JPS6042780B2 - Substituted hydroquinone 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 range. .

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

In addition, in recent years, CH crucian carp HCH2 of Cholesteric Kunemachitsu
A display element that utilizes CH3(I) phase change has been developed, and a display element that utilizes the fact that the helical pitch of cholesteric liquid crystal changes as the electric field increases and decreases, as one of the color display elements that utilize liquid crystal, has also attracted attention. ing.

The cholesteric liquid crystal compounds used in these display devices have traditionally been mostly cholesterol derivatives, which have poor stability, resulting in short display device lifespans, and their practical use has been extremely limited. It has become a thing.

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. It is an object of the present invention to provide a novel liquid crystal compound which is chemically, thermally, optically and electrically stable and has a wide cholesteric liquid crystal temperature range, which can be used in the above-mentioned applications.

That is, the present invention relates to P-2-methylbutyl having optical activity represented by the general formula (wherein X represents hydrogen, fluorine, chlorine, bromine, methyl group, or methoxy group, and the end mark represents an asymmetric carbon atom). It is a substituted hydroquinone ester of oxybenzoic acid and a racemic form of the same compound.

Among these, the optically active substance is called a so-called 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 a substance, and has a wide cholesteric liquid crystal temperature range, so it can be widely used.

For example, by adding several percent of it to a nematic liquid crystal mixture with positive dielectric anisotropy, it is possible to improve the alignment of liquid crystals for twisted nematic liquid crystal display cells. 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, the compound of the present invention (1
), first, optically active or racemic P-2-methylbutyloxybenzoic acid is converted to acid chloride with thionyl chloride, and this is reacted with substituted hydroquinone in the presence of pyridine. It can be obtained by

This reaction can be expressed as a chemical equation as follows. (
In the formula, Not even.

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

Example 1 Optically active (+)-P-(2-methylbutyloxy)benzoic acid 2.1f and thionyl chloride 2y are placed in a 50 mt flask and heated on a water bath at 40 to 45°C.

The crystals gradually melt to become a homogeneous liquid, and after further heating three times, the excess thionyl chloride is distilled off under reduced pressure. On the other hand 10
Dissolve 0.55y of hydroquinone in 10ml of pyridine in a 0ml flask, cool on ice, and gradually add the acid chloride obtained as above to this solution. After standing overnight, pour into water, extract the precipitated oil with toluene, wash the toluene layer twice with hydrochloric acid, three times with 1N aqueous sodium hydroxide solution, and then with water until neutral. After distilling off toluene under reduced pressure, the remaining oil was recrystallized from ethanol to obtain colorless crystals 1.4y (yield: 57.1%). This compound (
That is, the melting point, phase displacement point, elemental analysis value, etc. of the formula (1) in which X is H are shown in Table 1 together with the results of other examples later.
Moreover, its infrared absorption spectrum is shown in FIG. Example 2
~5 In place of 0.55f of hydroquinone in Example 1, 0.2y of hydroquinone chloride (Example 4''2),
Methylhydroquinone 0.62y (Example 3), methoxyhydroquinone 0.7y (Example 4), bromide hydroquinone 0.94g (Example 5), fluorinated hydroquinone 0.64
y (Example 6) in the same manner as each substituted hydroquinone ester of optically active (+)-P-(2-methylbutyloxy)benzoic acid (in formula (1), X is C1
, CH3, CH3O, Br, . F) was obtained.

Their yields, analytical values, phase transition points, etc. are shown in Table 1. Moreover, infrared absorption spectra of the obtained compounds for Examples 2 to 4 are shown in FIGS. 2 to 4.

(2-Methylbutyloxy)benzoic acid was replaced with racemic P-(2-methylbutyloxy)benzoic acid in exactly the same manner except that the same amount of racemic P-(2-methylbutyloxy)benzoic acid was used. ) Hydroquinone ester of benzoic acid 1
．． 5y (yield 61.1%) was obtained. This compound is a nematic liquid crystal compound, and its phase transition point and elemental analysis values are shown in Table 1. Example 8 (Application example 1) 4″-pentyl-4-cyanobiphenyl 41.7%4
″-heptyl-4-cyanobiphenyl 25.1%4″
-pentyloxy-4-cyanobiphenyl
-9.4% 4″-heptyloxy-4-cyanobiphenyl
9.4% 4″-octyloxy-4-cyanobiphenyl 13.
A P-type nematic liquid crystal with a composition of 6% has a nematic temperature range of -8 to 496°C.

Here, the optically active (+)-P- obtained in Example 1
The product containing 10% hydroquinone ester of (2-methylbutyloxy)benzoic acid was a cholesteric liquid crystal at room temperature, with a clearing point of 52.8°C. This cholesteric liquid crystal was sealed in a cell with an electrode spacing of 6 μm, and the frequency was 1K.
When an AC voltage of a certain ratio was applied, a cholesteritschnematic phase transition occurred at a threshold voltage of 13 V, and the light transmittance suddenly increased. Example 9 (Application Example 2) In Example 8, the racemic P obtained in Example 7 was substituted for the optically active hydroquinone ester of (+)-P-(2-methylbutyloxy)benzoic acid. -(2-Methylbutyloxy)benzoic acid, the mixture is nematic liquid crystal and the clearing point is 52 as in Example 8.
．． It was 8℃.

Furthermore, when a liquid crystal cell with a thickness of 10 μm was assembled using this liquid crystal composition and operated at 25° C. with 3 V 125 Hz alternating current, the rise time was 1007 TLsec, the fall time was 150 w1. It was hot in sec.

[Brief explanation of drawings]

Figures 1, 2, 3, and 4 are examples 1, 2, and 4, respectively.
FIG. 3 is an infrared absorption spectrum diagram of the substituted hydroquinone ester of (+)-P-(2-methylbutyloxy)benzoic acid obtained in Steps 3 and 4.

Claims (1)

[Claims] 1 General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, X represents hydrogen, fluorine, chlorine, bromine, methyl group, or methoxy group, and the * mark represents an asymmetric carbon atom) A substituted hydroquinone ester of P-(2-methylbutyloxy)benzoic acid represented by: 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.