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Author: Subject: Antimony analog of Paris Green?
National Hazard

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[*] posted on 6-2-2009 at 18:16
Antimony analog of Paris Green?

Supposedly (I've not seen a comparison) the best blue colors for fireworks come from using Paris Green (cupric acetoarsenite, C4H6As6Cu4O16, CAS#12002-03-8). Horribly and cumulatively toxic due partly to it emitting arsine (AsH3) when moist. Poisonous wallpaper was one historical case.

Since antimony is considerably less toxic, I've wondered if there are any analogous ions/complexes of antimony, some organic acid, and copper. In a fit of blind trials, I mixed acetic acid, copper chloride, and antimony trioxide, and got some pretty needle-like blue/blue-green crystals. They're quite acidic and are unstable in air, so whatever it was I made is unsuitable for the purpose. Pretty, though, and I'll post a picture of the ones I have in a sealed jar if anyone is interested.

I think the virtue of Paris Green is that the Cu+2 is in a flammable compound with an overall reductive power which will give the Cu+1 in a flame since (poly)CuCl is the blue emitter desired. The other requisite is that the compound be insoluble in water or nearly so.

My access to literature is very limited, since I either have to prevail on friends working in academia for online copies of articles or bamboozle my way into local college libraries which usually don't have the periodicals needed :mad: However, any promising leads will be followed!
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[*] posted on 7-2-2009 at 01:26

Antimony trioxide is much less acidic than arsenic trioxide. While it does form antimonates these salts readily hydrolyse in water, unlike the arsenates which are either insoluble or can be crystallised from aqueous solution.

Of possible interest is NH4CuS4, with copper as Cu(I), made by adding a strong solution of CuSO4 to a saturated solution of sulfur in ammonium sulfide; it separates as fine red crystals with no water of crystallisation.

A complex cuprous thiosulfate is made by adding alkaline thiosulfate to a solution of a cupric salt. I have next to no information on it, but thiourea forms a cuprous complex Cu(thiourea)2Cl that is insolubile in water.
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[*] posted on 7-2-2009 at 01:34

I believe Paris Green was copper acetoarsenate. I do not know if Sb forms acetoantimonates.

In general antimony compounds are powerful chemosterilants and systemic heavy metal poisons not to be trifled with. Not as acutely toxic as arsenicals. But nasty.

Sic gorgeamus a los subjectatus nunc.
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[*] posted on 7-2-2009 at 09:50

Thanks to you both! I mistyped - acetoarsenate is what I meant. Alchemists were fascinated by antimony and suffered from it's toxicity - not trivial, thanks. How cumulative are its effects?... probably nothing good. At least Cu toxicity is usually avoided because it tastes so incredibly bad.

All those copper-nitrogen-sulfur compounds look interesting. Some CuNH4 complexes are dangerous accelerators or decomposition catalysts when combined with chlorates and have a dubious reputation in general, so any experimentation will be with very small quantities!
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[*] posted on 9-3-2009 at 22:47

**Copy/Pasting all this from a previous post I made about 8 days ago at RogueSci... With a bit of formatting. Some of these theories may be interesting to you.**

I remembered some info and speculation was posted to PML back in early February about paris green. I couldn't remember the details so I ended up digging it up out of the PML archive. I'm only re-posting a few SMALL bits of it that I feel are particularly relevant to this thread in particular. There is a lot of info on reactions applicable to other stars that are similar and very enlightening (pun intended). I'm surprised no one else has thought to post some of this. I'd just link to the archive if it were not user/pass protected. Surely many of you are on PML... right?


In the section on blue and white in (Shidlovski's book) there is this, bearing out what
Mike Swisher has reported. p 170:
"In the absence of sulfur, cuprous chloride is not formed in the flame.
In this case, sulfur reacts with potassium chlorate to form free chlorine:
2KClO3 + 2S -> K2SO4 + SO2 + Cl2"
--AFN translation of Shidlovski's
"Principles of Pyrotechnics" p. 166


Arsenic must play a similar role to sulfur in the chlorine production,
given a number of paris green blues with potassium chlorate. I've never
tried (or seen this composition in use) from Weingart:

Paris green 25
potassium chlorate 50
Stearin 8
Dextrin 5

Quoted parts of a post by Charley Wilson from PML archives
posted Sun Feb 1 17:34:40 EST 2009


Charley, while it may be true that the presence of arsenic in a chlorate
composition leads to the liberation of free chlorine in burning, I've never
seen a reference to this in the literature.

On the other hand, Bernie Douda indicates in RDTN No. 71 ("Theory of Colored
Flame Production," NAD-Crane, 1964) that copper acetate survives at flame
temperature and emits in the blue range. (NOTE: In posts several days later it is added that "Acetate is mentioned
on page 14 of the PDF, 26 of the original, in connection w/ sodium-strontium-barium."--Mr. Emous, Anon.) It is possible that copper acetate
is one of the intermediate products of the decomposition of Paris green
(copper acetoarsenite) and that it accounts for the relative success of blue
compositions containing Paris green and potassium chlorate, but no chlorine
donor. Further support for this hypothesis is provided by the inferior
performance of Scheele's green (copper arsenite) when compared to that of
Paris green, as noted by several authorities.

Pyrotechnic color production was extensively investigated in the middle
nineteenth century. I doubt that Chertier, Tessier, and Websky - one or
another of them - failed to investigate just about any composition that had
promise and could be made with materials available to them. It is noteworthy
that some of the earliest blue compositions of the chlorate era utilized
copper acetate. It is sometimes unclear whether the neutral or the basic
acetate was meant by the trivial descriptions "verdigris" or "Grünspan."
However, the problem either salt poses for the pyrotechnist is the presence
of water of hydration. Note the similarities of their structures, and the
way the arsenite radical effectively substitutes for the water of hydration:

Basic copper acetate (blue verdigris): Cu(C2H3O2)2.CuO.6H2O

Cupric acetate (neutral verdigris): Cu(C2H3O2)2.H2O

Paris green: Cu(C2H3O2)2.3Cu(AsO2)2

Quoted post by Mike Swisher from PML archive
Posted Mon Feb 2 14:10:36 EST 2009


In any event, chlorate blue compositions rarely use soluble copper compounds
or contain sulphur these days. In the past there was some use of copper
sulphate, which is soluble (e.g., blue star formula #1, p. 134 of the 1947
edition of Weingart) - and they were known to have stability problems
(Weingart writes: "The first of these formulas is an old one which was used
before it was possible to obtain the chemicals used now. It is only suitable
when the work is to be used within a few weeks.") There is a much less
recondite explanation for the instability of mixtures of potassium chlorate
and copper sulphate than the putative formation of copper chlorate and its
subsequent crystallization with potassium chlorate to form a doped crystal
lattice. It is that copper sulphate in water solution has a very acidic pH.
That is why its customary name is "blue vitriol." Visita interiora terræ,
rectificando invenies occultum lapidem!

The addition of sulphuric acid to compositions containing potassium chlorate
is a reliable - one might say "well-known" - way of causing them to ignite.
The presence of sulphur oxides in sulphur, when the latter is mixed with
potassium chlorate, is a "well-known" cause of spontaneous combustion, the
reason why such mixtures are avoided if at all possible. These phenomema are
quite independent of any presence of copper compounds. We don't need to seek
arcane explanations for a phenomenon when a simple and obvious one has been
known for a century and a half, or more.

Quoted part of a post by Mike Swisher from PML archive
posted Tue Feb 3 13:58:47 EST 2009


I've always figured that the use of copper arsenite was simply a
of the work of Chertier, dropping the aceto..

That raises a few interesting questions for research:
1). What is the decomposition pathway for copper acetoarsenite? Is acetic
acid one of the products, or is it copper acetate, etc.

2). How about a ghost mine experiment:
One way of achieving a sort of sky blue with methanol is with a copper salt
soluble in the alcohol, with added 23 baume muriatic acid as the chlorine
(don't breath the combustion products).

Add glacial acetic acid to it and see what happens. Perhaps even strong
white vinegar.

Quoted post by Charley Wilon from PML archive
Posted Tue Feb 3 21:32:03 EST 2009


Chemists' Dictionary of Synonyms : Incorporating Rouse's Synonyms of
Chemists, Their Assistants and Apprentices
The Chemist and Druggist, London 1940.

Copper Arsenite [Cupric arsenite]-Cuprum arsenicosum, mineral green, Scheele's green.
[Usually considered to be CuHAsO3. The Merck Index. 14th.]
Based on personal experience years ago w/ a blue lance/flare using on of Weingart's
p-green comps.... downwind there was a strong smell of acetic acid, not as bad as
the glacial stuff (which you at one time buy in a photo store), but still strong a strong odour.

Quoted post by Mr. Emous, Anon. from PML archive
Posted Wed Feb 4 10:29:29 EST 2009

Ah... Bleh. Fine I'll add a bit more related content not specific to paris green.


Mr Westfield, try the following:

Strontium nitrate - 25
Ammonium picrate - 5
Lampblack - 1
Paraffine - 1

This is from Tessier, the second edition of 1883 (p. 383, composition no.
105). No chlorine compounds, no sulphur; it is highly praised, Tessier's
remarks being "Ce rouge est beau, bien que légèrement orangé. Il est
eblouissant à ce point de faitguer l'¦il qui se dirigerait directement sur
la flamme. Il est aussi beau de reflet."

Formula 107, as follows:

Strontium nitrate - 40
Ammonium picrate - 10
Lampblack - 2
Paraffine - 1

Is even more praised as "Admirable dæéclat et de reflet."

These two compositions are quoted by Davis, p. 71. Tessier gives green
analogues to these mixtures, which are also quoted by Davis, but describes
them as having pale flames. This supports my belief and the experience I've
had in using red star compositions without chlorine donors that an adequate
red can be made based on the SrOH band (as implied by Tessier's comment that
"this red is pretty, although slightly orangey." However, barium nitrate
cannot make a comparably good green without a chlorine donor.

Quoted post by Mike Swisher from PML archive
Posted Wed Feb 4 13:57:05 EST 2009


Myke, it has often seemed to me that Paris green had some fuel value, and
this may reflect the oxygen-scavenging capacity of arsenic. An illustration
is Lancaster's blue pumped star formula on p. 87 of the first edition:

Potassium chlorate 68
Paris green 22
Colphony resin 6
Dextrine 4

Unless we assume the Paris green has some fuel value, this composition looks
fuel-starved, and that would not suggest its yielding as good a color as it

Quoted post by Mike Swisher from PML archive
Posted Wed Feb 4 14:03:32 EST 2009


On the calomel question, not only is it a good chlorine donor because the
chlorine easily parts from the mercury to combine with a more strongly
electropositive cation - but the mercury vapor in the flame enlarges the
flame envelope and gives it a luminous quality unlike other chlorine donors.
It slows combustion, but without choking the flame - just as the old authors

Quoted post by Mike Swisher from PML archive
Posted Wed Feb 4 15:10:18 EST 2009


Another possible explanation of the role of using arsenic compounds in
the production of blue colored flames is that it (arsenic) has a
number of blue lines in its own spectrum that, given appropriate
excitation conditions, the hue(s) of its own emission lines may
combine to enhance CuCl emission lines and yield a more pronounced
blue flame hue.

See the following site for a rendition of a flame emission spectrum of arsenic:

Quoted post by Richard Dilg from PML archive
Posted Mon Feb 2 17:04:44 EST 2009

(Apparently the archive listing isn't necessarily sorted by post date, however this seems to fit in about anywhere... So I'll just leave it here.)

Also a few posters had offered up paris green for sale at "good" prices. Those who were interested didn't seem to want much, just enough for a couple small tests. Can't imagine why (sarcasm)...

Internet connection deities... please don't let this connection time out yet again.

So many ideas... too few dealing with chemistry.
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[*] posted on 10-3-2009 at 12:17

"Paris Green" is also called Schweinfurth Green, and is Cu(II) acetoarsenite(III). It is emerald-green, water-insoluble, and has the approximate formula 3Cu(AsO2)2.Cu(C2H3O2)2, being made from As2O3 and Cu(II) acetate. It is used chiefly as a green pigment, an insecticide, and wood preservative (with both fungicidal and insecticidal actions). However, for the last use, it has been largely superseded by a copper chromate-arsenate mixture, called Tanalin and other names.
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[*] posted on 10-3-2009 at 12:29

Well: Why not use Copper-Chlorate ? Just from Ba(ClO3)2 + CuSO4 ==> BaSO4 (ppt) + Cu(ClO3)2 ...
Only question: Will the Cu(ClO3)2 be stable (non explosive) ?
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[*] posted on 24-3-2009 at 07:13

Copper chlorate, as I recall, is indeed explosive, but also highly hygroscopic. A primary explosive at that. It will "deactivate" itself with atmospheric water within a few hours unless kept in a dessicator. The hygroscopic nature is the reasoning for coordinating it with amines. Amines being a stronger ligands, prevent the compound from absorbing water.

I've heard many theories about Paris Green, and why it was so good. From talking with the old timers, the absolute best blues also employed hexachlorobenzene in addition to the paris green and chlorate. I was always curious if the blue color of the AsCl3 flame enhanced the color, or at least didn't offer any interference.
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