- Synthesis process of 2, 3-difluoro-4-alkoxy phenol
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The invention discloses a synthesis process of 2, 3-difluoro-4-alkoxy phenol, and belongs to the technical field of organic synthesis. The process comprises the following steps: using 2, 3-difluorophenylalkyl ether as a raw material, carrying out lithiation by use of n-butyllithium under an ultralow temperature condition, reacting with boric acid ester, adding an alkali for quenching to obtain 2,3-difluoro-4-alkoxy benzene borate, oxidizing in the presence of hydrogen peroxide, and performing acidolysis to obtain 2, 3-difluoro-4-alkoxy phenol, so that the purity of the purified product can reach more than 99.95 %, the impurity content is less than 50ppm, and the requirements of electronic-grade products are met. Boric acid and the alkali can form salt, the salt is dissolved in water and subjected to a homogeneous reaction for an oxidation reaction during oxidation in the presence of the hydrogen peroxide, the reaction conditions are mild, impurities are few, the product purity is high, the solvent can be recycled, and industrial production is easy to achieve.
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Paragraph 0030; 0033; 0034; 0037; 0038; 0041
(2020/04/06)
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- Preparation method of 2, 3-difluoro-4-alkoxy phenol
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Relating to the technical field of organic synthesis, the invention discloses a preparation method of 2, 3-difluoro-4-alkoxy phenol. 2, 3-difluorobenzene ether, n-butyllithium, trimethyl borate, acetic acid and hydrogen peroxide are adopted as the raw materials, tetrahydrofuran is taken as the solvent, and by means of organic lithiation, boration, oxidization, pulping filtration and other steps, a 2, 3-difluoro-4-alkoxy phenol product can be obtained. The method provided by the invention has the advantages of cheap and easily available raw materials, mild reaction conditions, simple aftertreatment operation, low production cost, a total yield up to more than 66%, and product purity of more than 99.9%, and is suitable for industrialized production.
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Paragraph 0019
(2018/02/04)
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- Liquid crystalline compound, liquid crystal composition comprising the liquid crystal-line compound, and liquid crystal display device using the liquid crystal composition
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The invention is to provide liquid crystalline compounds which have a low viscosity, high negative dielectric anisotropy, high resistivity, and high voltage holding ratio, and are stable against heat and ultraviolet light; to provide liquid crystal compositions comprising the liquid crystalline compound; and to provide liquid crystal display devices using the liquid crystal composition therein; the liquid crystalline compound is expressed by the general formula (1) ?wherein R1and Y1represent an alkyl group having 1 to 20 carbon atoms; X1, X2, and X3independently represent single bond, 1,2-ethylene group, vinylene group, —COO—, —CF2O—, or —OCF2—; ring A1, ring A2, ring A3, and ring A4independently represent trans-1,4-cycloliexylene, or 1,4-phenylene hydrogen atom on the ring may be replaced by fluorine atom or chlorine atom provided that at least one of ring A2, ring A3, and ring A4represents 2,3-difluoro-1,4-phenylene; m and n are 0 or 1, and each element which constitutes this compound may be replaced by its isotope.
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- Liquid crystal compound having negative dielectric anisotropy, liquid crystal composition containing said liquid crystal compound and liquid crystal display device using said composition
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A liquid crystal compound has a group represented by the following general formula (1) and a ring represented by the following general formula (2) in the general structure of the compound: wherein G represents an alkylene group having 1 to 3 carbon atoms wherein at least one hydrogen atom constituting the alkylene group may be substituted with a fluorine or chlorine atom; W1 and W2 each independently represents a hydrogen, fluorine or chlorine atom, provided that at least one of W1 and W2 represent a fluorine or chlorine atom; W3 and W4 each independently represents a fluorine or chlorine atom, and provided that each atom constituting the compound may be substituted with its isotope. The liquid crystal compound has a negative dielectric anisotropy value whose absolute value is large, a low viscosity, a controlled optical anisotropy value, a high specific resistance and a high voltage-holding ratio and is stable against heat and irradiation with ultraviolet rays.
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- Process for the preparation of 2,3-difluorobenzenes
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1,4-disubstituted 2,3-difluorobenzenes according to formula I are suitable as intermediates for the synthesis of liquid crystalline compounds.
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