Manganese(III) acetate
Encyclopedia
Manganese acetate is an inorganic compound
that is used as an oxidizing agent
in organic synthesis
and materials science
. Like the analogous acetates of iron and chromium, it is an oxygen-centered coordination complex containing three manganese
atoms bridged by acetate
units. The anhydrous form of this compound crystallizes as a linear coordination polymer, with an additional acetic acid molecule bridging between manganese atoms on consecutive three-manganese clusters. The chemical is therefore not a simple metal acetate ionic compound
nor does the actual structure of it reflect the simple "Mn(OAc)3" chemical formula
that is commonly given. It is usually used as the dihydrate, though the anhydrous form is also used in some situations. The dihydrate is prepared by reacting potassium permanganate
and manganese(II) acetate
in acetic acid
; addition of acetic anhydride
to the reaction produces the anhydrous form.
Mangese triacetate has been used as a single electron oxidant
. It can oxidize alkenes via addition of acetic acid to form lactones.
This process is thought to proceed via the formation of a •CH2CO2H radical
intermediate, which then reacts with the alkene, followed by additional oxidation steps and finally ring closure. When the alkene is not symmetric, the major product depends on the nature of the alkene, and is consistent with initial formation of the more stable radical (among the two carbons of the alkene) followed by ring closure onto the more stable conformation of the intermediate.
When reacted with enone
s, the carbon on the other side of the carbonyl reacts rather than the alkene portion, leading to α'-acetoxy
enones. In this process, the carbon next to the carbonyl is oxidized by the manganese, followed by transfer of acetate from the manganese to it.
It can similarly oxidize β-ketoesters at the α carbon, and this intermediate can react with various other structures, including halides and alkenes. One extension of this idea is the cyclization of the ketoester portion of the molecule with an alkene elsewhere in the same structure.
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
that is used as an oxidizing agent
Oxidizing agent
An oxidizing agent can be defined as a substance that removes electrons from another reactant in a redox chemical reaction...
in organic synthesis
Organic synthesis
Organic 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...
and materials science
Materials science
Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates...
. Like the analogous acetates of iron and chromium, it is an oxygen-centered coordination complex containing three manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
atoms bridged by acetate
Acetate
An acetate is a derivative of acetic acid. This term includes salts and esters, as well as the anion found in solution. Most of the approximately 5 billion kilograms of acetic acid produced annually in industry are used in the production of acetates, which usually take the form of polymers. In...
units. The anhydrous form of this compound crystallizes as a linear coordination polymer, with an additional acetic acid molecule bridging between manganese atoms on consecutive three-manganese clusters. The chemical is therefore not a simple metal acetate ionic compound
Ionic compound
In chemistry, an ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. Usually, the positively charged portion consists of metal cations and the negatively charged portion is an anion or polyatomic ion. Ions in ionic compounds are held together...
nor does the actual structure of it reflect the simple "Mn(OAc)3" chemical formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
that is commonly given. It is usually used as the dihydrate, though the anhydrous form is also used in some situations. The dihydrate is prepared by reacting potassium permanganate
Potassium permanganate
Potassium permanganate is an inorganic chemical compound with the formula KMnO4. It is a salt consisting of K+ and MnO4− ions. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the...
and manganese(II) acetate
Manganese(II) acetate
Manganese acetate is the chemical compound with the formula Mn2. It is used as a desiccant, a catalyst, and as fertilizer.-Reactions:...
in acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
; addition of acetic anhydride
Acetic anhydride
Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula 2O. Commonly abbreviated Ac2O, it is the simplest isolatable acid anhydride and is a widely used reagent in organic synthesis...
to the reaction produces the anhydrous form.
Mangese triacetate has been used as a single electron oxidant
Oxidizing agent
An oxidizing agent can be defined as a substance that removes electrons from another reactant in a redox chemical reaction...
. It can oxidize alkenes via addition of acetic acid to form lactones.
This process is thought to proceed via the formation of a •CH2CO2H radical
Radical (chemistry)
Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...
intermediate, which then reacts with the alkene, followed by additional oxidation steps and finally ring closure. When the alkene is not symmetric, the major product depends on the nature of the alkene, and is consistent with initial formation of the more stable radical (among the two carbons of the alkene) followed by ring closure onto the more stable conformation of the intermediate.
When reacted with enone
Enone
An enone is an unsaturated chemical compound or functional group consisting of a conjugated system of an alkene and a ketone. The simplest enone is methyl vinyl ketone or CH2=CHCOCH3....
s, the carbon on the other side of the carbonyl reacts rather than the alkene portion, leading to α'-acetoxy
Acetoxy group
Acetoxy group, abbreviated AcO or OAc, is a chemical functional group of the structure CH3-C-O-. It differs from the acetyl group CH3-C- by the presence of one additional oxygen atom...
enones. In this process, the carbon next to the carbonyl is oxidized by the manganese, followed by transfer of acetate from the manganese to it.
It can similarly oxidize β-ketoesters at the α carbon, and this intermediate can react with various other structures, including halides and alkenes. One extension of this idea is the cyclization of the ketoester portion of the molecule with an alkene elsewhere in the same structure.