Methyl ethyl ketone peroxide

{{Use dmy dates|date=October 2020}}

{{Chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 464362130

| ImageFile = MEK peroxide linear dimer.png

| ImageFile1 =

| ImageSize1 = 175px

| PIN = 2,2′-Peroxydi(butane-2-peroxol)

| OtherNames = 2-[(2-Hydroperoxybutan-2-yl)peroxy]butane-2-peroxol
2-Hydroperoxy-2-[(2-hydroperoxybutan-2-yl)peroxy]butane
Ketonox
Mepox
Thermacure

|Section1={{Chembox Identifiers

| CASNo = 1338-23-4

| CASNo_Ref = {{cascite|correct|CAS}}

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = W2545087UL

| PubChem = 3672772

| ChemSpiderID = 2905622

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| EINECS = 215-661-2

| UNNumber = 3105

| MeSHName = Methyl+ethyl+ketone+peroxide

| Beilstein = 1759757

| SMILES = CCC(C)(OO)OOC(C)(CC)OO

| StdInChI = 1S/C8H18O6/c1-5-7(3,11-9)13-14-8(4,6-2)12-10/h9-10H,5-6H2,1-4H3

| StdInChI_Ref = {{stdinchicite|changed|chemspider}}

| StdInChIKey = WFUGQJXVXHBTEM-UHFFFAOYSA-N

| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}

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|Section2={{Chembox Properties

| C=8 | H=18 | O=6

| Appearance = Colorless liquid

| Density = 1.170 g cm⁻³

| Solubility = Soluble

| BoilingPt = Decomposition beyond {{convert|80|C}}

| BoilingPt_ref ={{GESTIS | ZVG = 70120 | CAS = 1338-23-4 | Name = 2-Butanone peroxide | Date = 10 March 2013}}

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|Section3={{Chembox Explosive

| ShockSens = High

| DetonationV = 5200 m/s

| REFactor = 0.9

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|Section4={{Chembox Hazards

| MainHazards = Explosive, Toxic

| FlashPtC = 75

| FlashPt_ref =

| AutoignitionPt =

| GHSPictograms = {{GHS01}} {{GHS07}} {{GHS08}}

| GHSSignalWord = DANGER

| HPhrases = {{H-phrases|202|205|241|300|315|318|335}}

| PPhrases = {{P-phrases|102|220|243|250|261|264|280|283|370+380|372|404}}

| NFPA-F = 2

| NFPA-H = 2

| NFPA-R = 4

| PEL = none{{PGCH|0416}}

| IDLH = N.D.

| REL = C 0.2 ppm (1.5 mg/m³)

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Methyl ethyl ketone peroxide (MEKP) is an organic peroxide with the formula [(CH₃)(C₂H₅)C(O₂H)]₂O₂. MEKP is a colorless oily liquid. It is widely used in vulcanization (crosslinking) of polymers.{{Ullmann |doi=10.1002/14356007.a19_199|title=Peroxy Compounds, Organic|year=2000|last1=Klenk|first1=Herbert|last2=Götz|first2=Peter H.|last3=Siegmeier|first3=Rainer|last4=Mayr|first4=Wilfried}}

It is derived from the reaction of methyl ethyl ketone and hydrogen peroxide under acidic conditions. Several products result from this reaction including a cyclic dimer.{{cite journal | author = Pastureau, P. | title = Le superoxyde de la méthyléthylcétone | journal = Comptes Rendus | year = 1907 | volume = 144 | issue = 2 | pages = 90–93 | url = https://books.google.com/books?id=zloDAAAAYAAJ&pg=PA90 }} The linear dimer, the topic of this article, is the most prevalent.{{cite journal |author1=Milas, N. A. |author2=Golubović, A. | title = Studies in Organic Peroxides. XXV. Preparation, Separation and Identification of Peroxides Derived from Methyl Ethyl Ketone and Hydrogen Peroxide | journal = Journal of the American Chemical Society | year = 1959 | volume = 81 | issue = 21 | pages = 5824–5826 | doi = 10.1021/ja01530a068 |bibcode=1959JAChS..81.5824M }} and this is the form that is typically quoted in the commercially available material.{{cite web | url = http://www.sigmaaldrich.com/catalog/Lookup.do?N5=All&N3=mode+matchpartialmax&N4=2-Butanone+peroxide&D7=0&D10=2-Butanone+peroxide&N1=S_ID&ST=RS&N25=0&F=PR | title = 2-Butanone peroxide | publisher = Sigma-Aldrich | accessdate = 2011-12-05 }}

Solutions of 30 to 40% MEKP are used in industry and by hobbyists as catalyst to initiate the crosslinking of unsaturated polyester resins used in fiberglass, and casting. For this application, MEKP often is dissolved in a phlegmatizer such as dimethyl phthalate, cyclohexane peroxide,{{clarify|reason=Is this (cC6H11)OO(cC6H11)?|date=January 2023}} or {{ill|diallyl phthalate|de|Diallylphthalat}} to reduce sensitivity to shock. Benzoyl peroxide can be used for the same purpose.{{cn|date=January 2023}}