Oxalyl chloride

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Oxalyl chloride
IUPAC name
Oxalyl dichloride
Systematic IUPAC name
Ethanedioyl dichloride
Other names
Oxalic acid chloride
Oxalic acid dichloride
Oxalic dichloride
Oxaloyl chloride
Molar mass 126.93 g/mol
Appearance Colorless liquid
Odor Acrid
Density 1.4785 g/cm3
Melting point −16 °C (3 °F; 257 K)
Boiling point 63–64 °C (145–147 °F; 336–337 K)
Solubility Reacts with alcohols, amines, carboxylic acids
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Related compounds
Related compounds
Oxalic acid
Thionyl chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Oxalyl chloride is the acyl chloride of oxalic acid. It is used as a chlorinating agent, similar to thionyl chloride. Like other acyl chlorides, it is also used for producing derivatives of the parent acid such as esters. Aromatic esters of oxalic acid are used in glowsticks.



Oxalyl chloride behaves similarly to other acyl chlorides in that reacting with alcohols produces the corresponding ester. Unusually, however, reaction with water does not yield the parent acid, but instead results in decomposition to carbon dioxide, carbon monoxide, and hydrogen chloride.

Other carboxylic acids can be converted to the corresponding acyl chloride by treatment with oxalyl chloride in the presence of a catalytic amount of a nitrogen base such as dimethylformamide, triethylamine, or pyridine. The byproducts produced by this reaction are carbon dioxide and carbon monoxide.

Oxalyl chloride can also be used to formylate arenes by Friedel-Crafts acylation.



Oxalyl chloride is available from chemical suppliers but due to its hazards it is often hard to get for amateurs.


Oxalyl chloride is usually prepared by reacting anhydrous oxalic acid with phosphorus pentachloride. Unusually, thionyl chloride cannot be used to chlorinate oxalic acid.


  • Make Bis(2,4,6-trichlorophenyl)oxalate for glowsticks



Oxalyl chloride is very toxic and presents a severe inhalational hazard. It should only be used with very good ventilation.

Contact with water produces highly toxic carbon monoxide gas, along with corrosive hydrogen chloride.


In airtight bottles.


Should be dissolved in an excess calcium hydroxide solution, which will cause calcium oxalate to precipitate.


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