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IUPAC names
butane-2,2-diyl dihydroperoxide (monomer)
2-hydroperoxy-2-((2-hydroperoxybutan-2-yl)peroxy)butane (dimer)
Other names
Methyl ethyl ketone peroxide, MEKP, MEK Peroxide
3D model (JSmol)
C4H10O4 (monomer)
C8H18O6 (dimer)
Molar mass 122.12 g mol-1 (monomer)
210.22 g mol-1 (dimer)
Appearance Colorless, high-viscosity liquid
Density 1.170 g/mL
Melting point -8 °C
Boiling point 110-117.8 °C (decomposes)
Vapor pressure <0.01 mmHg at 20 °C
Main hazards Strong Oxidizer, Explosive, Toxic
S-phrases (outdated) S3/7, S14, S36/37/39, S45, S50
NFPA 704
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g., diesel fuel Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 82 °C
Explosive data
Shock sensitivity High
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
  • Tracking categories (test):

Methyl ethyl ketone peroxide (MEKP) is an organic peroxide similar to acetone peroxide. MEKP is a colorless, oily liquid with an odor similar to that of acetone. MEKP is a strong oxidizer and a severe irritant. Pure MEKP is shock sensitive, and is therefore diluted for commercial and industrial use as a catalyst for the room temperature polymerization of polyester resins.

Commercially available MEKP is a mixture of two different forms: the monomer, C4H10O4, and the dimer, C8H18O6.[1] It may also exist as a cyclic dimer (with the formula C8H16O4), as well as higher cyclic oligomers.[2]


Methyl ethyl ketone peroxide is produced by the reaction between butanone and hydrogen peroxide. Temperature and the use of a catalyst such as nitric, sulfuric, or hydrochloric acid will affect the resulting yield of each oligomer.[1][3]

To prevent detonation, MEKP is diluted


See also[edit]

External links[edit]