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pepsimax
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[*] posted on 20-11-2013 at 09:30
urushibara catalyst preparation


Hi, going to prepare this catalyst to see if it's amazing as people make out.

However, I don't have a any ethanol or methanol to hand. I have anhydrous IPA, or I distilled a bottle of methelated spirits a few times so have about 500ml mostly ethanol alcohol mix. H2SO4 was added to boiling flask to create a pyradine salt which won't pass over.

Could straight IPA be used or would my alcohol mix be OK? The msds suggested it only contained 95% ethanol, methanol, pyridine and methylene violet, most of which will have been removed.

Also, I'll try a few variations of the catalyst, mainly zinc and aluminium. I have zinc dust but only Al foil. Would Al powder be of benefit at all?

Thanks
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[*] posted on 20-11-2013 at 09:35


Do you intend to precipitate the Ni with the Zn or Al, or do you mean an analogous catalyst from each metal?

<a href="http://en.wikipedia.org/wiki/Urushibara_nickel" target="_blank">Urushibara nickel</a> <img src="../scipics/_wiki.png" />

P.S. It's pyr<u>i</u>dine, not "pyr<u>a</u>dine."




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pepsimax
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[*] posted on 20-11-2013 at 14:31


Apologies, my phone corrected it to that.

Yes I intend to precipitate the Ni with Al or Zn, not simultaneously. Though may try other variations. My question was, would using IPA, anhydrous or diluted to 95% make any difference as the patents call for 95% ethanol or methanol. As above I have a crude high ethanol mixture too, would that be better.

Thanks!

I'll be washing the nickel with NaOH if that makes a difference regarding my alcohol question, but from the link you kindly provided I presume any alcohol would be fine as long as the nickel chloride dissolves?



[Edited on 20-11-2013 by pepsimax]

[Edited on 20-11-2013 by pepsimax]
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[*] posted on 20-11-2013 at 15:27


Hmm, tried with IPA, couldn't get the nickel to dissolve properly. the solution turned green with heat but the yellow anhydrous nickel chloride wouldn't dissolve. Any tips?
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[*] posted on 21-11-2013 at 01:02


I'm no expert but I'm going to guess you should try your alcohol mix after distillation. Have a gut feeling the methanol/ethanol mix won't hurt but the pyridine might. So you might need to do some workup to remove that prior to running your reaction.

On the other hand you could try wetting your IPA. You said the patents do call for a 95% alcohol so perhaps the water is necessary for dissolving the salts.

Either way it doesn't sound like a water sensitive reaction as you end up washing with aqueous NaOH. Probably the main reason they use alcohol is for slow controlled precipitation of the nickel. I used a similar procedure to produce my zinc dust along time ago by suspending a magnesium bar in a mix of isopropanol and aqueous zinc chloride. Worked like a charm.
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[*] posted on 21-11-2013 at 02:44


Pyridine is a very good complexing agent for nickel.

NiCl2 has limited solubility in EtOH, I don't know about IPA.




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[*] posted on 21-11-2013 at 05:51


Thanks, I got the IPA boiling so vigourously that I couldn't really tell if the yellow nickel had dissolved but dumped some Al in anyway. This dissolved after a few mins so added more. It seemed to me all the nickel crashed out far too quickly, the dark grey nickel powder was sat at the bottom within minutes and didn't seem to grow.

Ended up with a light blue solution with Al powder sat on top of very dark nickel chunks. I presume the reaction is botched as adding more Al just seemed to increase the amount of Al sat doing nothing (or is it?)

I thought the nickle was supposed to precipitate slowly to react with the Al in a controlled slow reaction. However, the patents I've read using Zinc seem to suggest it's made in a few minutes?!

Confused here.

I take it my catalyst is a dud :(

[Edited on 21-11-2013 by pepsimax]
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[*] posted on 21-11-2013 at 06:01


Don't make assumptions. Test it's activity. A very dark precipitate <em>could</em> indicate a porous structure with high surface area.



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[*] posted on 21-11-2013 at 10:09


Very true my friend.

What would be an easy chemical to reduce to verify? Something with an obvious property change?
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[*] posted on 21-11-2013 at 17:55


Use the right stuff. Endless problems are possible if you don't.
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[*] posted on 21-11-2013 at 18:34


@ Pepsimax
Excuse me, could you tell us which patents you are referring to?

AFAIR, long ago when I made my Urushibara, I referred to the original article by Kazuo Hata. That article is available on erowid archives.

The preparation uses distilled water. The organic solvent (methanol etc) replaces water in the end only if water medium is not desired in final application.

A typical procedure from Hata paper is given below.
Preparation 1: U-Ni-B

Ten ml of solution prepared from 2 g of crystalline nickel chloride is warmed to 80-90°C and added, over a period of 1-2 minutes with stirring, to 5 g of zinc dust, which has been mixed with a small amount of water and placed in a water bath of the same temperature. Immediately afterward, the precipitate is filtered off with a sintered glass filter and washed with a small amount of hot distilled water. It is then plunged into 100 ml of 10% sodium hydroxide solution as quickly as possible and left standing for 15-25 minutes on a water bath at 50-60°C with occasional stirring. The supernatant liquid is decanted, and the remainder is washed with two 40 ml portions of distilled water at 50-60°C. Then the wash-water is replaced by ethanol. The catalyst, containing 0.45 g of nickel adhering to 2 g of zinc, is thus obtained. The last step, in which ethanol replaces the wash-water, can be omitted when reduction is to be carried out in an aqueous solution.

Gsd
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[*] posted on 22-11-2013 at 09:50


Good substrate to test Urushibara Nickel?

Please open threads without references only in the Beginnings section. See the forum guidelines for more information.




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[*] posted on 22-11-2013 at 10:06


Quote: Originally posted by gsd  
........
AFAIR, long ago when I made my Urushibara, I referred to the original article by Kazuo Hata.
..........

Gsd


Do you by accident also remember somewhat what you used it for and how you used it, say reaction conditions? And how successful it was? No writeup, just a very rough outline would make me already happy.

I ask for as AFAIK the UN was a bit of a disappointment for most trying it, to put it politely. Amazing - yes, amazingly inert though. Also I remember that Urushibara himself hinted strongly that elevated, or better high pressure was beneficial if not a must when using UN.
This correlates nicely with Raney Nickel which behaves a lot the same (if not prepared in sophisticated ways).

regards
/ORG

[Edited on 22-11-2013 by Organikum]




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[*] posted on 22-11-2013 at 23:15


Quote: Originally posted by Organikum  
Quote: Originally posted by gsd  
........
AFAIR, long ago when I made my Urushibara, I referred to the original article by Kazuo Hata.
..........

Gsd


Do you by accident also remember somewhat what you used it for and how you used it, say reaction conditions? And how successful it was? No writeup, just a very rough outline would make me already happy.

I ask for as AFAIK the UN was a bit of a disappointment for most trying it, to put it politely. Amazing - yes, amazingly inert though. Also I remember that Urushibara himself hinted strongly that elevated, or better high pressure was beneficial if not a must when using UN.
This correlates nicely with Raney Nickel which behaves a lot the same (if not prepared in sophisticated ways).

regards
/ORG


[Edited on 22-11-2013 by Organikum]


That was really along time ago however broadly I remember the details.

The compound was Na salt of substituted Benzoic Acid. The aim was to hydrogenate C=O group in the side chain which was at ortho position. The solvent was distilled water as the Na salt was nicely soluble. I conducted the hydrogenation in 2 lit autoclave.
I made a detailed comparative study of 3 catalysts - 1) 10 % Pd/C; 2) Urushibara Ni - A; 3) Raney Ni. I prepared Urushibara myself whereas Pd/C &Raney Ni were bought-out items.

I do not have exact operating conditions at hand, so I can't of-hand tell the exact temp, pressure, cat-loading & reaction duration.

The result broadly were:

10 % Pd/C worked like a charm giving complete hydrogenation of C=O to CH2 @ about 3 bar pressure, 125 Dec C, 5 % loading and in 3 hrs duration.

Raney Ni converted C=O to C-OH. It refused to go beyond that inspite of drastic conditions - 15 Bar, 200 Deg C, 10 % loading & 8 hr reaction time.

To my surprise, Urushibara produced the target compound with 10 Bar, 170 deg C, 10 % loading & 8 hr Reaction time.

I could reuse the Pd/C about 8 times however after few runs conditions had to be more severe and towards the 7 & 8 th run, the yields also suffered.

I managed to recycle the Urushibara for about 3-4 times but again the conditions had to be drastic & after 2nd run the yields were low.

I hope this helps.

In my view Urushibara is extremely useful and safe catalyst. Very easy to prepare, use and recycle. I wonder why it is so underutilized.

Gsd
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[*] posted on 23-11-2013 at 01:14


Gsd, thank you for sharing such valuable information (too bad that 95% of all process development is never published). In my experience Raney Ni works great for the reduction of ketones to alcohols, but I never managed to get it to work at debenzylating benzyl ethers despite some claims in the literature that under specific conditions it can do that (I guess you need specific substrates as well). For this reason, I'm surprised to see that Urushibara Ni worked in a benzylic reduction where Raney Ni failed. Next time I might consider trying it for debenzylations where Pd is not applicable (thioethers, sulfur heterocycles, some azines, etc.).



…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)

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[*] posted on 23-11-2013 at 13:52


Quote: Originally posted by gsd  
@ Pepsimax
Excuse me, could you tell us which patents you are referring to?

AFAIR, long ago when I made my Urushibara, I referred to the original article by Kazuo Hata. That article is available on erowid archives.

The preparation uses distilled water. The organic solvent (methanol etc) replaces water in the end only if water medium is not desired in final application.

A typical procedure from Hata paper is given below.
Preparation 1: U-Ni-B

Ten ml of solution prepared from 2 g of crystalline nickel chloride is warmed to 80-90°C and added, over a period of 1-2 minutes with stirring, to 5 g of zinc dust, which has been mixed with a small amount of water and placed in a water bath of the same temperature. Immediately afterward, the precipitate is filtered off with a sintered glass filter and washed with a small amount of hot distilled water. It is then plunged into 100 ml of 10% sodium hydroxide solution as quickly as possible and left standing for 15-25 minutes on a water bath at 50-60°C with occasional stirring. The supernatant liquid is decanted, and the remainder is washed with two 40 ml portions of distilled water at 50-60°C. Then the wash-water is replaced by ethanol. The catalyst, containing 0.45 g of nickel adhering to 2 g of zinc, is thus obtained. The last step, in which ethanol replaces the wash-water, can be omitted when reduction is to be carried out in an aqueous solution.

Gsd


I'm not sure on the exact patent, I read so many articles I think I confused myself.

However, I tried the above procedure and it seemed to work very well with Al foil strips instead of zinc. I got a far larger amount of chunky dark nickel. Thank you very much my friend! I'm haven't tested if it's active yet. I did however add a few drops of HCl to help the Al dissolve, would this hinder the reaction at all?

Tomorrow I'm going to try washing the Al with NaOH solution before precipitating the nickel without acid added.

One thing, storing the catalyst. Do I keep it in distilled water/ethanol or dry? Also, should one only collect the dark chunky nickel and discard the lighter Al powder or mix it together?
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[*] posted on 24-11-2013 at 01:56


Quote: Originally posted by pepsimax  
I'm not sure on the exact patent, I read so many articles I think I confused myself.

However, I tried the above procedure and it seemed to work very well with Al foil strips instead of zinc.

I don't quite understand. You can't call it Urushibara catalyst if you are doing it differently that proscribed by the literature. That makes no sense. The method of metallic Ni precipitation is what defines the catalyst activity and other properties. Just reducing Ni(II) to metallic Ni by a method of choice does not warrant the desired activity. The Urushibara catalysts types are defined by the preparation procedures, just like the Raney Ni catalysts are. How can you expect that whatever you got by your procedure will have the same activity as described in the literature, if you did it differently? You didn't even use zinc for the reduction, so it is not even close to the U-Ni-A and U-Ni-B catalysts.

If you used aluminium, even in acidic instead of neutral or basic media, you can be sure that what you got will be even less active than any Raney Ni catalyst would be. And by the experience gsd describes above, the Urushibara catalysts can have activity where Raney Ni does nothing. Whatever you got might or might not have catalytic activity in a chosen reduction system, but to give it a name you need a literature reference where its preparation and properties were described.




…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)

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[*] posted on 24-11-2013 at 15:02


Quote: Originally posted by Nicodem  
Quote: Originally posted by pepsimax  
I'm not sure on the exact patent, I read so many articles I think I confused myself.

However, I tried the above procedure and it seemed to work very well with Al foil strips instead of zinc.

I don't quite understand. You can't call it Urushibara catalyst if you are doing it differently that proscribed by the literature. That makes no sense. The method of metallic Ni precipitation is what defines the catalyst activity and other properties. Just reducing Ni(II) to metallic Ni by a method of choice does not warrant the desired activity. The Urushibara catalysts types are defined by the preparation procedures, just like the Raney Ni catalysts are. How can you expect that whatever you got by your procedure will have the same activity as described in the literature, if you did it differently? You didn't even use zinc for the reduction, so it is not even close to the U-Ni-A and U-Ni-B catalysts.

If you used aluminium, even in acidic instead of neutral or basic media, you can be sure that what you got will be even less active than any Raney Ni catalyst would be. And by the experience gsd describes above, the Urushibara catalysts can have activity where Raney Ni does nothing. Whatever you got might or might not have catalytic activity in a chosen reduction system, but to give it a name you need a literature reference where its preparation and properties were described.


I understand that, however i've read so many methods using zinc, alu and magnesium. The wiki article above states that also. They're all referred to as Urushibara. Is the zinc method above the only true Urushibara then?
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[*] posted on 27-4-2014 at 13:56


I also wonder about storage of UN? Anybody know?
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[*] posted on 14-2-2017 at 14:57


Quote: Originally posted by nannah  
I also wonder about storage of UN? Anybody know?



10.1002_047084289X.ru003

"Urushibara Catalysts. The Urushibara catalysts are a family of precipitated metal catalysts that have been compared to the more common Raney Nickel catalysts. Although the two can catalyze many of the same reactions, Urushibara metals offer several advantages: they are nonpyrophoric, are easily generated, have a long shelf life, and can catalyze highly regio- and stereoselective reductions.

Handling, Storage, and Precautions: Urushibara catalysts do not
appear to degrade upon short exposure to air(4 ). Protection from
moisture is required for long-term storage.
4, Ishige, M.; Shiota, M., Can. J. Chem. 1975, 53, 1700."


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[*] posted on 14-2-2017 at 16:54


Has anyone actually succeeded at reducing anything with a urushibara type catalyst? I have seen much talk about preparing them, but I have never seen a successful hydrogen gas hydrogenation or transfer hydrogenation reported here.
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