JPS58203943A - Novel nematic liquid crystal compound - Google Patents

Abstract

NEW MATERIAL:A 4-[trans( equatorial - equatorial )-4-alkylcyclohexylmethoxy ]phenyl 4'-alkylbenzoate of formula I [R and R' are 1-9C straight chain alkyl; the configuration of the cyclohexane ring is trans(equatorial-equatorial) configuration]. USE:Useful as electrooptical display materials, capable of suppressing the viscosity increase in a narrow limit in preparing practically usable mixed liquid crystals having >=65 deg.C (N-I) point, and usable as a material for dynamic light scattering type display cells by mixing with another nematic liquid crystal compound or as electric field effect type display cells by mixing with a nematic liquid crystal compound having the strong positive dielectric anisotropy. PROCESS:A compound of formula II is reacted with hydroquinone to give a compound of formula III, which is then reacted with a compound of formula IV to afford the aimed compound of formula I .

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to novel nematic liquid crystal compounds of benzoic acid derivatives which are also useful as electro-optical display materials. The novel nematic liquid crystal compound provided by the present invention is 4-1 trans(equatorial-equatorial)-4-alkylcyclohexylmethoxy)phenyl 4'-'furkyl benzoate represented by the general formula.

M-shut (M-8) is a typical liquid crystal display cell.
chadt )%(APPLIED PHYSIC8L
ETTER818, 127-128 (1971))
Field effect mode cell proposed by G. Eiteken Beilmeier (G@K Hsi1m@1er)% [PROCEW
DING OF THE I, EJ, E, 56 116
2-1171 (1968)) or the dynamic scattering mode cell proposed by G.H.
lmeier) etc. [APPLIED PHYSIC8
LETTER 813, 91 (1968)] or D. L. Whit.) etc. [J
OURNAL OF APPLIED PHYSIC8
45, 4718 (1974)).

The liquid crystal materials used in these liquid crystal display cells are required to have various characteristics.

Having a nematic phase over a wide temperature range including room temperature is an important characteristic commonly required for various display cells.

Many of the practical materials with such properties are usually .

It is prepared by mixing several or more components consisting of a compound having a nematic phase near room temperature and a compound having a nematic phase in a temperature range above room temperature.

Most of the above-mentioned mixed liquid crystals currently in practical use are
It is required that the compound has a nematic phase over the entire temperature range of -60°C to +65°C1. -(-14,4'-substituted terphenyl, 4,4'-substituted biphenylcyclohexane, 4,4'
-Crystalline phase at about 100°C, such as substituted benzoyloxybenzoic acid phenyl esters -Nematic phase transition temperature (C-
Compounds having a nematic phase-isotropic liquid phase transition temperature (N-I point) of about 200° C. are often used. However, when these compounds are mixed in an amount sufficient to bring the N-4 point of the mixed liquid crystal to a temperature of 65°C or higher, they increase the viscosity of the resulting mixed liquid crystal, thereby decreasing the response speed. lower
) (7) It has 1 undesirable property.

The compound of formula ([) according to the present invention is a novel compound with improved properties. That is, the compound of the formula ([) can be mixed with one or more other nematic liquid crystal compounds to prepare a practically usable mixed liquid crystal having an N-I point of 65°C or higher. Compared to liquid crystal compounds, the increase in viscosity of mixed liquid crystals can be suppressed to a much smaller extent. Historically, the compound of formula (1) was developed by the applicant in Japanese Patent Application Laid-Open No.
Publication No. 83694 describes it as a nematic liquid crystal material with excellent time-division driving characteristics.Since it has extremely good compatibility with phenyl 4,4'4-substituted cyclohexylcarboxylic acid, it cannot be mixed with these compounds. Therefore, even better mixed liquid crystals can be produced.

The compound of formula ([) according to the present invention can be prepared according to the following manufacturing method 1
can be manufactured.

First step: A compound of formula (■) is reacted with hydroquinone in ethanol in the presence of an alkali such as potassium hydroxide or sodium hydroxide to produce a compound of formula ([II).

2nd step The compound of formula (m) produced in the 1st step is catalyzed with a basic compound such as pyridine in an inert organic solvent such as ether, benzene, or toluene to form a compound of formula (IV).
The compound of formula (f) according to the present invention is produced by reacting the compound of formula ([)].The transition temperature of the compound of formula ([) thus produced is listed in 1 &.

1st table Rot RR' Transition temperature (℃) i n-C5Hy n -C1lH798(C-+
N) 159(N,!I)2 n-C411,-n
-C,H,-80(C-+N) 151(N,!I
)3 m (4H, 1-n-C3H, -74(C→N
) 153(N;I) In the table, C1 represents a crystalline phase, N represents a nematic phase, and ■ represents an isotropic liquid.

The compound of the formula ([) according to the present invention is a nematic liquid crystal compound having a weak negative dielectric constant anisotropy, and therefore, for example, other nematic liquid crystals having a negative or weak positive dielectric constant anisotropy. It can be used as a dynamic likelihood display cell material in the state of mixture with compounds, and also has strong positive attraction.
It can be used as a material for field-effect &yN cells in a mixture with other nematic liquid crystal compounds having WIL rate anisotropy.

Preferred typical examples of use in combination with the compound of formula 1 ([) include 4,4'-substituted benzoic acid phenyl ester, 4,4'-substituted cyclohexanecarboxylic acid phenyl ester, etc. , 4 , 4'-
M-converted cyclohe-+sancarvone version biphenyl ester,
4(4-[Substituted cyclohexanecarbonyloxy)benzoic acid 4'-substituted phenyl ester 4(4-substituted cyclohexyl)benzoic acid 4'-substituted phenyl ester, 4(4-
(substituted cyclohexyl)benzoic acid 4'-substituted cyclohexyl ester, 4,4'-biphenyl, 4,4'-phenylcyclohexane, 4,4'-ftm terphenyl,
4,4'-biphenylcyclohexane, 2 (4'
-6 phenyl) 5-substituted pyrimidine, and the like.

Table 2 shows 80*t% of the base liquid crystal (A), which is currently widely used as a nematic liquid crystal material with excellent time-division driving characteristics, and 41.42% of the compound of formula ([) shown in Table 1. The N-I point and viscosity measured for each mixed liquid crystal consisting of ~2011% of A3 are posted, and for comparison, the base liquid crystal (
The N4 point and viscosity measured for Al itself are displayed. In addition, the parent liquid crystal (A) consists of and.

Table 2 Point N-I Viscosity (A) 42.5 21.2(A)+
(41) 65.6 28.1(A) -to(, &12) 64,1
28.5(k)+(Als>64,5
28.6 From the data listed in Table 2, it can be seen that the compound of formula (I) can raise the N-I point of the mixed liquid crystal to a practically sufficient level without significantly increasing the viscosity of the mixed liquid crystal. I can understand it. Approximately 28cm boise/2
The viscosity value at 0℃ is 65℃, which is the current average practical level.
This value is considerably lower than the viscosity value of the 6-layer mixed liquid crystal having the above N-I points. The fact that a mixed liquid crystal with such a low viscosity can be obtained gives the compound of the formula ([) a high practical value.

The effects of the present invention are also clarified by the following comparative experiments. A known compound of the formula whose chemical structure is similar to the compound of formula (1) according to the present invention and which is widely used for the purpose of increasing the N-I point of the mixed liquid crystal is used as the base liquid crystal (A)K. Mixed at a constant rate.

Similarly, one of the compounds according to the invention, ie, a compound of the formula, was mixed in various proportions into the parent liquid crystal matrix. 2 obtained by
For each type of mixed liquid crystal, the N-I point and the dead rate were measured. Based on these measurement results, attached Figure 1 shows the relationship between the N-I point and the amount added, Figure 2 shows the relationship between the viscosity and addition, and Figure 3 shows the relationship between the N-I point and the viscosity. The relationship was broken.

From these facts, it can be understood that the compound of formula ([) according to the present invention exhibits a much smaller increase in mulch as the N-I point increases compared to typical known similar compounds. .

Example 1 Ethanol 300CCK85% potassium hydroxide 198I
(u5UOmoj) Hydroquinone 16.511 (0,
150 mol) was added and trans-4-n was added under reflux.
-219 g of propylcyclohexylmethyl bromide (
0,100mo#) gradually increased to 7. After the completion of the reaction, the mixture was refluxed for 2 hours to distill off the ethanol.

The reaction product was extracted with benzene, the extract was washed with water and dried, and then pensene was distilled off from this solution. The obtained reaction product was recrystallized from ethanol and then from methanol to obtain the following compound 11.9# (0,0480 moj
) was obtained.

Ltd Compound 1 t91! (0,0480 moj of toluene was added to 100,100 ccv, and pyridine 5.
Add 69jl (0,0720 mol) and stir at room temperature.
(10480rnol) was added dropwise. After completion of the dropwise addition, the mixture was refluxed for 2 hours, and after completion of the reaction, the reaction product was extracted with toluene.

After washing the extract with water and drying, toluene was distilled off from this liquid.
, the obtained reaction product was recrystallized from methanol-ethanol to obtain the following compound 15.6. ! i'(α0396m
o/) 1, yield 696% transition temperature 9
8°C (C→N) 159°C (N:I) Example 2 The following compound was obtained in the same manner as in Example 1.

Yield: 6B, 2% Transition temperature: 80°C (C-+N
) 151°C (N; t) Example 3 The following compound was obtained in the same manner as in Example 1.

Yield: 4 [11% Transition temperature: 74°C (C→N)
155℃ (N=■)

[Brief explanation of drawings]

Figures 1, 2 and 6 show one compound of the present invention (AI).
and each mixture obtained by adding the known compound (a) to the parent liquid crystals (A) and K, respectively! In. The graphs show the relationships between the amount added and the N-I point, the amount added and viscosity, and the N-1 point and viscosity. Dou 1 Part V Determination /, ri (E sea ink 4 cracks raised + 1 split into 1 Fig. 10 20 (A) + C No. 1) C No. 1) Su 1j (A)
+ (α> lsj 10 ruru (mu) 9m early%'v7z included jo 20

Claims (1)

[Claims] general formula A compound represented by