Transposition Method of 1-Cyclohexyl-2,3-Difluorobenzene
A cyclohexyl and difluorobenzene technology, applied in the field of liquid crystal materials, can solve problems such as harsh reaction conditions
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Embodiment 1
[0058] 1-(4-Propyl)cyclohexyl-2,3-difluoro-4-ethoxybenzene
[0059]
[0060] The transposition method of the cis-isomer is as follows: add 400ml of petroleum ether, 100ml of dichloromethane, and 100g of the cis-isomer to a 1000ml three-necked bottle, stir and dissolve, and add bromine’s dichloro Methane solution (5g of bromine dissolved in 50ml of dichloromethane), insulation reaction for 3 hours after the completion of the dropwise addition, after the completion of the reaction, take a sample and analyze the reaction solution to obtain 80mol% of the trans isomer (GC retention time 11.1min) , cis-isomer 0.6 mol% (GC retention time 10.3 min). Add 50ml of water to the above reaction solution, separate layers, and when the organic layer is concentrated to almost no solvent, then use 200ml of ethanol to crystallize three times; %, after the mother liquor is collected, transposition can be obtained again to obtain the trans isomer.
Embodiment 2
[0062] 1-(4-Propylcyclohexyl)cyclohexyl-2,3-difluoro-4-ethoxybenzene
[0063]
[0064] The transposition method of the cis-isomer is as follows: add 400ml of n-heptane, 100ml of dichloromethane, and 100g of the cis-isomer into a 1000ml three-necked bottle, stir and dissolve, and add dichloride dichloride dropwise with chlorine gas at a controlled temperature between 30-40°C. Methane solution (2g chlorine is dissolved in 50ml dichloromethane), insulation reaction 3 hours after completion of the dropwise addition, after completion of the reaction, take a sample and analyze the reaction solution to obtain 72mol% of the trans isomer and 27mol% of the cis isomer , add 50ml of water in the above-mentioned reaction solution, separate layers, when the organic layer is concentrated to almost solvent-free, then use 200ml ethanol to crystallize three times, 100ml ethanol, 50ml n-heptane to crystallize once, obtain the trans isomer of 99.9mol%. The rate is 67%. After the mother liquor ...
Embodiment 3
[0066] 1-(4-Propylcyclohexyl)cyclohexyl-2,3-difluoro-4-ethoxybenzene
[0067]
[0068] The transposition method of the cis isomer is as follows:
[0069] Add 400m toluene and 100g cis-isomer to a 1000ml three-necked flask, stir to dissolve, control the temperature between 30-40°C and add dropwise a solution of bromine in dichloromethane (2g of bromine dissolved in 50ml of dichloromethane), dropwise After the completion of the insulation reaction for 3 hours, after the completion of the reaction, the reaction solution was sampled and analyzed to obtain 74mol% of the trans-isomer and 25mol% of the cis-isomer. 50ml of water was added to the above-mentioned reaction solution, the layers were separated, and the organic layer was concentrated to When there is almost no solvent, use 200ml ethanol to crystallize three times, and 100ml ethanol and 50ml n-heptane to crystallize once to obtain 99.9% trans isomer with a yield of 53%. After the mother liquor is collected, transposition ...
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