JPS6025418B2 - 4,4'-dihydroxybiphenyl ester of P-(2-methylbutyloxy)benzoic acid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel liquid crystal compound, and more particularly to a compound that is chemically, thermally, optically, and electrically stable and exhibits a cholesteric liquid crystal phase or a nematic liquid crystal phase over a wide temperature range. .

Cholesteric liquid crystals are used to display temperature by taking advantage of the fact that the wavelength of their scattered light changes with temperature.

In addition, display elements that utilize the phase change of cholesteric nematics have been developed in recent years, and one color display element that utilizes liquid crystals utilizes the fact that the helical pitch of cholesteric liquid crystals changes depending on the increase or decrease in exposure. Display elements are also regulated. Cholesteric liquid crystal compounds used in these display elements have traditionally been mostly cholesterol derivatives, which have poor stability, resulting in short display element lifespans, and their practical applications are extremely limited. ing.

In order to improve this drawback, there is a demand for compounds that exhibit a stable cholesteric liquid crystal phase even under various adverse conditions. The object of the present invention is to provide a novel liquid crystal compound which can be used for the above-mentioned applications, is chemically, thermally, optically and electrically stable and has a wide cholesteric liquid crystal temperature range.

That is, the present invention is an ester compound of P-(2-methylbutyloxybenzoic acid and 4,4'-dihydroxybiphenyl) and a racemic same compound having optical activity represented by the following formula.

Among these, the optically active substance is called a chiral nematic liquid crystal compound (a general term for non-cholesterol compounds having an optically active group and exhibiting a cholesteric liquid crystal phase), and is the main object of the present invention. It is a stable compound that can be easily synthesized rather than derived from cholesteric liquid crystals, and has a wide cholesteric liquid crystal temperature range, so it can be widely used.

For example, by mixing a few percent of this compound into a nematic liquid crystal compound having positive dielectric anisotropy, it is possible to improve the orientation of liquid crystal for twisted nematic type liquid crystal display cells. Furthermore, the racemic form exhibits a nematic phase and can be used in dynamic scattering mode, twisted nematic type liquid crystal display elements, and liquid crystal display elements that utilize the host-guest effect.

Next, to briefly explain the method for producing compound (1) of the present invention, first, 2 moles of optically active or racemic P-
Compound (1) is obtained by converting (2-methylptoxy)benzoic acid into dichloride with excess thionyl chloride, and then reacting with 1 mole of P.P'-monodihydroxyphenyl in the presence of pyridine.

The chemical reaction formula for this is shown below. It goes without saying that the presence or absence of optical activity of compound (1) is determined by the presence or absence of optical activity of the raw material P-(2-methylbutyloxy)benzoic acid.

The optically active compound (1) thus obtained exhibits a phase change of crystal-smectic liquid crystal-cholesteric liquid crystal-transparent liquid, and the racemic compound (1) exhibits a phase change of crystal-smectic liquid crystal-transparent liquid. The manufacturing method and application examples of the present compound will be explained in more detail with reference to Examples below.

Example 1 (-)-P-(2-Methylbutoxy)benzoic acid 2 thionyl chloride was added and heated for 1 hour in a flask equipped with a reflux condenser, and excess thionyl chloride was removed to give acid. Obtain chloride.

This acid chloride was added to an ice-cooled mixture of 4,4'-dihydroxybiphenyl (0.9 ml) and pyridine (5 ml). After standing overnight, water was added and extracted with toluene 50% Z, and the toluene layer was washed with carp hydrochloric acid and then with an aqueous sodium hydroxide solution. After thoroughly washing with water, the toluene layer is dried over anhydrous sodium sulfate, and the toluene is removed under reduced pressure to precipitate crystals. The crystals are recrystallized with 10 parts of acetone to obtain the desired 4,4'-dihydroxybiphenyl ester of (1)-P-(2-methylbutyloxy)benzoic acid (1).
) was obtained (yield 42.4%). The crystalline smectic point of this compound is 123.500, the smectic cholesteric point is 142.5qo, and the cholesteric point is 123.500.
The clearing point was 227.900. The elemental analysis values are as follows, which agree well with the calculated values. Analytical value Calculated value (as C36 days 3806) C 701% 763% days 6.5% 6.8% In addition, the infrared absorption spectrum is shown in the figure.

Example 2 Racemic P-(2-
Racemic compound (1) was obtained in exactly the same manner except that methylbutyloxybenzoic acid was used. The compound has a crystal-smetic point of 122.8 ○, a smectic-nematic point of 143.0 qo, and a nematic-clearing point of 228.0°C, showing a nematic phase instead of the cholesteric phase of the compound of Example 1. They differ in some respects. In addition, the elemental analysis values are as follows and are in good agreement with the calculated values. Analysis value Calculated value (as C36th 3806) C 76.2%
76.3% day 6.6% 6.8% Example 3 (Application example) 4'-benthyl-4-cyanobiphenylene/di 41.7% (same weight below) 4'-heptyl-4-cya/biphenyl 25.1%
The P-type nematic liquid crystal of the composition is 10.2% of 4'-bentyloxy-4-cyanobiphenyl, 9.4% of 4'-heptyloxy-4-cyanobiphenyl, and 13.6% of 4-octyloxy-4-cyanobiphenyl. It has a nematic temperature range of -8 to 49°C.

Add 5% of the optically active compound (1) obtained in Example 1 to this.
．． When 0% is added, the liquid crystal becomes a cholesteric liquid crystal at room temperature, and the clearing point increases to 57.9%. When this cholesteric liquid crystal was sealed in a cell with six electrode spacings and a voltage with a frequency of IK was applied, a cholesteric → nematic phase transition occurred at a threshold voltage of 1.2 V, and a rapid increase in light transmittance was observed. . Example 4 (Application example) In Example 3, if the racemic compound (1) obtained in Example 2 is used instead of the optically active compound (1), a nematic liquid crystal composition can be obtained.

This nematic liquid crystal was sealed in a twisted nematic type liquid crystal cell with an electrode spacing of 10 microns, and when its characteristics were investigated, it responded, the voltage was 1.5V, and the response saturation voltage was 2.1V.
Met. Also, when operating with 3V, 32Hz AC at 25oo, the rise time is 100 seconds and the fall time is 15 seconds.
It was 0mSeC. A simple illustration of the drawing is an infrared absorption spectrum diagram of 4,4'-dihydroxyphenyl ester of (1)-P-(2-methylbutyloxy)benzoic acid obtained in Example 1.

Claims (1)

[Claims] P-(2-methylbutyloxy)benzoic acid and 4.4' represented by the following primary formula ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (In the formula, the * mark represents an asymmetric carbon atom) -Dihydroxybiphenyl ester compound. 2. The compound according to claim 1, which is an optically active compound based on the asymmetric carbon atom marked with * in formula (I). 3. The compound according to claim 1, which is a racemate.