JPH0523254B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a halogeno aromatic compound, which is a novel liquid crystal compound, and a liquid crystal composition containing the compound. [Prior art] Display elements using liquid crystals utilize the optical anisotropy and dielectric anisotropy of liquid crystal materials. Liquid crystal phases include nematic, smectic, and cholesteric phases, of which nematic liquid crystal is The one used is currently the most widely put into practical use.
These include TN type (twisted nematic type), DS type (dynamic scattering type), guest-host type, and DAP type, and the properties required of the liquid crystal dielectric used for each type are different. However, in any case, it is desirable that the liquid crystal dielectric used in these display elements exhibit a liquid crystal phase over as wide a temperature range as possible, and it is also required to be stable against moisture, light, heat, air, etc. Ru. However, at present, there is no single compound that satisfies all of these conditions, and liquid crystal compositions obtained by mixing several types of liquid crystal compounds or liquid crystal-like compounds are currently in practical use. Many compounds have been developed in the past to meet such demands, and compounds with alkoxymethyl groups are also disclosed, for example, in JP-A No. 58-59956;
These compounds are known from JP-A-59-175453, JP-A-59-128354, JP-A-58-134046, JP-A-58-219137, etc., but these compounds have a narrow liquid crystal temperature range. However, it had the disadvantage of high viscosity. Also, general formula Compounds represented by (in the formula R is a straight-chain alkyl group having 1 to 8 carbon atoms) are also known (Japanese Unexamined Patent Application Publication No. 1983-1999).
No. 180465), this product lacks stability, particularly light stability, and has the problem of liberating iodine and yellowing when exposed to ultraviolet light, for example. Therefore, this compound is merely an intermediate for obtaining a nitrile derivative in the next step, and cannot be called a liquid crystal compound. [Object of the Invention] The object of the present invention is primarily to provide a novel liquid crystal compound suitable for use as a component of a liquid crystal composition for a TN display element. [Structure of the invention] That is, the present invention is based on the general formula (In the formula (), R represents an alkyl group having 1 to 5 carbon atoms, and c and d each independently represent H, F or CI, and at least one of them is F or CI). The present invention provides a halogen aromatic liquid crystal compound represented by the above formula and a liquid crystal composition containing at least one type of the compound. Among the compounds of the present invention, compounds in which c in formula () is F or both c and d are F are preferred because of their low viscosity. In addition, R in formula (), that is, an alkyl group, is preferably a straight chain, but compounds where R is a branched chain are also compatible with other liquid crystal compounds or liquid crystal compositions that are already widely used. Because it's better
Useful in some cases. [Operations and effects of the invention] The compound of the present invention is a high-temperature liquid crystal with a high clearing point and a wide liquid crystal temperature range, and has excellent compatibility with other liquid crystal compounds, making it suitable for use as a component of liquid crystal compositions. It has the effect of increasing its clearing point. Furthermore, since it has a relatively low viscosity, the increase in viscosity of the obtained liquid crystal material can be suppressed slightly. A liquid crystal composition useful for display devices can be obtained by mixing at least one compound of the formula () of the present invention with one or more of the following known liquid crystal compounds. (X in the above formula is

【formula】,

【formula】,

【Formula】Also teeth

[Production method of compound]

The compound of formula () can be produced by the following steps. ( ^R2 is an alkyl group, preferably a tertiary butyl group) That is, first, an acid chloride and an alkyl hydroperoxide are reacted to form an ester of formula (), and then this ester of formula () is reacted with a halogen group of formula (). By reacting benzene ()
A compound of formula is obtained. This reaction is generally carried out in the presence of an inert solvent, such as benzene, from about 0 to about 150°C, preferably from 60 to 110°C.
It is preferable to carry out the reaction at a temperature of . In addition, in the reaction of producing perester from acid chloride, it is desirable to add a base such as pyridine or triethylamine to neutralize the produced hydrogen chloride. formula

〔Example〕

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples. Example 1 [trans-4-methyloxymethyl-1-
Production of (4″-fluorobiphenyl-4′)cyclohexane (when R is CH ₃ , c is F, and d is H in the formula ())] trans-4-methyloxymethyl-1-
(4'-iodophenyl)cyclohexane 5g
(0.015 mol) 0.1 g (0.15 mol) of bis-triphenylphosphine nickel () chloride is dissolved in 20 ml of dry diethyl ether, and the surroundings of the flask are cooled with ice water and kept below 5°C. To this, an ether solution of Grignard reagent prepared from 2.9 g (16.7 mmol) of fluorobromobenzene and 0.4 g (16.7 mmol) of magnesium was added at a reaction temperature of 10 mm.
Drop at a rate that does not exceed ℃. After the dripping is finished,
After stirring at 20 to 25°C for 1 hour, the mixture was heated under reflux for 4 hours. After the reaction is complete, add 100% water to the reaction solution.
ml. The precipitated oil was extracted with 20 ml of toluene, and the extracted toluene layer was dried over anhydrous sodium sulfate. This toluene solution was treated with chromatography (silica gel), toluene was distilled off from the obtained toluene solution, and the obtained crude crystals were recrystallized from ethyl acetate to obtain the desired product, trans-4-methyloxy. Methyl-1-(4″-fluorobiphenyl-4′)cyclohexane 2.1g
(45.2%). This substance shows a liquid crystal phase and C-N
Point (crystal phase - nematic phase transition point) 104.1℃, N
-I point (nematic phase - isotropic liquid phase transition point) 146.0
It was warm at ℃. Example 2 [trans-4-methyloxymethyl-1-
(3″,4″-difluorobiphenyl-4′)cyclohexane (in the formula (), R is CH ₃ , c and d
9 g of tert-butyl hydroperoxide and 7.9 g of pyridine were dissolved in trans-4-
Add to a solution of 2.7 g of methyloxymethylcyclohexylbenzoic acid chloride at 10°C. After stirring at 10℃ for 1 hour, the generated pyridine-
The hydrochloride salt was removed by suction. Add 11.4 g of orthodifluorobenzene to the liquid perester solution. After this, the reaction mixture was heated under reflux for 20 hours. After the reaction was completed, the reaction solution was washed with water and then dried over anhydrous sodium sulfate. Benzene was distilled off from the dry solution, and the remaining crude crystals were purified by recrystallization from ethyl acetate to obtain the target product, trans-4-methyloxymethyl-1-(3″,4″-difluorobiphenyl-4 ') 16.5 g (yield 52%) of cyclohexane was obtained. This material was a monotropic liquid crystal, and its phase transition point was 98.3°C at the C-I point and 86.7°C at the N-I point. Examples 3 to 5 The following compounds were obtained by a method similar to Examples 1 and 2. trans-4-methyloxymethyl-1-
(4″-Chlorobiphenyl-4′)cyclohexane; C-N point 141.3°C, N-I point 177.0°C. trans-4-methyloxymethyl-1-(3″-fluorobiphenyl-4 ') Cyclohexane; C-I point
76.5℃. trans-4-ethyloxymethyl-1-
(4″-Fluorobiphenyl-4′)cyclohexane; C-N point 80.2°C, N-I point 122.8°C. Example 6 Trans-4-propyl-(4-cyanophenyl)cyclohexane 30% (by weight, (same below) trans-4-pentyl-(4-cyanophenyl)
The N-I point of a liquid crystal composition consisting of 40% cyclohexane (by weight, the same hereinafter) and 30% trans-4-heptyl-(4-cyanophenyl)cyclohexane is 52°C, and the dielectric constant anisotropy Δ〓 is 11.2 at 20°C. The viscosity was 23.4 cp. Trans-4 produced in Example 1, which is a compound of the present invention, was added to 85% by weight of this liquid crystal composition (A).
-Methyloxymethyl-1-(4''-fluorobiphenyl-4') The N-I point of the liquid crystal composition to which 15% by weight of cyclohexane was added rose to 62°C, and Δ〓 was 13.0.
It increased to In addition, the viscosity at 20°C was 25 cp, which was a slight increase. Example 7 Example 3 was added to 85% of the liquid crystal composition A in Example 6.
compound, trans-4-methyloxymethyl-
The N-I point of the liquid crystal composition obtained by adding 15% of 1-(4″-chlorobiphenylyl-4′)cyclohexane increased to 62.6°C, and the viscosity at 20°C was 25.7 cp. Example 8 Example 2 to 85% liquid crystal composition A in Example 6
compound, trans-4-methyloxymethyl-
The liquid crystal composition obtained by adding 15% of 1-(3'',4''-difluorobiphenyl-4')cyclohexane had an N-I point of 54 DEG C. and a viscosity of 25.6 cp at 20 DEG C. Example 9 Example 5 was added to 85% of the liquid crystal composition A in Example 6.
compound, trans-4-ethyloxymethyl-
N-I of the liquid crystal composition obtained by adding 15% of 1-(4″-fluorobiphenyl-4′)cyclohexane
The temperature was 55.1°C, and the viscosity at 20°C was 25.3 cp. Comparative example trans-4-methyloxymethyl-1-
(4″-fluorobiphenyl-4′) cyclohexane, trans-4-methyloxymethyl-1-(4″-iodo A liquid crystal composition was obtained in the same manner as in Example 6 except that -4'-biphenylyl)cyclohexane was added. The N-I point of this composition is 57.2°C, Δ〓 is 12.2°C,
The viscosity at 20°C was 28.2 cp, and it was found that the increase in viscosity was particularly remarkable compared to Examples 6 to 9.

Claims (1)

[Claims] 1. General formula (In the above formula, R represents an alkyl group having 1 to 5 carbon atoms, and c and d are independently H, F or
C1, but at least one of them is F or C1). 2 General formula (In the above formula, R represents an alkyl group having 1 to 5 carbon atoms, and c and d are independently H, F or
C1, at least one of which is F or C1)
A liquid crystal composition comprising: