meta-Chloroperoxybenzoic acid (mCPBA) is a peroxycarboxylic acid used widely as an oxidant in
organic synthesisOrganic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
. mCPBA is often preferred to other peroxy acids because of its relative ease of handling. The main areas of use are the conversion of
ketoneIn organic chemistry, a ketone is a type of compound that features a carbonyl group bonded to two other carbon atoms, i.e., R3CCO-CR3 where R can be a variety of atoms and groups of atoms...
s to
esterEsters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s (
Baeyer-Villiger oxidationThe Baeyer-Villiger oxidation is an organic reaction in which a ketone is oxidized to an ester by treatment with peroxy acids or hydrogen peroxide. Key features of the Baeyer-Villiger oxidation are its stereospecificity and predictable regiochemistry...
),
epoxidationAn epoxide is a cyclic ether with three ring atoms. This ring approximately defines an equilateral triangle, which makes it highly strained. The strained ring makes epoxides more reactive than other ethers. Simple epoxides are named from the parent compound ethylene oxide or oxirane, such as in...
of alkenes, oxidation of
sulfideA sulfide is a chemical compound containing sulfur in its lowest oxidation number of −2.- Properties :...
s to
sulfoxideA sulfoxide is a chemical compound containing a sulfinyl functional group attached to two carbon atoms. Sulfoxides can be considered as oxidized sulfides...
s and
sulfoneA sulfone is a chemical compound containing a sulfonyl functional group attached to two carbon atoms. The central sulfur atom is twice double bonded to oxygen and has two further hydrocarbon substituents. The general structural formula is R-S-R' where R and R' are the organic groups. The use of...
s, and oxidation of
amineAmines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
s to produce
amine oxideAn amine oxide, also known as amine-N-oxide and N-oxide, is a chemical compound that contains the functional group R3N+-O−, an N-O bond with three additional hydrogen and/or hydrocarbon side chains attached to N...
s. mCPBA is a strong oxidizing agent that may cause fire upon contact with flammable material.
mCPBA can be prepared by reacting m
-chlorobenzoyl chloride with hydrogen peroxideHydrogen peroxide is a very pale blue liquid, slightly more viscous than water, that appears colorless in dilute solution. It is a weak acid, has strong oxidizing properties, and is a powerful bleaching agent. It is used as a disinfectant, antiseptic, oxidizer, and in rocketry as a propellant...
in the presence of magnesium sulfateMagnesium sulfate is a chemical compound containing magnesium and sulfur, with the formula MgSO4. In its hydrated form the pH is 6.0 . It is often encountered as the heptahydrate, MgSO4·7H2O, commonly called Epsom salt. Anhydrous magnesium sulfate is used as a...
, aqueous sodium hydroxideSodium hydroxide , also known as lye and caustic soda, is a caustic metallic base. It is used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents and as a drain cleaner. Worldwide production in 1998 was around...
, and dioxane, followed by acidification.
As a pure substance, m
-CPBA can be detonated by shock or by sparks.
meta-Chloroperoxybenzoic acid (mCPBA) is a peroxycarboxylic acid used widely as an oxidant in
organic synthesisOrganic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
. mCPBA is often preferred to other peroxy acids because of its relative ease of handling. The main areas of use are the conversion of
ketoneIn organic chemistry, a ketone is a type of compound that features a carbonyl group bonded to two other carbon atoms, i.e., R3CCO-CR3 where R can be a variety of atoms and groups of atoms...
s to
esterEsters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s (
Baeyer-Villiger oxidationThe Baeyer-Villiger oxidation is an organic reaction in which a ketone is oxidized to an ester by treatment with peroxy acids or hydrogen peroxide. Key features of the Baeyer-Villiger oxidation are its stereospecificity and predictable regiochemistry...
),
epoxidationAn epoxide is a cyclic ether with three ring atoms. This ring approximately defines an equilateral triangle, which makes it highly strained. The strained ring makes epoxides more reactive than other ethers. Simple epoxides are named from the parent compound ethylene oxide or oxirane, such as in...
of alkenes, oxidation of
sulfideA sulfide is a chemical compound containing sulfur in its lowest oxidation number of −2.- Properties :...
s to
sulfoxideA sulfoxide is a chemical compound containing a sulfinyl functional group attached to two carbon atoms. Sulfoxides can be considered as oxidized sulfides...
s and
sulfoneA sulfone is a chemical compound containing a sulfonyl functional group attached to two carbon atoms. The central sulfur atom is twice double bonded to oxygen and has two further hydrocarbon substituents. The general structural formula is R-S-R' where R and R' are the organic groups. The use of...
s, and oxidation of
amineAmines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
s to produce
amine oxideAn amine oxide, also known as amine-N-oxide and N-oxide, is a chemical compound that contains the functional group R3N+-O−, an N-O bond with three additional hydrogen and/or hydrocarbon side chains attached to N...
s. mCPBA is a strong oxidizing agent that may cause fire upon contact with flammable material.
Preparation
mCPBA can be prepared by reacting m
-chlorobenzoyl chloride with hydrogen peroxideHydrogen peroxide is a very pale blue liquid, slightly more viscous than water, that appears colorless in dilute solution. It is a weak acid, has strong oxidizing properties, and is a powerful bleaching agent. It is used as a disinfectant, antiseptic, oxidizer, and in rocketry as a propellant...
in the presence of magnesium sulfateMagnesium sulfate is a chemical compound containing magnesium and sulfur, with the formula MgSO4. In its hydrated form the pH is 6.0 . It is often encountered as the heptahydrate, MgSO4·7H2O, commonly called Epsom salt. Anhydrous magnesium sulfate is used as a...
, aqueous sodium hydroxideSodium hydroxide , also known as lye and caustic soda, is a caustic metallic base. It is used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents and as a drain cleaner. Worldwide production in 1998 was around...
, and dioxane, followed by acidification.
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. The peracid can be purified by washing the commercial material with a slightly basic buffer solution and then drying. Peracids are generally slightly less acidic than their carboxylic acid counterparts, so one can extract the acid impurity by careful control of
pHpH is a measure of the acidity or basicity of a solution. It is defined as the cologarithm of the activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations...
. 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.
Epoxidation example
The following reaction shows the reaction of cyclohexeneCyclohexene is a hydrocarbon with the formula C
6H
10. This cycloalkene is a colorless liquid with a sharp smell. It is an intermediate in various industrial processes...
with mCPBA to give an epoxide; the reaction mechanism is not shown. The epoxidation mechanism is concerted: the cis
or trans geometry of the alkene starting material is retained in the epoxide ring of the product.
