guy
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Making Lead(IV) acetate
Lead(IV) acetate is described in my chemical dictionary as Pb(II) acetate plus Cl2 gas. It is a powerful oxidizer.
I'm confused on the details. Would this reaction be taken place in solution or dry and under what conditions? I don''t think it could
be solution because the Cl- ion would react to precipitate PbCl2.
Does anyone know anything about this?
thx
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Esplosivo
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This synthesis was already detailed elsewhere. Please search. It's in the PbO2 thread, created by axehandle. The method was given by chemoleo.
Theory guides, experiment decides.
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Eclectic
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I searched and couldn't find it. He's asking about lead TETRAacetate. Usually prepared from Pb3O4 and acetic anhydride.
However, if you bubbled Cl2 through a lead(II) acetate solution, I suspect you would get more PbO2 than lead tetraacetate. The ony way I can see it
working is if the chlorine oxidizes half of the lead(II) acetate to lead tetraacetate and half of the lead is precipitated as PbCl2.
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Esplosivo
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Man I must be going blind, lately I'm making so many mistakes. Lead tetraacetate is made by reacting Pb3O4 (red lead - possibly obtainable from
old ironmongers) with glacial acetic acid (glacial is usually used, I don't recall the use of dilute. A conc. solution >55% will probably be
enough). A mixture of lead (II) and lead (IV) acetates results. For the method of seperation I'll must check it out. Thank you Eclectic for
correcting me and sorry for correcting.
Edit: I've checked out for the seperation. It turned out that my old chem book has only a short reference to it, and only said to leave the
mixture to crystallize. Lead (II) acetate must be formed due to the reaction with a mixed oxide (2PbO.PbO2), but it was not mentioned. The use of PbO2
with glacial acetic acid should be tested, maybe it will work. I've never heard about such a preparation though, sorry.
Edit2: Ecletic, I checked out your procedure. A mixture of glacial acetic and acetic anhydride can also be used. They do not mention the formation of
lead (II) acetate. Maybe none is formed this way. Nice to know.
[Edited on 3-3-2005 by Esplosivo]
[Edited on 3-3-2005 by Esplosivo]
Theory guides, experiment decides.
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Organikum
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Preparation without acetic anhydride (AA): Pb3O4 is slowly added to GAA, the temperature is kept below 60°C or the formed acetate is hydrolysed.
Purification by recrystalsation from GAA.
Another method using GAA and AA is described whereby a second crop of the acetate is yielded by venting dry Cl2 through the soup after the first batch
has precipitated. This second batch is contaminated but can be cleaned by recrystallisation from GAA.
From the Brauer.
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guaguanco
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| Quote: | Originally posted by Esplosivo
Edit2: Ecletic, I checked out your procedure. A mixture of glacial acetic and acetic anhydride can also be used.
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I've done this preparation long ago. It's really extremely easy when an excess of Ac2O and AcOH is used. The Pb(OAc)4 crystallizes out as
white needles.
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BromicAcid
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Although out of the correct section (should be in technochemistry I guess), does anyone know any information on the electrochemical prepratory methods
for lead tetraacetate?
The inorganic synthesis collection had this to say on lead tetracetate (BTW, is it tetraacetate or tetracetate? I get a fair number of either
spellings in references). | Quote: | | As is the case with most salts of higher valence metals, lead tetracetate may be obtained by electrolytic oxidation. This may be done by direct
oxidation of the lower actate<sup>(1)</sup> or indirectly through the sulfate.<sup>(2)</sup> |
(1)Elbs and Rixon: Zeit. Elektrochem., 9, 267 (1903)
(2)Elbs and Fisher: Zeit. Elektrochem., 7, 345 (1900)
Also in a synthesis for lead tetraacetate I found online by Cherrie Baby there were more references to the electrochemical preparation of this
compound: | Quote: | [5] CA 51, 16146 (1957)
[6] CA 74, 49005x (1971)
[7] Oxidations in Org. Chem. part A, Wiberg, 1965, p277-366 - Academic Press. |
I imagine the electrochemical
methods might be just as taxing on my chemical supplies as the chemical methods of preparation but out of curiosity I was wondering if anyone had
something else to go on.
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aliced25
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The attached paper, from IUPAC, goes into quite a description of the difficulties surrounding preparing & keeping Lead Tetraacetate. Based upon
the discussion in the first part of the paper, of the problems caused by Acetic Anhydride (which apparently reacts with & presumably alters the
product), the author describes the preparation using glacial acetic acid. Interesting read really.
| Quote: | Preparation
Lead tetraacetate may be prepared (i) by the action of red lead (Pb3O4) with anhydrous acetic acid - a substantial amount of lead diacetate is also
formed - the lead(II) salt may be separated by making use of its lower solubility in glacial acetic acid; (ii) by oxidation of lead diacetate with
gaseous chlorine, again in a medium of glacial acetic acid; the PbCl2 formed is removed by filtration; (iii) for volumetric purposes we recommend the
reagent to be prepared by dissolving red lead (Pb3O4) in glacial acetic acid at elevated temperatures; the lead tetraacetate crystals formed are
isolated, recrystallized and the required amount is dissolved in a known volume of glacial acetic acid; solutions thus prepared contain no lead(II)
salts, and if kept in dark-coloured stock bottles will remain stable for periods of several months. Their stability is decreased substantially by the
presence of acetic anhydride or alkaline metal acetates. Due to the great volume changes of glacial acetic acid with temperature variations,
conditions used must be such that the temperature does not vary within a range of more than +/- 1C during the analysis. |
Attachment: Zyka.Analytical.Study.of.the.Basic.Properties.of.Lead.Tetraacetate.as.Oxidizing.Agent.pdf (1004kB)
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platedish29
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I guess, not sure about it, but lead ii, iv acetate can be prepared by dissolving lead with H2O2 Ac acid mix.
Pure lead IV acetate can be separated by Cl- as i didn't
ps.: a sort PbO2.H2O seems to exist aswell PbO.H2O, and it is white, calcining at mild heat reveals red lead oxide as product, first mistaken as Cd
contamination
[Edited on 1-1-2013 by platedish29]
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Refinery
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If Pb3O4 is reacted with vinegar(10%), will it form tetra or only diacetate?
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