CN1329481C - Liquid crystal compound containing monofluoro ethylene bridge and its preparing method - Google Patents

Abstract

The present invention discloses a liquid crystal compound containing monofluoro ethylene bridge bond and a preparing method thereof, the liquid crystal compound containing monofluoro ethylene bridge bond provided by the present invention has a general formula I structure, wherein n shows the positive integers of 1 to 7, and m shows the positive integers of 1 to 5. fluorin atoms apperar on a center bridge bond of the liquid crystal compound of the present invnetion. The present invention has the characteristics of simple preparation method, low fusing point, wide temperature range of liquid crystal phase, low viscosity, etc., and has wide application foreground in the liquid crystal display field.

Description

Liquid crystal compound containing monofluoroethylene bridge bond and preparation method thereof

technical field

The invention relates to a liquid crystal compound and a preparation method thereof, in particular to a liquid crystal compound containing a monofluoroethylene bridge bond and a preparation method thereof.

Background technique

Since entering the 21st century, thin-film transistor (Thin Solid Film: TFT) liquid crystal display has fully covered the display fields of large, medium and small sizes, and is widely used in various terminal displays such as TVs, portable computers, desktop computers, cameras, and mobile phones. The mainstream of flat panel displays. With the rapid development of TFT liquid crystal display technology, the requirements for high-performance liquid crystal materials are becoming more and more urgent. Therefore, the development of high-performance liquid crystal materials with good thermal, chemical, electrical and light stability, high charge retention rate, low viscosity and high resistivity Liquid crystal material is the future research direction of liquid crystal material for TFT.

Since it is impossible for any single monomer liquid crystal to meet all performance requirements in display, a mixed liquid crystal material composed of various monomer liquid crystals in proportion is used in display. Due to its structural particularity, when it exists as a component of mixed liquid crystals, it can reduce the viscosity and optical anisotropy of mixed liquid crystals, broaden the use temperature range of liquid crystal phases, and also have good Light stability and chemical stability, so it is a liquid crystal material with good performance. Yasuyuki Goto of Japan's Chisso Company synthesized various ethane-based liquid crystal monomers (US Patent 4797228, US Patent 4820443) containing -CH2CH2-central bridge bonds, and Shuichi Matsui and others also did research on ethane-based liquid crystal monomers. A lot of research has been done (US Patent 5468421).

Contents of the invention

The object of the present invention is to provide a liquid crystal compound containing monofluoroethylene bridges and a preparation method thereof.

The liquid crystal compound containing monofluoroethylene bridge provided by the present invention has a structural formula such as formula I,

Wherein, n is a positive integer of 1-7; m is a positive integer of 1-5.

Specifically, the above-mentioned liquid crystal compound is one of the following compounds:

1-(4'-trans-(4"-trans-methylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-ethylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-butylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-pentylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-hexylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-heptylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-methylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-ethylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-butylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-pentylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-hexylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-heptylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-methylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-ethylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-butylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-pentylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-hexylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-heptylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-methylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-ethylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-butylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-pentylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-hexylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-heptylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-methylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-ethylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-butylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-pentylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-hexylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-heptylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane.

The preparation method of the liquid crystal compound comprises the following steps:

1) Preparation of 1-(4'-trans-(4"-trans-alkylcyclohexyl)cyclohexyl)-1-hydroxyl-2-(4'-alkylphenyl)ethane with a structure such as formula II : the 4-alkylphenyl bromide of the formula III structure is first reacted with metal magnesium to generate the Grignard reagent, and then reacted with the 4-trans-(4'-trans-alkylcyclohexyl)cyclohexylcarbaldehyde of the formula IV structure Reduction reaction, obtains formula II compound;

Wherein, n is a positive integer of 1-7; m is a positive integer of 1-5;

2) Preparation of the liquid crystal compound of formula I: reacting the compound of formula II with diethylaminosulfur trifluoride having the structure of formula V to obtain the liquid crystal compound of formula I.

(C ₂ H ₅ ) ₂ N·SF ₃ (Formula V)

Wherein, the solvent used in the step 1) Grignard reaction is tetrahydrofuran, and the reaction temperature is 20-30°C; the solvent used in the reduction reaction is tetrahydrofuran, and the reaction temperature is -10-5°C.

Step 2) The reaction solvent is dichloromethane, and the reaction temperature is -80～-70°C.

Fluorine atoms appear on the central bridge of the liquid crystal compound of the invention, the preparation method is simple, the melting point is low, the temperature range of the liquid crystal phase is wide, the viscosity is low, etc., and the liquid crystal compound will have broad application prospects in the field of liquid crystal display.

Detailed ways

Embodiment 1, the preparation of 1-(4'-trans-(4 "-trans-propylcyclohexyl) cyclohexyl)-1-fluoro-2-(4'-ethylphenyl) ethane

1. Preparation of 1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-hydroxyl-2-(4-ethylphenyl)ethane

Add 19.9g (0.1mol) of 4-ethylphenyl bromide, 100ml of tetrahydrofuran, 2.43g (0.1mol) of magnesium metal and 1~2 grains of iodine into a 500ml three-necked flask, and initiate the reaction at room temperature (20~30°C) Stir for 1 hour to make Grignard reagent. The solution was cooled to 0°C with ice water, and a mixed solution containing 23.6g (0.1mol) of 4-trans-(4'-trans-propylcyclohexyl)cyclohexylcarbaldehyde and 200ml of tetrahydrofuran was slowly added dropwise to the solution , and stirred for 12 hours after the dropwise addition, a light yellow turbid solution was obtained. To this solution was added dropwise 50ml of 0.1mol hydrochloric acid to obtain a yellow clear solution. The solution was extracted three times with 750 ml of ether, and the extracts were combined. After the ether solution was washed twice with 100 ml of 2% NaHCO ₃ aqueous solution, the ether solution was dried with anhydrous Na ₂ SO ₄ for 4 hours, and the ether was distilled off to obtain 28 g of a light yellow solid. Recrystallized with 200ml of absolute ethanol to give white solid 1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-hydroxyl-2-(4-ethylphenyl) Ethane-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-hydroxy-2-(4-ethylphenyl)ethane 21.5g, gas chromatography purity 99.1 %, the yield is 60.4%.

IR: 3300, 2962, 2920, 2846, 1520, 1444, 1425, 1370, 1320, 1265, 1223, 1100, 1065, 1020, 975, 850, 810, 670;

MS: 356(M+), 355, 339, 296, 237, 220, 207, 132, 119, 117, 91, 83, 69, 55, 43;

2. Preparation of 1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2-(4-ethylphenyl)ethane

Add 7.2g (0.02mol) 1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-hydroxy-2-(4-ethylphenyl) into a 500ml three-necked flask ) ethane and 180ml of dichloromethane mixed solution, then cool the solution to -70°C with a mixture of liquid nitrogen and ethanol, add diethylaminosulfur trifluoride (DAST) and 50ml of dichloromethane dropwise under stirring Solution, keep the reaction temperature not higher than -70°C, stir for 10 hours. Warm up to -45°C, add 100ml saturated aqueous sodium bicarbonate solution, rise to room temperature. Leave to separate liquids, extract the aqueous phase with dichloromethane, combine the organic phase, washed with water until neutral, and then dried with anhydrous sodium sulfate for 5 hours. Suction filtration and rotary evaporation to obtain 4.8 g of a white crude product, which was separated with a silica gel column, rinsed with petroleum ether and spin-dried to obtain 3.5 g of a white solid. Then recrystallized with absolute ethanol to obtain white crystal 1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2-(4-ethylphenyl ) ethane 2.8g, the gas chromatography purity is 99.5%, and the yield is 39.1%.

DSC: Cr 38.7°CN 160.7°CI

IR: 2980, 2920, 2846, 1516, 1444, 1429, 1375, 1261, 1223, 1097, 1050, 1020, 972, 940, 854, 810, 687

MS: 358(M+), 339, 253, 239, 220, 149, 132, 119, 103, 91, 83, 69, 55, 43, 41

Viscosity (η): 20mm ² ·s

It shows that the structure of the obtained compound is correct.

Its DSC and viscosity data show that the compound is a liquid crystal compound with excellent properties.

Using the same method as above, react 4-alkylphenylbromethane with metal magnesium to generate Grignard reagent, and then reduce it with 4-trans-(4'-trans-alkylcyclohexyl)cyclohexylcarbaldehyde to obtain 1-(4'-trans-(4"-trans-alkylcyclohexyl)cyclohexyl)-1-hydroxyl-2-(4'-alkylphenyl)ethane. Then 1-(4 '-trans-(4"-trans-alkylcyclohexyl)cyclohexyl)-1-hydroxy-2-(4-alkylphenyl)ethane with diethylaminosulfur trifluoride (DAST ) can be reacted to obtain the following compounds, which are also excellent liquid crystal compounds:

1-(4'-trans-(4"-trans-methylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-ethylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-butylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-pentylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-hexylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-heptylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-methylphenyl)ethane,

1-(4'-trans-(4"-trans-methylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-ethylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-butylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-pentylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-hexylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-heptylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-ethylphenyl)ethane,

1-(4'-trans-(4"-trans-methylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-ethylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-butylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-pentylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-hexylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-heptylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-propylphenyl)ethane,

1-(4'-trans-(4"-trans-methylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-ethylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-butylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-pentylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-hexylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-heptylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-butylphenyl)ethane,

1-(4'-trans-(4"-trans-methylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-ethylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-butylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-pentylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-hexylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane,

1-(4'-trans-(4"-trans-heptylcyclohexyl)cyclohexyl)-1-fluoro-2-(4'-pentylphenyl)ethane.

Claims (5)

1. A liquid crystal compound containing a monofluoroethylene bridge, whose structural formula is as in formula I, (Formula I) Wherein, n is a positive integer of 1-7; m is a positive integer of 1-5. 2. The liquid crystal compound according to claim 1, characterized in that: the compound is 1-(4'-trans-(4"-trans-propylcyclohexyl)cyclohexyl)-1-fluoro-2 -(4'-Ethylphenyl)ethane. 3. The preparation method of the liquid crystal compound according to claim 1, comprising the steps of: 1) Preparation of 1-(4'-trans-(4"-trans-alkylcyclohexyl)cyclohexyl)-1-hydroxyl-2-(4'-alkylphenyl)ethane with a structure such as formula II : the 4-alkylphenyl bromide of the formula III structure is first reacted with metal magnesium to generate the Grignard reagent, and then reacted with the 4-trans-(4'-trans-alkylcyclohexyl)cyclohexylcarbaldehyde of the formula IV structure Reduction reaction, obtains formula II compound;

Wherein, n is a positive integer of 1-7; m is a positive integer of 1-5; 2) Preparation of liquid crystal compound of formula I: reacting compound of formula II with diethylaminosulfur trifluoride of formula V structure to obtain liquid crystal compound of formula I (C ₂ H ₅ ) ₂ N·SF ₃ (Formula V). 4. The preparation method according to claim 3, characterized in that in step 1) the solvent used for the Grignard reaction is tetrahydrofuran, and the reaction temperature is 20-30°C; the solvent used for the reduction reaction is tetrahydrofuran, and the reaction temperature is -10-5°C . 5. The preparation method according to claim 3, characterized in that: step 2) the reaction solvent is dichloromethane, and the reaction temperature is -80～-70°C.