Conversion method of 1-cyclohexyl-2,3-difluorobenzene derivative cis-trans-isomers

A technology of difluorobenzene derivatives and cis-isomers, applied in the field of 1-cyclohexyl-2, can solve the problems of increasing product cost, increasing production cost, and difficult disposal of waste liquid, so as to avoid direct discharge and reduce Pollution, the effect of increasing production

Active Publication Date: 2014-04-09
SHIJIAZHUANG CHENGZHI YONGHUA DISPLAY MATERIALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If these cis-structure products are directly discharged as waste compounds, it will not only increase the production cost and cause serious waste,

Method used

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  • Conversion method of 1-cyclohexyl-2,3-difluorobenzene derivative cis-trans-isomers
  • Conversion method of 1-cyclohexyl-2,3-difluorobenzene derivative cis-trans-isomers
  • Conversion method of 1-cyclohexyl-2,3-difluorobenzene derivative cis-trans-isomers

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Example 1 trans 1-ethoxy-2,3-difluoro-4-(4-pentylcyclohexyl)benzene (R 1 is pentyl, R 2 is ethoxy, n is 0)

[0039]

[0040] In the synthesized 1-ethoxy-2,3-difluoro-4-(4-pentylcyclohexyl)benzene, the molar percentage of the cis isomer is 82%, and that of the trans isomer The mole percentage is 17%.

[0041] The method for converting the cis isomer to the trans isomer is as follows.

[0042] In a 250ml there-necked flask, add 25g1-ethoxy-2,3-difluoro-4-(4-pentylcyclohexyl)benzene, catalyst palladium carbon Pd / C (mass percentage of Pd) of 1.5g in dry weight The content is 5%), install the thermometer, stir, install a Y-shaped tube on one of the three-necked bottles, one port of the Y-shaped tube is connected to the trachea and the other is filled with a balloon. Fill the three-necked flask with nitrogen, vent the air with nitrogen for 5 times, and then vent the nitrogen with hydrogen for 5 times, and keep the balloon in an inflated state. At this time, the pressur...

Embodiment 2

[0051] Example 2 trans 1-ethoxy-2,3-difluoro-4-(4-propylcyclohexyl)benzene (R 1 is propyl, R2 is ethoxy, n is 0)

[0052]

[0053] In the synthesized 1-ethoxy-2,3-difluoro-4-(4-propylcyclohexyl)benzene, the molar percentage of the cis isomer is 85%, and that of the trans isomer The mole percentage is 14%.

[0054] The method for converting the cis isomer to the trans isomer is as follows.

[0055] Add 25g of 1-ethoxy-2,3-difluoro-4-(4-propylcyclohexyl)benzene into a 250ml three-necked flask, the dry weight is 5gPt / C (the mass percentage of Pt is 5% ), and ethanol 10g, water 10g, dioxane 5g. Install the thermometer, stir, install a Y-shaped tube on one mouth of the three-necked bottle, and connect one mouth of the Y-shaped tube to the trachea and install a balloon on the other mouth. Fill the three-necked flask with nitrogen, vent the air with nitrogen for 5 times, and then vent the nitrogen with hydrogen for 5 times, and keep the balloon in an inflated state. At this ti...

Embodiment 3

[0064] Example 3 trans 4'-(4-methyl-2,3-difluorobenzene)-4-propyl bicyclohexane (R 1 is propyl, R 2 is methyl, n is 1)

[0065] In the synthesized 4′-(4-methyl-2,3-difluorobenzene)-4-propylbicyclohexane, the molar percentage of the cis-isomer is 90%, and the trans-isomer The mole percent content is 9%.

[0066] The method for converting the cis isomer to the trans isomer is as follows.

[0067] In the 500ml autoclave, add the 4 '-(4-methyl-2,3-difluorobenzene)-4-propyl bicyclohexane of 50g, the palladium charcoal that dry weight is 0.125g (the mass percent composition of Pd is 5%), install the lid of the kettle, keep the airtightness good, and install the thermometer. Fill the autoclave with nitrogen to exhaust the air 5 times, then use hydrogen to exhaust the nitrogen 5 times, then fill the autoclave with hydrogen to a pressure of 5.0 atm, start stirring, heat to 240 ° C, and carry out the catalytic reaction for 1 hour.

[0068] The reaction liquid was sampled and analyz...

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Abstract

The invention discloses a conversion method of 1-cyclohexyl-2,3-difluorobenzene derivative cis-trans-isomers. The method comprises the following steps: in a hydrogen atmosphere, evenly mixing 1-cyclohexyl-2,3-difluorobenzene derivative cis-trans-isomers disclosed as Formula I and a catalyst to perform catalytic reaction, and after the reaction finishes, obtaining the 1-cyclohexyl-2,3-difluorobenzene derivative trans-isomers disclosed as Formula I. The method can convert most cis-structure products into a trans-structure liquid crystal material, avoids the direct discharge of the cis-structure products as waste compounds, reduces the pollution, and greatly increases the yield of the trans-structure liquid crystal material, thereby lowering the production cost of the 1-cyclohexyl-2,3-difluorobenzene derivative liquid crystal monomer. Formula I.

Description

technical field [0001] The invention relates to a conversion method of cis and trans isomers of 1-cyclohexyl-2,3-difluorobenzene derivatives. Background technique [0002] Lateral fluorine-containing liquid crystals have been widely used in mixed liquid crystals for VA-TFT displays due to their excellent properties such as low viscosity, high charge retention rate, high chemical stability, and negative dielectric anisotropy. Such liquid crystal compounds can effectively reduce the dielectric constant of the mixed liquid crystal to increase the steepness of the electro-optical curve, thereby achieving multi-channel driving capability and improving the relationship between contrast and viewing angle. [0003] In the synthesis process of this type of liquid crystal monomer, two isomers, cis and trans, will inevitably appear. Since the isomer with the cis structure does not have the properties of liquid crystals, if it cannot be converted into a liquid crystal material with the ...

Claims

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Application Information

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IPC IPC(8): C07C43/225C07C41/32C07C25/18C07C17/358C07B55/00
CPCC07C17/358C07C41/32C07C2601/14C07C43/225C07C25/18
Inventor 员国良温刚华瑞茂崔红梅张芳苗韩耀华
Owner SHIJIAZHUANG CHENGZHI YONGHUA DISPLAY MATERIALS CO LTD
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