{{DISPLAYTITLE:''meta''-Chloroperoxybenzoic acid}} {{chembox | Verifiedfields = changed | Watchedfields = changed | Name =''meta''-Chloroperoxybenzoic acid | verifiedrevid = 431090189 | ImageFileL1 = Meta-Chloroperoxybenzoic acid.svg | ImageFileR1 = Meta-chloroperbenzoic-acid-Spartan-HF-6-31Gstar-3D-balls.png | PIN = 3-Chlorobenzene-1-carboperoxoic acid | OtherNames = {{ubl| *3-Chloroperoxybenzoic acid *3-Chloroperbenzoic acid *3-Chlorobenzoperoxoic acid *''meta''-Chloroperoxybenzoic acid *''m''-Chloroperoxybenzoic acid *''meta''-Chloroperbenzoic acid *mCPBA *''m''-CPBA }} |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 63480 | InChI = 1S/C7H5ClO3/c8-6-3-1-2-5(4-6)7(9)11-10/h1-4,10H | InChIKey = FQAWBGAIOYWONH-UHFFFAOYAN | StdInChI_Ref = {{stdinchicite|changed|chemspider}} | StdInChI = 1S/C7H5ClO3/c8-6-3-1-2-5(4-6)7(9)11-10/h1-4,10H | StdInChIKey_Ref = {{stdinchicite|changed|chemspider}} | StdInChIKey = NHQDETIJWKXCTC-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 937-14-4 | PubChem = 70297 | EC_number = 213-322-3 | UNNumber = 3106 | UNII = G203D4H1RB | SMILES = ClC1=CC(C(OO)=O)=CC=C1 | RTECS = SD9470000 }} |Section2={{Chembox Properties | C=7 | H=5 | Cl=1 | O=3 | Appearance = White powder | Density = | MeltingPtC = 92 to 94 | MeltingPt_notes = decomposes | BoilingPt = | Solubility = | pKa = 7.57 }} |Section3={{Chembox Hazards | MainHazards = Oxidizing, corrosive, explosive | FlashPt = | AutoignitionPt = | GHSPictograms = {{GHS02}}{{GHS05}}{{GHS07}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|226|314|335}} | PPhrases = {{P-phrases|210|220|233|234|240|241|242|243|260|261|264|271|272|280|301+330+331|302+352|303+361+353|304+340|305+351+338|310|312|321|332+313|333+313|337+313|362|363|370+378|403+233|403+235|405|411|420|501}} }} |Section8={{Chembox Related | OtherAnions = | OtherCations = | OtherFunction = | OtherFunction_label = | OtherCompounds = peroxyacetic acid; peroxybenzoic acid}} }}
'''''meta''-Chloroperoxybenzoic acid''' ('''mCPBA''' or '''''m''CPBA''') is a peroxycarboxylic acid. It is a white solid often used widely as an oxidant in organic synthesis. mCPBA is often preferred to other peroxy acids because of its relative ease of handling.<ref name = portal/> mCPBA is a strong oxidizing agent that may cause fire upon contact with flammable material.<ref name=eros>{{cite book|chapter=m-Chloroperbenzoic Acid|first1=A. Somasekar |last1=Rao|first2=H. Rama |last2=Mohan|first3=André|last3= Charette|title=Encyclopedia of Reagents for Organic Synthesis|year=2005|doi= 10.1002/047084289X.rc140.pub2|isbn=0471936235 }}</ref>
==Preparation and purification== mCPBA can be prepared by reacting m-chlorobenzoyl chloride with a basic solution of hydrogen peroxide, followed by acidification.<ref>{{OrgSynth | first1= Richard N. | last1=McDonald | first2= Richard N. | last2=Steppel | first3 = James E. | last3=Dorsey | name-list-style=amp | title = ''m''-Chloroperbenzoic Acid | volume= 50 | page = 15| year = 1970 | doi= 10.15227/orgsyn.050.0015}}</ref>
It is sold commercially as a shelf-stable mixture that is less than 72% mCPBA, with the balance made up of ''m''-chlorobenzoic acid (10%) and water.<ref name = portal>{{cite web | title = 3-Chloroperoxybenzoic acid | publisher = Organic Chemistry Portal | url = https://www.organic-chemistry.org/chemicals/oxidations/meta-chloroperbenzoicacid.shtm}}</ref> The peroxyacid can be purified by washing the commercial material with a sodium hydroxide and potassium phosphate solution buffered at pH = 7.5.<ref name=eros/><ref>{{cite book |author1=Armarego, W. L. F. |author2=Perrin, D. D. |title= Purification of Laboratory Chemicals |edition= 4th |year= 1996 |publisher= Butterworth-Heinemann |location= Oxford |isbn= 0-7506-3761-7 |page= 145 }}</ref> Peroxyacids are generally slightly less acidic than their carboxylic acid counterparts, so the acid impurity can be extracted if the pH is carefully controlled. The purified material is reasonably stable against decomposition if stored at low temperatures in a plastic container.
In reactions where the exact amount of mCPBA must be controlled, a sample can be titrated to determine the exact amount of active oxidant.
== Reactions== The main areas of use are the conversion of ketones to esters (Baeyer-Villiger oxidation), epoxidation of alkenes (Prilezhaev reaction), conversion of silyl enol ethers to silyl α-hydroxy ketones (Rubottom oxidation), oxidation of sulfides to sulfoxides and sulfones, and oxidation of amines to produce amine oxides. The following scheme shows the epoxidation of cyclohexene with mCPBA.
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The epoxidation mechanism is concerted: the ''cis'' or ''trans'' geometry of the alkene starting material is retained in the epoxide ring of the product. The transition state of the Prilezhaev reaction is given below:<ref name="Li-2003">{{cite book |last1=Li |first1=Jie Jack |title=Name Reactions: A Collection of Detailed Reaction Mechanisms |date=2003 |publisher=Springer |location=Berlin, Heidelberg, New York |isbn=978-3-662-05338-6 |page=323 |edition=2nd}}</ref> alt=|center|frameless|350x350px The geometry of the transition state, with the peracid bisecting the C-C double bond, allows the two primary frontier orbital interactions to occur: π<sub>C=C</sub> (HOMO) to σ*<sub>O-O</sub> (LUMO) and n<sub>O</sub> (HOMO, regarded as a filled p orbital on a sp<sup>2</sup> hybridized oxygen) to π*<sub>C=C</sub> (LUMO), corresponding, in arrow-pushing terms, to formation of one C-O bond and cleavage of the O-O bond and formation of the other C-O bond and cleavage of the C=C π bond.
==References== {{reflist|colwidth=30em}}
{{DEFAULTSORT:Chloroperoxybenzoic acid, meta-}} Category:3-Chlorophenyl compounds Category:Organic peroxy acids Category:Reagents for organic chemistry