Malonyl chloride
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| ImageFile = CH2(COCl)2.png
| ImageSize =
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| PIN = Propanedioyl dichloride{{cite book |author=International Union of Pure and Applied Chemistry |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=The Royal Society of Chemistry |pages=797 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}
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| Section1 = {{Chembox Identifiers
| CASNo = 1663-67-8
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = PDF3ZL8FTK
| PubChem = 74269
| EC_number = 216-772-9
| ChemSpiderID = 66875
| InChI=1S/C3H2Cl2O2/c4-2(6)1-3(5)7/h1H2
| InChIKey = SXYFKXOFMCIXQW-UHFFFAOYSA-N
| SMILES = C(C(=O)Cl)C(=O)Cl
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| Section2 = {{Chembox Properties
| C=3 | O=2 | Cl = 2 | H=2
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| Appearance = colorless liquid
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| MeltingPt =
| BoilingPtC = 58
| BoilingPt_notes = 28 mm Hg
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| Section3 = {{Chembox Hazards
| GHSPictograms = {{GHS02}}{{GHS05}}
| GHSSignalWord= Danger
| HPhrases = {{H-phrases|226|314}}
| PPhrases = {{P-phrases|210|233|240|241|242|243|260|264|280|301+330+331|303+361+353|304+340|305+351+338|310|321|363|370+378|403+235|405|501}}
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Malonyl chloride is the organic compound with the formula CH2(COCl)2. It is the acyl chloride derivative of malonic acid. It is a colorless liquid although samples are often deeply colored owing to impurities. The compound degrades at room temperature after a few days. It used as a reagent in organic synthesis.{{Cite encyclopedia|encyclopedia=Encyclopedia of Reagents for Organic Synthesis|title=Malonyl Chloride|year=2001|doi=10.1002/047084289X.rm016|author=Thomas Ziegler|isbn=0471936235}}
Synthesis and reactions
Malonyl chloride can be synthesized from malonic acid in thionyl chloride.{{Cite journal|author= Chittaranjan Raha|title=Di-tert-Butyl Malonate|year=1953|volume=33|page=20|url=http://orgsyn.org/demo.aspx?prep=CV4P0261|journal=Organic Syntheses|doi=10.15227/orgsyn.034.0026|url-access=subscription}} As a bifunctional compound, it is used in the preparation of a number of cyclic compounds by diacylation. Heating in the presence of non-nucleophilic base gives the ketene derivative O=C=C(H)COCl.