JPS59139353A - Liquid crystal substance having large positive dielectric anisotropy - Google Patents

Abstract

NEW MATERIAL:The compound of formula I (R is 1-15C alkyl or alkoxy; the group of formula II is group of formula III or IV). EXAMPLE:4-(trans-4-Hexylcyclohexanoyloxy)phenylpropiolonitrile. USE:A liquid crystal composition. It has large dielectric anisotropy (about +30) and is suitable for the production of a composition usable for the low-votage driving display element as well as the multi-digit driving liquid crystal display element. PROCESS:The compound of formula I can be prepared by brominating the compound of formula V with bromine to obtain the compound of formula VI, and dehydrobrominating the product with 1,8-diaza-bicyclo-(5,4,0)undecene-7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel liquid crystal material having large positive dielectric anisotropy and a liquid crystal composition containing the same.

Display elements using liquid crystals have come to be widely used in watches, calculators, etc. This liquid crystal display element utilizes the properties of optical anisotropy and dielectric anisotropy of liquid crystal materials, and liquid crystal phases include nematic liquid crystal phase, smectic liquid crystal phase, and cholesteric liquid crystal phase, among which nematic liquid crystal is used. The most widely used (practical) types include the TN (twisted nematic) type, DS (dynamically scattered dust) type, guest-host type, DAP type, and dual-frequency method type. The properties required for the liquid crystal materials used are different.

However, in any case, it is desirable that the liquid crystal materials used in these display elements exhibit a liquid crystal phase over as wide a range as possible in nature, but at present there is no single material that satisfies such conditions. Currently, by mixing several types of liquid crystal substances or non-liquid crystal substances, we have obtained substances that can withstand the use of linings.Also, these substances are resistant to moisture, light, heat, air, etc. Needless to say, it must be stable, and furthermore, it is desirable that the threshold voltage and saturation voltage required to drive the display element be as low as possible, and that the viscosity be as low as possible in order to increase the response speed.

Incidentally, recent advances in liquid crystal display technology have been remarkable, and multi-digit drive systems have been developed to display a large amount of information. It has been found that the liquid crystal composition required for this method is a combination of one with a small positive dielectric anisotropy value and one with a large positive dielectric anisotropy value. However, many materials with large positive dielectric anisotropy values are currently known, and these materials have poor safety.

The present inventors discovered a new liquid crystal material that satisfies such requirements and arrived at the present invention.

That is, the present invention relates to an ester derivative of 4-hydroxyphenylpropiol nitrile of a carboxylic acid represented by the general formula (the middle hole of the above formula is alkyl having 1 to 15 carbon atoms), and a liquid crystal composition characterized by containing at least one thereof. It is.

The compound of the present invention exhibits a nematic liquid crystal phase and has a large dielectric anisotropy value of about +30, making it suitable for producing compositions for use in low-voltage drive display elements as well as multi-digit drive type liquid crystal display elements. be.

Next, the method for producing the compound of the present invention is shown. An ester derivative of 4-hydroxycinnamitrile of a carboxylic acid produced by a known method is brominated with bromine. ) Undesen-7 (hereinafter DB
The desired ester derivative of 4-hydroxyphenylpropiol nitrile of the carboxylic acid was produced by dehydrobromation with (abbreviated as U). This is shown as a chemical formula (1't in the above formula,
(→- is the same as above) Hereinafter, the compound of the present invention will be explained in more detail by showing production examples and usage examples of the compound of the present invention as Examples. Production of cyclohexanoyloxy)phenylpropiolic acid nitrile] 17g of 4-(trans-4-hexylcyclohexanoyloxy)cinnamonitrile was mixed with 200d of chloroform.
Add 10 g of bromine at room temperature and leave for 1 day. When the chloroform is distilled off under reduced pressure, an oily substance remains.

Dissolve this oil in 500 ml of toluene, add 50 g of DBU at room temperature (without stirring), and react for 1 day. After the reaction is complete, pour the reaction solution into water and separate the toluene layer. Dissolve the toluene layer in 3N hydrochloric acid. Then, 2N hydroxide l-1
After washing with water, wash with water until the washing solution becomes neutral. After drying the toluene layer over anhydrous sodium sulfate, the toluene was distilled off under reduced pressure, and the remaining oil was recrystallized twice from methanol to obtain the target compound, 4-(trans-4-hexylcyclohexanoyloxy). 7 g of phenylpropiolic acid nitrile was obtained. Yield 42%. Its C-N point halo 4.5
~66.5c, N-1 points were 7Q, 4C.

Examples 2 to 5 Similar operations were carried out to replace the 4-(trans-4-hexylcyclohexanoyloxy)cinamide nitrile in Example 1 with other 4-():lly-4-alkylcyclohexanoyloxy)cinnitrile. The first using nitrile or 4-(4-alkoxybenzoyloxy)cinnamitrile
A compound of formula (I) shown in the table was prepared.

Table 1 Example 6 (Use Example 1) Trans-4-propyl-(4'-cyanophenyl)cyclohexane 24 Thitrans-4-pentyl-(4'-cyanophenyl)cyclohexane
36% trans-4-heptyl-(4'-cyanophenyl)cyclohexane 25% 4-cyano-4'-(trans-4-pentylcyclohexyl)
N of liquid crystal composition A with a composition of 159 g of biphenyl
The −N point is 72C, and the dielectric anisotropy value Δε is +11.8. This liquid crystal composition was sealed in a TN cell (twisted nematic cell) with a cell thickness of 10 μm, and the operating threshold voltage was 1.83V and the saturation voltage was 2.53V. Further, the viscosity was 28 cp at 20tZ'.

In Example 1 of the present invention, 90 parts of this liquid crystal composition was added to ff.
The N-N point of the liquid crystal composition obtained by adding 10 parts of 4-(trans-4-hexylcyclohexanoyloxy)phenylpropiolic acid nitrile is 69tZ', and Δε is +1
8.0, threshold voltage is 166■, saturation voltage is 2
．． The voltage was 28V and the viscosity was 350p at 20C.

As described above, by using the compound of the present invention, it was possible to increase Δε and lower the threshold voltage and saturation voltage.

Example 7 (Use Example 2) Similarly, 4-( produced in Example 3) was added to 90 parts of liquid crystal composition A.
trans-4-octylcyclohexanoyloxy//
) phenylpropiolic acid nitrile lO part (3-N point is 66C1Δε is +15.0, threshold voltage is 1
．． 67V, the saturation voltage is 2.47V, and the viscosity! ! Hi
20 tll' te38 cp teti, tsuta.

that's all

Claims (2)

[Claims] (1) The general formula (the middle hole in the above formula is an alkyl group having 1 to 15 carbon atoms) is shown. ) An ester derivative of 4-hydroxyphenylpropiol nitrile of a carboxylic acid represented by: (2) At least one ester derivative of 4-hydroxyphenylpropiol nitrile of a carboxylic acid represented by the general formula (in the above formula, R is alkyl having 1 to 15 carbon atoms (>- or -(indicates δ←)). A liquid crystal composition comprising: