02-21-01 19:39
No 174784
You guys will love this;
US patent #3941717 has some amazing stuff. First, how to make the catalyst;
100g 1% Pt/C suspended in 400 ml of H2O is heated to 60C, 1g DMSO is added, and the suspension is held at 60C for 15 minutes. That's it, filter, wash, and dessicate.
These sulfided catalysts show almost no reactivity towards benzene rings, hydrogenolysis of amines, and ketones. However, they are highly active towards nito compounds and imines.
The reaction examples they present are amazing, 98% yields using 0.5g of catalyst per 155g of starting material, etc.. Lots of insanely high yielding reductive aminations. Anyway, check the ref. out, you won't be sorry.
(Daddy)
02-22-01 07:37
No 174873
Hydrazine(s),( NH2NH2 ); or nonsubstituted hydrazinehydrate (80-85% solution commercially available from Eastman Kodak, if you wanna know how to make it, I can tell) must be used for extra activation of catalyst selectivity. No need for H2 for activation during preparation of the catalyst.
Pt/C is more interesting : better yields, NOWADAYS cheaper, and less weight needed (relation Pt to C ~ 1 to 16000 ; relation Pd to C ~ 1 to 6400).
Exeptionally good catalysator prparation :
Mix Pt/C in water with DMSO (dimethylsulfoxide, !non poisonous! opposed to sulfides)solution in water for 10 min, add then 24% hydrazinehydrate solution in water, mix again for 10 min and filter. (best results between 50 and 80 C.) Catalyst can be used wetted.
Hydrogenation of aromatic chlor/nitro complexes at ~ 10 bar, and temperatures to max 105 C. Higher is possible.
Good find, got many new ideas while looking up some related info. Thanks, LT/
WISDOMwillWIN
(Hallucinogenius)
02-22-01 12:21
No 174918
US #5498585 Lays out a much better catalyst preperation, without having to use hydrazine;
The platinum content of the final catalyst may be between 0.1 and 5 wt. %
with respect to the activated carbon. Addition of an oxidizing agent to the
aqueous solution of platinum compound before impregnating the powdered
support of activated carbon leads, surprisingly, to a platinum-containing
phase which greatly improves the catalytic performance after sulphidizing
with conventional sulphidizing agents.
Also astonishing is the fact that the catalyst prepared by means of adding
an oxidizing agent does not really exhibit an improved performance in
catalytic reactions before sulphidizing.
------------------------------------
To prepare a catalyst with 3% platinum load, 97 g of activated carbon (dry
weight) were stirred into distilled water with a stirring speed of 300 rpm.
12 g of a 25% strength aqueous solution of hexachloroplatinic acid
hexahydrate (corresponding to 3 g of Pt) and 3 ml of a 30% strength aqueous
solution of H.sub.2 O.sub.2, corresponding to 2 moles of H.sub.2 O.sub.2 per
mole of platinum, were added to this suspension.
Then the suspension was heated to 80.degree. C. and sodium carbonate was
added with continuous stirring, to precipitate barely soluble hydroxides. To
reduce the precipitate, 1.8 ml of 37% strength formaldehyde solution was
then added. The temperature of the suspension was also kept constant at
80.degree. C. during reduction. After reduction, the catalyst was filtered
off on a nutsch filter and washed with DI water.
B) Preparing the sulphidized catalyst according to the invention (Pt+H.sub.2
O.sub.2 +S)/C.
To prepare a catalyst with a 3% platinum load according to the invention, a
catalyst was first prepared in accordance with part A and then sulphidized
with dimethyl sulphoxide in accordance with example 1 in DE-PS 21 50 220.
The total sulphur content of the sulphidized catalyst was about 0.4 moles of
S per mole of Pt.
-----------------
The german patent procedure they refer to is simply the same procedure above (the one with just straight DMSO). Neither of these references really give the examples of reductive amination that make this catalyst so sexy. I'll try to find the original red. amin. references that got me started on this whole thing. If you have any good ones LT I'd love to see them.
(Hive Addict)
02-22-01 16:31
No 174951
Lots of insanely high yielding reductive aminations.
But you can get the same yields from plain PtO or Pt/C without bothering to sulfide the catalyst.
(Hallucinogenius)
02-22-01 18:10
No 174965
Not like this you can't. Look at LabTops PtO4 writeup. He describes usage of a very expensive quantity of the catalyst. You could use close to the same weight of 3% sulfided catalyst and get equal if not better results. You also must control the pressure to help reduction of imines in preference to ketones, which can cost time. The sulfided catalysts (1) Require less catalyst per quantity of ketone (2) Provide better yields (admittedly only slightly since the current techniques are already high yielding) and (3) Are poisoned much more slowly and therefore remain active longer. If you are going to be using a platinum catalyst for this sort of procedure, you might as well go through with such a simple procedure to improve it so much.
Also, this extreme selectivity finally opens up the possibility of a one-pot nitro->amine, amine+ketone->imine->amine catalytic hydrogenation reaction. Previously, side reactions while the amine was forming would have made this impossible, but now it is well in reach! And not a intensely nonscaleable Al/Hg type reaction, just dumped all your goodies together and blast it.
(Daddy)
02-23-01 15:44
No 175129
A minor correction : Adams catalyst (a brown powder)is neither PtO or PtO4, it is known as PtO2.H2O, also called Pt(IV)O2.
In the actual hydrogenation the platinumIVoxide PtO2.H2O is first reduced to an active form of finely-divided platinum, which is the real catalyst.
That's why Pt-black, pure Pt powder, was also used in the past.
The cost of the catalyst was not such a big deal in those days (20 years ago), because the price of the endproduct was at least 10x higher as nowadays, and nobody even knew, or was interested in, your intentions with it.
KrZ is totally right, reading these patents seem to give us both the same ideas, this opens up a whole new field of research for us, you guys seem to switch slowly when it comes to inventive thinking (It seems to take 2 years here before you can stamp innovative ideas in the mudbrains from most of you
. Luckily we also have some brighter ones, or they would still try to aminate peanutbutter. The ones who read this are excluded ofcourse from this lecture.)With these catalysts, an in situ catalytic amination of nitromethane to methylamine seems feasable, then in the same pot a MeNH2/ketone imination, then hydrogenation to amine, all with the same catalyst !
Well, to add something valuable also to this interesting topic, here's my way of working up all those filtrates/solvents with your precious catalyst in it :
. Test a small portion of your filtrates or solvent for platinum rests by acidifying with HCl and adding a few drops of stannous chloride solution : a yellow or brown colour develops according to the quantity of platinum present.
The yellow colour is soluble in ether, thus rendering the test more sensitive.
If Pt is found, treat the filtrate/solvent with excess of formaldehyde and NaOH solution and heat; Pt-black separates on standing and may be filtered and worked up with other Pt residues, f.e. :
[II]. Dissolve the Pt metal or Pt residues in aqua regia, evaporate just to dryness several times with concentrated HCl, dissolve the final residue in a little water and precipitate as ammoniumchloroplatinate with excess of saturated ammoniumchloride solution. Filter and dry the precipitate at 100 C.
Then you can make any favorable Pt complex with it, f.e. make PtO2.H2O again from it with sodium nitrate in 1 hour.
A damm simple way of avoiding all this is to just re-use your Pt "contaminated" solvents in your next hydrogenation, of course. LT/
WISDOM[i]willWIN
(Kitty-KrZ / Eraser)
03-04-01 15:46
No 176506
Damn. I hate you and I love you all at the same time you bastard-genius-god-you. Where DO YOU find all this good shit? (And I'm warning you: if you insult me with your response, it's back to the old vandal kitty once again!)
--PK
(Hallucinogenius)
03-05-01 08:27
No 176718
I was looking at the reaction catalyst guide on www.chemicals.matthey.com and saw this;
Both platinum and palladium are effective reductive alkylation catalysts. Sulfided platinum catalysts are recommended
in systems where ring saturation or hydrogenolysis is to be avoided. Using a sulfided platinum catalyst will also prevent undesired hydrogenation
of the aldehyde or ketone during reductive alkylation. Palladium catalysts generally become less suitable as the molecular weight of the carbonyl
compound increases. Palladium catalysts are used predominantly for reductive amination reactions. Reactions are typically carried out from 50 to
300ºC with 1 to 50 atmospheres H2 pressure using the aldehyde or ketone precursor as a solvent.
-Which sent me digging around for references on the subject. The guide is really unparalleled for up to date info on process catalysis.
(Hive Bee / Eraser)
03-12-01 12:28
No 178102
yep johnson - m - acros is a FINE company to do biz with nowadays.....
ifn yer a biz / .edu .....
hell they even make festerlytic contraptions to your specs at pseudo-reasonable costs.....
now look at some of their entries in their "ion targets" section....
interesting alloys will bee found in the strangest places....
intersting info ya'll dug up.....
jus a ravin inta da birdseye in da afternoon......
"remember little ones, love is real,not fade away, so pass some ammo on today......"
(Hive Addict)
03-12-01 19:55
No 178131
Maybe the metal "pure catalyst" is in fact poisioned by some kinda "ghost metal" and simply adding the sulfer to the solution makes the rare earth more catalytic:)
=======================================
I would think irridium would be very hard to remove from such metals such as platnium and also paladium, perhaps though if hydrazine like solutions were employed and suffecient "gradding" were employed, perhaps the irridium itself would become a catalytic artifiact in the process, usually "such" are extreemly difficult to issolate and purify, apart from electro-gradding and voltage specific processing, overall it is impossible to remove the final last percentage, there is allways improvements made to the processing resulting in ever increasiing technicial specifications regarding "purity"
Irridium forms brown black bluepurple and redish solutions, these solutions are can be controled and the substance makes an ideal observation catalyst, influenced by current tempature pressure ionic pH and gasses to name a few, um employed to make hyperdermic needles hard.
Amethystium
(Stonium's Main Man)
03-13-01 04:12
No 178211
No FMAN, the sulfur will render the most active sites on that catalyst inactive (called catalyst poisoning). Less activity means more selectivity, since those most active sites are responsible for aromatic ring hydrogenation. This won't happen anymore when the catalyst is poisoned.
(Daddy)
03-13-01 17:31
No 178328
Psychokitty, to partially answer your question also:
Post 35725 (LaBTop: "Re: KrZ posts deleted, some questions left.", Methods Discourse) ; Post 35725 (LaBTop: "Re: KrZ posts deleted, some questions left.", Methods Discourse), type in IE/Edit/Find(onThisPage) Johnson Matthey, 4 finds ; Post 35725 (LaBTop: "Re: KrZ posts deleted, some questions left.", Methods Discourse), idem, 1 find ; Post 35725 (LaBTop: "Re: KrZ posts deleted, some questions left.", Methods Discourse).
"Heck" olefination :
http://www.chemicals.matthey.com/catalys
Many functional groups are compatible with Heck conditions, which would enable one to synthesize carbo- and heterocyclic compounds and C-C bonded isomerized products, including natural products.
Very interesting, aint'it?
Look for "quantum leap" and also :
Regio- and stereoselectivity of Heck C-C couplings have been successfully demonstrated as the first instance of a respectable optical induction by Hayashi and Ozawa, f.e:
C=C Couplings (http://www.chemicals.matthey.com/cataly
Many more interesting developments, like this one:
Recently F. Mathey (Angew. Chem. Int. Ed. Engl., 1997, 36(21), 2364) introduced a ten-membered tetraphosphole macrocycle based Pd catalyst for Heck couplings. Mathey et. al., made a comparative study of palladacycles with Herrmann et. al. and concluded that his catalyst was active even after 48 hours of additional heating with quantitative conversions. The structure of the catalyst is given below.
And then have a look at Rhodiums Link page at the SynGen link, and view the lysergic acid routes the artificial intelligence program came up with [our friend Hughes is not such an idiot as many of you think, he just has a very touchy personality
heheh.One gmole or KGmole of LSD for a few thousand dollars! LT/
The FUCKIN Lycaeum PicProxy or the whole goddamm MarkUp doesn't work again, I get a main headache from this shit, the fuckin slow server can't get in sync with fast thinking and typing, constantly these server reboots, KILL the fuckin machine, so they HAVE to put a FAST Hive server there, the SCROOGES!
(Daddy)
03-13-01 21:12
No 178362
http://www.chemicals.matthey.com/catalys
Chiral Catalysis
Be amazed, and do not ever forget that we, in this place, are FAR behind the reality of these guys.
But we are learning fast, or not?
LT/WISDOMwillWIN
(Master Searcher)
03-15-01 03:32
No 178649
US patent 2402626 discloses poison resistant metal sulfide catalysts. I found this one recently while looking through 564/375.
http://www.geocities.com/dritte123/PSPF.
http://www.privacy.org/article.php?sid=6
http://www.privacy.org
(Stranger)
05-14-01 03:45
No 194257
heterogeneous catalysis is the use of finely divided platinum to catalyze the reaction? yes? catalytic converters mounted on automobiles have that stuff...
this is my first post, so burn me, if I did this wrong!
(Old P2P Cook)
04-23-02 23:52
No 300700
You guys will love this;
US patent #3941717 has some amazing stuff.
I just read the abstract of this patent and I do not see the amazing stuff that you saw.
These sulfided catalysts show almost no reactivity towards benzene rings, hydrogenolysis of amines, and ketones.
This may or may not be true however it is certainly not what is claimed in the patent. The patent makes no claims either way about this.
However, they are highly active towards nito compounds and imines.
The patent only claims the catalysts to be suitable for the hydrogenation of aromatic nitro groups. The patent makes no claims as to activity towards imines.
The reaction examples they present are amazing, 98% yields using 0.5g of catalyst per 155g of starting material, etc.. Lots of insanely high yielding reductive aminations. Anyway, check the ref. out, you won't be sorry.
Again, the only hydrogenations I see in this patent are of nitrobenzenes to anilines. The hydrogenation of nitrobenzenes is known to procede much more rapidly and with much lower catalyst concentration than than the hydrogenation of many other functional groups. To apply the claims in this patent about catalyst loading in the hydrogenation of nitrobenzenes to the hydrogenation of other functional groups is spurious.
(Hive Bee)
04-29-02 07:07
No 302983
All BS with this new catalysts?
I do not understand.
...this opens up a whole new field of research for us, you guys seem to switch slowly when it comes to inventive thinking..
thus was LabTop´s opinion
Post 175129 (LaBTop: "Re: Sulfided Platinum Catalysts", Novel Discourse)
If somebody skilled in the art would be able and willing to disclose how catalyst ratio, catalyst loading, pressure, solvent and temperature affect activity to functional groups I would be very pleased.
So thats what I want to know so hardly.
thanks
ORGY