Diphenyl oxalate

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| Watchedfields = changed

| verifiedrevid = 447061584

| ImageFile = Diphenyl oxalate.svg

| ImageSize = 200

| ImageAlt = Skeletal formula of diphenyl oxalate

| ImageFile1 = Diphenyl oxalate 3D ball.png

| ImageSize1 = 220

| ImageAlt1 = Ball-and-stick model of the diphenyl oxalate molecule

| PIN = Diphenyl oxalate

| OtherNames = diphenylethandioate, oxalic acid diphenyl ester, cyalume, DPO

|Section1={{Chembox Identifiers

| CASNo_Ref = {{cascite|correct|??}}

| CASNo = 3155-16-6

| PubChem = 18475

| SMILES = O=C(Oc1ccccc1)C(=O)Oc2ccccc2

| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}

| ChemSpiderID = 17449

| InChI = 1/C14H10O4/c15-13(17-11-7-3-1-4-8-11)14(16)18-12-9-5-2-6-10-12/h1-10H

| InChIKey = ULOZDEVJRTYKFE-UHFFFAOYAB

| StdInChI_Ref = {{stdinchicite|changed|chemspider}}

| StdInChI = 1S/C14H10O4/c15-13(17-11-7-3-1-4-8-11)14(16)18-12-9-5-2-6-10-12/h1-10H

| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}

| StdInChIKey = ULOZDEVJRTYKFE-UHFFFAOYSA-N

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|Section2={{Chembox Properties

| Formula = C₁₄H₁₀O₄

| MolarMass = 242.227 g/mol

| Appearance = solid

| Density =

| MeltingPtC = 136

| BoilingPt =

| Solubility =

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|Section3={{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt =

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|Section4={{Chembox Thermochemistry

| DeltaGf =

| DeltaHc =

| DeltaHf = 129·0 ± 0·8{{cite journal|last1=Carson|first1=A. S.|last2=Fine|first2=D. H.|last3=Gray|first3=P.|last4=Laye|first4=P. G.|title=Standard enthalpies of formation of diphenyl oxalate and benzoic anhydride and some related bond dissociation energies|journal=Journal of the Chemical Society B: Physical Organic|date=1971|pages=1611|doi=10.1039/J29710001611}}

| Entropy =

| HeatCapacity =

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| Section9 = {{Chembox Related

| OtherAnions =

| OtherCations =

| OtherFunction =

| OtherFunction_label =

| OtherCompounds = Dimethyl oxalate

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Diphenyl oxalate (trademark name Cyalume) is a solid whose oxidation products are responsible for the chemiluminescence in a glowstick. This chemical is the double ester of phenol with oxalic acid. Upon reaction with hydrogen peroxide, 1,2-dioxetanedione is formed, along with release of the two phenols.{{cite journal|last1=Orosz|first1=György|title=The role of diaryl oxalates in peroxioxalate chemiluminescence|journal=Tetrahedron|date=January 1989|volume=45|issue=11|pages=3493–3506|doi=10.1016/S0040-4020(01)81028-0}} The dioxetanedione then reacts with a dye molecule, decomposing to form carbon dioxide and leaving the dye in an excited state. As the dye relaxes back to its unexcited state, it releases a photon of visible light.

:Image:Cyalume-reactions.svg

The reaction rate is pH dependent, and slightly alkaline conditions, achieved by adding a weak base, such as sodium salicylate, give a faster reaction and therefore produce brighter light.

The 2,4,6-trichlorophenol ester is a solid and thus easier to handle.{{clarify|reason=the diphenyl itself is also a solid|date=February 2019}} Furthermore, since trichlorophenolate is the better leaving group, the reaction will proceed faster, again producing brighter light, as compared to the phenol ester.

The following colors can be produced by using different dyes:

class="wikitable"
Color ! Compound
Green | 9,10-Diphenylanthracene
Blue | 9,10-Bis(phenylethynyl)anthracene
Yellow-green | Tetracene
Yellow | 1-Chloro-9,10-bis(phenylethynyl)anthracene
Orange | 5,12-Bis(phenylethynyl)naphthacene, Rubrene, Rhodamine 6G
Red | Rhodamine B