meta-Chloroperoxybenzoic acid
IUPAC name	3-chloroperoxybenzoic acid
Other names	meta-chloroperoxybenzoic acid; m-chloroperoxybenzoic acid; meta-chloroperbenzoic acid; 3-chloroperbenzoic acid; mCPBA
Identifiers
CAS number	937-14-4 Y
RTECS number	SD9470000
SMILES	O=C(OO)C1=CC(Cl)=CC=C1
Properties
Molecular formula	C7H5ClO3
Molar mass	172.57 g/mol
Appearance	White powder
Melting point	92 - 94 °C, decomposes
Acidity (pKa)	7.57
Hazards
R-phrases	R7 R22 R34
S-phrases	S17 S26 S36/37/39 S45
Related compounds
Related compounds	peroxyacetic acid; peroxybenzoic acid
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

meta-Chloroperoxybenzoic acid (mCPBA) is a peroxycarboxylic acid used widely as an oxidant in organic synthesis. mCPBA is often preferred to other peroxy acids because of its relative ease of handling. The main areas of use are the conversion of ketones to esters (Baeyer-Villiger oxidation), epoxidation of alkenes, oxidation of sulfides to sulfoxides and sulfones, and oxidation of amines to produce amine oxides.^[1] mCPBA is a strong oxidizing agent that may cause fire upon contact with flammable material.

Contents 1 Preparation 2 Availability and purity 3 Epoxidation example 4 References

[edit] Preparation

mCPBA can be prepared by reacting m-chlorobenzoyl chloride with hydrogen peroxide in the presence of magnesium sulfate, aqueous sodium hydroxide, and dioxane, followed by acidification.^[2]

[edit] Availability and purity

As a pure substance, m-CPBA can be detonated by shock or by sparks. It is therefore sold commercially as a much more stable mixture that is less than 72% m-CPBA, with the balance made up of m-chlorobenzoic acid (10%) and water.^[1] The peracid can be purified by washing the commercial material with a slightly basic buffer solution and then drying.^[3] Peracids are generally slightly less acidic than their carboxylic acid counterparts, so one can extract the acid impurity by careful control of pH. The purified material is reasonably stable against decomposition if stored at low temperatures in a plastic container.

In reactions where the exact amount of m-CPBA must be controlled, a sample can be titrated to determine the exact amount of active oxidant.

[edit] Epoxidation example

The following reaction shows the reaction of cyclohexene with mCPBA to give an epoxide. 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 general mechanism can be presented in the following simplified way using curly arrows^[4]:

[edit] References

1. ^ ^{a b} "3-Chloroperoxybenzoic acid". Organic Chemistry Portal. http://www.organic-chemistry.org/chemicals/oxidations/meta-chloroperbenzoicacid.shtm. 
2. ^ Richard N. McDonald, Richard N. Steppel, and James E. Dorsey (1988), "m-Chloroperbenzoic Acid", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6p0276 ; Coll. Vol. 6: 276 
3. ^ Purification of Laboratory Chemicals (4^th ed. ed.). Oxford: Butterworth-Heinemann. 1996. p. 145. ISBN 0750637617. 
4. ^ Clayden et al. Organic chemistry