21739-92-4Relevant articles and documents
An efficient chromium(iii)-catalyzed aerobic oxidation of methylarenes in water for the green preparation of corresponding acids
Jiang, Feng,Liu, Shanshan,Wei, Yongge,Yan, Likai,Yu, Han,Zhao, Wenshu
supporting information, p. 12413 - 12418 (2021/09/28)
A highly efficient method to oxidize methylarenes to their corresponding acids with a reusable Cr catalyst was developed. The reaction can be carried out in water with 1 atm oxygen and K2S2O8as cooxidants, proceeds under green and mild conditions, and is suitable for the oxidation of both electron-deficient and electron-rich methylarenes, including heteroaryl methylarenes, even at the gram level. The excellent result, together with its simplicity of operation and the ability to continuously reuse the catalyst, makes this new methodology environmentally benign and cost-effective. The generality of this methodology gives it the potential for use on an industrial scale. Differing from the accepted oxidation mechanism of toluene, GC-MS studies and DFT calculations have revealed that the key benzyl alcohol intermediate is formed under the synergetic effect of the chromium and molybdenum in the Cr catalyst, which can be further oxidized to afford benzaldehyde and finally benzoic acid.
Preparation method 5 - bromo -2 -chlorobenzoic acid
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Paragraph 0040-0041; 0044-0045; 0049; 0052-0054; 0057-0058, (2021/09/01)
The invention provides a preparation method of 5 -bromo -2 -chlorobenzoic acid, which comprises (1) contacting 2 - chlorobenzonitrile with a bromination reagent for bromination reaction to obtain 5 - bromo -2 - chlorobenzonitrile. (2) Hydrolysis of 5 - bromo -2 - chlorobenzonitrile in the presence of a base to give 5 - bromo -2 -chlorobenzoate. The 5 - bromo -2 -chlorobenzoate is then contacted with a protic acid to give 5 - bromo -2 -chlorobenzoic acid. The preparation method has the advantages of simple process, high safety, cheap and accessible raw materials, low cost and 5 - bromo -2 - chlorobenzoic acid yield, high purity and the like.
Highly efficient oxidation of alcohols to carboxylic acids using a polyoxometalate-supported chromium(iii) catalyst and CO2
Han, Sheng,Wang, Ying,Wei, Yongge,Wu, Zhikang,Yu, Han
, p. 3150 - 3154 (2020/06/19)
Direct catalytic oxidation of alcohols to carboxylic acids is very attractive, but economical catalysis systems have not yet been well established. Here, we show that a pure inorganic ligand-supported chromium compound, (NH4)3[CrMo6O18(OH)6] (simplified as CrMo6), could be used to effectively promote this type of reaction in the presence of CO2. In almost all cases, oxidation of various alcohols (aromatic and aliphatic) could be achieved under mild conditions, and the corresponding carboxylic acids can be achieved in high yield. The chromium catalyst 1 can be reused several times with little loss of activity. Mechanism study and control reactions demonstrate that the acidification proceeds via the key oxidative immediate of aldehydes.