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Diphenyl oxalate

Diphenyl oxalate

IUPAC name	Diphenyl oxalate
Other names	Diphenylethandioate, oxalic acid diphenyl ester, Cyalume®, DPO
Identifiers
CAS number	3155-16-6
PubChem	18475
SMILES	O=C(Oc1ccccc1)C(=O)Oc2ccccc2
Properties
Molecular formula	C₁₄H₁₀O₄
Molar mass	242.227 g/mol
Appearance	Solid
Melting point	136°C
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Diphenyl oxalate (trademark name Cyalume) is a solid ester whose oxidation products are responsible for the chemiluminescence in a glowstick. It can be synthesized by fully esterifying phenol with oxalic acid. The reaction with hydrogen peroxide that diphenyl oxalate undergoes to produce a photon of light is shown below:

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The reaction rate is pH dependent, and slightly alkaline conditions achieved by adding a weak base, e.g. sodium salicylate, will produce brighter light. The 2,4,6-trichlorophenole ester of oxalic acid is a solid and thus easier to handle. Furthermore, since trichlorophenolate is the better leaving group, the reaction will proceed faster, again producing brighter light, as compared to the phenole ester.

The following colors can be produced by using different dyes:

Color	Compound
Blue	9,10-Diphenylanthracene
Green	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