Sciencemadness Discussion Board

Good substrate to test Urushibara Nickel?

mnick12 - 14-11-2011 at 20:36

Hello everyone,

I have a question which I hope some of you may be able to help me with. It has been a few weeks since I have been able to do anything in my lab. As such I decided that some sort of project must be started. I remembered reading a few articles on "Urushibara Nickel", which claimed Urushibara metals to be viable substitutes for standard Hydrogenation catalysts. I thought this would be a fun relatively simple project to try out. Anyways I just prepared a small of Urushibara nickel (UNi-A) according the procedure outlined here: http://www.erowid.org/archive/rhodium/chemistry/urushibara.h...

The procedure was conducted without any hickups, and I now posses a couple hundred milligrams of a damp dark black catalyst. Anyways my question is, what do you think would be a good substrate to test the effectiveness of Urushibara Nickel as a catalyst. My initial thought was something common like dehydrorheosmin or something similar. However I am open to suggestions. Also I am interested in Urushibara Nickel's potential at reducing aliphatic nitro- compounds.

Any ideas?

Thanks!

smuv - 14-11-2011 at 21:00

Styrene

azo - 14-11-2011 at 21:02

reduction of potasium permanganate is a good way to test your urishabara


regards azo

DrNoiZeZ - 16-11-2011 at 10:45

Well, I remember trying that once and I think I couldnt get anything usefull. I think it was a nitropropene made from benzaldehyde, or a nitrostyrene. The point is I couldnt make it work.
You can try using nitrobenzene, I think it can be easy to identify the aniline produced.

mnick12 - 16-11-2011 at 18:59

Just a little update,

Not having any styrene or permanganate, I opted for 4-butoxy-3-methoxyphenylbutenone which was prepared earlyer by a base catalyzed Aldol. The unsaturated butenone had a yellowish color, and had a characteristic "peppery" smell. For the actual reduction I used a 25ml rbf with one of those T-shaped adapters I used 1g of butenone, 0.1g of moist catalyst, and 10ml of dry methanol (arbitrary amounts this was just a test run) . The mix was heated to 50 degrees evacuated twice then supplied with an over pressure of dry H2. The mix was stirred at 900rpm and allowed to reduce for a total of 1hr. After workup which consisted of gravity filtration followed by precipitation of the material in water, the starting material was recovered. So as of now it appears as thought 1 day old UNi-A is ineffective as a hydrogenation catalyst. Perhaps tomorrow I will try reducing some of the catalyst under H2 before trying another reduction. Also I will give aniline a shot as I have about 30ml of pure nitrobenzene.

Anyway Im bummed that it was unsuccessful, but I have not given up yet.

smuv - 17-11-2011 at 01:46

Do the reduction in the same way but try using ~.3g of compound. For some reason very high concentrations of substrate tend to lead to poor reductions. Also read up on urshubara Ni to make sure it is indeed active at atmospheric pressure. I would let the reduction go longer, and also stir the thing as fast as you can without the stirbar decoupling from the magnet. Make sure there are no leaks in your system, you need to grease all your joints and make sure no solvent splashes onto the joints.

Edit: also phenols can sometimes slow reductions over Pd catalysts, IDK if this is an issue for Ni (usually these are harder to poison). Adding acid makes Pd catalysts much more active, I think this trick works for Ni as well.

[Edited on 11-17-2011 by smuv]

Nicodem - 17-11-2011 at 07:27

You sure used a difficult substrate to test your catalyst. Enones are not reduced as easily as normal alkenes. Depending on the catalyst used, they can be quite slow. Rather use a substrate that is known to be easily reduced by hydrogenation over nickel catalysts. If you have no styrene, try with anethole or eugenol. Both of these are easily hydrogenated over Pd-C at <1 mol% even at atmospheric pressure, so they should go easily with a high loading of urushibara nickel. Though, these substrates might be hard to distinguish from their saturated products by TLC and the products are liquids thus making the isolation troublesome.
Alternatively, nitroaromatics, oximes and nitriles should reduce readily to the corresponding amines. If you don't have any such substrate, you can easily prepare some. The advantage is in that the successful reduction is more clearly visible by TLC, when compared to the alkene to alkane reduction.

mnick12 - 17-11-2011 at 17:22

I have a few ml of eugenol I could try reducing, but I am not quite sure how to test if hydrogenation has occurred. Would a bromine test be sufficient? Also I have some nitrobenzene waiting to be reduced, but my one of my books on cat hydrogenation claims amines are often times poisons to catalysts and suggest adding an excess of HCl or some other mineral acid to react with amine as it is formed. I am worried though that adding any strong acid would dissolve the UNi-A before reduction occurs, would the use of a weaker acid such as acetic acid prevent this problem? Or is this something that does not need to be worried about?

Anyway I hope to continue this project later tonight.

Thanks!

Sedit - 17-11-2011 at 18:11

If its all about a test why not just reduce Acetone to IpOH? Yields can be determined by removal of unreacted acetone using Sodium Bisulfite.


More interesting and slightly off topic is a patent posted over at The Vespiary some time back that was a transfer hydrogenation performed by using Anhydrous MeOH with Nickle Chloride dissolved it in. IIRC Zinc powder or possibly Aluminum was used to precipitate the Nickle which abstracted a hydrogen from the Methanol to perform a reduction. My memory is a bit fuzzy on the mechanics of it so take this with a grain of salt until I can retrieve and upload the patent.

[Edited on 18-11-2011 by Sedit]

There is issues with our forum so I cant get it just yet, The paper is...

BullChemSocJap1992-p1739-1740

[Edited on 18-11-2011 by Sedit]

Got it but its for aryl halides, I wounder if its effective for other substrates. There where some other papers I have to look for that suggest it will. Does anyone have a 4shared premium account?

[Edited on 18-11-2011 by Sedit]

Attachment: BullChemSocJap1992-p1739-1740.pdf (298kB)
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Nicodem - 18-11-2011 at 07:34

Quote: Originally posted by Sedit  
If its all about a test why not just reduce Acetone to IpOH?

Aliphatic ketones are generally not reduced to alcohols at room temperature and low hydrogen pressure by using Ni/Pd/Pt based catalysts at a useful rate. They require harsher conditions or different catalysts.

Sedit - 18-11-2011 at 09:43

Quoted from the source given by the OP.
Quote:
U-Ni-B is effectively employed in catalytic reductions for which the presence of alkali is favorable; whereas U-Ni-A is appropriate for those reductions where the presence of alkali interferes. For example, a trace amount of alkali favors the reduction of ketones, aldehydes, nitriles, and oximes, for which the use of U-Ni-B is desirable. On the other hand, the reduction of aromatic nitro compounds is hindered by the presence of alkali and U-Ni-A can conveniently be used in this case.


Quote:
U-Ni-BA, like U-Ni-A and U-Ni-B, can be used for the hydrogenation of olefins, or the reduction of carbonyl and nitro compounds, but it gives somewhat poorer results. We can see this in the high-pressure reduction of acetophenone. For general purposes other than for benzene ring hydrogenation, the use of U-Ni-A or U-Ni-B, with their high activity, stability, and availability is recommended.


I haven't checked literature yet however to see what conditions are employed in the reduction of the Ketones.

Nicodem - 18-11-2011 at 14:05

Unfortunately, that does not say much, because of the ease with which some ketones, particularly the aromatic ketones (phenones and similar), reduce with many catalysts that do nothing to aliphatic ketones at the same conditions. It can be expected that these type of ketones would reduce similarly with Urushibara-Ni.
However, to my surprise, apparently even some aliphatic ketones can be reduced under mild conditions, so I was generalizing too much in my previous post. According to Handbook of heterogeneous catalytic hydrogenation for organic synthesis, pp 186-190 (Nishimura, 2001) Pd-C is more or less inactive for the hydrogenation of aliphatic ketones. The Pt-C, Rh-C and Ru-C work more or less, depending on the medium and conditions. In regard to Raney-Ni there also are known examples of reduction of aliphatic ketones at 1 atm and RT. There is even acetone among the examples, though the use of essentially equal mass of the catalyst in relation to the substrate was applied (that is one good advantage of the cheap nickel over the expensive metals). In the presence of NaOH the reduction went faster. Acetone was the most easily reducible ketone of those tested. Sterically hindered aliphatic ketones failed to give complete conversion. To verify if an Urushibara-Ni catalyst can do the same, I would have to review the literature which is beyond my interest. I assume mnick12 already did a literature search.
Quote: Originally posted by mnick12  
I have a few ml of eugenol I could try reducing, but I am not quite sure how to test if hydrogenation has occurred. Would a bromine test be sufficient?

Not really, as dihydroeugenol also reacts with bromine. You might be able to get a resolution on TLC. Otherwise, without a GC, HPLC, IR or NMR you are pretty much stuck to derivatization methods to get a solid product for which you can determine the mp. Anethole would perhaps be a more suitable substrate, if nothing else, because at least the product should have a somewhat different aroma and the derivatization might be simpler. The "bromine test" might be applicable with the proviso that the hydrogenation product would also react, but much more slowly. It is available OTC as anise oil (essentially pure anethole).


[Edited on 19/11/2011 by Nicodem]

S.C. Wack - 18-11-2011 at 15:31

Surely mgs. of the alkene can be shown in a semi-quantifiable way, e.g. sulfuric acid or permanganate.

Nicodem - 18-11-2011 at 17:12

Yes, indeed that should be a fairly acceptable evidence for the dihydroanethole (but it might give a false negative result for the dihydroeugenol as it is a relatively easily oxidizable phenol). The drawback is the false negative one would get from an incomplete reaction or due to contamination with oxidizable impurities from an improper isolation (residual solvents, for example). But a positive result, where the permanganate color would be relatively persistent in comparison to the control experiment done on the starting material, would be quite conclusive.

Sedit - 19-11-2011 at 18:58

What about testing it on Benzyl alcohol? I am seeing mixed reports that suggest it may reduce BnOH to Toluene. Is this correct?

Palladium - 24-11-2011 at 16:37

Quote: Originally posted by mnick12  
Hello everyone,

I have a question which I hope some of you may be able to help me with. It has been a few weeks since I have been able to do anything in my lab. As such I decided that some sort of project must be started. I remembered reading a few articles on "Urushibara Nickel", which claimed Urushibara metals to be viable substitutes for standard Hydrogenation catalysts. I thought this would be a fun relatively simple project to try out. Anyways I just prepared a small of Urushibara nickel (UNi-A) according the procedure outlined here: http://www.erowid.org/archive/rhodium/chemistry/urushibara.h...

The procedure was conducted without any hickups, and I now posses a couple hundred milligrams of a damp dark black catalyst. Anyways my question is, what do you think would be a good substrate to test the effectiveness of Urushibara Nickel as a catalyst. My initial thought was something common like dehydrorheosmin or something similar. However I am open to suggestions. Also I am interested in Urushibara Nickel's potential at reducing aliphatic nitro- compounds.

Any ideas?

Thanks!


My experience says that the information at that source you linked to is defective. They simply can't explain the process good, and this in comparison to much more sophisticated catalysts than U-Ni - e.g. Pd/C and PtO2.

They have plenty of discussion about how good U-Ni is, as if it was from a seller. They are impressive bad at explain exactly how the Ni-salt through metathesis makes the catalytic activity with Al. Then they are good at working on to write as much text as possible about all alternatives with all kinds of unnecessary routes instead of explaining the basics.

I have made this catalyst in many ways, and the last was from Nickel Acetate in GAA for avoiding HCl at all. It became a light green solution which went to dark grey the more Al I dissolved. It smelled terrific during the end (the smell of oxime without any smell of styrene), but probably stopped at the oxime. However, this didn't succeed to reduce all the way. It was a great overload of Ni and even more patience. I did spend the whole day for this, without any result at all.

I tried to once hydrogenate this Ni-Al-chunk made from NiCl2 and HCl, up to 4 bars at steam bath temp. Every time I released the H2-pressure the Al released millions of H2-bubbles, which was not expected. I repeated this H2 pumping-releasing like 20 times, and this reduction is the only one which really worked all the way with Ni-salt. I haven't read about this anywhere, but it worked.

According to what I know this far, I wouldn't spend any time or money on that slow and solvent/time-expensive catalyst U-Ni. Performed in GAA it becomes even more expensive and you have to love it to continue. Personally, I hate U-Ni.

mnick12 - 26-11-2011 at 21:33

Yea so far this is looking like it is not going to work.

I tried hydrogenating 1.4ml of nitrobenzene in acidic methanol, but all I recovered was the the starting material no amine or any intermediate. I still have some of the nickel powder left and I may try reducing it under H2 at an elevated temp before trying another reduction.

It might be a few days before any results are posted.

Palladium - 27-11-2011 at 11:35

Quote: Originally posted by mnick12  
Yea so far this is looking like it is not going to work.

I tried hydrogenating 1.4ml of nitrobenzene in acidic methanol, but all I recovered was the the starting material no amine or any intermediate. I still have some of the nickel powder left and I may try reducing it under H2 at an elevated temp before trying another reduction.

It might be a few days before any results are posted.


It doesn't surprise me at all. I still think U-Ni is waste of time, and would like to see reductions in real labs where they can analyze the yield afterwards. The more successful type of dissolved metal reduction of nitro aryls is (haven't tried, but it's the most preferred) with Hg/Al. Red-Al is also recommended.

According to what I know about nitro compounds to amines in case of aryls, this is not an easy reduction. I have made reductions with Pd/C with poor results. High pressure H2, at ~80C with a big load of RaNi is the best way I know, and the most high-yielding.

Nicodem, as I always use to mention, knows this far more better than me - and I would like to hear his further comments.

[Edited on 27-11-2011 by Palladium]

DrNoiZeZ - 10-12-2011 at 03:25

As I can remember I've made some nitrobenzene reduction using Fe/HCl and it worked well, the aniline was separated with steem destilation. I think Zn/HCl may work as well or even Zn/formate. The Fe/HCl reduction is on Voguel pg 564 3. ed (it also has another reduction using tin ).