583-78-8Relevant academic research and scientific papers
New metabolites in the degradation of α- and γ- hexachlorocyclohexane (HCH): Pentachlorocyclohexenes are hydroxylated to cyclohexenols and cyclohexenediols by the haloalkane dehalogenase LinB from Sphingobium indicum B90A
Raina, Vishakha,Rentsch, Daniel,Geiger, Thomas,Sharma, Poonam,Buser, Hans Rudolf,Holliger, Christof,Lal, Rup,Kohler, Hans-Peter E.
, p. 6594 - 6603 (2008)
Technical hexachlorocyclohexane (HCH) and lindane are obsolete pesticides whose former production and use led to widespread contaminations posing serious and lasting health and environmental risks. Out of nine possible stereoisomers, α-, β-, γ-, and -HCH are usually present at contaminated sites, and research for a better understanding of their biodegradation has become essential for the development of appropriate remediation technologies. Because haloalkane dehalogenase LinB was recently found responsible for the hydroxylation of β-HCH, δ-HCH, and δ-pentachlorocyclohexene (δ-PCCH), we decided to examine whether β- and γ-PCCH, which can be formed by LinA from α-and γ-HCH, respectively, were also converted by LinB. Incubation of such substrates with Escherichia coli BL21 expressing functional LinB originating from Sphingobium indicum B90A showed that both β-PCCH and γ-PCCH were direct substrates of LinB. Furthermore, we identified the main metabolites as 3,4,5,6-tetrachloro-2-cyclohexene-1-ols and 2,5,6-trichloro-2-cyclohexene-1,4-diols by nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry. In contrast to α-HCH, γ-HCH was not a substrate for LinB. On the basis of our data, we propose a modified γ-HCH degradation pathway in which γ-PCCH is converted to 2,5-cyclohexadiene-1,4-diol via 3,4,5,6-tetrachloro-2-cyclohexene- 1-ol and 2,5,6-trichloro-2-cyclohexene-1,4-diol.
Method for preparing 2, 5-dichlorophenol through continuous oxidation of p-dichlorobenzene
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Paragraph 0025; 0027; 0028; 0030; 0031; 0033, (2020/01/25)
The invention discloses a method for preparing 2, 5-dichlorophenol by directly oxidizing p-dichlorobenzene in a micro-channel reactor, and belongs to the field of fine chemical engineering. Accordingto the method, the p-dichlorobenzene is used as a raw material, hydrogen peroxide is used as an oxidant, acetic acid is used as a solvent, and one or more of iron, iron oxide or an iron metal complexis/are used as a catalyst to complete the preparation process of the 2, 5-dichlorophenol in a micro-channel reactor system. According to the method, the temperature and the retention time in the reaction process can be strictly controlled, the accumulation of oxygen is reduced, the reaction temperature is accurately controlled, temperature runaway is prevented, and the safety of a reaction deviceis improved; due to the strong mass transfer effect of the micro-channel reactor, the mass transfer effect among the raw materials in the reaction system is enhanced, and the reaction efficiency is greatly improved.
Method for hydroxylating aromatic compound
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Paragraph 0108-0109, (2020/06/17)
The invention provides a method for directly hydroxylating an aromatic compound. The method comprises the following steps: dissolving the aromatic compound in a solvent, adding hydrogen peroxide and anitroxide free radical compound, and reacting. The nitroxide free radical compound is used as a catalyst, hydrogen peroxide is used as an oxidizing agent, and hydroxylation of the aromatic compound is directly catalyzed and oxidized. Compared with a traditional process, the method has the advantages of high product selectivity, mild reaction conditions, reusability of the catalyst, easiness in separation of oxidation products and raw materials and the like.
Vanadium-pyridine catalyst for preparing 2, 5-dichlorophenol through catalytic oxidation and synthesis method and application of vanadium-pyridine catalyst
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Paragraph 0025-0027, (2020/11/09)
The invention discloses a vanadium pyridine catalyst for preparing 2, 5-dichlorophenol through catalytic oxidation and a synthesis method and application of the vanadium pyridine catalyst. The catalyst is a Py-V complex as shown in the following structural formula, and is prepared by dissolving pyridine-2, 6-dicarboxylic acid in methanol, adding vanadyl acetylacetonate, refluxing, filtering, washing, drying and the like. The operation steps are simple and easy to control, the yield is 60% or above in terms of vanadium, the whole synthesis process is short in time consumption, and the method issuitable for industrial production. In the process of preparing 2, 5-dichlorophenol through catalytic oxidation of 1, 2, 4-dichlorobenzene, the Py-V complex is adopted as a catalyst, the excessive oxidation of 2, 5-dichlorophenol can be effectively inhibited while the catalytic efficiency is improved, the excessive oxidation product can be controlled to be 10% or below, the selectivity of 2, 5-dichlorophenol reaches 90% or above, and the oxidation reaction efficiency and yield are obviously improved.
A new process to prepare 3,6-dichloro-2-hydroxybenzoic acid, the penultimate intermediate in the synthesis of herbicide dicamba
Walker, Daniel P.,Harris, G. Davis,Carroll, Jeffery N.,Boehm, Terri L.,McReynolds, Matthew D.,Struble, Justin R.,van Herpt, Jochem,van Zwieten, Don,Koeller, Kevin J.,Bore, Mangesh
, p. 1032 - 1036 (2019/03/17)
Glyphosate [N-(phosphonomethyl)glycine] is a broad spectrum, post-emergent herbicide that is among the most widely used agrochemicals globally. Over the past 30 years, there has been a development of glyphosate-resistant weeds, which pose a significant challenge to growers and crop scientists, resulting in lower crop yields and increased costs. 3,6-Dichloro-2-methoxybenzoic acid (dicamba) is the active ingredient in XtendiMax a standalone herbicide developed by Bayer Crop Science to control broadleaf weeds, including glyphosate-resistant species. 3,6-Dichloro-2-hydroxybenzoic acid (3,6-DCSA) is the penultimate intermediate in the synthesis of dicamba. Existing dicamba manufacturing routes utilize a high temperature, high pressure Kolbe-Schmitt carboxylation to prepare 3,6-DCSA. Described in this Letter is a new, non-Kolbe-Schmitt process to prepare 3,6-DCSA from salicylic acid in four chemical steps.
Method using iron-carrying activated carbon to catalyze 1,4-dichlorobenzene hydroxylation to prepare 2,5-dichlorophenol
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Paragraph 0020-0027, (2019/01/23)
The invention relates to a method using iron-carrying activated carbon to catalyze 1,4-dichlorobenzene hydroxylation to prepare 2,5-dichlorophenol. The method is characterized in that various activated carbon processed by nitric acid and H2O2 is used as the carrier to introduce active components Fe(NO3)3 of different mass through an impregnation method to prepared a Fe-AC catalyst for subsequent reaction; the reaction uses 1,4-dichlorobenzene as the substrate, acetonitrile as the solvent and H2O2 as the oxidizing agent; the reaction is performed in a r round-bottom flask connected with a reflux condensation device, 30% H2O2 solution is slowly fed through a peristaltic pump at constant speed or directly fed into the round-bottom flask in one step, and continuous stirring and heating are performed for a certain period of time during the reaction to obtain the 2,5-dichlorophenol; iron content in the Fe/AC is 0-0.5mmol/g; the mass ratio of p-dichlorobenzene to the Fe/AC is 1:0.1-1:0.5; themole ratio of the p-dichlorobenzene to the H2O2 is 1:1.5-1:29.6; reaction temperature is 30-80 DEG C; reaction time is 10-300 minutes. The method has the advantages that 10mL of 30% H2O2 is added into optimal 0.3g of 0.20mmol/g Fe/HAC-j, 6.63mmol p-dichlorobenzene and 10mL of acetonitrile in one step to perform reaction at 60 DEG C for 2 hours, p-dichlorobenzene conversion rate can reach 70.9%, the yield of the 2,5-dichlorophenol is 39.5%, the selectivity of the 2,5-dichlorophenol is 55.8%, and the whole reaction process is clean and efficient and conforms to the green development concept.
A dichlorophenol synthesis method (by machine translation)
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, (2019/06/05)
The present invention provides a kind of dichlorophenol synthetic method, comprises the following steps: S1, will be 1, 4 - dichlorobenzene alkylation reaction, to obtain the 1, 4 - dichloro - 2 - isopropyl benzene; or the 1, 3 - dichlorobenzene alkylation reaction, to obtain the 1, 3 - dichloro - 4 - cumene; or the 1, 2 - dichlorobenzene alkylation reaction, to obtain 1, 2 - dichloro - 4 - cumene; S2, to the 1, 4 - dichloro - 2 - cumene in alkyl, 1, 3 - dichloro - 4 - cumene in alkyl or 1, 2 - dichloro - 4 - alkyl in the cumene, through oxidation, the formula x structure obtained dichloro peroxide; S3, will the catalytic decomposition of the peroxide states two chlorine respectively, to obtain the dichlorophenol and acetone. The present invention provides a method for synthesizing of the dichlorophenol obtained the product content is high, the three waste less generation, mild reaction conditions, easy operation, low production cost. (by machine translation)
Ammonium Salt-Catalyzed Highly Practical Ortho-Selective Monohalogenation and Phenylselenation of Phenols: Scope and Applications
Xiong, Xiaodong,Yeung, Ying-Yeung
, p. 4033 - 4043 (2018/05/22)
An ortho-selective ammonium chloride salt-catalyzed direct C-H monohalogenation of phenols and 1,1′-bi-2-naphthol (BINOL) with 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) as the chlorinating agent has been developed. The catalyst loading was low (down to 0.01 mol %) and the reaction conditions were very mild. A wide range of substrates including BINOLs were compatible with this catalytic protocol. Chlorinated BINOLs are useful synthons for the synthesis of a wide range of unsymmetrical 3-aryl BINOLs that are not easily accessible. In addition, the same catalytic system can facilitate the ortho-selective selenylation of phenols.
A 2, 5 - dichlorophenol green synthesis method (by machine translation)
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Paragraph 0012-0019, (2019/01/08)
The invention belongs to the field of fine organic chemical industry, to provide a paradichlorobenzene as raw material to direct hydroxylation to prepare 2, 5 - dichlorophenol green synthesis method. In the specific content is 0.5 - 90 °C and under the normal pressure, paradichlorobenzene, hydrogen peroxide and a solvent in the reaction under the mesoporous catalyst 60 - 480 min, one-step reaction can be directly obtained after the separation of 2, 5 - dichlorophenol product, product purity ≥ 99.5%, the product yield can reach 85%. The catalyst is a mesoporous catalyst, mesoporous molecular sieve type is SBA - 15, Ti - MWW, MCM - 41, MCM - 48, MSU - 2, Ti - MWW, MCM - 41, MCM - 48, MSU - 2, solid acid type as phosphorus, sulfur, manganese, tungsten, nickel, cobalt, iron, molybdenum, zinc, [...] solid acid. Hydrogen peroxide and benzene molar ratio of 1:1 - 8:1, the amount of a catalyst is the material of the total amount of 1 - 15%, solvent is methanol, ethanol, propanol, isopropanol, toluene, DMSO, tertiary butyl alcohol, acetone, butanone and acetonitrile or their mixed solvent; hydrogen peroxide concentration is 27.5% -50%; to dichlorobenzene and solvent molar ratio of 1:1 - 1:50. (by machine translation)
A 2, 5 - dichlorophenol preparation method
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Paragraph 0037; 0038; 0039; 0040; 0041; 0042; 0043-0121, (2017/08/25)
The invention provides a preparation method of 2, 5-dichlorophenol. The preparation method of the 2, 5-dichlorophenol comprises the following steps of pretreatment of catalyst and assistant agents, 1, 4-dichlorobenzene one-step-method product synthesizing, continuous rectification of 2, 5-dichlorophenol and recycling of a substrate and solvent. By the preparation method, the catalyst and the assistant agents are pretreated, the catalytic performance and the catalytic effect of the catalyst can be improved effectively, the efficiency and the yield of synthesis reaction are improved, the use level of the catalyst and the use level of the assistant agents can be reduced obviously, production cost is reduced, heavy components are reduced, and follow-up separation and purification operation is facilitated. Synthetic reaction products are rectified, separated and purified, the purity of the obtained 2, 5-dichlorophenol is greater than 99.5%, the purify of the 1, 4-dichlorobenzene, the solvent and water which are obtained by recycling is greater than 99%, the recycled raw material and the recycled solvent can be directly used for next synthetic reaction, the production cost is reduced, and environmental protection is facilitated.
