posted 09-15-99 05:35 PM         

The book: "New Hydrogenation Catalysts: Urushibara Catalysts", by Kazuo Hata, 1971.

"By adding zinc dust to a solution of nickel chloride a nickel powder was obtained, a powder which hereafter is referred to as 'preceptiataed nickel'. The preceptitated nickel was added to an aklaline solution of estrone and aluminium grains were then added to reduce the estrone by means of nascent hydrogen generation, in combonation with the nickel. The result was a complete sucess as expected, and estradiol was obtained in good yeild. Preceptitated copper obtained in the same way from a solution of copper sulfate and zinc dust also proved to be efficent in reducing estrone to estrdiol."
"However, Urushibara took a further step; to an alkaline solution of estrone he added preceptitated nickel, and then passed hydrogen through it while shaking. This was done with a negative expectation; for he presumed that reduction would not take place when hydrogen was merely passed through the solution without adding alumium grains, and that the preceptitated nickel or copper would be catalytically active only when combined with nascent hydrogen. To his pleased surprise, reduction took place, and estradiol was obtained. Preceptitated nickel exhibited catalytic activity!"

It goes on to state that the nickel can be preceptitated by alumium grains instead of zinc dust, and that infact the preceptitated nickel produced in this manner is more active . It even hydrogenates aromatic groups, and it comparable to raney nickel in almost all aspects. The preceptitated nickel is also easyier to handle than raney nickel, it won't catch fire, and therefore easyly recycled by takeing the preceptitated nickel and turning it into a salt to again be preceptitated.

posted 09-15-99 06:07 PM         

"Preparation 17: U-Ni-BA (Modified Method)
Place 50 g of aluminum grains (40-80 mesh) in a beaker, wash well with water, and add 50 ml of 6 N hydrochloric acid on a water bath. When the surface of the grains has become clean, the upper liquid is decanted and the aluminum is washed several times with water. It is then transferred to a 11 wide-necked round-bottomed flask (Note 1), and 200 ml of solution containing 40.4 g of NiCl2,6H2O (corresponding to 10 g of nickel) is poured onto the aluminum grains all at once. The mixture is gently heated for a short time on a water bath to start a mild reaction. The temperature should be maintained below 70 C (Note 2) to prevent the reaction from getting out of control, and the mixture is stirred occasionally with a stainless steel spatula. The aluminum grains gradually turn black as nickel deposits on them, and the reaction mixture becomes a viscous slush. When the reaction subsides, the mixture is heated on a boiling water bath (Note 3). A violent reaction begins again and the whole mixture becomes a massive gel with the green color of the nickel ion disappearing. The semi-solid product is washed several times with water to remove water-soluble matter and the wash-ings are decanted. After the gel-like substance is removed, the resultant slushy solid is collected on a Buchner funnel and dried. The precipitated nickel obtained weighs 65-70 g, differing slightly according to the case, and contains about 10 g of nickel. The precipitated nickel can be stored in a moisture-free vessel. In all of the above procedures, tap water may be used for washing.
To obtain U-Ni BA containing about 2 g of nickel, one-fifth of the above precipitated nickel is treated with sodium hydroxide solution. The dry precipitated nickel is added in small portions with vigorous stirring to a 11 or larger three-necked round-bottomed flask equipped with a good stirrer and a thermometer, and containing 250 g of 20% sodium hydroxide solution. As a violent reaction takes place with the evolution of hydrogen, the flask should be cooled in an ice bath with vigorous stirring to maintain the temperature at 50-55 C. Addition of the entire amount of precipitated nickel requires 10-15 minutes. Stirring is continued until the evolution of hydrogen ceases, with the occasional application of heat, if necessary, on a water bath to maintain the temperature at about 50 C. When the reaction is complete, the mixture is left standing for a few minutes to allow the black particles to settle (Note 4), and the upper liquor is decanted. Thc black matter is transferred to a 100 ml beaker with distilled water and washed with 200 ml of warm distilled water divided into several portions. At the end of this operation, the wash-water should be neutral to phenolphthalein. The solid is washed with the solvent to be used for the hydrogenation, e.g., ethanol, and transferred to the reduction vessel.

posted 09-15-99 06:11 PM         

What is an esterone?

what is an esterdiol?

What is hydrogenation?

posted 09-15-99 06:18 PM         

is the solution Ammonia, does it say explictly what the solutions is tell me it does not-is it 111triclorethelene? the catalyst???

What was that stuff that makes salt in a solution of ammonia ya mentioned?

Which layer do I put the electrodes in ONCORE MAN I am getting real close

posted 09-15-99 11:01 PM         

------------------
-the good reverend drone

posted 09-16-99 02:39 PM         

Should a topic touched on in another forum 9 months ago never be spoken of again?

Have you had any experience with reductive aminations using this method?

What is your opinion of this technique?

posted 09-17-1999 05:36 PM         

What's with this "Chem, I mean Rev" business?

I've done a few hydrogenations, but none with this particular catalyst. Hydrogenation is NOT a method for the novice -- without training and proper equipment, pressurized hydrogen is quite dangerous. But for pilot plant scale batches, this is definately a good way to go.

------------------
-the good reverend drone

posted 09-17-1999 07:46 PM         

If my attribution is in error, I apologize.

=====================

However, this is an excellent opportunity to ask you a question: if you have no direct experience your best informed guess will nevertheless be appreciated.

1. A safe way to electrolytically produce hydrogen @ 60 PSI in a divided cell has been developed and previously described.

2. Production of "molasses" {molasses is methamphetamine: honey having recently been circumscribed as regards it's usage in this forum's principle goal} has been described by Lone Ranger as possible in an acidic (20% H2SO4 ) hydrogen rich aqueous solution at 40 PSI or so, over Pd, with significant agitation.

This has been confirmed by at least one experimenter to be true, using the above referenced equipment, and Pd/C: although yields were reported to still be unacceptable. (A guess of 35 to 55%: pure guess: uncalibrated test monkey)

A competent on-line associate,
\/\/AR]-[AMMER has stated that Raney Nickle is the preferred catalyst, but it is essentially unavailable to those on the west coast without undue risk.

This appears to offer an IMPROVED substitute as you have said.

QUESTION: (at last!)

The above estrone-estradiol was done in basic solution with something that appears to me to be similar to the "lost metal" reduction (maybe wrong but that's not my question anyway.)

1. Can the hydrogen be produced by the electrolysis of water in a basic solution containing pre-molasses with any expectation of success in accord with Chem Guy's first line in this thread?

2. Inasmuch as the Ni is not being potentially "contaminated" by the addition of another metal to generate nascent Hydrogen, do you surmise the Ni would have to be re-precipitated each time??

3. Many of the electro-reductive attempts arising from "Fester's New Method" (or whatever) have been disappointing because of the yields in the different steps. This technique appears to be one that may perhaps go to completion and stop.

Or is tht wishful thinking.

The theoretical # of coulombs per gram of source material has had to be multiplied by at least 2 or 3 in prior experiments: is this a function of the efficiency of the catalyst, and if so have you any idea of the factor which should be applied to this catalyst.

finally:

4. Is it just the HUGE surface area of this precipitate that makes it catalytic in these reactions?? If not, what??

Thanks , Rev.

dwarfer

posted 09-18-1999 01:58 PM         

2) This is a hydrogenation catalyst, just like raney nickel and in fact more powerful and easier to obtain and easier to handle. And just like raney nickel it can reduce a benzyl alcohol to an aromatic hydrocarbon.

3) The solvent is caustic water. In the examples, NaOH was preferred because it created a more active catalyst.

4) Yes, this method works for reductive amination, but it has promise for other clandestine ventures. (The variation used for reductive amination uses NH3 as the caustic wash instead of NaOH.)

Dwafer:

This method can use molecular hydrogen instead of nascent hydrogen, but I think that the production of hydrogen is more easily produced by Al in a NaOH solution rather than, electrolysis for example.

The Ni isn't harmed or consumed in anyway by the process of hydrogenation, either by Al in NaOH or simple addition of molecular hydrogen. Just like Pd or Pt it slowly degrades in quality though, but unlike like Pd or Pt it is easily regenerated. All that is needed is to make the Ni and turn it back into NiCl2 and repreceptitate it.
You can store the preceptitated Ni for long preriods before use if you don't do the caustic wash before hand. So just preceptitate a large batch of the Ni and let it sit until use. At that point wash it with the NaOH to activate it and either use molecular hydrogen or add Al into the NaOH solution as well to start the hydrogenation.

The NaOH wash actually washes away an impurty that deactives the preceptitated Ni. The compound is ZnClOH, which is rather soluble in caustic or acidic conditions, which is way you wash the Ni with a caustic solution. You can use an acetic acid or HCl wash instead, but the catalyst created in this manner is less potent.

As for your last question dwarfer, the catalytic activity is in part due to the huge surface area of the Ni, but it is more due to the fact that the preceptitated Ni has a free d- orbitial. (I read that in the book) When it preceptitates out of solution it binds to, either the Zn or Al, and opens its d orbitail. I guess it's kind of like the Hg-Al amalgam in that respect. If the Cl ions are present, they interfer with the d orbitial and fuck the shit up, which is why the HCl wash creates a much less potent catalyst.

posted 09-18-1999 03:42 PM         

I'm happy to offer my help where I can. I like "molases"; its a good honest-sonding wholesome name. Let's go down you list of questions:

1) "Pre-molases" isn't soluble in basic water, and so you run into a few problems. You need H2O, since its your hydride source, but your reagents won't dissolve without acid, which will poison your catalyst.

Now here's one of the big differences between palladium catalysts and its neighboring Ni and Pt counterparts: while Pd seems to work well in a acidic atmosphere, in the cases of Ni and Pt, their catalytic activity is greatly reduced. Thus base is added.

So how will a strongly ionic substance like NaOH affect the efficiency of the H2 generator? not well, I'm afraid. It will work, but expect (depending on concentrations, etc.) a greater electricity demand.

2. No, not really. The point behind this novel catalyst preparation technique is to produce a final product of elemental Ni, with as much surface area as possible. Ni is actually rather stable in this form. If the material was partially reoxidized, it would be reduced to its original 0 formal charge state during the first steps of the hydrogenation.

Now this doesn't mean you can treat it just ay old way. Other metals can poison your catalyst, as can compounds like pyridines. Acids will do it too. After time, the catalyst simply won't do what you hope it to, but this should take at least several runs.

3.Catalytic hydrogenation is very clean, with essentially no side reactions possible. If you are willing to dismiss the dangers of handling pressurized H2 (you are, and you seem to know what you're doing), then yes, this method is great.

However, the electrolysis makes things a little more complcated. Electrolysis adds a whole new gamut of variables, with numerous side reactions possible, and this CAN affect you catalysts as well. Yes, ester and halide electrolysis are very clean, but to be perfectly honest, I can't guaruntee the same with OH reducing on phenylpropanolamines. I think H2 would be best generated in a separate containter, then added.

4.You're right: the increased catalytic activity of this catalyst over the Raney nickel predecessor has to do with the fact that the only place this reaction can occur is on the surface of the metal.

The mechanism, as chem guy indicated, utilizes the bonding and anti-bonding that Ni 's emply d-orbitals have when it interacts with the pi-orbitals of the oxygen, and the s-orbital of elemental hydrogen. The anti-bonding (or "back-bonding") weakens the electron density of the pinorbitals, making the oxygen more receptive to a nucleophilic attack by the hydride.

This is not however the same phenomenon ovberved with Al(Hg), where it is presumed to be driven more by an electron transfer mechanism.

------------------
-the good reverend drone

posted 09-20-1999 01:03 AM         

I think (or guess, or intuit, or wishfully hope) that this thread may be revolutionary.

I'll look for the book but suspect it may only be available at the Univ library 60 miles away.

chem Guy and Rev.: thank you for your information and assistance.

posted 09-20-1999 03:06 PM         

How many articles are there??

Howsabout sending me your addy to hivedwarfer@hotmail.com??

Or use zipmail if you prefer.

posted 09-20-1999 03:12 PM         

Sorry.

Would carboxilic acids have the same potential to inactivate the Ni as mineral acids??

thx

Wonder if freebase HAS to go acidic to dissolve: never tried to approach the neutral and see.

Slap me if I need it.