Chrome orange

{{Short description|Chemical compound and inorganic pigment}} {{Chembox | ImageFile = Chromorange 2.jpg | ImageSize = | ImageAlt = | IUPACName = | OtherNames = {{ubl|Basic chromium lead oxide|Chromium dilead pentaoxide|Chromium lead oxide|Dilead chromate oxide|Lead chromate oxide|Lead chromate(VI) oxide}} | Section1 = {{Chembox Identifiers | CASNo = 18454-12-1 | ChEBI = | ChEMBL = | ChemSpiderID = 27052 | EC_number = 242-339-9 | InChI = 1S/Cr.5O.2Pb/q;;;;2*-1;;+2 | InChIKey = BXVHGCHMBBNRBU-UHFFFAOYSA-N | KEGG = | PubChem = 29078 | SMILES = [O-][Cr](=O)(=O)[O-].O=[Pb].[Pb+2] | UNII = }} | Section2 = {{Chembox Properties | Properties_ref = <ref name=PubChem>{{Cite web |last=PubChem |title=Lead chromate oxide |url=https://pubchem.ncbi.nlm.nih.gov/compound/29078 |access-date=2026-02-11 |website=pubchem.ncbi.nlm.nih.gov |language=en}}</ref> | Pb=2 | Cr=1 | O=5 | Appearance = red solid | Density = 6.63 g/cm³ | MeltingPtC = 920 | Solubility = insoluble | SolubleOther = soluble in acids, alkalis }} | Section3 = {{Chembox Structure | Structure_ref = <ref>{{Cite journal |last=Morita |first=Shinichi |last2=Toda |first2=Kohji |date=1984-04-01 |title=Determination of the crystal structure of Pb2CrO5 |url=https://pubs.aip.org/jap/article/55/7/2733/168411/Determination-of-the-crystal-structure-of-Pb2CrO5 |journal=Journal of Applied Physics |language=en |volume=55 |issue=7 |pages=2733–2737 |doi=10.1063/1.333271 |issn=0021-8979|url-access=subscription }}</ref> | CrystalStruct = monoclinic | SpaceGroup = c2/''m'' | PointGroup = | LattConst_a = 14.018 Å | LattConst_b = 5.683 Å | LattConst_c = 7.143 Å | LattConst_alpha = | LattConst_beta = 115.23 | LattConst_gamma = | UnitCellVolume = 514.8 ų | UnitCellFormulas = 4 units per cell | Coordination = }} | Section4 = {{Chembox Thermochemistry | Thermochemistry_ref = <ref>{{Cite journal |last1=Sahu |first1=Sulata Kumari |last2=Ganesan |first2=Rajesh |last3=Gnanasekaran |first3=T. |date=2010-01-01 |title=Standard molar Gibbs free energy of formation of Pb5CrO8(s), Pb2CrO5(s), and PbCrO4(s) |url=https://www.sciencedirect.com/science/article/pii/S0021961409001748 |journal=The Journal of Chemical Thermodynamics |language=en |volume=42 |issue=1 |pages=1–7 |doi=10.1016/j.jct.2009.06.026 |s2cid=55549520 |issn=0021-9614|url-access=subscription }}</ref> | HeatCapacity = | Entropy = | DeltaHform = | DeltaGfree = -1161.3 kJ/mol | DeltaHcombust = | DeltaHfus = | DeltaHvap = | DeltaHsublim = }} | Section7 = {{Chembox Hazards | MainHazards = | ExternalSDS = | IDLH = 100.0 mg/m³ | TLV = 0.0002 mg/m³ | TLV-STEL = 0.0005 mg/m³ | NIOSH_ref = <ref name=PubChem /> | GHS_ref = <ref name=PubChem /> | GHSPictograms = {{GHS07}}{{GHS08}}{{GHS09}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|H302|H332|H360|H373|H410}} | PPhrases = {{P-phrases|P203|P260|P264|P270|P271|P273|P280|P301+P317|P304+P340|P317|P318|P319|P330|P391|P405|P501}} }} | Section8 = {{Chembox Related | Related_ref = | OtherAnions = | OtherCations = | OtherCompounds = }} }} '''Chrome orange''' is a mixed oxide with the chemical formula Pb₂CrO₅. It has found use as a pigment.

==Properties== Visible light activity up to 550 nanometers has been recorded.<ref>{{Cite journal |last1=Lee |first1=Heung Chan |last2=Cho |first2=Sung Ki |last3=Park |first3=Hyun S. |last4=Nam |first4=Ki Min |last5=Bard |first5=Allen J. |date=2017-08-24 |title=Visible Light Photoelectrochemical Properties of PbCrO 4, Pb 2 CrO 5, and Pb 5 CrO 8 |url=https://pubs.acs.org/doi/10.1021/acs.jpcc.7b03230 |journal=The Journal of Physical Chemistry C |language=en |volume=121 |issue=33 |pages=17561–17568 |doi=10.1021/acs.jpcc.7b03230 |issn=1932-7447|url-access=subscription }}</ref>

==Synthesis== Pb₂CrO₅ can be made by treating a lead(II) salt with an alkaline solution of a chromate or by treating chrome yellow (PbCrO₄) with strongly basic solution.<ref name=Ullmann>{{cite encyclopedia|author=Völz, Hans G.|display-authors=et al|title=Pigments, Inorganic|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|year=2006|publisher=Wiley-VCH|doi=10.1002/14356007.a20_243.pub2|isbn=3527306730}}.</ref>

It can also be synthesized using a gas-liquid precipitation process.<ref name=":0">{{Cite journal |last1=Gu |first1=LiNa |last2=Meng |first2=GuangYao |date=2007-09-05 |title=Synthesis and characterization of two PbO-chromium oxides |url=https://www.sciencedirect.com/science/article/pii/S0032591007000198 |journal=Powder Technology |language=en |volume=178 |issue=1 |pages=1–4 |doi=10.1016/j.powtec.2007.01.017 |issn=0032-5910|url-access=subscription }}</ref> Changing the pH controls whether PbCrO₄ or Pb₂CrO₅ is created.<ref name=":0" />

===Nanomaterial=== Orthorhombic nanocrystals can be selectively synthesized by a room temperature solution reaction.<ref>{{Cite journal |last1=Ma |first1=Ming-Guo |last2=Zhu |first2=Ying-Jie |last3=Li |first3=Shu-Hong |date=2009-02-04 |title=A simple route to the synthesis of BaCrO4 microstructures at room temperature |url=https://www.sciencedirect.com/science/article/pii/S0025540808002067 |journal=Materials Research Bulletin |language=en |volume=44 |issue=2 |pages=288–293 |doi=10.1016/j.materresbull.2008.06.003 |issn=0025-5408|url-access=subscription }}</ref>

Using a microwave-assisted ionic liquid (MAIL) method, bundle and rod-like nanocrystals of Pb₂CrO₅ are formed.<ref name=":1">{{Cite journal |last1=Wang |first1=Wei-Wei |last2=Zhu |first2=Ying-Jie |date=2005-03-01 |title=Synthesis of PbCrO 4 and Pb 2 CrO 5 Rods via a Microwave-Assisted Ionic Liquid Method |url=https://pubs.acs.org/doi/10.1021/cg0497546 |journal=Crystal Growth & Design |language=en |volume=5 |issue=2 |pages=505–507 |doi=10.1021/cg0497546 |issn=1528-7483|url-access=subscription }}</ref> In basic solution, single-crystalline Pb₂CrO₅ could be formed by heating lead acetate and potassium dichromate with microwave radiation for only 10 minutes at 90&nbsp;°C.<ref name=":1" /> The MAIL process is simple, fast, and does not employ surfactants.<ref name=":1" /> The presence of hydroxide changes the phase that is formed. Using NaOH, monoclinic Pb₂CrO₅ is formed.<ref name=":1" /> The bundle and rod-shaped structures are sensitive to electron beam irradiation, which will turn them into many small particles.<ref name=":1" />

===Pigment=== In a catalog published c. 1835, Winsor and Newton paint company identify ten synthetic pathways for producing chrome orange, also called deep yellow.<ref name=":2">{{Cite journal |last1=Otero |first1=Vanessa |last2=Pinto |first2=Joana V. |last3=Carlyle |first3=Leslie |last4=Vilarigues |first4=Márcia |last5=Cotte |first5=Marine |last6=João Melo |first6=Maria |year=2017 |title=Nineteenth Century Chrome Yellow and Chrome Deep from Winsor & Newton |journal=Studies in Conservation |volume=62 |issue=3 |pages=123–149 |doi=10.1080/00393630.2015.1131478 |s2cid=138176187 <!-- |via=EBSCO Host -->}}</ref> Chrome orange is made of PbCrO₄ mixed with basic lead chromate (Pb₂CrO₅).<ref name=":2" /> It has been described as a "yellowish red or sometimes a beautiful deep red" in alkaline conditions.<ref name=":2" /> A deep yellow can be created using PbCrO₄ and lead sulfate.<ref name=":2" /> There are ten synthetic methods for preparing deep chrome yellow (that made with Pb₂CrO₅), which require a chromate source, a basic lead source, additives, and a sulfate source.<ref name=":2" /> Controlling the pH was Winsor and Newton's method for creating pigments from the pale yellow to the deep chrome orange.<ref name=":2" /> The resulting product has a high stability to light, which is always coveted by artists and collectors.<ref name=":2" />

==Use as a pigment== [[File:Flaming_June,_by_Frederic_Lord_Leighton_(1830-1896).jpg|thumb|left|Chrome orange was used extensively in Frederic Leighton's ''Flaming June'' (1895; Museo de Arte de Ponce).<ref name=":4">{{cite book |author=<!--no by-line.--> |title=Color in the Making |location=London|publisher=Black Dog Publishing|page=104 |date=2013 |isbn=9781907317958 }}<!--|accessdate=15 Apr 2014--></ref>]] {{infobox color | title=Chrome Orange | hex=E73501 | image= | source=ColourLex<ref>{{cite web |title=Chrome orange – ColourLex |url=https://colourlex.com/project/chrome-orange/ |website=ColourLex |access-date=22 December 2022}}</ref> | isccname=}} Chrome orange can range in color from light to deep orange and is no longer in production as a pigment.<ref name=":3" /> It has also been known as Derby red, Persian red, and Victoria red.<ref name=":3" /> It was first recorded as a pigment in 1809 and was perfect for some impressionist painters in the nineteenth century. The yellow-orange pigment of the boat in Renoir's 1879 painting, The Seine at Asnières (The Skiff) at the National Gallery, London.<ref name=":3" /> Chrome orange was used extensively in Frederic Leighton's ''Flaming June'' (1895; Museo de Arte de Ponce).<ref name=":4" />

==History== The natural mineral crocoite was discovered in 1797 by Louis Vauquelin and chrome orange was synthesized as a pigment for the first time in 1809.<ref name=":3">{{Cite web |title=Pigments through the Ages – Overview – Chrome orange |url=http://www.webexhibits.org/pigments/indiv/overview/crorange.html |access-date=2022-05-11 |website=webexhibits.org}}</ref> Pb₂CrO₅ is found in mineral form as phoenicochroite, which is a monoclinic, red, translucent mineral found in various places across the world, including Russia, the US, and Chile.<ref>{{Cite web |title=Phoenicochroite |url=https://www.mindat.org/min-3194.html |access-date=2022-05-11 |website=mindat.org}}</ref>

==See also== * List of inorganic pigments

==References== {{reflist}}

==Further reading== * Kühn, H. and Curran, M., "Chrome Yellow and Other Chromate Pigments", in ''Artists' Pigments. A Handbook of Their History and Characteristics'', Vol. 1, L. Feller, Ed., Cambridge University Press, London 1986, pp.&nbsp;208–211. {{ISBN?}} * [http://colourlex.com/project/chrome-orange/ Chrome Orange] at ColourLex

{{Shades of orange}}

{{DEFAULTSORT:Chrome Orange}} Category:Inorganic pigments Category:Lead(II) compounds Category:Chromates Category:Shades of orange