smokemouth
(Member)
04-11-00 23:56
No 107796
      Practical palladium salt recovery - rev drone
(Rated as: good read)
 Bookmark   

  [Image]  [Image]  the Hive BB
           [Image][Image]  Methods Discourse
           [Image][Image]  Practical palladium salt recovery (Page 1)

                         [Post New Topic]  [Post A Reply]
                  profile | register | preferences | faq | search
                                          next newest topic | next oldest
  This topic is 2 pages long:   1  2                               topic
  Author        Topic:   Practical palladium salt recovery

  rev drone     [Image] posted 07-17-1999 02:46 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                I thought I'd open this thread, since despite the
                popularity of the Wacker oxidation, little discussion has
                gone into practical, eficient methods of recovering that
                oh-so-expenisve catalyst from the reaction.

                I've been giving this problem A LOT of attention as of
                late, trying to find an easy way to get back clean, pure
                PdCl2 (or its equivalent) without too much mess, too much
                heat, too much disgusting organic tar impurities, etc.

                Thus far, the most promising method looks like a cute
                cheating trick, used by inorganic chemists to purify
                precious metals. By adding ammonium chloride, followed by
                excess ammonium and gently heating, the ammonia will
                chelate with the palladium salt, forming Pd(NH3)2Cl2,
                which precipitates out nicely (this relies on the fact
                that palladium, despite its formal +2 charge, is
                4-coordinating and likes the nitrogen's lone pairs;
                d-block chemistry is wierd, ain't it?) Another even
                quicker, cleaner method might be with dimethylgyoxime (
                H3C-C(=NOH)-C(=NOH)-CH3 ), which apparently chelates even
                better. The precipated palladium complex is extremely
                pure, filters well, and is very insoluble in damn near
                everthing. Apparently, these complexes can be converted
                back into our belove catalysts with the aide of hot Hcl
                solution.

                I have ref's, and I'm still pouring through all the
                literature, but I thought this little nugget might get
                people thinking, and thus perhaps help 'catalyze' the
                developement process of this technique. The more people
                working on this, the better. Input is always appreciated.

                So what do people think? Despite my best efforts, I
                couldn't find too many hot procedures our there in the
                clandestine literature, but that doesn't mean its not
                there. If anyone has an obsucre nugget of chemical
                technology that they'd like to share that will blow my
                suggestions out of the water, please do so.

                Looking forward to your input,

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

  rev drone     [Image] posted 07-17-1999 02:52 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                Of course, I mean "chelating", not "cheating". Also I
                forgot to mention methods involving simply precipitating
                Pd(OH)2 by adding conc. base, though this doesn't strike
                me as an easy-to-filter thing to do. Another thing to
                consider is using ETDA as a ligand; not sure how it would
                work, but I'm sure something could be arranged.

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

  Semtex        [Image] posted 07-17-1999 06:29 PM
  Enigma
  Hive Bee      [Click Here to See the Profile for Semtex Enigma]
                [Reply w/Quote]
                ---------------------------------------------------------
                Drone!!! Nice to see you back up and about, that Spitball
                PiMP didn't treat you too badly did he? I had a
                discussion some time ago with some people about this very
                subject(Pd recovery) and came to the conclusion that in
                an air or O2 powered wacker one could usually recover a
                good 70%+ of the PdCl2 by repeatedly filtering the rxn
                mixture at the end of the rxn. It is recovered as PdCl2
                so there is no need to convert it back. Fine filter paper
                and LOTS of filtrations give the best results from what
                I've heard. However I think most people are using the
                benzo wacker now, would your recovery method work with it
                as well???

                Good to see you again, can't wait for the next sermon...
                [Image]

  rev drone     [Image] posted 07-17-1999 06:57 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                SE,

                Thanks SE; glad to be back. Yeah, it was kinda harsh at
                Spitball's little "Economic Empowerment Camp", but I'm
                still alive. Remeber this: if you ever consider
                responding to one of those sleazy ads like "Make Money
                FAST, FAST, FAST", or "Lose weight...And get paid while
                doing it!", remember there's a good chance that Spitball
                is the one behind it, and you too might end up sewing
                together fake afro's (or worse yet, put on "mule detail"
                -- ouch!!)

                Anyways, 70% is pretty good, but I'm shooting for 99% if
                possible. If this were done on a large scale (which is
                concievbly could), then filtering large volumes of
                solution for semi-suspended microparticles doesn't sound
                fun. What was the URL for this discussion? Definately,
                the method that you suggested has a lot of merit,
                considering the simplicity.

                Say, what about crashing it out by adding some highly
                soluble chloride salt, thus precipitating it due to the
                effect of competing ions? Perhaps saturating the solution
                with ammonium choride? It might precipitate the copper
                salt as well, but who knows? Maybe if it were saturated
                with CuCl2, the PdCl2 would simply crash out, and could
                be washed clean with something? I dunno. just a thought.
                I think I may have the solubility thing backwards, so
                please correct me if I'm wrong.

                Thanks for sharing; anybody else out there want to join
                in the discussion?

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

  ymir          [Image] posted 07-17-1999 08:12 PM
  Hive Bee
                [Click Here to See the Profile for ymir]
                [Reply w/Quote]
                ---------------------------------------------------------
                Doesn't Brauer's recommend the use of ammonium chloride
                for this recovery? It would seem that this particular bit
                of recycling would be of immense use to many members of
                the Hive. A patent was mentioned (US patent #5,304,233)
                by r2d3 awhile ago. This bee would be very interested in
                any information in this matter.

  Semtex        [Image] posted 07-17-1999 08:22 PM
  Enigma
  Hive Bee      [Click Here to See the Profile for Semtex Enigma]
                [Reply w/Quote]
                ---------------------------------------------------------
                Giving the URL would bee difficult as this discussion
                took place thru email. I'm not sure if the method you
                suggest would work because I am not into the chem-speak
                as deep as you are. It doesn't seem all that difficult
                and it means one less thing to keep buying, with LaBTop's
                method(s) to madness(25KG!!!) that's a LOT of PdCl2...
                [Image]

  Semtex        [Image] posted 07-17-1999 08:26 PM
  Enigma
  Hive Bee      [Click Here to See the Profile for Semtex Enigma]
                [Reply w/Quote]
                ---------------------------------------------------------
                Oh yeah, Drone before I forget, go get yourself an
                account at http://www.hushmail.com  , on the fly encryption, can
                be used WITH PGP to add another layer of security...
                [Image]

  ymir          [Image] posted 07-18-1999 05:02 AM
  Hive Bee
                [Click Here to See the Profile for ymir]
                [Reply w/Quote]
                ---------------------------------------------------------
                Semtex: Did any of the bees try using Celite (aka Filter
                Aid, or Dimotaceous Earth) to cut down on the
                filtrations?

  ymir          [Image] posted 07-18-1999 08:59 AM
  Hive Bee
                [Click Here to See the Profile for ymir]
                [Reply w/Quote]
                ---------------------------------------------------------
                Other methods that may bear fruit, depending on equipment
                availability and skills, would be cementation or
                reductive precipitation, and electrolytic precipitation.
                An iron cathode is used to cement copper, this may
                provide a means of seperation of copper from palladium.
                Electrowinning is a more selective technique than
                cementation, it has been used to seperate copper from
                other metals. By carefully controlling the cell
                potential, a selevtive seperation is possible. This is
                the method of choice for refining copper. The copper
                serves as the soluble anode. Another technique of
                possible use is solvent extraction. Several extractions
                are usually required. Sulfuric acid is most often used
                for sludge extraction. A few good references that should
                be looked at are: Metal Recovery from Industrial Waste,
                by C. S. Brooks (1991); Solvent Extraction, Part II, G.
                M. Ritcey and A. W. Ashbrook (1984) and Industrial
                Electrochemistry, C. L. Mantell (1950).

  LaBTop        [Image] posted 07-18-1999 09:41 AM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                A Centrifuge. LT/

                ------------------
                EMOTIONSwill always beFREE!

  LaBTop        [Image] posted 07-18-1999 09:46 AM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                A Resin filled chromatographic pressure column with
                tubing pump. LT/
                PS: 25 kg we used to call a sample run...

                ------------------
                EMOTIONSwill always beFREE!

  LaBTop        [Image] posted 07-18-1999 09:54 AM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                A piston/cylinder thingy with a paperfilter at the
                bottom. Press all the fluids through, burn the filter +
                rest at 800 C in a little oven. Hope PdCl2 stays behind.
                Or lower temp. LT/

                ------------------
                EMOTIONSwill always beFREE!

  r2d3          [Image] posted 07-18-1999 11:58 AM
  Hive Bee
                [Click Here to See the Profile for r2d3]
                [Reply w/Quote]
                ---------------------------------------------------------
                The patent I mentioned, uses sodium borohydride to
                recover palladium salts from an acidic solution. Check it
                out on the IBM patent server.

  Semtex        [Image] posted 07-18-1999 02:02 PM
  Enigma
  Hive Bee      [Click Here to See the Profile for Semtex Enigma]
                [Reply w/Quote]
                ---------------------------------------------------------
                LaBTop: Could I be the "taste tester" for your "sample
                run"?!? [Image]

  LaBTop        [Image] posted 07-19-1999 08:40 AM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                What about 1:1 PdCl2 / 37% formaldehyde, and 30% NaOH
                added to slightly alkaline, heat to 80 C, stirr 10 min,
                let catalyst settle down.
                Decant the supernatant solution, replace by water and
                resuspend the catalyst.
                Wash the catalyst by decantation 8-10 times with water
                and then collect it on a medium-porosity sintered glass
                funnel, wash with five 25 ml portions of water and suck
                as dry as possible.
                Dry the funnel and contents at 80 C , powder the catalyst
                and store in a tightly stoppered bottle.
                Catalysts reduced with formaldehyde contain no absorbed
                hydrogen and are less pyrophoric. (If you used them in a
                hydrogynator).
                Why not use PdCl2 on carbon? Can be stored indefinitely.
                The palladium salt is reduced to the finely metal as
                required:
                PdCl2 + H2 --> Pd + 2HCl
                or as finely-devided metal deposited upon activated
                carbon (5 or 10 % Pd):
                Na2PdCl4 + HCHO + 3NaOH --> Pd + HCOONa + 4NaCl + 2H2O .
                I mixed a few methods here, see what you can do with it.
                Have more if you want. Am sleepy.
                LT/

                ------------------
                EMOTIONSwill always beFREE!

  spitball      [Image] posted 07-20-1999 04:30 AM
  Pimp Master
                [Click Here to See the Profile for spitball]
                [Reply w/Quote]
                ---------------------------------------------------------
                Let me sum up suggestions thus far into 5 separate
                categories to aid in our discussion.

                1) Simple filtration

                a)A Centrifuge (LabTOp)

                b)Resin filled chromatographic pressure column with
                tubing pump [i.e. a preparative-scale HPLC
                machine](LabTOp)

                c)Celite (aka Filter Aid, or Dimotaceous Earth) to cut
                down on the filtrations (Ymir)

                d)A piston/cylinder thingy with a paperfilter at the
                bottom. (LabTop)

                2) Electrolytic methods

                a)cementation or reductive precipitation (Ymir)

                b)electrolytic precipitation (Ymir)

                3) Solvent Extraction (Ymir,myself)

                (no details mentioned)

                4)Chemical reduction

                a)sodium borohydride to recover palladium salts from an
                acidic solution (r2d3)

                b)1:1 PdCl2 / 37% formaldehyde, and 30% NaOH added to
                slightly alkaline, heat to 80 C, stirr 10 min, let
                catalyst settle down. [etc.] (LabTop)

                5)Chelation/titration

                a)basify, then filter out Pd(OH)2 ppt. (rev drone)

                b)chelate with NH4Cl to precipitate Pd(NH4)2Cl4, which
                would be worked back into PdCl2 (rev drone)

                c)chelate with dimethylglyoxime, filter out ppt. (rev
                drone)

                Thus far, here are my thoughts on the suggested
                procedures:

                1) Merely filtering out the precipitated PdCl2 salt is
                all well and good, but the yield of this recovery method
                doesn't sound too promising. Simple? Yes, but the fact
                only aout 70% or so is recovered makes me hesitant. This
                is definately the way to go wen you don't feel like
                wasting time, and maybe will turn out to be the best way
                overall -- who knows?

                2) There are three main drawbacks here. First, we still
                need to remember the fact that some very precious ketone
                is floating in there, and if one isn't conscius of the
                conditions, organic compounds like delicate ketones in an
                electrolytic cell can get ugly FAST. The next big
                drawback is equipment -- most organic chem labs aren't
                equiped with electrolytic equipment, neither is the
                average home, and nor are most organic chemists
                well-aquainted with the operation of said equipment. But
                hey, if its a clean, easy way, and you have some
                practical literature pertaining to it, please bring it
                on.

                3) Now this would be nice, if only there was somebody
                with literature on this. Just one or two solid ref's of
                Pd recovery using this would be of immense help. I
                thought about this one myself, but haven't found anything
                in the literature yet. Attractive, but really not too
                much to go by here.

                4) There is a BIG problm with one of these methods: using
                NaBH4 will reduce your ketone too! The formaldehyde
                reduction doesn't sound too aweful, but again, the
                catalyst would need to be oxidized back to Pd2+ at the
                end.

                5)Lastly, there is the precipitation using chelating
                ligands. Cheap, effective, simple -- or so it would seem.
                I still haven't found a good example of recovering PdCL2
                from the tetrachloro complex, though the glyoxime
                apparently is quicky made back into PdCl2 by treatment
                with aq. HCl (don't quote me on that; all I remember
                right now is that its simple.) If a straight forward
                means of converting Pd(NH4)Cl2 to PdCl2 is available,
                this method really looks slick. Otherwise, the glyoxime
                precipitates the Pd2+ species very quickly.

                So, we have a good list with some healthy variety in it.
                You can see my preference shining though, but that's just
                me. This is a good discussion -- let's keep it going.

                ------------------
                "I'm your Mama, I'm your Daddy
                I'm that nigga in the alley
                I'm your doctor, when in need
                Want some Toast? Have some weed
                You know me, I'm your friend
                Your main boy, thick and thin
                I'm your Pusherman"

  spitball      [Image] posted 07-20-1999 10:08 AM
  Pimp Master
                [Click Here to See the Profile for spitball]
                [Reply w/Quote]
                ---------------------------------------------------------
                Uhhh, Just FYI, that above post was Rev. Drone, using MY
                computer and not stopping the look at the fact that MY
                name was posting. Fucking how DARE he disgrace my good
                name with this garbage!
                The signature is pretty funny though after drone's name!
                hahaha..

                -spitball-

  LaBTop        [Image] posted 07-20-1999 10:14 AM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                I think the centrifuge would work the fastest, but I need
                some explanation into what mix of chems you are left with
                at the end of the process, then I can give you a
                procedure for that.
                Btw, has rev drone found your password, boss?
                Your writing suddenly looks identicall and nearly no
                typos....not one fuck in it... amazing! [Image] LT/

                ------------------
                EMOTIONSwill always beFREE!

  spitball      [Image] posted 07-20-1999 10:26 AM
  Pimp Master
                [Click Here to See the Profile for spitball]
                [Reply w/Quote]
                ---------------------------------------------------------
                Yeah, fuck.

                -spit'fuckin'ball

  Xeolite       [Image] posted 07-21-1999 04:30 AM
  Hive Bee
                [Click Here to See the Profile for Xeolite]
                [Reply w/Quote]
                ---------------------------------------------------------
                I saw one typo right off the bat:

                I'm your pusherman?!

                PUSHERMAN? HAHAHAHA

  LaBTop        [Image] posted 07-21-1999 10:38 AM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                rev drone, a neat trick could be to use a layer of DCM
                ,d=1,2 in the centrifuge and pipette your PdCl2 +
                solution slurry carefully on top of it. The PdCl2 (heavy)
                can enter the DCM, all other fluid products will stay on
                top of it after spinning.
                To make your own centrifuge is first year mechanics
                stuff, easy as chickenshit. [Image] LT/

                ------------------
                EMOTIONSwill always beFREE!

  rev drone     [Image] posted 07-22-1999 11:19 AM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                LabTop,

                I don't think a centrifuge is practical. like I said, my
                pilot plant-scale centrifuge is in the shop right now.
                [Image] I sent it in just to get a tune-up, but now they
                told me it needed a new transmission and a lot of work on
                the engine block, and wouldn't say when they'd be done.
                The lousy bastards. [Image] I'm sure most other bees are
                in the same situation.

                To tell you the truth, my experience is rather limited
                with centrifuges, so you'll have to explain to me why the
                ketone, which is also fairly dense as well as
                hydrophobic, won't follow the PdCl2 into the DCM layer.

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

  prickleberry  [Image] posted 07-22-1999 01:18 PM
  Hive Bee
                [Click Here to See the Profile for prickleberry]
                [Reply w/Quote]
                ---------------------------------------------------------
                Welcome back sir Reverend Drone, the Hive is a much
                better place with you around. [Image] Hope you'll give us
                a little warning next time you reply to one of those "get
                rich quick adverts". We were all worried sick about you.
                [Image] Anyway, my knowlege is limited in this area, but
                a few methods I have seen posted around here and in books
                are as follows.
                * Hydrazine is used to reduce the Pd back to the metal,
                then filter out.
                * A ball of steel wool is tossed in the reaction (or
                another more active metal) the Pd gets reduced back to
                the metal, and filters out. HCl acid may be needed to get
                things moving.
                *The whole reaction mix is filtered through an alumina
                column, with the Pd getting stuck in it.
                These are all un-tested by prickleberry....so they might
                not work, prickleberry is just keeping the ideas
                rolling.....
                Prickleberry out.. [Image]

  equarius      [Image] posted 07-22-1999 02:45 PM
  Hive Bee
                [Click Here to See the Profile for equarius]
                [Reply w/Quote]
                ---------------------------------------------------------
                Simple filtration recovery is not practical. I mean you
                can do it, and I've the dirty filtration papers to prove
                it, only a fraction is removed (~50%). If any bee has
                ever recovered Pd from multiple wackers and converted it
                back to PdCl2 in any amount, then used it again with
                success, then they should speak up. Besides for air or O2
                wackers I'd rather just say screw that little bit of Pd
                and move directly on to purification.

                The best method must convert it to PdCl2 and make it
                insoluble so it could then easilly be filtered out,
                without wrecking our fragile ketone.

  LaBTop        [Image] posted 07-22-1999 03:46 PM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                I still do'nt know what slurry we talk about(what's in
                it?) and what the next step should be, but let's assume
                you want to aminate with NaBH4 the MDP2P.
                I would then dissolve the sludge in a minimal amount of
                MeOH to get a solution with a lower density then DCM, but
                with the Pd salt as the only heavier part in it.
                Then I liberate the front wheel of my little sisters bike
                in the name of science and we gonna make a nice little
                centrifuge from that. Bet she will like that too!
                Fastest way is to weld a small, thick piece of pipe over
                the axis of the wheel halfway and the other half fits
                over the axis of a nonsparking induction elektro motor(
                we do'nt want to burn the little girl while she's
                watching our caprioles, aint it?)
                Now we mount this piece of ingenuiety(?) on a firm
                standing table.
                Next we make 2,4,6,8 etc plastic bottles with each 2
                holes in the open sides at the top, oppossite of each
                other. Then we make 4,8,12,16 exactly the same length and
                weight steel wire hooks.
                We hang the bottles opposite of each other at the wheel
                with them hooks.
                VOIL- : Your homemade kgscale centrifuge ! Full power on
                the motor and test first with EQUAL amounts of water in
                the bottles. Cola cans will do also, all the same weight
                and only a small opening......

                The PMK will dissolve in the MeOH, thus becoming overall
                less dense, and your Clean PdCL2 will be left in the DCM.
                (I hope...)You can proceed with the MeOH/PMK solution to
                the next step! [Image] LT/

                ------------------
                EMOTIONSwill always beFREE!

  LaBTop        [Image] posted 07-22-1999 04:02 PM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                Greetings from my little sister Guinevievre McGuiver, and
                you can make a bid for her frontwheel over at Ebay
                Auctions. (Btw, she's only 51, but still very playfull!).
                She's particualary fond of Chemical Detonations, the
                little Schmuck. Red hair, but I forgot if its her natural
                or if its chemically induced...Likes to play in the Lab,
                so..... LT/

                ------------------
                EMOTIONSwill always beFREE!

  rev drone     [Image] posted 07-23-1999 02:58 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                LabTop,

                Just to clarify what system we're looking at, let's take
                a typical situation. Actually, I already posted it, but
                let's lo

 
 
 
 
    smokemouth
(Member)
04-12-00 00:05
No 107797
      Re: Practical palladium salt recovery - rev drone  Bookmark   

rev drone     [Image] posted 07-23-1999 02:58 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                LabTop,

                Just to clarify what system we're looking at, let's take
                a typical situation. Actually, I already posted it, but
                let's look at it again, shall we? The SRV/KRV variation
                of the Wacker.

                At the end, in the solutioner we have:

                EtOH
                ketone
                isomerized starting material
                red tarry gunk
                CuCl2
                PdCl2

                There is also some PdCl2 precipitated out of the solution
                in the vessel. This is the situation we're looking at.

                At this point, there is no "sludge", per se. The solution
                is already less dense than DCM, and again the solvent
                here is EtOH, which is miscible with DCM. "the Pd salt as
                the only heavier part in it." Don't forget that the
                densities of CuCl2, ketone, and isomerized starting
                material are *all* denser than MeOH, in fact they are all
                denser than H2O, and in the case of the inorganic
                compounds, denser than DCM.

                I really think precpitation is sounding better and
                better. Dimethylgyoxime chelates the Pd2+ species, and
                crashes out. This is filtered, and the filtrate added to
                a ammonium hydroxide solution, boil. Now add HCl, and you
                will precipitate out Pd(NH3)2Cl2, or palladium yellow.
                This is kinda where it get's stuck...

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

  LaBTop        [Image] posted 07-24-1999 06:16 AM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                Are these Pd salts perhaps attrackted by a magnet?
                If not, why not decant the mix,red tarry gunk GONE. Then
                dissolve all the decants in DCM, and centrifuge.
                Now you decant again, and you have a LAYERED mix of 2
                solids: CuCl2 and PdCl2.
                That looks simple to me to seperate...
                The decanted fluids is another story, to be continued.
                Eeh, do'nt forget I do'nt know the SRV/KRV, give me a url
                please. [Image] LT/

                ------------------
                EMOTIONSwill always beFREE!

  LaBTop        [Image] posted 07-24-1999 11:42 AM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                Some new info on use of hexane to get rid of the tar from
                MethylMan:
                http://hive.lycaeum.org/ubb_board/Forum1/HTML/002102.html
                [Image] LT/

                ------------------
                EMOTIONSwill always beFREE!

  rev drone     [Image] posted 07-24-1999 12:30 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                Pd salts aren't ferromagnetic, but that certainly is good
                thinking. How would you remove the red tarry gunk? To
                clarify myself, the gunk is dissolved in the EtOH.

                I think we're having a communication problem. Let me
                re-state what the situation is. At the end of the
                reaction, one is left with an ethanolic solution of the
                following:

                * ketone (the actual final product of the reaction)
                * isomerized starting material (a byproduct of the
                reaction)
                * red tarry gunk (a polymerized byproduct, fairly soluble
                in organic solvents)
                * CuCl2 (the cocatalyst)
                * PdCl2 (the catalyst)

                Everything I just lised is DISSOLVED in EtOH; they're all
                in there, floating around together in solution. There is
                a small amount of precipitated PdCl2. This is easily
                enough filtered out, but it does not represent the bulk
                of PdCl2 present; most of that is still dissolved in
                EtOH.

                Regarding all this "decanting", I think you must mean
                something else.

                     quote:
                     -----------------------------------------------
                     decant \De*cant"\, v. t. [imp. & p. p.
                     Decanted; p. pr. & vb. n. Decanting.] [F.
                     d['e]canter (cf. It. decantare), prop., to pour
                     off from the edge of a vessel; pref. d['e]-(L.
                     de) + OF. cant (It. canto) edge, border, end.
                     See Cant an edge.] To pour off gently, as
                     liquor, so as not to disturb the sediment; or
                     to pour from one vessel into another; as, to
                     decant wine.
                     -----------------------------------------------

                The red tarry gunk *CANNOT* be simply separated off by
                decantation. As for your "Decants", I can only assume you
                mean either 1)the sendiments left over after pouring, 2)
                the liquid that was poured off. Either way, I don't
                understand what you're doing.

                Now I have to admit I'm skeptical. I have a hard time
                believing that a home-made centrifuge, using a bicycle
                tire, is going to be powerful enough to cause the two
                inorganic salts in question to precipitate out in even
                layers. Typical commercial centrifuges run in the range
                of 10,000 to 100,000 rpm. If you're doing this on a small
                scale, you're still talking about at least a kilogram of
                solution being spun around at rather high velocities. If
                you're taking about an industrial-scale batch (like one
                of your 25 kg "sample batches"), you're talking about
                using a centrifuge rotating possibly HUNDREDS of liters
                of solution at 10,000 rpm. Your little sister's bicycle
                wheel PROBOBLY won't work here. Then again, I guess I've
                never seen what kind of bicycle your sister rides.

                Now what I meant of course was a system THEORETICALLY
                similar to the SRV/KRV procedure, which can be found at
                http://rhodium.lycaeum.org/chemistry/mdp2p.srv.txt  . The
                practical oxidation of safrole is a nice system to
                analyze, but all of this is of course only academic
                musings.

                There are numerous chelating procedures in the
                literature, though the one that stands out the most is
                with dimethylglyoxime. The question is, once you've
                formed a nicely-cheltated metal cmplex, how do you remove
                the ligands to return to PdCl2?

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

  rev drone     [Image] posted 07-24-1999 12:40 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                I guess what I'm saying is, its very easy to recover
                palladium using DMG, ETDA, 2,4-pentadione, etc., but then
                one is left with an insoluble palladium chelate, like
                PdDMG, but not PdCl2. MY question is, would treating the
                chelated precipitate with HCl lead to PdCl2 again? If its
                that easy, we 're set.

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

  Osmium        [Image] posted 07-26-1999 05:05 AM
  PimpBee
                [Click Here to See the Profile for Osmium]
                [Reply w/Quote]
                ---------------------------------------------------------
                IMHO it would be best to quench the SRV with water,
                extract the organics with hexane (which hopefully does
                not dissolve anything inorganic), and collect the aq.
                solution. Once you have enough of it (like several liters
                containing 20g Pd or so), you can start your recycling.
                Reducing agent which doesn't reduce the copper, followed
                by some aqua regia or HCl/Cl2 or HBr/Br2 to make PdCl2
                again. Or any other of the procedures mentioned above.

  LaBTop        [Image] posted 07-26-1999 11:58 AM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                I support the advise of Osmium, plus:
                Palladium can be recovered by heating the spent catalyst
                to redness in order to remove organic impurities.
                The palladium is then dissolved out with aqua regia and
                the solution evaporated; the residue is dissolved in hot
                water and hydrochloric acid to form palladium chloride.
                Vogel,first edition, 1948, page 670, Section IV,120,the
                Rosenmund reduction of acid chlorides.
                That's a simple answer to a simple question.
                BTW, my sister rides a Norton Commander, a collectors
                item.She's a wild woman, looks abit like, eeeh, Cher, but
                then red. [Image] LT/

                ------------------
                EMOTIONSwill always beFREE!

  LaBTop        [Image] posted 07-26-1999 12:00 PM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                I support the advise of Osmium, plus:
                Palladium can be recovered by heating the spent catalyst
                to redness in order to remove organic impurities.
                The palladium is then dissolved out with aqua regia and
                the solution evaporated; the residue is dissolved in hot
                water and hydrochloric acid to form palladium chloride.
                Vogel,first edition, 1948, page 670, Section IV,120,the
                Rosenmund reduction of acid chlorides.
                That's a simple answer to a simple question.
                BTW, my sister rides a Norton Commander, a collectors
                item.She's a wild woman, looks a bit like, eeeh, Cher,
                but then red. [Image] LT/
                PS: why do I think your not satisfied with this.....?

                ------------------
                EMOTIONSwill always beFREE!

  LaBTop        [Image] posted 07-26-1999 12:01 PM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                I support the advise of Osmium, plus:
                Palladium can be recovered by heating the spent catalyst
                to redness in order to remove organic impurities.
                The palladium is then dissolved out with aqua regia and
                the solution evaporated; the residue is dissolved in hot
                water and hydrochloric acid to form palladium chloride.
                Vogel,first edition, 1948, page 670, Section IV,120,the
                Rosenmund reduction of acid chlorides.
                That's a simple answer to a simple question.
                BTW, my sister rides a Norton Commander, a collectors
                item.She's a wild woman, looks a bit like, eeeh, Cher,
                but then red. [Image] LT/

                ------------------
                EMOTIONSwill always beFREE!

  rev drone     [Image] posted 07-26-1999 01:49 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                LabTop,

                Sounds like your little sister would DEFINATELY not want
                that to happen to her bike. [Image] Well, I guess you
                think I'm not satisfied for several reasons: 1) Because
                palladium chloride has a surprising tendancy to be
                readily soluble in a lot of non-polar solvents, and so a
                simple extraction like that is questionable (many Pd
                complexes favor non-polar solvents; a fact that is
                utilized in cases of Pd recovery where large amouns of
                organic products aren't involved), 2) Because the
                purification of palladium by reducing and regenerating
                PdCl2 sounds like more work than it has to be 3) because
                I can be a pernicious little jerk when it comes to this
                stuff (I can't rest until I've examined something like
                this backwards and forwards and from every possible
                angle.)

                Extracting with hexanes would nice, but I'm not so sure
                it'll work. Oh yes, hexanes will extract the ketone, but
                I'm not convinced that it wouldn't leave the palladium
                salts alone. DCM, a rather non-polar solvent, when used
                in this fashion, does an EXCELLENT job extracting both
                product AND catalyst together. Now hexanes are definately
                more non-polar, and this may do the trick -- I guess
                someone will have to try it out (if I hear any rumors in
                the near future, I'll keep y'all posted.) I'm definately
                not ruling it out, mind you; this may be the way to go.
                I'm just pointing out the fact this may not be the
                solution.

                As for the catalyst purification, yes heating palladium
                to redness will destroy impurities, but I'd prefer to
                avoid having to go back to the metallic form and
                regenerating PdCl2 with aqua regia and HCl. Of course, if
                all else fails, this would work, and it might not be so
                bad if combined with the chelation step ( PdDMG is
                precipitated, then reduced by roasting or by NaBH4 in
                chloroform to the metallic form, yada, yada, yada.)

                As I said before, Chelating Pd to extract it is still
                pretty nice looking, though I have to admit I'm still not
                100% certain as to the best means of making it back into
                PdCl2. Thus far, I propose:

                1. Precipitate Pd out of the solution with PdDMG
                2. Dissolve PdDMG in excess NH4OH sol., boil, then add
                HCl to crash out Pd species as easily-filtered palladium
                yellow, Pd(NH3)Cl2

                Now those extra amine ligands are a pain-in-the-ass, as
                they are bonding to the palladium right where our
                catalyst friend does its magical thing, but this may not
                be too much of a problem. Those amines are very
                loosely-bonded ligands.

                Here's a question: if you carefully heated palladium
                yellow, could it be selectively decomposed to PdCl2?
                Rather than roast it all the way to Pd(0), could one just
                heat it up enough to liberate the two ammonia
                equivalents? According to the CRC, palladium yellow
                decomposes at a fairly low temperature; is the product
                from decomposition the stuff we want?

                The problem is, there are tons of ref's on recovering Pd
                as a metal, but few on keeping it as a salt. The result:
                ton's of descriptions of recovering catalytically useless
                salts and roasting them into Pd sponge.

                Incidentally, in case anyone wanted to know, as everyone
                already knows, Pd is oxidized by aqua regia, and PdCL2 is
                obtainable that way, as well as by Cl2 gas at red heat,
                but Pd can also be oxidized by nitric acid, yielding the
                nitrate, Pd(NO3)2. This, when heated in H2O, decomposes
                to yield Pd(OH)2 (a very active hydrogenation catalyst
                indeed), which could be acidified to yield PdCl2.

                Anyways, that's all I have to say 'bout that for now.
                Please, if anyone out there knows the answer to my
                question about the decomposition of Pd(NH3)2Cl2, pleeeez
                say so.

                Take care,

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

  LaBTop        [Image] posted 07-26-1999 06:42 PM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                Some ECONOMIC ruling of thumb:
                When you have to consider the amount of labour, risk and
                chemicals involved, would'nt it be a bit wiser to forget
                the damned stuff, bill the EVENTUAL clients with a raise
                in price, and buy from that your next batch of PdCl2 ? So
                just filter it out?

                And you still can liberate the pure Pd and use that in
                numerous other (pressurized)hydrogenation
                techniques...easier by the way...more yield by the way...

                But I have the same problem: if it looks impossible,
                that's the point when it gets really interesting, there's
                allways a way, but at what costs and risks? [Image] LT/

                ------------------
                EMOTIONSwill always beFREE!

  rev drone     [Image] posted 07-26-1999 07:18 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                I did a search, and found that, yes indeed in
                http://hive.lycaeum.org/ubb_board/Forum4/HTML/000402.html
                everyman mentioned that extracting the ketone w/
                petroleum ether was the preferred method, since it
                extracts the ketone, while leaving the catalyst and red
                tar behind. This is very good.

                So, with this nugget of information, we know to add H2O,
                then extract with pet. ether a few times. At that point,
                The red gunk has (mostly) precipitated out, so a quick
                filtration should get rid of most of the gunk remaining,
                leaving a fairly clean solution of CuCl2 and PdCl2. The
                PdCl2 can be extracted from there with DCM. For added
                extraction power, tossing in a little more HCl ought to
                persuade more of the PdCl2 to dissolve in the DCM layer.

                For small-scale Wacker oxidations, it really doesn't pay
                to get the palladium out. But for larger batches, at
                $7/gram (bulk, and only if you're lucky), PdCl2 gets very
                expensive.

                Which reminds me of something. You seem to know a thing
                or two about industrial production, so I figure you'd be
                the one to ask. What industrial ketone synthesis would
                you recommend? (Hypothetically speaking, of course.) It
                seems it isn't a variation of the Wacker oxidation, so
                which one is it?

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

  LaBTop        [Image] posted 07-26-1999 08:42 PM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                In my very past, I studied many ways of ketone synthesis,
                and based on a few facts, mostly economical, only 2 made
                it into the final:
                [1]the one from I think UF with the bathtube safrole to
                ketone, using PdCl2, and
                [2]the performic acid one.
                So with those recipees and a "bit" of money I went off to
                the far east. There a perfume factory in financial
                trouble was found, and after finding out they could not
                get PdCl2 in sufficient quantities and on a steady
                delivery basis, the choice was made for the performic
                method. A lot of resistance had to be mastered about the
                environmental aspects of the shitload of remaining
                chemicals after the process, untill they found a way to
                bring those to a waste-burning facility for a reasonable
                price.
                We made a setup from two 1000 liter reaction tanks,
                rigged together with 3 big watercoolers/boilers and 2
                watercooled tanks above that for the starting mix process
                of the iso and the rest, so that that mixed together and
                was controlled in a sight-glass by 2 valves. It then
                flowed to the first 1000 liter water cooled tank and the
                rate of flow controlled the reaction temp. A big mixer
                inside provided enough vortexes.
                After reaction ended, it was tapped in the second 1000
                liter tank and 15 % H2SO4 was added etc etc.
                That way they delivered every 4 weeks 1000 kg 65 to 85 %
                raw MDP2P, which was transported to a seaport and brought
                on board the ship under another name on the bill of
                loading etc. etc.,then LOTS of trouble to get it in the
                desired country where it was distillated to get 98% pure
                MDP2P and you may guess what we did then... So,: the
                Classical Performic Acid Method, very reliable, allways
                ketone, only discrepancy in yields which were never
                satisfactedly solved. [Image] LT/

                ------------------
                EMOTIONSwill always beFREE!

  equarius      [Image] posted 07-27-1999 09:52 PM
  Hive Bee
                [Click Here to See the Profile for equarius]
                [Reply w/Quote]
                ---------------------------------------------------------
                Instead of recovering the Pd what about re-using the Pd
                and solvent in solution as is. The goal being to create a
                re-ussable catalytic reaction vessel.

                This is pretty tricky because it would have to be
                accomplished by extracting the oils without extracting
                the Pd. A top dwelling extraction solvent would be much
                preferred. Possible pet ether, ether, or toluene. Then
                once extracted all one would do is add more CuCl2 and
                Olefin, then wack away.

                Obviuosly I don't have the chem knowledge, or even the
                memory of what top dwells and what doesn't to make this
                work.

                Feasable??

  jimwig        [Image] posted 07-28-1999 04:19 PM
  Hive Bee
                [Click Here to See the Profile for jimwig]
                [Reply w/Quote]
                ---------------------------------------------------------
                Spitball-give Curtis Mayfield a credit line for writing
                those words and music.

  rev drone     [Image] posted 07-31-1999 04:53 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                Equarius,

                The problem is that there are still other byproducts in
                there as well. Good thinking, but when this stuff is
                over, there is some quite visible impurities that may
                have an unpleasant effect on things. Remember this
                mantra: garbage in, garbage out.

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

  ymir          [Image] posted 07-31-1999 06:44 PM
  Hive Bee
                [Click Here to See the Profile for ymir]
                [Reply w/Quote]
                ---------------------------------------------------------
                It turns out that LabTop is probably correct about a
                bicycle being able to be converted a centrifuge. A.
                Gallenkamp and Co. Ltd., London marketed a hand
                centrifuge in the past that worked similarly. The tubes
                should pivot, and be balanced with .1 gram. One thing
                about centrifugal seperations that should be noted is
                that the tubes should be spun for at least five minutes,
                and then allowed to slow down over a period of around ten
                minutes, to prevent particles supernatent solution from
                dispersing by swirling.

  rev drone     [Image] posted 07-31-1999 07:22 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                How on Earth are you going to practically make a
                centrifuge from a bicycle tire that could separate even a
                medium-sized batch of ketone? I'll stick to separation
                technology.

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

  ymir          [Image] posted 07-31-1999 07:43 PM
  Hive Bee
                [Click Here to See the Profile for ymir]
                [Reply w/Quote]
                ---------------------------------------------------------
                The same as any other engineer, by building one. I am
                looking at a diagram of the aforementioned machine, it
                got up to 3000 RPM. It's gear driven like a bicycle, so
                his idea could be built by one with enough mechanical
                aptitude. Obviously, not every member of the hive is able
                to build their own equipment. Some are!

  ymir          [Image] posted 07-31-1999 09:13 PM
  Hive Bee
                [Click Here to See the Profile for ymir]
                [Reply w/Quote]
                ---------------------------------------------------------
                A reference that explains how the early centrifuges used
                in the sugar industry were built is to be found in
                Metallurgical and Chemical Engineering, Vol. XI, No. 6,
                p338-9. A basket design is published in Sugar, September
                1919, p. 476. These designs are lower speed overhead
                shaft drive units that need not be so precisely balanced.

  rev drone     [Image] posted 07-31-1999 09:22 PM
  Hive Bee
                [Click Here to See the Profile for rev drone]
                [Reply w/Quote]
                ---------------------------------------------------------
                I still am not sure as to what advantage a 3000 rpm
                centrifuge would have over an extraction procedure, but
                if an industrially useful one can be made, perhaps its
                not entirely that impractical. I'm curious what these
                schemes look like. What is your information source for
                the A. Gallenkamp and Co. model centrifuge? I'll give
                that other source a try as well.

                Still though, why the interest in centrifuges over the
                extraction/separation techniques?

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

  Osmium        [Image] posted 08-02-1999 04:06 AM
  PimpBee
                [Click Here to See the Profile for Osmium]
                [Reply w/Quote]
                ---------------------------------------------------------
                I wouldn't want to be close when one of those home-made
                bicycle-wheel centrifuges loaded with several liters of
                spent solvents disintegrated. Good luck.

 

 
 
 
 
    smokemouth
(Member)
04-12-00 00:06
No 107798
      Re: Practical palladium salt recovery - rev drone  Bookmark   

LaBTop        [Image] posted 08-02-1999 05:32 AM
  PimpBee
                [Click Here to See the Profile for LaBTop]
                [Reply w/Quote]
                ---------------------------------------------------------
                1. I talked about a (Norton Commander)motorbike front
                wheel, magnesium or SS reinforced, new, factory balanced
                for you nontechnical Neanderthalers [Image].
                2. You make friends with a Instrument maker technician at
                any university's instrument makers facility (I did it the
                hard way and followed a 5 years evening course which
                piled up my hobbies to several more, took glassblowing
                lessons in the go,too), and let him construct the baskets
                and swing arms.
                3. That little sucker can easily go to 10.000 rpm and if
                you balance out both ends of the axis, 30.000 rpm is no
                problem also.
                You only need a special motor.
                4. The baskets must be weighted out(filled!) with a good
                digital balance.
                5. You can buy second hand industrial centrifuges at
                specialiced laboratory/chemical-plants engrossers
                (forestallers, buyer-ups), for amazing low prices.
                6. All your big scale/small scale acetone washings can be
                done in a cup-formed low speed centrifuge, with a drain
                at the bottom, and then constant input from fresh acetone
                at the top. In 10 minutes 100 kg/100 gram powder is
                snowwhite and nearly dry.
                btw, for those interested,buy: Perry's Chemical
                Engineers' Handbook, 7th Edition, ISBN
                nr.0-07-115448-5(intnl.ed.)or 0-07-049841-5(us ed.).On
                the second page it lists another 35 chem.engineering
                books of interest! Its circa 1500 pages(no page nr's)
                7. Osmium, if you make your own wheely, do'nt forget to
                include a segment of thick steel pipe diam. 1m to put the
                thing in. If something happens, it happens only to the
                steel and not to your balls, which I presume you need for
                further adventures into the wonderfull world of
                professional sex courses....,or want to preserv for any
                further offspring, can't be too carefull with them little
                babies...wear a icehockey-protector... [Image] LT/

                ------------------
                EMOTIONSwill always beFREE!

  Osmium        [Image] posted 08-02-1999 01:33 PM
  PimpBee
                [Click Here to See the Profile for Osmium]
                [Reply w/Quote]
                ---------------------------------------------------------
                I already have some shots of my juice in the freezer, in
                case something goes wrong with my cohones, don't worry
                about my future offspring, LaBToP!
                And I don't plan to build a wheel, because I'm not into
                industrial scale production anymore and still need my
                Japanese motorcycle for weekend fun. And I surely won't
                rip it apart for a few lousy grams of Pd...
  This topic is 2 pages long:   1  2      next newest topic | next oldest
                                                                    topic
  All times are CT (US)

     Administrative Options: Close Topic | Archive/Move | Delete Topic
  [Post New Topic]  [Post A Reply]                             Hop to:

                           Contact Us | the Hive

             Powered by: Ultimate Bulletin Board, Version 5.43c
     _ Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.


***********************************

            PAGE 2

***********************************

  [Image]  [Image]  the Hive BB
           [Image][Image]  Methods Discourse
           [Image][Image]  Practical palladium salt recovery (Page 2)

                         [Post New Topic]  [Post A Reply]
                  profile | register | preferences | faq | search
                                          next newest topic | next oldest
  This topic is 2 pages long:   1  2                               topic
   Author      Topic:   Practical palladium salt recovery

   ymir        [Image] posted 08-02-1999 05:06 PM
   Hive Bee
               [Click Here to See the Profile for ymir]
               [Reply w/Quote]
               ----------------------------------------------------------
               The illustration of a hand centrifuge is to be found on
               page 120 of J A Elvidge's and P G Sammes 2nd Ed of "A
               Course in Modern Techniques of Organic Chemistry",
               published by Butterworth and Co., London, 1966. Doubtless
               this product was marketed to schools as an inexpensive
               alternative to the real thing. The company has been
               acquired by Sanyo, whether they make the product still is
               unknown to me. Like the reasonably priced Brinkmann
               rotary evaporator, this product probably doesn't exist
               anymore. Since it is an illustration of a gear driven
               centrifuge, it supports LabTop. Another way besides the
               local university to get some help fabricating such
               machinery would be to befriend a retired tool and
               diemaker, with a shop, since these guys know a lot more
               than the average bear

   Osmium      [Image] posted 08-03-1999 11:44 AM
   PimpBee
               [Click Here to See the Profile for Osmium]
               [Reply w/Quote]
               ----------------------------------------------------------
               BTW, why did you use an expensive, rare, way too valuable
               Norton wheel? Crashed the bike before and it was left? I
               mean, car wheels are almost free and much more common!

   LaBTop      [Image] posted 08-03-1999 05:00 PM
   PimpBee
               [Click Here to See the Profile for LaBTop]
               [Reply w/Quote]
               ----------------------------------------------------------
               Car wheels: too heavy, too small, too high
               and they do'nt have them little holes in them for the
               spikes. Remove 2,4,8 pairs of spikes at opposite sides,
               voila.
               LT/,-you_can't_be_too_caring_for_your_precious_fluids-!!

               ------------------
               EMOTIONSwill always beFREE!

   Icepick     [Image] posted 10-12-1999 03:27 PM
   Hive Bee
               [Click Here to See the Profile for Icepick]
               [Reply w/Quote]
               ----------------------------------------------------------
               Here is an excerpt from "Palladium Reagents in Organic
               Synthesis" by Richard F. Heck pp. 16-17...(printed w/o
               permission etc etc)
               1.5. Palladium Recovery and Formation of Some
               Catalytically Useful Salts

               At present, the cost of palladium is low enough to make
               its recovery unneccessary from small-scale catalytic
               reactions, although if numerous reactions are run metal
               residues can be accumulated. In our laboratory, when
               sufficient volume of liquid plus solid
               palladium-containing residues are available, we recover
               the metal in the following manner. Liquid and/or solid
               materials, about 10-20g at a time, are placed in a large
               porcelin or other heat-resistant dish and cautiously
               heated with a Bunsen burner in the hood. Volatile
               material evaporates or is burned off and the solids are
               heated with the full heat of the burner for an hour or
               two. After cooling, the porous black residue is scraped
               from the dish, ground up, and reheated with the burner
               for another hour. After cooling, the solid is reground if
               neccessary and extracted once with excess hot
               hydrochloric acid to remove soluble metals and then twice
               with aqua regia. The aqua regia solution is decanted or
               filtered from the carbonaceous residue and concentrated
               to a small volume by heating in the hood. The resulting
               solution is diluted with hydrochloric acid, concentrated
               again, diluted with water, made strongly basic with
               sodium hydroxide, and the palladium metal is precipitated
               by addition of excess hydrazine. The black powdered metal
               obtained is seperated by filtration and air dried. The
               material is suited for converison into palladium acetate
               or palladium chloride as described below.

               Palladium Acetate
               Palladium sponge (10g)(or recovered powder) was boiled
               gently under reflux with a solution of glacial acetic
               acid (250ml) and concentrated nitric acid (6ml) in a hood
               until evolution of brown fumes ceased. A small residue of
               palladium should remain undissolved; if not, a little
               more spong should be added and boiling continued until no
               trace of brown fumes is observed. This process is
               necessary to avoid contamination of the product with
               Pd(NO2)OAc. The brown boiling solution was filtered and
               allowed to cool, whereupon most of the product appeared
               as orange-brown crystals that were seperated, washed with
               acetic acid and water, and air dried (mp 205 C dec). The
               pale reddish-brown acetic acid mother liquor may be used
               for further preperations. The yield was virtutally
               quantitative.

               Palladium Chloride.
               Palladium metal (recovered powder, black, or sponge) was
               dissolved in aqua regia, the solution evaporated to
               dryness, and the residue heated to about 500 C to expel
               hydrogen chloride and chlorine. The palladium chloride
               remaining was obtained as a brown powder.

               Any spelling errors are mine [Image]. Any other errors
               are not, just quoting what was found in an interesting
               book. Hope this helps kids,

               Icepick

               By will alone, I set my mind in motion

   equarius    [Image] posted 02-10-2000 11:56 PM
   Hive Bee
               [Click Here to See the Profile for equarius]
               [Reply w/Quote]
               ----------------------------------------------------------
               Consider this for large runs using 10g+ (look ma process
               a kilo).

               Fasten a keg to the basin of a regular vertical clothes
               washer to the side of the center column. Counterbalance
               with an equal weight on the other side. Hack off the lid
               and plug the little open / close activation switch. Set,
               or hack, the washer to spin and centerfuge away.

               Now, I'm not exactly certain of how a centerfuge works
               except that there is spinning involved. Does the spinning
               vessell have to be the center of rotation or is offset
               (as I described above) the correct way?

               Or, use steel wool (idea from other thread) to convert to
               Pd(0), then centerfuge.

               hmmm
  This topic is 2 pages long:   1  2      next newest topic | next oldest
                                                                    topic
  All times are CT (US)

     Administrative Options: Close Topic | Archive/Move | Delete Topic
  [Post New Topic]  [Post A Reply]                             Hop to:

                           Contact Us | the Hive

             Powered by: Ultimate Bulletin Board, Version 5.43c
     _ Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.

 
 
 
 
    lab_bitch
(Stranger)
04-03-02 05:02
No 291678
      Re: 1. Precipitate Pd out of the solution with ...  Bookmark   


1. Precipitate Pd out of the solution with PdDMG
2. Dissolve PdDMG in excess NH4OH sol., boil, then add
   HCl to crash out Pd species as easily-filtered palladium
   yellow, Pd(NH3)Cl2

Now those extra amine ligands are a pain-in-the-ass, as
They are bonding to the palladium right where our
catalyst friend does its magical thing, but this may not
be too much of a problem. Those amines are very
loosely-bonded ligands.




That's not really correct.  If you read the article pertaining to the O2 wacker in the Eur. Journal of Organic Chemistry 1998, 1901-1906, you will see that the amine ligands actually increase the selectivity of the catalyst.  These ligands probably are temporarily displaced by the olefin in the complex formed during the reaction.

Also, there should be a temperature below the dec. point that these ligands will come off.  They are bound in the same fashion that water is bound to the dihydrate, so should come off at an even lower temperature since N is less nucleophilic than O.  Don't quote me on this, though.  It's just a guess.