Common oxidant -- ceric ammonium nitrate

[physical properties] orange crystal, soluble in water (1.41 g / ml at 25 OC, 2.27 g / ml at 80 OC), also soluble in alcohol, nitric acid and other proton solvents, soluble in acetonitrile, insoluble in dichloromethane, chloroform and carbon tetrachloride.

[preparation and commodity] it is sold by major reagent companies.

[precautions] at present, there is no report of toxicity, but it is generally considered to have low toxicity.

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Ceric ammonium nitrate can is a strong oxidant with stronger oxidation under acidic conditions, second only to F2, xeo3, ag2 +, O3 and HN3. In aqueous solution and other proton solvents, can is a single electron oxidant. The consumption of can can can be judged from the change of color (from orange to light yellow). Due to the limitation of solubility in organic solvents, most of the reactions involving can are carried out in mixed solvents such as water / acetonitrile. In the presence of other oxidants such as sodium bromate, tert butyl hydrogen peroxide and oxygen, the recycling of Ce4 + can be realized, so as to realize the catalytic reaction. In addition, can is also an effective nitration reagent.

Can has oxidation activity for oxygenated compounds such as alcohols, phenols and ethers, and has specific oxidation activity for secondary alcohols. If benzyl alcohol is oxidized to the corresponding aldehyde ketone (formula 1) [2], even p-nitrobenzyl alcohol can be oxidized to p-nitrobenzyl ketone by can / O2 catalytic oxidation system. In addition, for special secondary alcohols such as 4-enol or 5-enol, cyclic ether compounds (formula 2) [3] can also be obtained.

Catechol, hydroquinone and their methyl ether compounds can be oxidized to quinone under the action of can. For example, catechol is converted to o-benzoquinone (formula 3) [4], hydroquinone is rapidly converted to p-benzoquinone (formula 4) [5] under the action of can and ultrasound, and aryl ether is converted to p-benzoquinone.

For the oxidation reaction of epoxy compounds, dicarbonyl compounds (formula 5) can also be obtained [6]. In addition, can also has oxidative activity for carbonyl compounds with specific structures, such as the oxidation of polycyclic cage ketones to lactones (formula 6) [7].

As a single electron oxidant, can can also realize intermolecular or intramolecular carbon carbon bond formation reaction. For example, the oxidative addition reaction of 1,3-dicarbonyl compound and styrene system under the action of can (formula 7) [8], or the dimerization reaction of aniline itself (formula 8) [9].

In addition to oxidation reaction, can is also an effective nitration reagent, especially for the nitration of aromatic ring system. For example, in acetonitrile, can reacts with anisole to obtain ortho nitration product (formula 9) [10]. However, due to the strong oxidation of can, the aromatic ring system often undergoes nitrification, and even produces polymers that are difficult to separate. It is found that adsorption of can on silica gel can reduce its oxidation and reduce the formation of polynitro products. For example, in acetonitrile, carbazole and 9-alkyl carbazole are nitrated with can with silica gel as carrier, and the yield can be increased to 70% ~ 80% (formula 10) [11].