- Safety Aspects of the Under-Pressure Reaction of Trichloroacetyl Chloride and Acrylonitrile in the Preparation of 3,5,6-Trichloro-2-pyridinol
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The under-pressure reaction of trichloroacetyl chloride (1) with acrylonitrile (2) in the preparation of 3,5,6-trichloro-2-pyridinol becomes explosive in certain circumstances. The studies of the reaction's enthalpy, the instability of the 2-chloropropionitrile (8), and the observation of the unexpected increase of pressure have helped us to point out that the above feature is due to the exothermic nature of the reactions and the HCl released by the 2-chloropropionitrile decomposition at elevated temperature. So, controlling the temperature and well-done stirring of the reaction mixture is very important in large-scale production to avoid the explosion nature of the reaction.
- Fakhraian,Bazaz,Hadj-Ghanbary
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- Facile preparation of Mn3O4 hollow microspheres via reduction of pentachloropyridine and their performance in lithium-ion batteries
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Mn3O4 hollow microspheres have been facilely prepared via a green synthesis of 2,3,5,6-tetrachloropyridine reduced from pentachloropyridine by manganese. The specific hollow microspheres were made by a H2 gas bubble-templating method presenting a high specific surface area (87.1 m2 g-1) and a big total pore volume (0.2030 cm3 g-1). The Mn3O4 hollow microspheres as an anode material demonstrate a good electrochemical performance, with a high reversible capacity of 646.9 mA h g-1 after 240 cycles at a current density of 200 mA g-1. The good cycling performance is attributed to numerous mesopores, high specific surface area and big total pore volume, which can offer good electrical contact and conductivity as well as accommodate the mechanism strains. In addition, the yield and selectivity of 2,3,5,6-tetrachloropyridine achieved up to 99.2% and 99.5%, respectively.
- Jiang, Zhan,Huang, Kaihua,Yang, Dian,Wang, Shuai,Zhong, Hong,Jiang, Chongwen
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- A Convenient Synthesis of 2,3,5,6-Tetrahalogenopyridines and of 3,5-Bis(alkylthio)pyridines from 2,6-Diaminopyridine
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Controlled chlorination of 2,6-diaminopyridine (1) affords 2,6-diamino-3,5-dichloropyridine (2a) which is then bis(diazotised) to give 2,3,5,6-tetrachloropyridine (3a); similarly prepared are other 2,3,5,6-tetra(chloro/bromo) pyridines and 2,6-dichloro-3,5-bis(thiocyanato)pyridine (3h), from which 3,5-bis(alkylthio)pyridines are easily obtained.
- Chen, Ted K.,Flowers, William T.
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- Preparation method of 3,5-difluoro-2,6-diaminopyridine
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The invention discloses a preparation method of 3,5-difluoro-2,6-diaminopyridine, and belongs to the technical field of preparation methods of chemical drug intermediates. 2,3,4,5,6-pentachloropyridine is utilized as a raw material; and the 3,5-difluoro-2,6-diaminopyridine is prepared through reduction by a metallic reducing agent, fluorination and aminolysis. The method provided by the inventionis simple to operate, short in reaction time, environmentally friendly in process route and higher in yield, and has higher industrialization value; and an economical and high-efficiency catalyst is adopted.
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Paragraph 0009-0012
(2019/02/04)
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- Synthesis method of 2,3,5,6-tetrachloropyridine
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The invention provides a synthesis method of 2,3,5,6-tetrachloropyridine, and relates to the field of organic synthesis. The synthesis method comprises the following steps that pentachloropyridine, acatalyst and an acid binding agent are added into a high pressure reactor, and the high pressure reactor is sealed; the air in the high pressure reactor is replaced with hydrogen gas firstly, then hydrogen gas is pumped into the high pressure reactor till the pressure in the high pressure reactor reaches 2-6 MPa, the temperature is increased to be 200-500 DEG C, and a thermal insulation reaction is conducted for 0.5-6 hours; after the reaction is ended, sampling is conducted to detect the content of tetrachloropyridine, the temperature is decreased to be the room temperature, and the acid gasin the high pressure reactor is exhausted through decompression; the previous steps are repeated till the content of tetrachloropyridine is detected to be higher than or equal to 90%; and a solvent isadded into the high pressure reactor and stirred for 20-40 minutes, suction filtration is conducted, the filter liquid is subjected to vacuum concentration, water is added and stirred at the room temperature, suction filtration is conducted again, and a filter cake is dried. In the synthesis method, hydrogen gas serves as a cleaning reduction agent, the synthesis conversion rate is high, the synthesis cost is low, the synthesis method is simple and suitable for large-scale industrialized popularization, the three wastes are less, the majority of the solvent used in the synthesis method can berecycled and reused, and thus the environmental protection and cost pressure is relieved further.
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Paragraph 0035-0045; 0047-0054; 0056-0063; 0065-0070; 0072-0
(2018/09/12)
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- Preparation method of 2,3,5,6-tetrachloropyridine
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The invention discloses a preparation method of 2,3,5,6-tetrachloropyridine and belongs to the field of chemical industry. The preparation method comprises: introducing 2-chloropyridine and chlorine gas as raw materials into a fixed-bed reactor loaded with an activated carbon catalyst, and generating 2,3,5,6-tetrachloropyridine under the action of the activated carbon catalyst. The catalyst uses one or more of AlCl3, NiCl2, CuCl2, ZnCl2, FeCl3, CaCl2, BaCl2, MgCl2, CoCl2 and LaCl2 as active components and activated carbon as a support; the active components in the catalyst account for 4-27% bymass, and the activated carbon accounts for 73-96% by mass; the catalyst uses 2-chloropyridine and chlorine gas as raw materials, and the 2-chloropyridine and chlorine gas is generated under the action of the catalyst that is nontoxic and harmless; the preparation method has high conversion rate, good selectivity and zero pollution.
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Paragraph 0021-0023; 0026; 0029; 0031; 0033
(2018/03/25)
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- Method for synthesizing 2,3,5,6-tetrachloropyridine and co-producing manganous-manganic oxide
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The invention discloses a method for synthesizing 2,3,5,6-tetrachloropyridine and co-producing manganous-manganic oxide. With one or more of ester, lower alcohol and methylbenzene as the solvent, inorganic ammonium salt as the catalyst and manganese powder as the reducing agent, pentachloropyridine is reduced into tetrachloropyridine, and manganese powder is converted into manganous chloride or hydroxyl manganese chloride; manganous chloride or hydroxyl manganese chloride is oxidized by air to obtain manganous-manganic oxide. The method has the advantages of being high in reaction efficiency, mild in reaction condition and the like, the two products including 2,3,5,6-tetrachloropyridine and manganous-manganic oxide with high specific surface area can be obtained at the same time, the tetrachloropyridine purity reaches 98% or above, and the specific surface area of manganous-manganic oxide is 30-53 m/g.
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Paragraph 0078-0083; 0084-0089; 0100-0105; 0109-0125
(2017/10/31)
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- Preparation method of 2,3,5,6-tetrachloropyridine
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The invention provides a preparation method of 2,3,5,6-tetrachloropyridine, comprising: mixing pyridine, a chlorinating agent and a solvent, and chlorinating for 6-8 hours to obtain the finished 2,3,5,6-tetrachloropyridine; to be specific, adding pyridine into a solvent, maintaining the reaction solution at 20 DEG C, dropwise adding sulfur dichloride, and heating for reflux reaction for 6-8 h after dropwise adding; cooling the reaction solution to room temperature, and filtering to remove solid; maintaining inner temperature not less than 10 DEG C, and dropwise adding 20% sodium hydroxide solution until the reaction solution is neutral; separating the solution, collecting organic phase, drying with anhydrous magnesium sulfate overnight, removing the solvent under reduced pressure, and purifying by column chromatography to obtain the 2,3,5,6-tetrachloropyridine. The preparation method has the advantages of good condition mildness, high reaction speed, and high selectivity; the 2,3,5,6-tetrachloropyridine prepared by using the preparation method has purity of >97%.
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Paragraph 0021-0028
(2017/08/30)
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- Synthesis and crystal structure of 3,5-dichloro-6-morpholinopyridin-2-ol
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A new compound having potential bioactivities 3,5-dichloro-6- morpholinopyridin-2-ol (1) was synthesized and characterized by single crystal X-diffraction. The crystal is monoclinic, space group P21/c with a = 10.3609 (6), b = 10.5711 (7), c = 10.3190 (5) A, β = 108.9433 (15)°, V = 1068.99 (11) A3, Z = 4, C9H 10Cl2N2O2, D c = 1.548 g/cm3, μ (MoKα) = 0.71075 A, S = 1.01, F (000) = 512.00, R = 0.0397 and wR = 0.1364. In the unit cell, there are two independent molecules linked by intermolecular O-H???O (2.693(2) A) hydrogen bonds forming onedimensional expanded structure. Graphical Abstract: As part of our ongoing research work on pyridine derivatives, the title compound crystal structure is important to study the relationship between the structure and its biological activities, thus it is urgent to publish in time.[Figure not available: see fulltext.]
- Zheng, Hui,Liu, Yun-Kui,Shen, Chao,Xu, Zhen-Yuan
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scheme or table
p. 919 - 922
(2010/06/19)
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- Reactions of 4-(dimethylamino)pyridinium activated pentachloropyridine with nitrogen nucleophiles and hydride
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Substitution reactions on 2′,3′,5′,6′-tetrachloro-4-dimethylamino-[1,4]bipyridinyl-1-ylium chloride with nitrogen nucleophiles such as n-propylamine, isopropylamine, glycine, morpholine, and piperidine were examined. Highly functionalized Cl2,Cl3,N4,Cl5,Cl6- and N2,Cl3,N4,Cl5,Cl6-substituted pyridines were obtained, in part possessing unsubstituted 4-amino groups due to dealkylation. Detailed NMR studies were performed in order to elucidate the regiochemistry of these dealkylations.
- Schmidt, Andreas,Namyslo, Jan Christoph,Mordhorst, Thorsten
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p. 6893 - 6898
(2007/10/03)
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- Mild electrophilic halogenation of chloropyridines using CCl4 or C2Cl6 under basic phase transfer conditions
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Effective chlorination of 2,3,5,6-tetrachloropyridine to pentachloropyridine was realized under mild phase transfer conditions with carbon tetrachloride and 50% NaOH or solid K3PO4. Mechanistic study of this reaction indicated the possibility of an aromatic carbanionic intermediate. Hexachloroethane was established as a more selective electrophilic chlorination agent.
- Joshi, Ashutosh V.,Baidossi, Mubeen,Qafisheh, Nida,Chachashvili, Elsa,Sasson, Yoel
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p. 5061 - 5063
(2007/10/03)
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- Reinvestigation of the reaction of trichloroacetyl chloride and acrylonitrile in the preparation of 3,5,6-trichloropyridin-2-ol
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The synthesis of 3,5,6-trichloropyridin-2-ol via the CuCl-catalyzed reaction of trichloroacetyl chloride and acrylonitrile under both pressure and atmospheric conditions and the hydrolysis of the reaction mixture were reinvestigated. The products and byproducts formed in each case, before the hydrolysis step, were characterized, and the factors causing their formation are discussed. It was found that two newly identified byproducts influence the yield of the reaction.
- Fakhraian,Moghimi,Bazaz,Hadj-Ghanbary,Sadeghi
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p. 329 - 333
(2013/09/06)
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- Production of 2,3,5,6-tetrachloropyridine
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A novel, simple, high-yield process for the production of 2,3,5,6-tetrachloropyridine comprises reacting an ester of 2,2,4-trichloro-4-cyanobutyric acid with excess phosphorus oxychloride in the presence of a catalytic amount of hydrogen chloride and optionally in the presence of an aprotic inert solvent, at a temperature of 100°-160° C., preferably at 120°-140° C. for about 5-10 hours, under elevated pressure, if necessary.
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- Selective reduction of pentachloropyridine to 2,3,5,6-tetrachloropyridine with zinc dust in basic media
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The selective reduction of pentachloropyridine to 2,3,5,6-tetrachloropyridine is achieved by contacting the pentachloropyridine as a solution in perchloroethylene or methylene chloride with zinc dust in a basic aqueous medium.
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- Production of polychlorinated pyridine mixtures by liquid phase chlorination of 3,5-lutidine or 3,5-lutidine hydrochloride
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Preparation of high yields of mixtures rich in polychlorinated pyridines by maintaining a chlorine to 3,5-lutidine weight ratio of greater than about 7:1 when reacting chlorine and 3,5-lutidine or 3,5-lutidine hydrochloride non-catalytically in the liquid phase at temperatures in excess of about 150° C., the reactants being contained in a well mixed diluent producing 2 moles or less of hydrogen chlorine per mole of diluent by reaction with the chlorine in the indicated temperature range. Reaction in a primary reactor is followed by selective further chlorination to obtain desired final products useful as intermediates in the formation of herbicides and the like.
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- Process for producing 2,3,5,6-tetrachloropyridine and 3,5,6-trichloropyridin-2-ol
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2,3,5,6-Tetrachloropyridine and/or 3,5,6-trichloropyridin-2-ol can be obtained, using a simple novel process, by reacting trichloroacetyl chloride, in the presence of a catalyst, for example copper (I) chloride or -bromide, with acrylonitrile. 2,3,5,6-Tetrachloropyridine and 3,5,6-trichloropyridin-2-ol are suitable for producing various active substances, particularly for producing insecticides, herbicides and fungicides.
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- 3,3,5-Trichloroglutaric acid imide
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3,3,5-Trichloroglutaric acid imide can be produced either by reacting a trichloroacetic acid alkyl ester, in the presence of a catalyst, with acrylonitrile to the corresponding 2,2,4-trichloro-4-cyanobutyric acid alkyl ester, converting this into the amide, and cyclizing the 2,2,4-trichloro-4-cyano-butanecarboxylic acid amide, in an aqueous acid medium, to the 3,3,5-trichloroglutaric acid imide; or by reacting trichloroacetonitrile, in the presence of a catalyst, to 2,2,4-trichloro-4-cyanobutyronitrile, and cyclizing this, in an aqueous acid medium, to 3,3,5-trichloroglutaric acid imide. The catalyst used for the addition reactions can be for example copper(I) chloride or copper(II) oxide. 3,3,5-Trichloroglutaric acid imide can be converted, by treatment with a dehydrating chlorinating agent, such as POCl3, into the known 2,3,5,6-tetrachloropyridine, which for its part is used for producing various active substances, particularly insecticides, herbicides and fungicides.
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- Preparation of 2,3-dichloro-5-trichloromethylpyridine
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Preparation of 2,3-dichloro-5-trichloromethylpyridine in high yields and purity by chlorinating 2-chloro-5-trichloromethylpyridine at 70° to 250° C. with chlorine in the presence of a catalyst containing one or more molybdenum, tungsten or ruthenium compounds.
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- Process for producing 2,3,5,6-tetrachloropyridine
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A novel process for producing 2,3,5,6-tetrachloropyridine is described. In this process, pentachloropyridine is reacted, in an alkanephosphonic acid dialkyl ester (dialkyl alkane phosphonate) having 1 to 4 carbon atoms in each of the alkyl groups or in a phosphoric acid trialkyl ester (trialkyl phosphate) having 1 to 4 carbon atoms in each of the alkyl groups as the solvent, at 60° to 120° C., in the presence of 1.4 to 2.8 mols, per mol of pentachloropyridine, of an ammonium salt of an inorganic or organic acid, with 1.2 to 1.6 gram atoms of zinc per mol of pentachloropyridine, with selective dechlorination of the pentachloropyridine in the 4-position occurring. 2,3,5,6-Tetrachloropyridine is a valuable commercial product, which can be used for producing insecticidal formulations. Furthermore, 2,3,5,6-tetrachloropyridine is used as intermediate for the production of herbicidally effective α-[4-(3',5',6'-trichloropyrid-2'-yloxy)-phenoxy]-alkanecarboxylic acids and derivatives thereof. There are also described novel ammonium salts of methanephosphonic acid monomethyl ester, in the presence of which the selective dechlorination of pentachloropyridine in the 4-position can be advantageously performed.
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- POLYHALOGENOHETEROCYCLIC COMPOUNDS-3. RADICAL-ANIONS FROM HALOPYRIDINES
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Electrochemical reduction of pentafluoropyridine and other polyhalopyridines gives bipyridyl derivatives etc. and it is inferred from the structures of the products that, in the intermediate radical-anion, charge- and spin-density is concentrated at the 1- and 4-positions.This is further supported by measurement of Ep1/2 values.Trapping experiments with hydroquinone and carbon dioxide are described.
- Chambers, R. D.,Musgrave, W. K. R.,Sargent, C. R.,Drakesmith, F. G.
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p. 591 - 595
(2007/10/02)
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- Polyhalogenoaromatic Compounds. Part 43. Inter- and Intra-molecular Reactions of Polychloroaromatic Compounds with Copper
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The reaction of polychloroiodoarenes with copper in dimethylformamide gives good yields of the biaryls. 4-Bromotetrachloropyridine gives products of halogen exchange and reduction as well as coupling.Pentachloropyridine gave only tetrachloropyridines.Evidence against free radical or pyridyne intermediates is presented, and it is postulated that the reactions proceed via pyridylcopper compounds, although an electron transfer mechanism is not excluded.On reaction with copper, some 4-(o-halogenophenoxy)- and 4-(o-halogenothiophenoxy)-tetrahalogenopyridines give products of cyclisation, reduction, and halogen transfer.Copper reacts initially, at least in part, with the pyridyl group rather than with the o-halogenoaryl group.The results are again consistent with a reaction pathway involving a pyridylcopper intermediate.The products of nucleophilic substitution in pentahalogenopyridines by some phenols, thiophenols, and anilines are reported.
- Mack, Arthur G.,Suschitzky, Hans,Wakefield, Basil J.
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p. 1682 - 1687
(2007/10/02)
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- The Specificity of Reductive Dechlorination in the Polychloropyridine Series. Synthesis of 2,3,5-Trichloro- and 2,3,5,6-Tetrachloropyridine
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The high specificity of the reduction system zinc and ammonium salts in dimethyl methylphosphonate as solvent is demonstrated in several reductive dechlorination reactions of polychloropyridines.The reduction of pentachloropyridine with zinc/ammonium chloride system in dimethyl methylphosphonate yielded solely 2,3,5,6-tetrachloropyridine.Similarly, the reduction of 2,3,4,5-tetrachloropyridine with zinc and tetramethylammonium salt of methyl methylphosphonate furnished exclusively 2,3,5-trichloropyridine.A synthetic procedure for the preparation of the new ammonium salts of methyl methylphosphonate is given.
- Sutter, P.,Weis, C. D.
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p. 493 - 496
(2007/10/02)
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- Polyhalogenoaromatic Compounds. Part 41. Photochemical Dehalogenation and Arylation Reactions of Polyhalogenoaromatic and Polyhalogenoheteroaromatic Compounds
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Photolysis of pentachloro- and pentabromo-pyridine in diethyl ether or methanol leads to loss of β-halogen.A product (9) derived from attack on diethyl ether was also identified. 4-Bromotetrachloropyridine also undergoes loss of bromine and tetrachloro-4-iodopyridine loses iodine exclusively.Photodehalogenation of some perhalogenothiophens, tetrachloropyrimidine, and hexachlorobenzene is also described.Photolysis of pentachloroiodobenzene, tetrachloroiodopyridines, and trichloro-5-iodothiophen in benzene gives the corresponding polychloroaryl- or polychloroheteroaryl-benzenes.Photolysis of tetrachloro-4-(phenylthio)pyridine (3) gives 1,3,4-trichlorobenzothienopyridine (6), and the analogous perchloro(phenylthio)pyridine (37) gives the corresponding perchlorobenzothienopyridine (61).The scope of this type of photocyclisation has been explored; starting materials investigated include various arylthiopolyhalogenopyridines, some arylamino- and aryloxy-tetrachloropyridines, and 4-anilinotrichloropyrimidine.
- Bratt, Jack,Iddon, Brian,Mack, Arthur G.,Suschitzky, Hans,Taylor, Jack A.,Wakefield, Basil J.
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p. 648 - 656
(2007/10/02)
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- Preparation of chloro substituted pyridines
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In the process for preparing 2,3,5-trichloropyridine, 2,3,4,5- or 2,3,5,6-tetrachloropyridine by the oxidation of the appropriate trichloro- or tetrachlorohydrazinopyridine, the improvement which comprises carrying out the oxidation with an alkaline hypochlorite in the presence of a reaction medium.
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