java (Hive Bee)
08-01-03 21:19
No 451095
      A question about methylamine synthesis     

I've read the methods available ot Rhodium's for the synthesis of methylamine via nitromethane and methanol. More to the point , the synthesis via catalytic hydrogenating using Palladium/C, I saw KrZ method but he uses a mag stirrer for 120 hrs or 24 hrs. using the Parr hydrogenator I've not found any methods. I can only assume if I just load it up in methanol and add my catalyst , for which I will have to titrate , and hydrogenate till it takes no more, then filter off the catalyst ,then I have methyalamine in methanol which I would like to use like that but If i need to store the product in a HCl form.  The method suggested for doing this by KrZ , I question,as I don't know what the Na2SO4 was used for.  I thought a simple gasing would make the methylamine Hcl crystals but since it's soluble in methanol then,.....what  remove the methanol and the result will be my product but where  is the Hcl coming from..... I'm confused !

Edit: There are some rummors about the validity of Krz posts if so why are they stored at Rhodium's. As I read Krz admitted pushing the truth with the hydrogenation of Phenylalanine, should caution be used when reading all of his posts?

We're  all in this world together,
(Hive Bee)
08-02-03 07:23
No 451187
      "A question about methylamine synthesis"     

These are a few articles found thus far on the subject........

In the post  Post 291999 (Moriarty: "Using Rh/C", Serious Chemistry)
......"However, NO2 groups were reduced to NH2 in all the catalytic hydrogenation reductions mentioned in pages 31-36  Catalytic Hydrogenation in Organic Synthesis, Morris Freifelder, 1978."

 Also  in the post  Post 292326 (Ritter: "catalytic hydrogenation", Serious Chemistry).

...."Yields will be MUCH higher if an ethanolic solution of MeNO2/EtOH is reduced first and╩ liquids are decanted off into another Parr bottle"

An excellent article posted by Post 450229 (Rhodium: "Catalytic Reduction of Nitriles and Oximes", Methods Discourse)

NOTE : It would be great if someone could upload Freifelder's reference to Rhodiums and maybe he could post it here in PDF  as I have no access to this

We're  all in this world together,
(Hive Bee)
08-02-03 13:36
No 451224
      Methylamine from Nitromethane     

If you hydrogenate nitromethane, you produce methylamine and water

CH3NO2 + 3 H2 = CH3NH2 +  2 H2O

To remove the water, you add (dry) Na2SO4. Than you have dry MeOH with methylamine. To get the HCl Salt, you add HCl
(Hive Bee)
08-02-03 18:29
No 451263
      Re:A question about methylamine synthesis"     

roger2003,.... thank you for your input and  would you have any references or have you had experience running the hydrogenation. What were your observations as to conditions , exothermic reaction?,  pressure , amount of catalyst used,
any problems with poisoning of catalyst., solvent used......any and all of this information would be helpful to any bee wanting to go at it this route to

We're  all in this world together,
(Hive Bee)
08-03-03 02:27
No 451340

If I need Methylamine, I buy a 12 kg (gas) bottle. wink

The hydrogenation of nitromethane in one way to get methylamine, but I think, it is the last way.

The reduction of aliphatic nitro compounds is described in all chemistry books and a usual (exothermic) hydrogenation.

You can take all catalysts, but I think Pd (or Pt) is better than Pd/C.

Pressue and amount of catalyst are questions for the time of hydrogenation.

You need 3 Mol H2 for 1 mol nitromethane. If the hydrogen uptake is slowly, you need more pressue or (and) more catalyst.

An overview for methylamine synthesis you can find in
Organic Syntheses CV 1, 347
(Hive Bee)
08-04-03 00:44
No 451510
      Re: methylamine synthesis     

Yes I've herd of the many difficulties dealing with the catalytic hydrogenation of nitromethane , however I've also read some that worked .....of course if I could buy it I would not be going through

 Post 448417 (Barium: "US Patent 3458576 tried for 2,4-DMA", Methods Discourse)

We're  all in this world together,
(Hive Bee)
08-04-03 03:01
No 451524


It is not possible to transfer the reaction conditions from Bariums synthesis to the hydrogenation of nitrmethane.

If you reduce nitropropene (like Barium), there is the first step reducing a doublebond.

(Hive Bee)
08-04-03 18:08
No 451622

java....maybe the comment from Ullmann`s is helpful for you:

Production from Nitro Compounds

Whereas the reduction of nitro compounds is one of the most important methods for the synthesis of aromatic amines, this route has not become important for the production of aliphatic amines. Because the availability of appropriate nitroalkanes is restricted, this method is used only in a few special cases, e.g., the production of 2-amino-1-butanol, the precursor for the antituberculotic ethambutol.
The reduction proceeds via the nitroso or hydroxylamine intermediate, in some cases even at room temperature, and gives the amine in yields of 90 % or more. Platinum, palladium, rhodium, nickel, or copper is used as the hydrogenation catalyst [7]. The reaction is highly exothermic (ca. 500 kJ/mol per nitro group), and therefore heat must be removed rapidly to control the process. Nitroparaffins are more difficult to hydrogenate than their aromatic counterparts [21].
Functionalization of alkenes with NO or NO2 has been described; the reaction follows a radical path and affords a mixture of products, among them nitroalkenes. Reduction of the latter also leads to amines, but has found no industrial application so far. Likewise, primary amines were obtained from paraffins by nitration with HNO3 or liquid NO2 and hydrogenation of the resulting nitroparaffin/ketone mixture in the presence of ammonia [22]. The preparation of 1,2-diamines from nitroolefins and O-alkylhydroxylamines has been described [23].

[7]  J. Falbe, U. Hasserodt (eds.): Katalysatoren, Tenside und Mineral÷ladditive, Thieme Verlag, Stuttgart 1978.
[21]  Engelhard Industries, GB 925 458, 1960.
[22]  Gulf Research & Development Co., US 3 366 686, 1964 (R. W. Rosenthal, R. Seekircher); Texaco, US 3 739 027, 1971 (W. C. Gates, Jr.).
[23]  Mitsui Petrochemical Ind., JP 10 095 753, 1996.

08-04-03 20:59
No 451650
      Connecting threads :     

See also : Post 451607 (Barium: "Methylamine", Methods Discourse)

(Hive Bee)
08-05-03 07:06
No 451745
      Re: a question about methylamine synthesis     

Well thanks to Barium , he's had  hands on experience and info to shed some light on this procedure. I also ran into this patent

Post 400307 (PolytheneSam: "I found this one today.", Novel Discourse)
........"whereas the hydrogenation process is carried out by contacting an organic nitro compound with a catalytic amount of catalyst under hydrogenation conditions of temperature, pressure, and hydrogenation concentrations sufficient to produce an organic primary amine"

and here is some info provided by Roger 2003 on catalyst poisoning......

Post 451781 (roger2003: "Pd/C", Methods Discourse)

Edited: by java

We're  all in this world together,
(Hive Bee)
08-07-03 04:02
No 452209
      Re: A question about methylamine synthesis"     

As this inquiry got cross linked with another post dealing with  the synthesis  of methylamine I should update this with the current article found by Foxy2, in which the yiels are 80% of methylamine......

Post 353051 (foxy2: "Raney Nickel CTH Reduction of Nitro/Nitrile Groups", Methods Discourse)

We're  all in this world together,
(Hive Bee)
08-15-03 22:40
No 453792

You can find an overview for the hydrogenation of Nitroparaffins:

Patent GB925458


Nitroparaffins are hydrogenated to the corresponding amines by treating a methanolic solution of the nitroparaffin with hydrogen at pressures ranging from 0 to 200 psig. and reaction temperatures ranging from room temperature to 400 DEG C. and in the presence of a carbon-supported palladium or rhodium catalyst. Starting materials are preferably nitromethane, nitroethane, nitropropane, 1-nitrobutane and other nitroparaffins having up to 8 carbon atoms. Specification Patent GB925457 is referred to.

(Hive Bee)
08-16-03 01:33
No 453808
      Re:A question about methylamine synthesis"     

Roger 2003, a very good find , also a good proff to the non believers. As Barium  proved and noted taking it easy with amountsof nitromethane and catalyst until titrating a reasonable amount per hydrogenation thereby controlling the heat given off. Hence keeping the catalyst at the low end and starting at room temp one could hydrogenate a fair of nitromethane per hydrogenation cycle.

We're  all in this world together,
(Hive Bee)
12-09-03 21:41
No 475688
      RE: Patent GB925457     

Roger2003....I was sorting the patents and had a chance to read the Patent GB925457 in which I it claims C=O reduction by hydrogenation with a combined catalyst with good hydrogenation. It doesn't say anything about limiting it only to the one example in which Benzoic acid is reduced. This is a good find , tht must be tried on Phenylalanine in reducing the C=O to the desired product. I'm now re-reading it and see if it effects the amine group.

Excerpt  "the present invention relates to a process for hydrogenating certain organic compounds, namely carbocylic aromatic, heterocyclic aromatic, aromatic nitro compounds,aliphatic nitro compounds, aliphatic nitriles, aromatic nitriles, acetylenic diols, phenols, alkoxybenzenes, aromatic carboxylic acids, amines, oximes, hydroxylamines and imines, by contacting the compound to be hydrogenated with a supported catalyst containing ruthenium with another platinum group metal, particularly platinum, palladium, or rhodium as catalytically active metals, at reaction temperature."

What are  your thoughts on the

We're  all in this world together,
(Hive Bee)
12-11-03 14:24
No 476131

I don`t know the final hydrogenation product from Phenylalanine.

But I think, it`s not 2-amino-1-phenylpropan

(Chief Bee)
12-11-03 15:01
No 476139
      the end reduction product is phenylalaninol     

With phenylalanine the end reduction product is phenylalaninol after catalytic hydrogenation. The only reducing agent capable of reducing carboxylic acids to a methyl group in one step is triethylsilane together with a lewis acid: Post 194986 (Rhodium: "First published direct reduction of COOH to CH3", Serious Chemistry)

The Hive - Clandestine Chemists Without Borders
(Hive Bee)
12-11-03 16:54
No 476158

For the hydrogenation of carboxylic acids I know only this system:

Patent US4317918


An alcohol is produced in a high selectivity with a good yield from the corresponding carboxylic acid by reducing the latter with hydrogen in the presence of a rhenium catalyst in the coexistence of an organic base. An arylacetic acid, which is included in the starting carboxylic acid, can be produced in an excellent yield from the corresponding aryl aldehyde by reacting the latter with carbon monoxide and water in the presence of rhodium or its compound and hydrogen iodide.

But I`m doubtful about working in the presence of amino groups