JPS5910557A - Trans-4-(trans-4'-alkylcyclohexyl)cyclohexanecarboxylic acid ester of 3-alkyloxy-6-hydroxy-phthalonitrile - Google Patents

Abstract

NEW MATERIAL:A compound of the formula (R1 is 1-10C alkyl; R2 is 1-10C straight chain alkyl). EXAMPLE:trans-4-(trans-4'-Pentylcyclohexyl)cyclohexanecarboxylic acid ester of 3-butyloxy-6-hydroxy-phthalonitrile. USE:A liquid crystal composition which is a colorless substance having a remarkably high negative dielectric anisotropy value without absorbing light at >=350nm wavelength. PROCESS:A 3-alkyloxy-6-hydroxy-phthalonitrile is dissolved in a basic solvent, e.g. pyridine, and a solution containing a trans-4-(trans-4'-alkylcyclohexyl)cyclohexanecarboxylic acid halide dissolved in an inert solvent, e.g. toluene, is added to the resultant solution and reacted therewith to give the aimed compound of the formula.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel liquid crystal material, and more particularly to a liquid crystal compound having negative dielectric anisotropy and a significantly large value.

Liquid crystal materials with negative dielectric anisotropy are used in light-scattering type liquid crystal display devices that utilize the dynamic scattering of the liquid crystal layer when voltage is applied, and utilize the birefringence of liquid crystals by controlling the tilt of the liquid crystal. The so-called I displays multicolors using polarizing plates.
) AP-type liquid crystal display devices, and even so-called guest-host devices that use liquid crystal materials containing specific dyes.
It is already generally known that the color display device is an important component of the color display device of the st.Ho5t) type.

One of the objects of the present invention is to provide a novel liquid crystal compound having large negative diisotropy and suitable for forming liquid crystal materials used in these liquid crystal display devices.

In the above-mentioned liquid crystal display device, in order to lower the minimum voltage required for the liquid crystal to start responding to an applied voltage, that is, the threshold voltage, the contrast must be sufficiently increased by 1 for visual viewing. In order to reduce the operating type 1 voltage required to indicate this, the dielectric anisotropy (Δε) of the liquid crystal material is required to have a large negative value. However, for example, when using a liquid crystal with negative dielectric anisotropy (known as MBr3A (methoxybenzylidene butylaniline), Δε is about -0.5, and for liquid crystals made of benzoic acid phenyl esters, Δε is at most -0, Therefore, it has been desired to develop a liquid crystal material in which Δε has an even larger negative value.

A substance having one diano group on the side of the molecule has been proposed as one of the substances that can meet such demands, but the present inventors have proposed a compound with the fourth largest Δε suitable for this purpose. It has two CN groups on the same side. Invented a liquid crystal compound and applied for a patent. Immediately! -) In Japanese Patent Application No. 11591/1982, the following formula (n) (in the above formula, R1 and 2 are hydrogen or carbon numbers 1 to 1)
We propose a compound represented by a 1° alkyl group or an alkyloxy group)! -1 A compound having a lower liquid crystal temperature range is a compound of the linear formula (nt) (where 1 is an alkyl group having 3 to 5 carbon atoms, and 2 is an alkyl group with 1 carbon number).
to 10 alkyl groups) are disclosed in Japanese Patent Application No. 140710/1982 and Japanese Patent Application No. 1455/1983.
08 and Japanese Patent Application No. 54-9917, and furthermore, as a compound that can supplement the performance of those compounds (■ (1 is an alkyl group having 1 to 1 o carbon atoms, 几! is an alkyl group having 2 to 7 carbon atoms) (indicating a group) was filed as Japanese Patent Application No. 54-34545, and further (IV
), in which R1 is a branched alkyl group having 3 to 1 o carbon atoms, has been filed as Japanese Patent Application No. 141375/1983.

The present inventors have conducted further studies in order to further expand the limit value that can be reached in conjunction with the above-mentioned objective of providing a liquid crystal composition having a large negative dielectric anisotropy. The present invention was achieved by discovering that the compound of formula 1) is a suitable substance.

That is, the present invention relates to the general formula (however, in the above formula, 1 represents a straight chain or branched alkyl group having 1 to 10 carbon atoms, and 1-1R.2 represents a straight chain alkyl group having 1 to 10 carbon atoms) Alkyloxy-6-hydroxy-7
talonite 11 l tora〉/su 4-(trans-earkyl shift[]hegysyl) cyclohegysancano ", bonic acid nisputs and the l'!! system.

Practical liquid crystal compositions are required to maintain a liquid crystal state over as wide a temperature range as possible, but so far there are only seven compositions with a liquid crystal temperature range that can be used practically using a single substance, and at least a few. At present, it is possible to obtain liquid crystal compositions that can be used over a wide temperature range in practical use by mixing different substances. At least several types of compound pots with different liquid crystal temperature ranges are required. The compound of the present invention has a negative dielectric anisotropy, a large absolute value, and a characteristic temperature range different from those conventionally known. To explain in more detail the properties of the compound l of formula (1) of the present invention, it generally has a somewhat lower melting point than the compound (It), and a low melting point means that it is at the lower end of the usable temperature range of liquid crystals. It is preferable as a material for liquid crystal compositions because it spreads out), and has the same degree of transparency. Furthermore, compound (+) has the advantage of being able to provide compositions with lower viscosity than compound (n). Compound (1) also has a feature of having a much higher clearing point than the above-mentioned compound (m). Moreover, compound (1) has a chemical structure similar to the above-mentioned compound (IV). However, (1) has a lower melting point than (V),
It has a fairly high clearing point. Based on these properties, the compound (1) of the present invention is a compound (II), ([[), (M),
By using these materials in combination, it is possible to prepare a liquid crystal composition having a wider liquid crystal temperature range that exceeds the limits that can be reached using these known substances.

The compound (+) of the present invention has a large negative dielectric anisotropy reaching about -15 to -22, and is a colorless substance that does not absorb light with a wavelength of 350 m or more. It is exactly the same as the compounds (II), (III), and (■), and has excellent properties comparable to the compounds (■), (III), and (■).

Table 1 shows the phase transition temperatures of some of the compounds 0) of the present invention (mainly those in which R1 is a straight-chain alkyl group).

1. In the above table, C indicates solid phase, S indicates smectic phase, N indicates nematic phase, ■ indicates transparent phase, and black circles in each character column indicate that the compound in the left column indicates its liquid crystal phase. , the number between the black circles indicates the transition temperature between the phases indicated by both black circles.

As is clear from Table 1, some of these materials exhibit a nematic phase, others a smectic phase and a nematic phase, and some only a smectic phase. When these compounds are used as components of nematic liquid crystal compositions whose dielectric anisotropy has a large negative value, they are added to the nematic liquid crystal that is the main material, so these compounds (T) themselves have a smectic phase. Even if it is indicated, it will not cause any trouble.

A second object of the present invention is to provide a chiral substance which is extremely suitable for preparing a cholesteric liquid crystal composition by adding it to a nematic liquid crystal material having a large negative dielectric anisotropy.

Cholesteric liquid crystal compositions with negative dielectric anisotropy are used in liquid crystal displays based on the principle of nematic-cholesteric phase transition. One of them is the so-called reverse white
-Positive color display based on the Taylor type guest-host effect is known. In this case, in order to reduce the driving voltage as low as possible, it is desirable that the dielectric anisotropy be as large a negative value as possible, and therefore the chiral substance added also has a large polarity in the short axis direction of the molecule. Of course, it is desirable that the

However, conventionally, the chiral substances used are 4-
(2-Methyl-butyloxy)-4'-sitenobiphenyl (following A>, 4 (2) f+, -butyl>
-4'-cyanopephenyl (above B), 4-(2--
It had large polarity in the direction of the long axis of the molecule, like methyl-butyloxy)benzoic acid p-thia/'fer ester (C below).

These were originally developed for twisted nematic displays (TND) that use nematic liquid crystals with positive dielectric anisotropy, and when added to liquid crystal materials with negative dielectric anisotropy,
This has the opposite effect of canceling out negative values.

On the other hand, in formula (1) of the present invention, R1 has 4 to 4 carbon atoms.
The group of compounds that are optically active AJ-kyl groups in No. 10 have strong polarity in the short axis direction of the molecules, and therefore are excellent as force/fral additives for nematic liquid crystal materials having negative dielectric anisotropy. The chiral substance of the present invention has optically active 5-(
trans-4-()trans-4'-(2-cyanobutyloxy)-6-hydroxy-phthalonitrile, i.e., R in the (+) formula is optically active. Table 2 does not show the phase transition temperature of the 2-methylbutyl group (ie, those of the following formula (Ia)).

In the upper table of the 2nd table, -L Ch indicates cholesteric phase;
□Others are the same as Table 1.

As shown by the numbers in Table 2, the compound of formula (Ia) of the present invention has a clearing point close to 200°C, and when added to a nematic liquid crystal composition as a chiral additive, the clearing point, that is, the cholesteric The upper limit temperature of the phase of the compound (
Rather than lowering it like in A), (B), and (C), it helps to raise it. This is an excellent example of the compound of formula (Ia). Of course, the effectiveness of chiral additives is not determined by the value of ε or the breadth of the liquid crystal temperature range, but rather by the ability to induce cholesteric structure, i.e., the amount of chiral additive added. It is also important that a short cholesteric pitch is induced.

In this capacity, the compounds of Table 2 are similar to the above-mentioned compound (A).
, (C), but inferior to compound (13).

In addition to the above, the compound of formula (+) of the present invention can be used for the following uses by utilizing the fact that it exhibits a smectic phase over a wide temperature range as shown in Tables 1 and 2. can also be used. The industrial use of the smectic state has traditionally been delayed compared to the nematic state, but basic research into its use has been carried out since the 2000s. The compound of formula (1) of the present invention has particularly large polarization in the short axis direction of the molecule among substances exhibiting a smectic phase, and therefore has extremely large negative dielectric anisotropy. When considering the use of such smectic liquid crystals in, for example, liquid crystal display devices, molecules are oriented perpendicularly or nearly perpendicularly to the glass substrate, so that the smectic layer is aligned with the glass substrate at 1″t-′
- By using laser light or resistors arranged in a matrix as a heat source, the smectic phase is changed to a nematic phase, and a voltage is applied to align the direction of the liquid crystal molecules perpendicular to the direction of the electric field. , a guest-host type display in which a dichroic dye added to the liquid crystal emits 7r color in the same direction as the liquid crystal molecules, and a reverse Wb it C-1, "ayl e+ type display by adding a chiral substance. It is preferable that the dielectric anisotropy has a large negative value when producing a so-called thermal writing positive type liquid crystal display device in which the liquid crystal is cooled down to the tt smectic phase in which the molecular orientation is kept as it is. It is a nature. In particular, the compound of formula (Ia) in Table 2 exhibits a smectic phase having chirality,
It is noteworthy that the dielectric anisotropy has a large negative value.

Recently, attention has been drawn to the fact that certain chiral smectic phases, ie, chiral smectic C phase and chiral smectic H phase, have ferroelectric properties 1 and can be used in extremely high-speed electro-optic switching devices. In this case, it is known that a material with negative dielectric anisotropy is suitable as the liquid crystal material. Therefore, among the compounds of the present invention, the substances shown in Table 2 □ are considered to be suitable for this use.

Compound 0) of the present invention is preferably prepared by the method described below. That is, 3-alkyloxy-6-hydroxy-phthalonitrile (the alkyl group is R of the general formula (+)
1) in a basic solvent such as pyridine, and in this solution 2, trans-4-(+.trans-e-alkylcyclohexyl)cyclohexanecarboxylic acids (the alkyl group is It of general formula (1), )
Compound (1) is produced by adding and reacting a solution of an acid halogenide prepared by a conventional method with a halogenating agent such as thionyl chloride and a suitable inert solvent (e.g. toluene). Ru. Here trans-4
-(trans-e-alkylcyclohexyl)cyclohexanecarboxylic acids are known substances, and 3-alkyloxy-6-hydroxyphthalonitrile is a 2.6-
It is produced by alkylating dicyazunohydroquinone with a furkylating agent such as p-toluenesulfonic acid alkyl ester. The melting points of some of the compounds are shown in Table 3.

The compounds of the present invention will be explained in more detail with reference to Table 3 and Examples below.

Example 1 [3-Butyloxy-6-hyroxyphthalonitrile tolan,su-4-(trans-ypentylcyclohexyl)cyclohexanecarboxylic acid ester (0) In the formula, R+ "" C4Il-, 几2-C
HH11) Preparation 1 trans-4-()trans-4'-pentylcyclohexyl)cyclohegysancarboxylic acid 5.62 to thionyl chloride 30+++/! was added and heated under reflux on a water bath for 1.5 hours, and then excess dimenyl chloride was distilled off under reduced pressure to obtain a solid of trans-4-(trans-47-be/tylcyclohexyl)cyclohexanecarboxylic acid chloride. .

This product was dissolved in anhydrous toluene and used in the next IZ step without being purified. On the other hand, 3-butyl-6-hydroxyphthalonitrile was prepared by a known method (Japanese Patent Application Laid-Open No. 55-721
56), and 4.49 to 70
Me was dissolved in anhydrous pyridine, and while this was being stirred while cooling with water, the above toluene solution of the acid chloride was added dropwise to cause a reaction. After the dropwise addition, the mixture was heated to 80°C for 2 hours, and then added with ice and 6N hydrochloric acid to make it acidic. 41 layers were taken, and this was washed successively with water, an aqueous sodium hydroxide solution, and water. Toluene was distilled off under reduced pressure,・The obtained residue is recrystallized from ethyl acetate to obtain the target product, ro-butyloxy-6-hydroxyph-2ronitrilenottrans-4-()trans-
4'-pentylcyclohexyl)cyclohexanecarboxylic acid ester was obtained as colorless crystals. The yield was 6.22°, and the physical properties were as shown in Table 1 above. The other compounds shown in Table 1 were also produced by the same method.

lt Example 2 [trans-4-(trans-4'-propylcyclohexyl)cyclohexanecarboxylic acid ester of ro-(2-methylbutyloxy)-6-hydroxyphthalonitrile (in formula (1), the R word is optical) active 2
-Methyl-butyl group, g, = c,) (Production example of 7) p-) Luenesulfonic acid chloride and commercially available (c) 2-
(-)2-Butyl-p-toluenesulfonic acid ester 114F, 2,3-dicyano-p-no. synthesized from methyl-1-butanol by a known method.
Hydroquinone 75F, caustic soda 18.8F, water 440
- and stirred under reflux for 15 hours, and after cooling, 10
Add 400% caustic soda aqueous solution and stir for 10 minutes.
Insoluble matter is removed by suction and filtration [7. When the liquid is made acidic with hydrochloric acid, solids are separated. This solid contains 3-(2-methylbutyloxy)-6-hydroxyphthalonitrile and the raw material 2,5-dicyano-p-no-hydroquinone. When this solid is heated with 1 t of toluene and filtered hot, crystals are precipitated from the r liquid. By recrystallizing this from methanol, 3-(2-
methylbutyloxy)-6-hydroxyphthalonitrile (m, p, 164-165°C) was obtained.

On the other hand, trans-4-(trans-4'-propylcyclohexyl)cyclohexanecarboxylic acid 5. Add 50 me of thionyl chloride to the mixture, heat under reflux on a water bath for 1.5 hours, and remove excess thionyl chloride by distilling off under reduced pressure to obtain trans-4-(4'-propylcyclohexyl)cyclohexane. Obtain a solid carboxylic acid chloride.

This product was dissolved in anhydrous toluene and used in the next step without purification. That is, 70 m of 4.7 f of 3-(2-methyl-butyl)oxy-6-hydroxy-phthalonitrile obtained first! was dissolved in anhydrous pyridine and stirred while cooling with water, and a toluene solution of the above acid chloride was added dropwise to give 8.
After heating at 0° C. for 2 hours, the mixture was made acidic by adding ice and 6N hydrochloric acid, and the organic layer was separated and washed successively with water, an aqueous sodium hydroxide solution, and water. Toluene was distilled off under reduced pressure, and the resulting residue was recrystallized from ethyl acetate/L to obtain the target product, 3-(2-methylbutyloxy)-6-
5.52 purified colorless crystals of trans-4-(trans-4'-propylcyclohexyl)cyclohexanecarboxylic acid ester of hydroxy-phthalonitrile were obtained.

This product exhibited phase transitions as shown in Table 2 above. That is, it becomes a smectic liquid crystal at a melting point of 96°C, this smectic phase changes to a cholesteric phase at 176°C, and when the temperature is further increased to 181°C, it becomes an isotropic liquid.

In addition, a commercially available liquid crystal composition LIXO having a dielectric anisotropy of -5
This substance was added to N BN-34 (manufactured by Chisso ■) at 10% Owt.
The cholesteric pitch induced by the addition of 1.5% was measured and found to be 185 μm. By extrapolating the inherent cholesteric pitch of this material, a value of 19 μm is obtained.

Example 5 (Use Example 1) Trans-4-furoylcyclohexanecarboxylic acid p-
Methoxyphenyl ester 10 parts (weight, same below) trans-4-propylcyclohexanecarboxylic acid p-
Ethoxyphenyl ester 10 parts trans-4-butylcyclohexanecarboxylic acid p-methoxyphenyl ester 20 parts trans-4-butylcyclohexanecarboxylic acid p-ethoxyphenyl ester 20 parts trans-4-pentylcyclohexanecarboxylic acid p-methoxyphenyl ester 20 parts trans A liquid crystal composition (hereinafter abbreviated as liquid crystal introduction product) consisting of 20 parts of -4-pentylcyclohexanecarboxylic acid p-pentylphenyl ester has a clearing point (N-I point) of 63°C, and its dielectric anisotropy ( Δε) is −10. In 85 parts of this liquid crystal composition A, among the compounds represented by the formula (+) of the present invention, R7 is C,
H,, and R+ is husband h C71l1. CJ (and C4
A liquid crystal composition (hereinafter abbreviated as liquid crystal composition B) obtained by adding 5 parts of each compound of
℃, and Δε was -31.

A commercially available dichroic dye 1)-1 is added to this liquid crystal composition B.
6 (manufactured by LIDH) was injected into a liquid crystal display cell with a cell gap of 10 μm that had undergone vertical alignment treatment, and its electro-optical properties were measured. []V.

In the case of a composition in which the compound of the present invention is not added, that is, liquid crystal composition A, the threshold voltage is 6.2
Met. As described above, by adding the compound of formula (+) of the present invention, 1) the N-1 point can be improved, the absolute value of Δε can be increased, and the threshold voltage of electro-optic properties can be lowered. can be found to be very useful.

Example 4 (Use Example 2) Of the compounds represented by the formula (+) of the present invention in the liquid crystal composition A85 of Example 3, It is C, R7 is C, and 1 is C.
, iIq and C, H, , a liquid crystal composition obtained by adding 15 parts each of the compounds Cil: N-1 point 768
℃, and Δε was −3.6. When 2% by weight of dichroic dye D-16 was added in the same manner as in Example 6 and the electro-optical properties were measured, the threshold voltage was 1.8V. .

Example 5 (Use Example 6) 895 parts of the liquid crystal composition of Example 6 was added with a compound represented by the formula (+) of the present invention in which R is an optically active 2-methylbutyl group and R2 is C, H, 5 parts of the compound and -71 chromatic dye were added, and the same f:c cell gap as in Example 6 was obtained.
] μm liquid crystal display cell to produce an inverse White-Taylor type display element, and by applying 'ilf and river between the electrodes, a positive type color display element could be obtained. - The threshold voltage of its electro-optical effect was 1.7v.

that's all Patent applicant: Chisso Corporation

Claims (4)

[Claims] (1) 6 represented by the general formula (in the above formula, 1 represents a straight chain or branched alkyl group having 1 to 10 carbon atoms, and R2 represents a straight chain alkyl group having 1 to 10 carbon atoms) - trans-4()trans-4'-alkylcyclohexyl)cyclohexanecarboxylic acid esters of alkyloxy-6-hydroxyphthalonitrile. (2) The carboxylic acid esters according to claim 1, wherein in the formula (+), R+ is an optically active alkyl group having 4 to 10 carbon atoms. (3) Direct φβ of 2.3-dicyano-p-hydroquinone
or trans-t-(
trans-4'-alkylcyclohexyl)cyclo-\
A general formula characterized by reacting a xanate carboxylic acid halide in a basic solvent (however) 2, in the above formula, -C represents a straight chain or branched argyl group having 1 to 10 carbon atoms, It represents a straight-chain alkyl group having 1 to 10 carbon atoms) trans-4-(trans-4'-alkylcyclohexyl)cyclohexanecarboxylic acid ester of 6-alkyloxy-6-hydroxyphthalonitrile represented by Te manufacturing method of types. (4) General formula (11, in the above formula, 1 represents a straight or branched alkyl group having 1 to 1 carbon atoms, 2 represents a straight chain alkyl group having 1 to 10 carbon atoms) ) trans-4- of 6-alkyloxy-6-hydroquinphthalonitrile
(trans-4'-alkylcyclohexyl)cyclohegizancarboxylic acid ester! 1jlBl! or more”
- A Nemagtsuku liquid crystal composition characterized by containing ξ.