Diphenyl oxalate

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Diphenyl oxalate
Skeletal formula of diphenyl oxalate
Ball-and-stick model of the diphenyl oxalate molecule
IUPAC name
diphenyl oxalate
Other names
diphenylethandioate, oxalic acid diphenyl ester, cyalume, DPO
3D model (JSmol)
ECHA InfoCard 100.203.380
Molar mass 242.227 g/mol
Appearance solid
Melting point 136 °C (277 °F; 409 K)
129·0 ± 0·8[1]
Related compounds
Related compounds
Dimethyl oxalate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox 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 produces phenol and 1,2-dioxetanedione,[2] which excites the dye and releases a photon as it decomposes to carbon dioxide.


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-trichlorophenol 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 phenol 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


  1. ^ Carson, A. S.; Fine, D. H.; Gray, P.; Laye, P. G. (1971). "Standard enthalpies of formation of diphenyl oxalate and benzoic anhydride and some related bond dissociation energies". Journal of the Chemical Society B: Physical Organic: 1611. doi:10.1039/J29710001611. 
  2. ^ Orosz, György (January 1989). "The role of diaryl oxalates in peroxioxalate chemiluminescence". Tetrahedron. 45 (11): 3493–3506. doi:10.1016/S0040-4020(01)81028-0.