Bis(2,4,5-trichloro-6-(pentyloxycarbonyl)phenyl)oxalate

Bis[2,4,5-trichloro-6-(pentyloxycarbonyl)phenyl]oxalate (also known as bis(2,4,5-trichloro-6-carbopentoxyphenyl) oxalate or CPPO) is an organic compound with the formula (C5H11O2CC6HCl3O)2C2O2. A white solid, it is classified as a diester of oxalic acid. It is an active ingredient for the chemiluminescence in glowsticks. It can be synthesized by reacting 2-carbopentoxy-3,5,6-trichlorophenol with oxalyl chloride.

When mixed with hydrogen peroxide in an organic solvent (diethyl phthalate, ethyl acetate, etc...) in the presence of a fluorescent dye CPPO causes the emission of light, following its degradation to 1,2-dioxetanedione (note that many side-groups of the aromatic rings are not shown.):


 * [[Image:Cyalume-reactions.svg|500px]]

The reaction rate is pH dependent, and slightly alkaline conditions achieved by adding a weak base, e.g. sodium salicylate, will produce brighter light. Developed by American Cyanamid in the 1960s, the formulation containing CPPO, a fluorescer, and a glass capsule containing hydrogen peroxide and a base catalyst, all in dialkyl phthalate solvents, was marketed as Cyalume.

The following colors can be produced by using different dyes: