Oxalyl chloride
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2008-07-07T08:05:24Z
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{{Chembox new
| Name = Oxalyl chloride
| ImageFile = Oxalyl-chloride-2D.png
<!-- | ImageSize = 150px -->
| ImageName = Oxalyl chloride
| IUPACName = Oxalyl dichloride
| OtherNames = Ethanedioyl dichloride<br />Oxalic acid chloride<br />Oxalic acid dichloride<br />Oxalyl dichloride<br />Oxalic dichloride<br />Oxaloyl chloride
| Section1 = {{Chembox Identifiers
| SMILES = ClC(=O)C(=O)Cl
| CASNo = 79-37-8
| RTECS = KI2950000
}}
| Section2 = {{Chembox Properties
| Formula = C<sub>2</sub>O<sub>2</sub>Cl<sub>2</sub>
| MolarMass = 126.93 g/mol
| Appearance = colorless liquid
| Density = 1.4785 g/mL, liquid
| Solubility = Decomposes
| MeltingPt = −16 °C
| BoilingPt = 63–64 °C (1.017 bar)
| Viscosity =
| RefractIndex = 1.429
}}
| Section7 = {{Chembox Hazards
| ExternalMSDS = [http://ptcl.chem.ox.ac.uk/MSDS/OX/oxalyl_chloride.html External MSDS]
| EUClass = not listed
| NFPA-H = 3
| NFPA-F =
| NFPA-R = 1
}}
| Section8 = {{Chembox Related
| Function = [[acyl chloride]]s
| OtherFunctn = [[Malonyl chloride]]<br />[[Succinyl chloride]]<br /> [[phosgene]]
| OtherCpds = [[Oxalic acid]]<br /> [[Diethyl oxalate]]<br /> [[Oxamide]]<br /> [[Oxalyl hydrazide]]</br>[[Cuprizon 1]]
}}
}}
'''Oxalyl chloride''' is a [[chemical compound]] with the [[chemical formula|formula]] (COCl)<sub>2</sub>. This colourless liquid, the di[[acid chloride]] of [[oxalic acid]], is a useful reagent in [[organic synthesis]].<ref>Salmon, R. "Oxalyl Chloride" in Encyclopedia of Reagents for Organic Synthesis 2001, John Wiley & Sons, New York.DOI: 10.1002/047084289X.ro015</ref> It can be prepared by treating [[oxalic acid]] with [[phosphorus pentachloride]].<ref>Vogel, A.; Steffan, G.; Mannes, K.; Trescher, V. "Oxalyl chloride" DE 78-2840435 19780916.Chemical Abstracts Number 93:94818</ref>
==Applications in organic synthesis==
====Synthesis of acid chlorides====
It is mainly used in [[organic synthesis]] for the preparation of acid chlorides from the corresponding [[carboxylic acid]]s. Like [[thionyl chloride]], the reagent produces volatile side products in this application:
:RCO<sub>2</sub>H + (COCl)<sub>2</sub> → RC(O)Cl + HCl + [[carbon monoxide|CO]] + [[carbon dioxide|CO<sub>2</sub>]]
Oxalyl chloride tends to be a milder, more selective [[reagent]].
====Formylation of arenes====
Oxalyl chloride reacts with [[aromatic ring|aromatic]] compounds in the presence of [[aluminium chloride]] to give the corresponding [[acid chloride]] in a process known as a [[Friedel-Crafts acylation]].<ref>{{OrgSynth | author = Neubert, M. E.; Fishel, D. L. | title = Preparation of 4-Alkyl- and 4-Halobenzoyl Chlorides: 4-Pentylbenzoyl Chloride |collvol = 7 | collvolpages = 420 | year = 1990 | prep = cv7p0420}}</ref><ref>{{OrgSynth | author = Sokol, P. E. | title = Mesitoic Acid | collvol = 5 | collvolpages = 706 | year = 1973 | prep = CV5P0706}}</ref> The resulting acid chloride can be hydrolysed in water to form the corresponding [[carboxylic acid]].
====Preparation of diesters====
Like other acid chlorides, oxalyl chloride reacts with alcohols to give esters:
:2 RCH<sub>2</sub>OH + (COCl)<sub>2</sub> → RCH<sub>2</sub>OC(O)C(O)OCH<sub>2</sub>R + 2 HCl
Typically such reactions are conducted in the presence of a base such as [[pyridine]]. The diester derived from [[phenol]], [[phenyl oxalate ester]], is Cyalume, the active ingredient in [[glow sticks]].
====Oxidation of alcohols====
The combination of [[Dimethyl sulfoxide|DMSO]] and oxalyl chloride converts alcohols to the corresponding [[aldehyde]]s and [[ketone]]s via the process known as the [[Swern oxidation]].
==Precautions==
As with all [[acyl chloride]]s, oxalyl chloride reacts with [[water (molecule)|water]] liberating [[hydrogen chloride|HCl]] gas. Overall, its effects are comparable to those of [[phosgene]].
In March 2000 a [[Malaysia Airlines]] [[Airbus A330]] was damaged beyond repair after a falsely declared cargo of oxalyl chloride leaked into the cargo bay. <ref>{{cite news
| title = Firm told to pay $65 mln for ruining plane
| date = 2007-12-06
| url = http://www.reuters.com/article/oddlyEnoughNews/idUSN0620441720071206
| publisher=[[Reuters]]
| accessdate=2007-12-06}}</ref>
==References==
<references/>
[[Category:Acyl chlorides]]
[[de:Oxalylchlorid]]
[[fr:chlorure d'oxalyle]]
[[nl:Oxalylchloride]]
[[ja:塩化オキサリル]]
[[pl:Chlorek oksalilu]]
[[zh:草酰氯]]