- Recyclable anhydride catalyst for H2O2 oxidation:: N -oxidation of pyridine derivatives
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The catalytic efficiency and recyclability of poly(maleic anhydride-alt-1-octadecene) (Od-MA) and poly(maleic anhydride-alt-1-isobutylene) (Bu-MA) were evaluated for use in the development of a metal-free, reusable catalyst for the oxidation of pyridines to pyridine N-oxides in the presence of H2O2. The Od-MA catalyst was easily recovered via filtration with recovery yields exceeding 99.8%. The catalyst retained its activity after multiple uses and did not require any treatment for reuse. The Od-MA and H2O2 catalytic system described herein is eco-friendly, operationally simple, and cost-effective; thus, it is industrially applicable. Od-MA and H2O2 could potentially be used in place of percarboxylic acid as an oxidant in a wide range of oxidation reactions.
- Gajeles, Ghellyn,Kim, Se Mi,Lee, Kyung-Koo,Lee, Sang Hee,Yoo, Jong-Cheol
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p. 9165 - 9171
(2020/03/13)
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- Novel synthetic method of sodium pyrithione
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The invention discloses a novel synthetic method of sodium pyrithione. The method includes the following steps: synthesizing a pyridine n-oxide by using pyridine as a raw material, water as a solventand hydrogen peroxide as an oxidant in the presence of catalysts; and mixing the pyridine n-oxide with organic solvents, adding surfactants, vulcanizing agents and alkali reagents, refluxing water, and raising the temperature and pressurizing for reaction after water in the reaction system is separated to synthesize the sodium pyrithione. The novel synthetic method of sodium pyrithione uses the cheap pyridine as the raw material, has the advantages of easily available raw material, simply synthesis route, high total reaction yield, less ''three wastes'' generated by the reaction and low synthesis cost, and has extremely high industrial value.
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Paragraph 0038; 0040-0041; 0043-0044; 0046-0047; 0049-0050;
(2019/05/08)
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- A high-quality zinc pyrithione synthetic method (by machine translation)
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The invention discloses a high-quality zinc pyrithione synthetic method, in order to 2 - chloro pyridine as raw materials, through catalytic oxidation, then the thiolation reaction to obtain the pyridine sulfur [...] solution; pyridine sulfur [...] solution by reduced pressure distillation, separating out the sodium chloride solid salt; thermal insulation filtering, to obtain the pyridine sulfur [...] filtrate, - 10 - 10 °C low-temperature crystallization; filtering, to obtain the pyridine sulfur [...] solid and containing pyridine sulfur [...] filtrate, filtrate circulation process for preparing pyridine sulfur [...] solid; pyridine sulfur [...] solid preparation into the pyridine sulfur [...] solution with the water-soluble zinc salt reaction to obtain the zinc pyrithione product. The method of the invention the process is simple, easy to operate, the prepared product has high purity, the whiteness is good good stability; at the same time the synthesis process has reduced the three waste generation, environmental protection, and is favorable for industrial production. (by machine translation)
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Paragraph 0028; 0031; 0032
(2018/09/11)
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- Synthesis method of zinc pyrithione
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The invention discloses a synthesis method of zinc pyrithione. The method comprises the following steps: (1) nitrogen oxidation of 2-chloropyridine: adding 2-chloropyridine, a solvent and a catalyst into a reactor, dropwise adding hydrogen peroxide for reacting, and after the reacting, filtering to obtain a 2-chloropyridine nitrogen oxide solution; (2) sulfhydrylation: adding a sulfhydrylation reagent into the reactor, dropwise adding the 2-chloropyridine nitrogen oxide solution, and after the reacting, adjusting the pH value, and decolorizing with active carbon to obtain a 2-chloropyridine nitrogen oxide mercapto sodium salt solution; and (3) chelation to obtain salt: adding a zinc salt solution into the reactor, dropwise adding the 2-chloropyridine nitrogen oxide mercapto sodium salt solution, and after the reacting, filtering, washing the filter cake with deionized water, and drying to obtain zinc pyrithione. In the zinc pyrithione prepared by the method disclosed by the invention, the total yield is increased to 92%, and the product purity is increased to over 98%; the nitrogen oxidation reaction yield is increased to over 97%, and the catalyst can be regenerated for use; and moreover, the whole process is simple to operate and generates relatively few three wastes.
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Paragraph 0043; 0045
(2017/06/02)
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- Process for Preparing Alkali Metal Pyrithione and its Polyvalent Metal Complexes from Pyridine Oxide
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The present invention generally relates to a novel process for preparing alkali metal pyrithione from pyridine N-oxide, using a sulfurination agent and a base agent. In particular, the present invention relates to an efficient process for preparing polyvalent metal complexes of sodium pyrithione from the alkali metal pyridine N-oxide described herein.
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Paragraph 0046-0047
(2013/10/08)
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- Process for aromatic bromination
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A novel procedure for bromination of aromatic moieties utilizes N-bromosuccinimide or dibromodimethylhydantoin in an aqueous alkali medium. The bromination procedure is employed for the preparation of an intermediate used in the preparation of remoxipride, an antipsychotic compound.
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