitro compound............ HCOONH4 ... HCOOH .......... (%) .......
============================================================
Nitromethane.........................2....................2...................45.....(b,c)
Nitroethane............................5....................7...................50.....(b,c)
1-Nitropropane......................5....................7...................55.....(c)
1-Nitrobutane........................2....................4....................60.....(c)
1-Nitroethylethanoate.............5....................5....................65.........
4-Nitromethylbutanoate..........5....................7...................80..........
Nitrobenzene..........................8...................10..................90......(d)
o,m,p-Nitrophenol................3-5.................3-5................92-93.......
2,4-Dinitrophenol...................5....................5....................92..........
o,m,p-Nitrotoluene................3-5.................3-5................89-91..(d)
2,4-Dinitrotoluene..................5....................5....................90..........
o,m-Dinitrobenzene...............4-6.................4-6................90-91.......
o,p-Nitrobenzaldehyde..........8-10.............10-15..............89-90.......
o,p-Nitroacetophenone.........8-10.............10-15..............92-93.......
p-Nitrobenzophenone............10..................10...................92.........
p-Nitrobenzamide...................8...................10...................90.........
p-Nitrophenylacetate...............5....................5...................91.....(e)
o,m,p-Nitrobenzoic acid........3-5................5-6................93-94.......
o,m,p-Nitrochlorobenzene.....5-6................5-6................94-95.......
o,m,p-Nitrobromobenzene.....5-6................5-6................91-92.......
p-Nitroiodobenzene................5...................5....................89.........
p-Nitrocinnamic acid...............5...................7....................90.........
p-Nitrobenzonitrile..................10.................15...................93.........
p-Nitrophenylacetonitrile........10.................15....................93.........
p-Nitrophenylethylalcohol.......15.................20...................90.........
3,5-Dinitrosalicylic acid...........6...................6...................89.........
p-Nitroacetanilide...................5....................5...................90.........
============================================================
(a) Isolated yeilds are based on a single experiment and not optimized
(b) The low yeild of aliphatic amines is due to their volitility
(c) Isolated as hydrochloride salts
(d) Isolated as benzoyl derivatives
(e) Isolated as acetyl derivative
(d) All nitro groups are transformed to their corresponding amine, with no other functional groups affected.
 
 
 
 
    Rhodium
(Chief Bee)
09-02-02 23:11
No 352150
      Who will be the first to put this into practice?  Bookmark   

This reaction seems extremely easy. If the yields really hold up to the test, nitrostyrenes will be easily reduced to phenethylamines with this method following a NaBH4 reduction of the double bond.
 
 
 
 
    Barium
(Hive Bee)
09-03-02 08:45
No 352269
      Wow
(Rated as: excellent)
 Bookmark   

It works!!

3g (11.7 mmol) 1-(2,4,5-trimethoxyphenyl)-2-nitropropane was dissolved in 20ml MeOH containing 2.5g (38.2 mmol) zinc powder (activated by stirring in 20ml 5% aq. HCl for two minutes then washed with 3x50ml water and finally 20ml MeOH). To the stirred mixture 1.9g (30 mmol) ammonium formate wa added in one portion. The mixture became warm to the hand within one minute. After 15 minutes the mixture was filtered to remove the residual zinc and the solvent removed by distillation. The residual oil was dissolved in 25ml EtOAc and neutralized with dry HCl in IPA. The solution was heated to 60 deg C and vacuum applied to remove about 10ml EtOAc. The residual solution was slowly cooled to room temp and the walls of the flask scratched with a glass rod. Crystals begun to grow very quickly and within 1 minute the solution was a thick slurry. The crystals was isolated by filtration, washed with 50ml acetone and dried to constant weight.

Yield. 2.1g TMA-2*HCl

I will try this with 1-(2,5-dimethoxyphenyl)-2-nitroethane and 1-(2,4-dimethoxyphenyl)-2-propanone oxime. Reports will follow shortly.
 
 
 
 
    starlight
(Hive Bee)
09-03-02 09:49
No 352292
      fantastic  Bookmark   

that was quick off the mark!

that really is brilliant - so much easier and quicker than urushibara - if this works for other nitropropanes then it looks like the method of choice.
 
 
 
 
    GC_MS
(Hive Bee)
09-03-02 09:59
No 352296
      que?  Bookmark   

Excuse me, but does SWiM reads this correctly? Zn, HCOOH, HCOONH4 and some easily obtained nitropropane??? <insert many shocked here> God, does SWiM looooove India! Where is the lab, need to test this, test...!

I want to go to that girl that lives @ only 3000 km from my place...
 
 
 
 
    Cyrax
(Hive Bee)
09-04-02 15:28
No 352713
      Another example of the Zn / AcOH reduction of ...
(Rated as: excellent)
 Bookmark   

Another example of the Zn / AcOH reduction of aliphatic nitroalkanes can be found in British Patent 793,965.
 
 
 
 
    starlight
(Hive Bee)
09-17-02 10:37
No 357329
      formic acid confirmed as working  Bookmark   

the procedure posted by Barium above also works using an equivalent amount of formic acid in place of the ammonium formate for reducing TMP2Nitropropane. It is really easy. Be careful though, because when the formic acid is added, the methanol solvent can boil (maybe this could be done in a reflux apparatus, or only some of the formic added at a time).

Attempts with DMMDP2Nitropropane --> DMMDA-2 have so far been unsuccessful (although this could be related to problems with the preparation of the nitropropane from the nitropropene and problems crystallizing the final product). More news on this when available.....
 
 
 
 
    starlight
(Hive Bee)
10-26-02 09:24
No 372882
      still no success with the DMMDP2NP  Bookmark   

Three attempts at reducting the nitropropene to the nitropropane with NaBH4 and then to the amine with the above nitro reduction have failed.

I suspect (although do not understand why) that the NaBH4 reduction may not be working as the product of the reaction was reported to look the same as the input material (not the case with the TMP2NP reduction). Still, without some form of analysis like tlc its impossible to be sure...
 
 
 
 
    SpicyBrown
(Hive Bee)
01-02-03 21:57
No 395045
      Any updates?  Bookmark   


I will try this with 1-(2,5-dimethoxyphenyl)-2-nitroethane and 1-(2,4-dimethoxyphenyl)-2-propanone oxime.



Barium, did you ever give these compounds a go w/the activated Zn/Formate reduction? SWIM is considering trying it on 1-(2,5-dimethoxyphenyl)-2-nitroethane shortly and was wondering if it worked well.

-SpicyBrown

 
 
 
 
    Sunlight
(Pioneer Researcher)
01-03-03 09:34
No 395157
      The equation  Bookmark   

I don't understand.

R-NO2 + 3H2 -> R-NH2 + 2H20

Right ?

But in the procedure they put 5 mmol of nitro and 6 mmol of Zn what is a maximum of 6 mmol of H2 produced, so it is not a 3:1 ratio. Even the amount of formate is 7.9 mmol. It doesn't match, where am I wrong ?
 
 
 
 
    SpicyBrown
(Hive Bee)
01-03-03 21:56
No 395283
      Seemed odd to SWIM as well  Bookmark   

Sunlight, you would seem to be correct as far as SWIM can tell. Barium's trial up there producing TMA-2 seemed more reasonable than the article itself to SWIM, although there still aren't 3 equivalents of formate being used, and he still got decent yields. SWIM is a bit confused as well, and planned on using 3 equivalents of formic acid (don't have any formate salts currently) on an attempt with 2,5-dimethoxyphenyl-2-nitroethane, as an excess wouldn't hurt if SWIM, like Sunlight, is missing something on the theory here.

-SpicyBrown
 
 
 
 
    Sunlight
(Pioneer Researcher)
01-04-03 09:55
No 395413
      The old Zn and acetic acid  Bookmark   

Basically, the rdxn seems to be the same that the old Zn and acetic acid for nitrocompounds, like the one cited by Cyrax, and I think it needs a healthy excess, say 3:1 Zn and acid : nitro.
There's still a dark point, the rxn will produce Zn formate, is it completely unsoluble in methanol ? don't know, but I doubt it, nevertheless it is not mentioned in the paper or in Barium workup. Well it is just a question, may be Zn formate precipitates in the rxn ad it's just filtered and the remaining one is removed with the brine wahs when the paper says ammonium formate (instead of formates).
 
 
 
 
    starlight
(Hive Bee)
01-06-03 02:39
No 395776
      catalyst  Bookmark   

as far as I understand this reaction, the formate acts as a hydrogen donor and the Zn only acts as a catalyst.
 
 
 
 
    APOPLEX
(Stranger)
01-07-03 13:54
No 396231
      I would dream it, but....  Bookmark   

....whats about the C=C doublebound of Phenyl-betanitropropene ?

Why could this C=C bound not be reduced from the Zn/NH4COOH? The NH4COOH dissociated to NH3 <-> HCOOH. The Formic acid acts with the Zn reducing the nitropropene to the Ketone.The Ketone reacts with the amine (NH3) to the imine and is then hydrolyzed to the amine....but the C=C bound?

Does anyone know a method to reduce this C=C bound without LAlH4 or NaBH4 like Rhodium says in his Post..?

Why doesn`t work the Zn/NH4COOH on this C=C bound ?

Perhaps Zn/HCl ??

=----------=
= APOPLEX =
=----------=


 tongue
 
 
 
 
    Rhodium
(Chief Bee)
01-07-03 14:00
No 396235
      Nitroalkene reductions without LAH/NaBH4  Bookmark   

../rhodium/chemistry /znhg.alhg.reductions.txt
../rhodium/chemistry /tmp2np-red.html
 
 
 
 
    Sunlight
(Pioneer Researcher)
01-08-03 04:34
No 396386
      Not Zn/HCl  Bookmark   

Zn/HCl does not reduce nitropropenes to amines, or yield is insignificant.
 
 
 
 
    APOPLEX
(Stranger)
01-08-03 09:35
No 396424
      Maybe Zn-Cu works  Bookmark   

Thank you for the link Rhodium ;-)
In the <znhg.alhg.reductions.txt> I have read, that Zn-Cu may work to reduce a nitropropene to the amine. Any ideas wich rxn-conditions...? Would Zn-Cu(II)-chloride work like Zn-Ni(II)-cloride...?

=----------=
= Apoplex =
=----------=
smile
 
 
 
 
    karel
(Stranger / Eraser)
01-08-03 13:20
No 396467
      Hello Sunlight, have you tried those ...  Bookmark   

Hello Sunlight,
have you tried those conditions Post 245040 (Rhodium: "O Leminger's Phenethylamines - posted by Karel", Novel Discourse) ?
 
 
 
 
    Sunlight
(Pioneer Researcher)
01-09-03 10:40
No 396717
      Hi Karel  Bookmark   

As I've posted in that thread, I discovered it recently, I'll try it soon, I promise it to you, but I doubt to use methanol or 96 ethanol (with denaturants)... I hope it won't be important.
Thanks for your research.
 
 
 
 
    Sunlight
(Pioneer Researcher)
02-27-03 16:13
No 412404
      Excuse me  Bookmark   

I thought that the Zn/An formate rdxn of nitro compounds was something similar to the classic Zn acetic one. Then Rhodium posted another reference wich uses zinc and hidrazinium monoformate, very similar to this one, so I decide to try it and see what happens.
Initially I checked adding Zn to a solution of ammonium formate and methanol, and it makes nothing. Then I added nitromethane and zinc to methanol and then added the formate, and as sonn as it came in solution started a energic, exhothermic and effervescent reaction. The same, but immediatly, happened when the zn was added to a solution of nitromethane and ammonium formate in methanol, disappearing completely the Zn, wich was not pretreated with diluted HCl (but good quality one).
In conclusion I was wrong, but my doubts about the amount of reactants still persist. They use 0.6 mmol of Zn and 0.8 mmol of formate to reduce 0.5 mmol of nitrocompound, my best numbers are that the formate could decompose giving 0.8 mmol of H2 and the Zn could react with the NH3 producing 0.6 mmol of H2 more, 0.14, but it is necessary 0.15 for a 100 % efficiency. Furthermore, when formic acid is used instead of the formate, the Zn disappears, so I think it reacts forming the formate.
Any light about the mechanism of the reaction ?
 
 
 
 
    Antibody2
(Hive Addict)
06-11-03 15:35
No 439431
      sunlight - while pondering the ratios you...  Bookmark   

sunlight - while pondering the ratios you mention i am further intrigued by the massive XS of HCOOH they use in the proceedure, 48mmol. 8X the amount of ammonium formate they advocate using. Surely that has got to be a typo??

starlight - i agree the formic acid should probably be added slowly, it describes this as a room temp reaction, not a reflux reaction. maybe  even using a water bath?

anybees besides Barium have anything to report on this rxn?smile especially using formic acid instead of the salt
 
 
 
 
    starlight
(Hive Bee)
06-16-03 14:43
No 440364
      formic acid worked fine  Bookmark   

Formic acid worked fine when reducing 2,4,5-Trimethoxy Phenyl-2-Nitropropane to TMA-2. Can't remember exact yields as it was months ago, but they were good enough to call a success.
 
 
 
 
    Antibody2
(Hive Addict)
06-20-03 22:17
No 441497
      do you remember the ratios of formic used?  Bookmark   

do you remember the ratios of formic used?

Eh? ma faut n'exist pas.
 
 
 
 
    starlight
(Hive Bee)
06-27-03 06:01
No 442899
      xs as described  Bookmark   

the procedure has only been tested using the ratio of reactants described in the original paper.