dormouse (Member)
04-24-00 13:25
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      Ultrasound-Nickel - a new catalyst?? -Cherrie Baby  Bookmark   


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Author  Topic:   Ultrasound-Nickel - a new catalyst?? 
Cherrie Baby
Hive Bee   posted 10-20-1999 01:16 AM          
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The book "Chemistry under Extreme or Non-Classical Conditions", Wiley, 1997, ed. by Rudi van Eldik and Colin D. Hubbard has a very interesting chapter on sonochemistry which includes this nugget of information on page 368.
"Metal powders such as nickel are generally poor catalysts, but can be activated to perform as good catalysts by sonification before use. Thus 3 micron nickel which is a poor catalyst in hydrogenation can be made quite efficient by sonification in ethanol before being used in the hydrogenation of oct-1-ene. The reason for this increase in activity is undoubtedly the removal of a passivitating outer oxide layer. The Auger effect analysis of the surface of the nickel after sonification clearly reveals the effect of cavitation upon the change in the composition of the surface. Other analyses (XPS, Ar+ -ion sputtering, area measurement) confirmed that the surface area increase is negligible, but reactive sites are created and the chemical distribution is modified."

[They give a reference for an hydrogenation carried out by this catalyst - Ultrasonics Sonochemistry, 1 (1994), S45]

Ultrasonics could be a good way to reactivate catalysts and, possibly replace Raney Nickel and Urushibara Nickel with the much easier to make - Ultrasound-Nickel.

I'll root out some of the references they give and call back.


 
(Lloyd)
Hive Bee   posted 10-20-1999 07:54 PM          
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Cherie Baby and Psychokitty lead the way into new vibratory ways to attune your sensitivities to faster places.
Electro magnetic, or high frequency pressure pulses: either way, or both.

How nifty.
(Lloyd)


KrZ
Hive Bee   posted 10-20-1999 11:06 PM          
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THIS I like Cherrie Baby. I will indeed check out this reference, and as I am already equipped with both hydrogenation and sonification equipment I will dream of its usage on some legal compound. xoxoxox
-=@=-


dwarfer
Hive Bee   posted 10-21-1999 02:41 PM          
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So if a person was to make some Urushibara from NiCl2, put it in a small glass flask with some ephedrine freebase dissolved in Eoh, place it into an ultrasonic cleaner bath for an indeterminate amount of time, would there be an expectation of reduction with this setup, or would there have to be additional impetus either electrical or chemical?
dwarfer


Osmium
PimpBee   posted 10-22-1999 03:30 AM          
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You forgot the H2.
 
dwarfer
Hive Bee   posted 10-22-1999 02:04 PM          
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My confusion arises from my recollection and integration of the Urushibara method and the iterations of the possibilities:
If you basify the alcohol with NaOH, which also is holding the ephedrine freebase in solution, and then add Al powder, I presume that would work, but it would not be a gradual process and could become a mess I intuit.

a half cell inside the beaker inside the ultrasonic bath is conceivable, using basified EOH as the electrolyte, but it's not clear without thought if that would give the hydrogen needful: also I wonder if the ultrasonic bath would keep the Urushibara nickle suspended adequately or if another complication would be introduced through requiring a stirrer.

What are the half cell reactions for say, pH 12 NaOH Ethyl OH basic essentially anhydrous conditions? (Well, 190 proof?)

Or would it be better to use methyl?

Sorry: out of my knowledge arena here. If I get some help on the dynamics i'll get practical feedback return in short order.

thanks

dwarfer


dwarfer
Hive Bee   posted 10-22-1999 03:28 PM          
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OK, without being quite as lazy, an after re-reading chem Guy's and Rev's comments in "New(ish) Hydrogenation catalysts, et al" thread (09-15-99, Crystal Meth)
it appears to me that the integration of the information in these two threads would entail perhaps the following:

preparation of the precipitated nickel

placing of the nickel in alcohol in the ultrasonic unit will activate it and clean it.

addition of freebase and NaOH will set the stage.

Addition of aluminum powder or perhaps even aluminum foil pieces will effect nascent hydrogen production.

(Electrolosis to get the H2 would introduce side reactions and of course tend to plate nickel on the cathode. so it's not the way to go.)


the alcohol is specified to dissolve the freebase.

And, the alcohol cleans the catalyst..

I have no idea if the amount of NaOH dissolveable in ethyl OH will be sufficient to liberate enough hydrogen to get the job done: nor any idea of what factors should be applied to the stoichiometry .

Any light in this area would be appreciated.

Thanks.

dwarfer


dwarfer
Hive Bee   posted 11-11-1999 07:23 PM          
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Should the ethyl alcohol be saturated with NaOH: or is there a target pH one should use??
 
dwarfer
Hive Bee   posted 11-12-1999 06:54 PM          
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hello, is there a vacuum??
Maybe if I read the posts before "going off" people would actually not be laughing at me behind their computer screens.

Oh well, dwarve's have thick hides.

This REPLACES urushibara: although the precipitation of the micron nickel is similar I presume.

KrZ have you had any results as of yet??

dummydwarfer


FMAN
Hive Bee   posted 11-14-1999 12:06 AM          
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No vaacume >>>>>>>...ECHO-o-o-o-
Ok so who knows how to fom scratch?????

Where is the foundational approach can I hook up my wires and coat them and put this underwater, I need the baisic expert whoes going hunting??????I got crystals what how do I utalize them and go simple basic piezio device???? well? THANKS TAAKE YOUR TIME

And add this to the checkout list thankyou...

---Amethystium---


whoops
Hive Bee   posted 11-14-1999 12:26 AM          
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How about hydrogenperoxidases will not these critters stand these pH oh Dwarfer umm it might be a novel way not tradational, might be done in water, might be the resultant of an investigation and so forth......Microwaves are similiar to um the comboid device why not this is probabbly the most clandestine and feared method, I like clay myself  Hum now whats all this stuff I been reading of surf incorporating this "K" I shure hope this mean potasium because I likes potassium stuff in my dirt....
 
CHEM GUY
Hive Bee   posted 11-29-1999 04:25 PM          
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From "Sonochemistry and Sonoluminesesnce", edited by Lawrence A. Crum, Timothy J Mason, Jacques L. Reisse and Kenneth S. Suslick, 1999, page 315-316
"4.3 EFFECTS OF ULTRASOUND ON HETROGENEOUS CATALYSIS

Catalytic reactions are of enormous importance in both labatory and industrial appliactions. Hetrogeneous catalysts often require rare and expensive metals. The use of ultrasound offers some hope of activating less reactive, but also less costly, metals. Such effects can occur in three distinct stages: (1) during the formation of the supported catalysts, (2) activation of the preformed catalysts, or (3) enhancement of catalystic behavoir during a catalytic reaction. Some early investigators of the effects of ultrasound on hetrogeneous catalysis can be found in the Soveit literature [3, 84]. In this early work, increaces in turnover rates were usually observed upon ultrsonic irraditation, but were rarely more than tenfold. ...

More impressive effects, however, have been reported [3], especially for the hydrogenations and hydrosilations of alkenes by Ni or Raney Ni powder. For example, as shown in Figure 25, the hydrogenation of alkenes by Ni powder is enormously enhanced by ultrasonic irradition [76, 80]. ... AES revealed that there is a striking decrease in the thickness of the oxide coat after ultrasonic irradtion. It is the removal of this passivating layer that is responisible for the >10^(5)-fold increase observed in catalytic activity.

...
[3] Suslick, K.S. (1997) Sonocatalysis, in Handbook of Hetrogeneous Catalysis; Ertl, G.; Knoozzinger, H.; Weitkamp, J.; eds; Wiley-VCH, Weinheim; vol 3, ch. 8.6, pp 1350-57.

[76] J. Am. Chem. Soc. 109, 3459 (1987).

[80] Suslick, K.S.; Casadonte, D.J.; Doktycz C.J. (1989) Solid State Ionics. 32/33, 44-452.

[84] Zh. Fiz. Khim. 50, 1641 (1976)
"


CHEM GUY
Hive Bee   posted 12-09-1999 07:18 PM          
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Dwarfer? Are you still experimenting with the Ni? Are you using the Urushibara nickel? Or perhaps just nickel dosed in ultrasound?
By the way, I like that idea you had about hitting the metal pipe container to create some ultrasound. Very inventive...


Semtex Enigma
Hive Bee   posted 12-11-1999 12:46 AM          
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Are any hiver(s) or people hiver(s) don't know reporting successes with either Urushibara or Ultrasound Nickle catalysts? I've seen a lot of information floating about, just wanted to know if it has been proven to work on a beloved honey type'o compounds. As usual thanks for any and all help...
 
CHEM GUY
Hive Bee   posted 12-11-1999 11:27 PM          
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The topic of Urushibabra nickel was first presented by me about 2 months ago, and as of yet I think only dwarfer has tryed to discover it's merits.
Next off the topic of ultrasound nickel was introduced even less than two months ago so it has virtually no one experimenting with it.

The nickel catalyst ideas are relatively new, so if you want to know, just experimant yourself and earn your place in history.


CHEM GUY
Hive Bee   posted 01-01-2000 01:11 PM          
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I saw a neat devise at Wal-Green's last night... A ultrasoundic humidifer for ~$30.
It might be just what this Ultrasound Ni needs... Dwarfer, anyone...


Botzwan~C7h7Ch
Hive Bee   posted 01-01-2000 11:09 PM          
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Maybe its got a chunk in it who knows?
why not make your own a more usefull technique could be aluted from standard equipment and methodology such as foot bath

I think a microsonificiation device would be a very simple thingy but I have yet to make one how about the basic info and a link to something pratical as for to make bouncing betty???


CHEM GUY
Hive Bee   posted 01-06-2000 06:49 PM          
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Her's something new...
From "The Journal of the American Chemical Soceity", yr 1987, Vol 109,
pages 3459-3461

"Hetrogeneous Sonocatalysis with Nickel Powder

We have dicovered that ultrasonic irradition of Ni powder increases
it's activity as a hydrogenation catalyst by >10^5. ...

The use of high-intensity ultrasound to initiate or enhance both
homogeneous and hetrogeneous chemical reactions has been under
intense investigation [1-7],...

Simple Ni powder is an extremely inactive catalyst for hydrogenation of
alkenes. Even after 2 X 10^4 min, no alkanes are deteacted with rapid
stirring under 1 atm of H2 at 273 K (i.e., <10 nM/min). In comparison
under the same conditions, if the nickel was first irradiated with
ultrasound [12], 1-nonene is hydrogenated at millimolar per min rates,
as shown on Figure 1. Ultrasonic pretreatment of ~1 h gives optimal
activity, which decreases with longer irradiation. The hydrogenation
activity is quite general and shows little dependance on the choice of
alkene... ; no reduction of ketones or aldehydes was observed.

Other methods of creating active Ni catalysts exsist [13]. The thermal
hydrogenation rates at 1 atm of H2 and 273 K with high surface area Ni
sponge (Raney Ni [13a], Aldrich Chemicals, grade W-2) are comparable
to those obtained eith ultrasoniclly activated Ni powder. Compared to
Raney Ni, however, our activaed Ni powder is more selective
(C-O double bonds are untouched), much easier to produce, and much
simpler to handle (nonpryophoric). Activation of Ni powders by H2 at
150 C and 10 atm will also generate reactive catalysts [13b], which
rapidily lose activity upon exposure to O2.

..."

[1] Adv, Organomet. Chem. 1986, 25, 73. (b) Modern Syth. Methods 1986,
4, 1. (c) Ultrasound: Its Chemical, Physical and Boilogical Effects
1987. (d) J Chem. Ed. 1986, 63, 427. (e) Ultrasonics 1985, 23, 157.

[2] J. Am. Chem. Soc. 1983, 105, 5781. (b) J. Am. Chem. Soc. 1983,
105, 6042. (c) High Energy Processes in Organomettalic Chemistry,
American Chemical Society 1987, p 191.

[3] High Energy Processes in Organomettalic Chemistry, American
Chemical Society 1987, pp 209-222. (b) Organometallics 1986, 5, 1257.
(c) Nachr. Chem. Tech. Lab. 1983, 31, 797. (d) J Org. Chem. 1982,
5030.

[4] Ultrsonics 1987, 25, 40. (b) Tetrahedron Lett. 1986, 27, 3149.
(c) J. Org. Chem. 1985, 50, 910, 5761. (d) J. Amer. Chem. Soc. 1980,
102, 7926.

[5] Angew. Chem., Intl. Ed. Engl. 1983, 22, 728. (b) J. Am. Chem. Soc.
1984, 106, 6856.

[6] Ultrasonics 1987, 25, 45. (b) J. Lab. Pract. 1984, 33, 13 and
references therein.

[7] Tetrahedron Lett. 1986, 27, 415. (b) J. Am. Oil Chem. Soc. 1983,
60, 1257. (c) Chim. Ind. (Milan 1968, 50, 314.

[12] All sonications were performed with a Heat Systems-Ultrasonics
W375 cell disruptor with a titanium immersion horn at acoustic
intensties of ~50 W/cm^2 at 20KHz, as described elesewher in
detail [2]. Irradiation in a low-intenstity ultrasonic cleaning bath
does give hydrogenation, but at greatly reduced rates. Hydrogenation
reactions were carried out at 273 K under 1 atm of H2. In a typical
reaction, 1 g of Ni powder (200 mesh, EM Science, Cherry Hill, NJ
08034) was added to a 10% solution of alkene in octane. ...


[13] Reagents for Organic Synthesis 1967, by Fieser, L. F., Vol. 1,
pp 723-731. (b) Thomas, C. L., Catalytic Porcesses and Proven
Catalysts 1970, pp 126-133. (c) Somorjai, G. A.; Chemistry in Two
Dimensions: Surfaces; 1981, pp 445-447 (d) J. Phys. Chem. 1983, 87,
915. (e) High Energy Process in Organicmetallic Chemistry,
... pp 223-245.


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Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
dwarfer
Hive Bee   posted 01-11-2000 12:23 PM          
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It is interesting to note the significant differentiation between what is described as "nickel powder" and "precipitated nickel" or "Urushibara catalysts".
Am I right in thinking the last two are essentially the same?

I would like to know what they mean when they talk about the ultrasound device power level: I've a unit which draws 120 watts total: it was made for cleaning contact lenses, and was removed from the market because it produced side emissions which apparently interfered with FAA frequencies.

I've seen them occassionally at thrift stores, which I habituate looking for visionware.........(like to see my soup boil  )

Anyway, I have yet to prepare the Urushibara catalyst: but Blanka/Ben Dover has although he has been somewhat coy with spilling his guts, uh, I mean, sharing his knowledge.

I can say that the technique, even in my small unit, in basified alcohol, but using Pd/C, works. Let me not claim total success: a dearly loved associate threw out the end product liquor when he\she\it was mad at me.

It does produce tiny bubbles, and everything is agitated well in the process. no external stirrer is needed.


 

This unit is similar: @ http://jewelrycleaners.com/ 

Can you afford $19.95??

The complete package, only
$19.95 + $4.00 S+H includes:

THE PRINCESS
ELECTRO-SONIC
JEWELRY CLEANING
MACHINE


 


I'll try to pursue Ben Dover/Blanka for his elucidating input.

regards
dwarfer


 
dwarfer
Hive Bee   posted 01-11-2000 01:20 PM          
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or if you need kilowatt capacity...


dwarfer
Hive Bee   posted 01-11-2000 01:56 PM          
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Final final:
Here's a site that has intermediate sized units for not TOO
much. http://www.abtool.com/p97.htm 

OK FOR THE REALLY CHEAP:

You know those ultrasonic emitters that you put in the attic and plug in and it annoys the rodents sensitive little cute baby ears and they move out??

They cost about 4 or 5$.

Get a bunch of them and surround your beaker with em, see, and then turn 'em on, see, and

never mind!


CHEM GUY
Hive Bee   posted 01-11-2000 05:43 PM          
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Yes, dwarfer I think that Urushibara nickel is much different than mircon nickel, or preceptitated nickel. The Urushibara nickel is clean and not oxidized.
The article I quoted was to illustrate the power of nickel. The reactions were carried out at 273 K! or 0 C! and at 1 atm H2! Talk about MILD conditions. Just imagine if you used greater than 1 atm H2, or greater tempatures... But remember what you really want is the solublity of H2 to be large. If you increase the tempature too much it will be like hot soda, AKA flat. I would stay in the neighborhood of 0-50 C at 1-40 atm. (Just an educated guess from similar experiements involving benzyl alcohols and nickel)

By the way, in your ultrasound/Pd experiment, was your alcohol basified or was the ephedrine just a free base? And why don't you write that up for the Rdodium page?

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Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
CHEM GUY
Hive Bee   posted 01-12-2000 12:26 AM          
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Rdodium = Rhodium
Any mircowave experiments with that Pd/C, dwarfer? Try writing them up, I'm sure that Rhodium will post them on his page.

This whole nickel, ultrasound, mircowave thing is so cool. It's a completely undiscovered country, just waiting for the taking. If I had the time I might try a nickel mircowave experiment.

By the way, I don't know if you remember a simaliar dicussion we had about preceptiated nickel vs. urushibara nickel a long while back but here is the quote from "New Hydrogenation Catalysts: Urushibara Catalysts", by Kazuo Hata, 1971, page 235-237

"A.2 CATALYTIC ACTIVITY OF PRECEPITATED METALS IN HYDROGENATION AT RAISED TEMPATURES

In spite of the ealier observation that ppt-metals are not useful for catalytic hydrogenation unless they are digested with acid or alkali, it was found that they exhibit catalytic activity when they are refluxed in water with various organic compounds Post 471 (not existing). The results of these experiments are shown on in Table A-7. In these experiments, ppt-Ni was prepared from 10 g of zinc dust in water and 8.1 g of crystalline NiCl2*6 H2O, and U-Ni-B(s) by digesting the ppt-Ni with aqueous sodium hydroxide solution. Each catalyst, containing about 2 g of Ni, was washed with water and then with ethanol. ...[ NOTE: U-Ni-B(s) is where the NiCl2*6 H2O crystals are washed with the zinc dust and not completely disolved in the water; U-Ni-B(s) is less active than U-Ni-BA.]

... In the hydrogenation of benzylaldehyde at rising tempatures both catalysts gave about the same proportion of toluene and benzyl alcohol, ppt-Ni being slightly more effective than U-Ni-B(s). On the other hand, at a summer room tempature (31-32 C) both catalysts gave only benzyl alcohol, U-Ni-B(s) being much more effective than ppt-Ni. ...

..."

I suppose there should be a modifacation to my earlier statement; the nickel experiments should be done at higher tempature ( above 32 C) to deoxygenate the benzyl alcohol.

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Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
CHEM GUY
Hive Bee   posted 01-12-2000 12:53 AM          
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Ooops! Forgot table A-7
A summary of Table A-7, All hydrogenations carried out without solvent.

Compound/g of compound/catalyst/Temp/intial presure in kg per cm^2/time/product and yeild (%)
+++++++++++++

Benzylaldehyde/10.6/ppt-Ni/24-80 C/50/25 min/toluene(65.8%)-benzyl alcohol(34%)

Benzylaldehyde/10.6/U-Ni-B(s)/24-88 C/50/30 min/toluene(53%)-benzyl alcohol(28%)

Benzene/15.6/ppt-Ni/26-176 C/100/360 min/cyclohexane(37%)-unidentified substance(4%)

Benzene/15.6/U-Ni-B(s)/28-174 C/100/360 min/cyclohexane(37%)
________________________
Now the thing that gets me is the pressures are in kg/cm^2. ? That doesn't make much sense since pressure is force per area and not mass per area, oh well. Since 1 kg is roughly equal to 2 lbs. and a cm^2 is roughly equal to 0.155 in.^2 I would say that 50 kg/cm^2 is roughly 645 lbs./in.^2 which is roughly equal to 46 atm. The pressures are to hard to reach and if not obtained might extend a reaction time, but otherwise this is a good outline for "our" experiments...

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Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
Osmium
PimpBee   posted 01-12-2000 04:37 AM          
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Kg/cm^2 = atm
because kg is considered a force (F=g*m)

Be care ful with MW experiments! Especially with H2 gas present and metal catalysts! Are you sure this works? Do you have refs for that? We all know what happens when you put a piece of metal into the MW.

For a nice display, place one of those AOL CDs in the MW for a few secs at a low power setting. Looks really nice.


 
CHEM GUY
Hive Bee   posted 01-12-2000 05:22 PM          
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Os, Read the article on Rhodium's page in the mircowave section about catalytic transfer hydrogenation. That's the method I was referring to.
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Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
dwarfer
Hive Bee   posted 01-13-2000 03:06 PM          
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OK were talking about ultrasound here rather than microwaves: that's another interesting method to a 30 second cook time for those who have not the time to wait!
Chem Guy, I appreciate your assistance in keeping me straight: I'll try the reaction again and avoid having another person throw out the end liquor. If successful I'll surely share the results.

My recollection was it was accomplished in slightly acidic (5% conc sulf.) primary alcohol with Pd/C: in a small beaker. The ultrasonic unit was appropriatly filled with water: you add water till you get a good "resononce coupling" with the beaker, at which time the water surfaces "dance".

This seemed to be the best integration of information from various threads about ppt Ni; Urushibara Ni; and freebase soluability.

I did this with the Pd/C, though: i did not have time to prepare the Ni from the salt.

Compared to the pressurized electro technique, this is really pretty easy: but more experimentation is needed. (Like, do it woik??)

Hopefully the posts above about cheap ultrasound units will encourage others to branch out as well.

dwrfr


Blanka
Hive Bee   posted 01-15-2000 09:52 PM          
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everyone has a microwave right? STICK a metal piece in there for fun! watch mini lightning bulbs shoot out and melt the walls down! It works better if you get the most EXPENSIVE microwave...
 
Blanka
Hive Bee   posted 01-15-2000 09:53 PM          
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lightning bulbs = bolts
 
Blanka
Hive Bee   posted 01-15-2000 09:59 PM          
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never got to this catalyst BUT... precipitated Ni from NiCl2 put in Naoh WORKS in the cooking of molasses... working on details right now (how pressure, heat, agitation all fits into this)
Since this method works, there's no doubt in my mind that the Ultrasonic will work. Why? because these two are related in that they both lack that outer oxide layer... I guess chem man or guy or whatever was right about the d-orbital..
 
CHEM GUY
Hive Bee   posted 01-16-2000 12:48 AM          
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Blanka read the article on the Rhodium page, MW: Catalytic Transfer Hydrogenation. The metallic particles are in solution and they don't spark, if the MW time is about 3 minutes at a time. Just read it.
Also if you "know" that the Urushibara method works please post the fictious work up and yields.

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Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
CHEM GUY
Hive Bee   posted 01-16-2000 12:58 AM          
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Here's the link to the MW: catalytic transfer hydrogenation text. http://lycaeum.org/~rhodium/chemistry/mw.cth.txt 
------------------
Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
Blanka
Hive Bee   posted 01-16-2000 04:29 AM          
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If I post in a separate thread, everyone would jump on it and try it and wouldn't have the same results.. there are some inconsistencies and variables there that need to be cleared up before I post. I am in no way done to make a conclusive report on this thing. I need to know what elements help the reaction work and which impede the reaction. At this point, I am just saying that I have got it to work which most of you probably knew would happen. I was sick and haven't put much work in this recently so I won't be posting this for at least a week. Sorry to all for the damned delays.
 
CHEM GUY
Hive Bee   posted 01-16-2000 02:12 PM          
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I was pretty dam sure that it would work, but the only difficultly I was having was coming up with a "working" range of tempatures and pressures.
From "Hydrogenation in Solutions", by D. V. Sokol'skii, yr 1964,

page 130
"The system Pd - Ni

The systems Pd- Ni and Pt - Ni are extremely interesting because a
small amount of Pt and Pd deposited on the nickel catalyst increase
its catalytic activity many times. Studies on nickel-containing
systems are difficult, owing to their ready oxidation and solubilty
in acid media."

page 140
"The pallidium - platinum alloy possesses a higher cataytic activity
than is possessed separately by pallidium and platinum prepared under
identical conditions [49]. ... Thus, the mixed catalyst is 50 times
more active than platinum and apporaimately twice as active as pure
pallidium."

[49]- Ibid.,4 60. 1951.

page 388
"In an overwhelming majority of cases, the hydrogenation rate in
solution is directly porportional to a hydrogean presure, up to a
certain limit. ... it was shown that in the hydrogenation over Raney
Nickel the reaction order with respect to hydrogen changes from unity
to zero at pressures of 10 to 20 atm. In isolated cases, especially
at high tempatures (~200 [degrees]), the reaction rate continues to
increase also at pressures above 50 atm."
=======================================
This suggests that a nickel catalyst, comparable with Raney nickel, has a good working range of of below 200 C and in 10 - 20 atm.
======================================

From: "Reactions of Hydrogen with Organic Compounds over
Copper-Chromium Oxide and Nickel Catalysts" by Homer Adkins (1937)

" The hydroxyl group in primary and secondary alcohols and phenols is
so resistant to hydrogenolysis that the reaction has not been observed
to occur over nickel or copper-chromium oxide at tempatures below
250, except when R contaions a phenyl, furyl. pyrryl, hydroxyl,
carbonyl or carbalkoxyl group."

"For example, benzyl alcohol may be converted almost quantitively to
toluene over nickel at 100 to 125:"

"TABLE 27-Hydrogenation of carbon to oxygen bonds in aryl carbinols
(Carbinol to methylene)
[I'm going to have to change the format of the table so that i can
post it, by the way no temp. was indicated...]

Benzyl alcohol-@ 125 C...10 min...2 gms Ni on keilsghur...(0.23 mol)
... converted to 88% toluene

Diphenylcarbinol-@ 200 C...3 hours...2 gms Ni on keilsghur...(0.17 mol)
...converted to 92% Diphenylmethane
"
===============================

I think the most important procedure with preparing a nickel cataylst is ridding it of copper, chlorides and oxides. The washing of the Urushibara catalysts seems to do this well, so stick with it. The acid media for nickel seems to have some problems as alluded to in the first quote from "Hydrogenation in Solutions". Also use Al for the prep of Urushibara, not only is it cheap and OTC, it also creates the most active form of the catalyst. If given the chance add some Pd, or Pt, it greatly invreases activity.

The greatest factor I think is the quality of the ephedrine used.

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Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
Blanka
Hive Bee   posted 01-18-2000 05:03 AM          
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THE FOLLOWING IS A FABRICATION OF THE MIND, THEY ARE IN NO WAY TRUE EVENTS:
The results I'm talking about aren't as good as I thought it would be... got scared and skimped on the pressure... trying to figure out if my low yields were due to low pressure or insufficient catalyst, incorrect preparation, wrong temp, or if the Urushibara isn't meant to be, ect. I'm gonna do another experiment with higher pressure, but I need to get a safer vessel so I can increase the pressure. I'm gonna work with Dwarf to get this shit done so I can write up the procedures. BTW I'm not posting till I get >70% yields...


Blanka
Hive Bee   posted 01-18-2000 05:06 AM          
--------------------------------------------------------------------------------
where's ref on Urushibara.. can't find the post... where did it say that Al made it better? I precipitated and then activated with NaOH... no Al was used...maybe why I'm getting bad yields.. any info on optimal temp, pressure, ways to improve catalyst activity?


dwarfer
Hive Bee   posted 01-18-2000 02:34 PM          
--------------------------------------------------------------------------------
Chem guy brought to the crystal forum first about 5 months ago.
Author Topic: New(ish) hydrogenation catalysts: Urushibara Catalysts
CHEM GUY
Member posted 09-15-99 05:35 PM


dwarfer
Hive Bee   posted 01-18-2000 02:47 PM          
-------------------------------------------------------------------------------- Post 111004 (Sploofer: "Re: New(ish) hydrogenation catalysts: Urushibara Catalysts", Stimulants) 
 
dwarfer
Hive Bee   posted 01-18-2000 03:06 PM          
--------------------------------------------------------------------------------
Quote from Chem Guy thread.

"You can store the preceptitated Ni for long preriods before use if you don't do the caustic wash before hand. So just precipitate 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."

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

A convergence or divergence of techniques ensues, as regards reduction of freebase amine alcohols appended to a benzene ring.

Because such reductions necessitate acidic conditions (Sulf preferred 10% to 20%) : and because freebase will dissolve in primary alcohols, acidic alcohols are facile for suspension of the pre-molasses.

The aluminum added to water with NaOH in it in a separate chamber will generate H2: which conveyed to the chamber with the alcohol in it, all under 65 PSI guage, should effect a textbook desired change on -+ and ++ configured stereoisomers.

It is presumed that in such a set up that the bubbling H2, which allegedly (thoretically) goes BLURP as the poppett valves outgas their excess pressure occassionally, will provide mixing of the alkys to everyones satisfaction.

In fact, in an obscure journal I recently read an experimenter reported success using Pd/C: however, this thread is about Ultrasound nickel: so forget the whole thing.

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


 
CHEM GUY
Hive Bee   posted 01-18-2000 08:25 PM          
--------------------------------------------------------------------------------
I've never read anywhere that acidic conditions were necessary for the reduction of benzyl alcohols. Indeed it is suggested in many places that acidic solution help.
From "Practical Catalytic Hydrogenations; Techniques and Aplications"
by Morris Frefelder, 1971.

"Removal of O-benzyl and related groups is enhanced by carrying out
reations in acidic media. When benzyl alcohols are reduced in acetic
acid or in acetic acid containing strong acid, deoxygenation is assumed
to proceed through the acetate. Since it has been shown that the rate
of displacement in reductions of compounds, ArCH2OR (where R = H,
CH3CO, CF3CO), is CF3CO > CH3CO > H, it might be advisible to add
trifluroacetic acid to hydrogenolysis when difficulty is encountered.

When deoxygenation of benzyl alochols is carried out in a nuetral
solvent containing mineral acid, reaction may proceed thoughan ester.
It may also go through a benzyl-type halide if hydrogen halide is
used to catalyize hydrogenolysis. It is also possible in mineral
acid-catalyzed hydrogenolyses of alcohols, ArCHOHCH2R, that dehydration
takes place, ArCH=CHR, followed by reduction of the double bond.

...

When O-debenzylation of a compound containing a basic nitrogen group
atom is to be carried out, it is advisable to use an equivalent of
acid to reduce the compound as an acid salt. ...

O-DEBENZYLATION AND RELATED REACTIONS

Arylmethanols

Benzyl alcohols, ArCH2OH, and related compoundsgenerally are reduced to
hydrocarbons so readily in nuetral solution or in in acidic media with
palladium catalysts under mild conditions, that there does not seem to
be any reason to consider other catalysts for this purpose.

Nuclear substitution appears to have little effect on hydrogenolysis of
benzyl alcohols. ... The effect of an amino group on the activity of
the catalyst can be overcome easily by the addition of an equivalent
of of acid [2]. The presence of a bulky group adjacent to the -CH2OH
group may impede hydrogen uptake, but reduction in acetic acid or
acetic acid containing some strong acid should aid the deoxygenation."


------------------
Everything in this post is for informational purposes only, and is not intended to facilitate illegal activity. I've done nothing illegal and nor should you.


 
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