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Commonly used oxidants-manganese dioxide

wallpapers Tech 2020-06-09
Manganese dioxide is a dark brown powder, mp 535 oC (decomposition), d 5.03 g/cm3. Insoluble in water and organic solvents. It can be used as a commercial reagent.
In organic synthesis, MnO2 is used as an oxidant, and its reactivity is related to its structure, preparation method, and solvent polarity. The following are some examples of manganese dioxide participating in the oxidation reaction.

1. Oxidation of unsaturated fatty alcohols

MnO2 can be used to convert allyl alcohol to α,β-vinyl aldehyde. When alcohol or amine is present, acyl cyanide will be alcohol late or ammonolysis to give the corresponding α,β-vinyl ester, and ammonia. The propargyl alcohol can be oxidized by MnO2 to alkyl aldehydes and ketones, and the unstable propargyl aldehyde can further obtain Michael products.

2. Oxidation of phenyl alcohol and heterocyclic alcohol

Conjugated aromatic aldehydes or ketones can be obtained by oxidizing aryl alcohols with MnO2, while many other functional groups will not participate in the reaction

3. Oxidation of saturated alcohol

Saturated fatty alcohol and alicyclic alcohol react with MnO2 to obtain saturated aldehyde or ketone in high yield. 1,2-diol is readily oxidized by MnO2 to aldehyde or ketone, and 1,2-cycloidal reacts to form dialdehyde or diketone, which depends mainly on the structure of the reactants.

4. Synthesis of amine and alkyne

In the presence of sodium borohydride, α,β-unsaturated enol can be further reacted with amine after oxidation. After MnO2 oxidizes the primary alcohol, it can be treated with Bestmann-Ohira reagent (Seyferth-Gilbert carbon addition reaction) to obtain the terminal alkyne.

5. Conversion of cyano group to amide

With the participation of silica gel, MnO2 can convert cyano groups to amides.

6. Oxidation of amine compounds

Formamide, diazo compounds, etc. can be obtained with MnO2 amine oxide. Oxidation of dialkylhydroxylamine with MnO2 will give the corresponding nitrone.

7. Other reactions

MnO2 can also be used for other reactions, such as the cleavage of alpha-hydroxy acids, the oxidation of diarylethene, the conversion of diaryl ketones, the conversion of aldehydes to carboxylic acids, the preparation of disulfides from sulfur, and the preparation of phosphides from phosphorus Or to prepare ketones from amines. The green cycle method of adding potassium permanganate to manganese dioxide that has emerged in the past two years has also been widely used.

Trunnano is one of the world's largest producers of manganese dioxide. In addition to manganese dioxide, the company also has nano-oxide products such as manganese trioxide. If you are interested, you can consult Dr. Leo, email: brad@ihpa.net.Commonly used oxidants-manganese dioxide


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