Paris green

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Paris green
Schweinfurter Grün.svg
Names
Other names
C.I. pigment green 21, emerald green, Schweinfurt green, imperial green, Vienna green, Mitis green, Veronese green[1]
Identifiers
12002-03-8 YesY
Jmol 3D model Interactive image
PubChem 22833492
UN number 1585
  • InChI=1S/2C2H4O2.6AsHO2.4Cu/c2*1-2(3)4;6*2-1-3;;;;/h2*1H3,(H,3,4);6*(H,2,3);;;;/q;;;;;;;;4*+2/p-8
    Key: HTSABAUNNZLCMN-UHFFFAOYSA-F
  • CC(=O)[O-].CC(=O)[O-].[O-][As]=O.[O-][As]=O.[O-][As]=O.[O-][As]=O.[O-][As]=O.[O-][As]=O.[Cu+2].[Cu+2].[Cu+2].[Cu+2]
Properties
Cu(C2H3O2)2·3Cu(AsO2)2
Molar mass 1013.79444 g/mol
Appearance Emerald green crystalline powder
Density >1.1 g/cm3 (20 °C)
Melting point >345 °C
Boiling point decomposes
insoluble
Solubility soluble but unstable in acids
insoluble in alcohol
Vapor pressure {{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references
Paris green
 
About these coordinates     Color coordinates
Hex triplet #50C878
sRGBB  (rgb) (80, 200, 120)
CMYKH   (c, m, y, k) (60, 0, 40, 22)
HSV       (h, s, v) (140°, 60%, 78%)
Source [Unsourced]
B: Normalized to [0–255] (byte)
H: Normalized to [0–100] (hundred)

Paris green (copper(II) acetate triarsenite) is an inorganic compound more precisely known as copper(II) acetoarsenite. It is a highly toxic emerald-green crystalline powder[2] that has been used as a rodenticide and insecticide, and also as a pigment, despite its toxicity. It is also used as a blue colorant for fireworks.[3] The color of Paris green is said to range from a pale, but vivid, blue green when very finely ground, to a deeper true green when coarsely ground.

Preparation

Paris green may be prepared by combining copper(II) acetate and arsenic trioxide.[4]

Uses

Insecticide

Paris green was once used to kill rats in Parisian sewers, hence the common name.[5] It was also used in America and elsewhere as an insecticide for produce such as apples, around 1900, where it was blended with lead arsenate. This toxic mixture is said "to have burned the trees and the grass around the trees". Paris green was heavily sprayed by airplane in Italy, Sardinia, and Corsica during 1944 and in Italy in 1945 to control malaria.[6]

Pigment

Paris green, also called emerald green, was a popular pigment used in artists' paints by (among others) the English painter W. Turner, Impressionists such as Monet and Renoir and Post-Impressionists such as Gauguin, Cézanne and Van Gogh.[7]

Related pigments

Similar natural compounds are the minerals chalcophyllite Cu
18
Al
2
(AsO
4
)
3
(SO
4
)
3
(OH)
27
·36H
2
O
, conichalcite CaCu(AsO
4
)(OH)
, cornubite Cu
5
(AsO
4
)
2
(OH)
4
·H
2
O
, cornwallite Cu
5
(AsO
4
)
2
(OH)
4
·H
2
O
, and liroconite Cu
2
Al(AsO
4
)(OH)
4
·4H
2
O
. These vivid minerals range from greenish blue to slightly yellowish green.

Scheele's green is a chemically simpler, less brilliant, and less permanent, synthetic copper-arsenic pigment used for a rather short time before Paris green was first prepared, which was approximately 1814. It was popular as a wallpaper pigment and would degrade, with moisture and molds, to arsine gas. Paris green may have also been used in wallpaper to some extent and may have also degraded similarly. Both pigments were once used in printing ink formulations.

The ancient Romans used one of them, possibly conichalcite, as a green pigment. The Paris green paint used by the Impressionists is said to have been composed of relatively coarse particles. Later, the chemical was produced with increasingly small grinds and without carefully removing impurities; its permanence suffered. It is likely that it was ground more finely for use in watercolors and inks, too.

See also

Gallery

Illustrations of Paris green
Paris green pigment 
Mixing "Paris green" and road dust preparatory to dusting streams and breeding places of mosquitoes during World War II 
Use as insecticide, poster issued by US Public Health Service 

References

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  4. "H.Wayne Richardson, "Copper Compounds" in Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a07_567
  5. The Natural Paint Book, by Lynn Edwards,Julia Lawless, Table of contents
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  7. Emerald green, Colourlex

Further reading

  • Fiedler, I. and Bayard, M.A., Emerald Green and Scheele’s Green, in Artists’ Pigments, A Handbook of Their History and Characteristics, Vol 3: E.W. Fitzhugh (Ed.) Oxford University Press 1997, p. 219 – 271

External links