JPH0225894B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to di-substituted ethane and its use in liquid crystal materials and devices. The use of liquid crystal materials to produce electro-optical effects in display devices such as digital calculators, clocks, meters and simple word displays is known. However, no liquid crystal material is known that is ideal in all respects, and considerable effort is typically expended in the industry to improve its properties. Liquid crystal materials generally consist of specially selected mixture compositions, and improvements in the materials are made by forming new mixtures with improved compound properties. The composition of the electro-optical liquid crystal mixture depends on the display effect to be utilized and the special properties required for that effect. Various display effects are illustrated below. For all types of display effects, it is desirable that the mixture exhibits the best possible combination of the following general properties. (i) The liquid crystal temperature range should be as wide as possible, including room temperature (20℃); (ii) The melting point (solid-liquid crystal transition temperature) should be as low as possible; (iii) The clearing point (liquid crystal - isotropic liquid (iv) positive or negative (appropriate) dielectric anisotropy (permittivity measured parallel to the molecular axis minus conductivity measured perpendicular to the molecular axis) to minimize the display voltage; (v) The viscosity is as low as possible to minimize display switching speed; (vi) The temperature change in the electro-optical response is as small as possible; (vii) Chemical and photochemical stability. (viii) Good multiplexibility; (ix) Induced anisotropy can be switched by frequency. and (x) having birefringence of a specific magnitude; A liquid crystal mixture composition having a desired combination of properties is obtained by mixing components having various properties. Meeting the various characteristics required for displays on automobile dashboards is
It is said to be particularly difficult. In the above case, the viscosity must be low for rapid switching at low temperatures of -20 to -30°C, and the clearing point must be high (>
90°C), and backside illumination through the off-state display section causes light to "bleed".
It is desirable to have a high birefringence to prevent "through". To minimize manufacturing costs, it is desirable to have a minimum amount of constituents in the mixture while still having a satisfactory combination of the desired properties. Therefore, it is desirable that the individual components used have more than one of the desired properties.
Furthermore, in order to minimize the number of components, it is desirable that the individual components have good mutual solubility. The object of the present invention is to provide new liquid crystal compounds which are suitable components for liquid crystal mixture compositions for displays to be used in electro-optical displays, in particular on automobile dashboards. The fluorinated compound of the present invention has the following formula: [wherein R ₁ is alkyl with up to 12 carbon atoms, R ₂ is hydrogen, alkyl with up to 12 carbon atoms,

【formula】

[Formula] and

selected from formula where R ₃ is alkyl having up to 12 carbon atoms;

[Formula] represents a cyclohexane ring in the trans configuration when it is 1,4-disubstituted,

[Formula] represents a benzene ring, and each of X, Y and Z individually represents hydrogen or fluorine at one or more side positions of the benzene ring, provided that one of X, Y or Z is fluorine; , R ₁ and R ₂ are n-
When alkyl, the total number of carbon atoms in the two groups R ₁ and R ₂ is less than 10]. When used in nematic liquid crystal mixtures, the alkyl group in the compound represented by the formula is preferably linear. However, when used in chiral nematic (optically active) mixtures, one or more alkyl groups contained in the molecule may be used, for example (+)-CH ₃ (CH ₂ ) _o CH ( CH ₃ )CH ₂ (wherein n is 1 to 8 and (+)- represents a chiral group having a positive optical rotation angle, such as (+)-2-methylbutyl); could be. Specific examples of compounds having the formula are shown below. In the formula, each R _A is independently an alkyl group, for example, an n-alkyl group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, and R _B is independently hydrogen or an alkyl group, preferably 1 to 12 carbon atoms. is n having 1 to 8 carbon atoms
- is an alkyl group. In the case of compounds of formulas a and b, the proviso conditions described for the general formula also apply. That is,
When R _A is an n-alkyl group and R _B is n-alkyl, the total number of carbon atoms contained in the two groups is 10
less than Preferably, the total number of carbon atoms included in R _A and R _B is 4-8. A compound having the same general formula as formulas a and b, the number of carbon atoms in the terminal n-alkyl group is 10, and the total number of carbon atoms and oxygen atoms in the terminal n-alkyl group or n-alkoxy group is 10. A certain compound is
UK patent application no. on which the priority of this application is based
European patent application number announced after filing No. 8302119
Proposed in No. 84194. However, the properties of these compounds are not described or suggested in the European patent application. As will be shown below, these compounds exhibit significantly poorer injected smectic behavior in mixtures with positive nematic compounds than the corresponding compounds of formulas a and b. Therefore, the compounds proposed in the European patent application are excluded from the scope of the present invention. Compounds having formulas a through j are examples of compounds of formula I that are useful as liquid crystal compounds; Compounds having the formula are intermediates in the synthesis of certain liquid crystal compounds having the formula, particularly compounds of formulas a and e, where X, Y and Z are H or F, and at least one is F. This is an example of a compound that is useful as a body. Compounds of the formula can be very interesting components in liquid crystal materials for electro-optic displays. For example, compounds of formulas a and b (wherein R _A and R _B are n-alkyl groups) have the following outstanding advantages as described in the Examples. (i) It has a low melting point, generally below 30°C, which is advantageous in formulating liquid crystal mixtures with a low melting point; (ii) It has a high clearing point, about 100°C, and a very wide nematic range, about 70° C., which is advantageous when formulating liquid crystal mixtures with a wide nematic range; (iii) virtually no undesirable smectic phases; (iv) smectic phases in combination with nematic materials with positive induced anisotropy. (v) High solubility in nematic materials with positive induced anisotropy; (vi) Addition to mixtures with positive nematic materials that already contain components with high clearing points. (vii) have a property of relatively low viscosity and reduce the viscosity of known nematic mixtures; (viii) form the basis of mixtures with low temperatures and fast switching times; (ix) High birefringence compared to other known materials with comparable thermal properties and viscosity; (x) Extremely low temperature dependence of threshold voltage; () Chemical and photochemical stability Good properties; Owing to the attractive combination of various properties mentioned above, liquid crystal mixtures can be formed which have superior properties compared to known mixtures. basis

[Formula] (wherein R _A and X have the same meanings as above) are known (UK Patent Publication No.
2023136 and 2093057). However, in general, the new compounds having the formulas a and b in particular unexpectedly have a better overall combination of desirable properties than the known compounds as mentioned above. For example, a compound having the formula A (wherein R' _B is an alkyl, alkoxy or cyano group), it has a higher clearing point compared to the known compounds, but the melting point and viscosity are not significantly increased relative to it. Similarly, a compound having the formula B or formula C Compared to known additives with high clearing points, the melting point and viscosity are lower and the solubility in positive nematic materials is better. Furthermore, compounds having formula B are generally more reactive than compounds having formula B and may be added to materials with negative dielectric anisotropy used in certain specific applications as described below. It can be used as such material. Compounds of formula B have a high positive dielectric anisotropy and are therefore generally unsuitable for this purpose. By far the most remarkable properties of the compounds having the formula derive from the influence of the pendant fluorine atoms, which suppress and eliminate undesirable smectic phases. This is clear from Tables 1 and 2, which compare the phase transitions of compounds with and without fluorine atoms at side positions.

【table】

[Table] In Tables 1 and 2, K, S, N, and I represent solid, smectic, nematic, and isotropic phases, respectively, and K-N, etc. represent dislocation temperature (°C). In the table, all alkyl chains are linear. SS represents the transition from smectic phase to other phases. As mentioned above, in compounds that do not contain fluorine atoms in side positions, the smectic phase generally and often occurs.
It persists above 100°C, whereas in the case of compounds having the formula the smectic phase is extremely rarely seen at room temperature (20°C). Thus, by preparing eutectic mixtures of new compounds, the nematic range can be extended to lower temperatures. Referred to herein as "Mixture E", R ₁ = n −C ₃ H ₇ R ₂ = n −C ₃ H ₇ 26% by weight R ₁ = n −C ₃ H ₇ R ₂ = n −C ₅ H ₁₁ 35% by weight R ₁ = n −C ₅ H ₁₁ A mixture consisting of 39% by weight of R ₂ = C ₂ H ₅ exhibits a nematic phase in the range of melting point of −13.5°C to clearing point of 103.5°C without forming a smectic phase, has a low freezing point, and has a low freezing temperature. This provides an advantageous basis for rapidly switchable liquid crystal mixtures. According to one preferred embodiment of the invention, therefore, the nematic or chiral liquid crystal material consists of a mixture containing compounds of two or more formulas. The nematic or chiral nematic temperature range of such mixtures is extremely wide. The mixture may contain congeners of the same type of compound, for example two or more compounds of formula a. Further, compounds having the same general formula but having different structural isomer relationships, for example in terms of the positions of fluorine in X and Y, may be combined. That is, one compound may be a compound in which X=F and Y=H (for example, in formulas a and b), and the other compound may be a compound having the same structure but with Y=F and X=H.
Although the isomers have similar properties, mixing them can very effectively lower the melting point. Due to the action of the lateral fluorine atoms, not only the smectic phase is unexpectedly suppressed, but also the formation of the smectic phase, known as the "injection smectic phase", can be suppressed. The majority of commercially available electro-optical liquid crystal displays are
It is a twisted nematic display that operates by the twisted nematic effect. The curve obtained by plotting the light intensity output from a twisted nematic display against the applied voltage forms in the so-called optical threshold region (corresponding to liquid crystal molecules undergoing a rapid change from homogeneous to homeotropic arrangement). It is desirable that the slope be as steep as possible. The slope of the lightoutput versus voltage curve depends on the liquid crystal material used in the display. The majority of twisted nematic displays currently on the market are multiplexed displays, meaning that the individually addressed elements of the display have one set of electrodes on one side of the display panel and another set of electrodes on the other side of the panel. (each electrode of each set is shared by all elements in a given row or column). Multiplexing increases the amount of information to be displayed on a limited display area and requires fewer electrode connections per number of display elements to be addressed. In order to produce liquid crystal materials with suitable multiplexibility for use in multiplexed twisted nematic displays, two nematic components, one component containing a terminal cyano group (hereinafter referred to as The other component is formed from one or more compounds having no terminal cyano group (hereinafter referred to as "non-cyano material"). It is generally recognized in the art that the most suitable method is to form a nematic mixture of seeds. The non-cyano material has a small dielectric anisotropy. Preferably, the non-cyano material comprises at least 30% by weight of the two-component mixture. The twisted nematic effect occurs only when the liquid crystal material is in the nematic phase; for example, the effect is not exhibited when the material is in the smectic phase. When a cyano material is mixed with a non-cyano material, the mixture exhibits an undesirable smectic phase known in the art as a "smectic" phase, which smectic phase appears as an area on a temperature versus composition graph or phase diagram. appear. However, if each material is pure, it exhibits only a nematic liquid crystal phase. Compositions containing 30% by weight or more of non-cyano materials are close to compositions that are considered preferred for electrochemical operation, but in this case they tend to reach a peak on the injection smectic phase diagram. According to common knowledge in the art, for a given mixture of cyano material and non-cyano material, the smaller the area on the phase diagram occupied by the injected smectic phase, the smaller and the lower the temperature at which the injected smectic phase begins to appear. The more useful it is as a mixture for use in multiplexed twisted nematic devices. In any event, the materials used in commercially available twisted nematic effect displays must exhibit a nematic phase even when cooled to about -10 DEG C. or below. In other words, mixtures of cyano and non-cyano materials to be used in twisted nematic displays must not exhibit a smectic phase at this temperature. Conventional wisdom in the art is that the slope of the light output versus voltage curve is generally lower for liquid crystal materials in twisted nematic displays, such as n-alkyl or n-alkoxy groups, than for congeners with shorter chain end groups. It is believed that the use of compositions containing components with terminal groups with long target chain lengths results in increased risk. However, it is also recognized in the art that compounds with relatively long chain end groups generally have a greater tendency to form smectic phases than congeners with relatively short chain end groups. There is. The cyano materials used in twisted nematic displays are cyano biphenyl compounds, e.g.
-n-alkyl-4'-cyanobiphenyl. Among other reasons, the above compounds are preferred because the slope of the light output versus voltage curve is relatively steep. However, these compounds exhibit a tendency to form injectable smectic phases in mixtures with non-cyano materials. Therefore, in order for a given non-cyano material to be frequently utilized in conventional electro-optic displays, it is particularly important that it is capable of forming mixtures with widely available commercially available cyano materials, especially materials containing cyanobiphenyl compounds. and the individual compounds should form the individual compounds of the cyano material with the least tendency to exhibit injective smectic phases. Preferred compounds of the formula have little tendency to form single-shot smectic phases and the compounds of the invention are therefore highly suitable as "non-cyano" components in mixtures suitable for use in multiplexed twisted nematic displays. It is a compound that
Moreover, the slope of the threshold value can also be improved by using long-chain cyano components. For example, a mixture of 90% by weight of mixture E, which is a ternary eutectic mixture of compounds of formula, and 10% by weight of 4-cyano-4′-ethylbiphenyl,
or 75% by weight of the ternary eutectic mixture and trans-4
-40°C in the case of a mixture with 25% by weight of -n-propyl-1-(4-cyanophenyl)-cyclohexane
However, it did not show any injective smectic phase. This property is extremely advantageous in formulating mixtures that meet the requirements of the automotive industry, which require rapid switching at low temperatures. To minimize the tendency to form smectic phases, especially injective smectic phases, R ₁ and
_R2 (especially when these groups are n-alkyl groups), especially the total number of carbon atoms in R _A and R _B in formulas _a and b is preferably less than 10, preferably the total number is 4 to 8. Preferably, the number of carbon atoms in each group is 5 or less. A mixture of compounds having the formula, e.g.
In the case of mixtures containing compounds of formulas a and b in which R _A and R _B are n-alkyl groups, the number of terminal carbon atoms in each compound is preferably 4 to 8. As in the case of mixture E described above, it is more preferable that the number of carbon atoms in each terminal group of each compound differs within this range. The compounds having the formula can also be used in fields other than electro-optical devices, where it is preferred to use nematic or chiral nematic liquid crystal compounds. For example, a compound having the formula
It may also be incorporated as a high clearing point component of temperature sensitive, e.g. thermochromic materials used in the fields described, for example, in GB 2083244 and GB 2085585. Compounds of formula may be prepared by synthetic routes including procedures known per se. This route is entirely new. For example, the following routes 1 and 2 can be used. Here, R ₁ and R ₂ are the same or different alkyl groups,

[Formula] is 4,4'-biphenylyl substituted with fluoro at the side position. The starting materials for routes 5, 6, 7 and 8 may be prepared as described in co-pending UK Patent Application No. 8319849. The compound of the formula has a relatively small dielectric anisotropy, and in particular a liquid crystal substance with a positive or negative dielectric anisotropy (greater than the compound of the formula) is used to obtain a mixture with a suitable dielectric anisotropy. materials) (these are known and are referred to herein as "positive material" or "negative material", respectively). As is well known to those skilled in the art, dielectric anisotropy in liquid crystal materials is necessary to obtain electro-optic operation, and the sign of a liquid crystal material (at a given frequency) is Selected depending on the type of optical device. A compound with an appropriately low melting point is preferred as the highly dielectric anisotropic compound. For example, the following known classes of compounds are suitable as positive substances: Here, each R is each n-alkyl or n-alkoxy, and each R _A is each n-alkyl. Alternatively (or in addition), a compound of formula
For example, to lower the melting point, viscosity of the mixture,
Or it can be added to other compounds with low dielectric anisotropy to improve diversity. Examples of such other compounds include the following classes of compounds: Here, each R is each n-alkyl or n-alkoxy, and each R _A is each n-alkyl,
Each R' ¹ is respectively n-alkyl, n-alkoxy or hydrogen, X=H or F and Q=halogen, such as Cl or F. Thus, one or more compounds of formula a may be further optionally added to one or more compounds of formula a to i.
It can be added to one or more of the compounds of ~n. In addition, the above mixtures have other clear-
ing point) compounds may be included. Such compounds include, for example, one or more compounds selected from the following: Here, R, R _A , X and Y are as defined above. Certain other known additives, such as chiral additives of the following formula, may be incorporated into the mixture if desired. where R _C =(+)-2-methylbutyl, R _D =
(+)-2-methylbutoxy. Liquid crystal materials obtained by blending compounds of the formula with other classes of compounds as described above are as follows. (i) Positive nematic materials for use in twisted nematic effect devices, including diversified devices; examples of devices of this type are described below. (ii) Negative materials, preferably also containing pleochroic dyes, for use in Fre-edericksz effect devices (negative nematic type); in such devices the molecular arrangement is changed from the homeotropic organization (OFF state) to approximately can be converted into one tissue (ON state), an example of which is described below. (iii) The molecular arrangement is transformed by an electric field from a homogeneous organization (OFF state) to a homeotropic organization (ON state) (of positive nematic type).
(iv) a negative material which is a cholesteric (chiral nematic) with a suitable resistivity (approximately 10 ⁹ ohm-cm); The arrangement becomes uniform (OFF) due to the electric field.
focal state) scattered from the focal state (focal
conic) used for cholesteric storage mode devices that are converted to tissue (ON state). (v) A strongly negative material that is cholesteric and preferably also contains a pleochroic dye; the molecular arrangement changes from a weakly scattering or clear surface-aligned homeotropic structure (OFF state) to a strongly scattering twisted uniform structure (ON state) by an electric field. Used in cholesteric-nematic phase change effect devices (positive contrast type). (vi) a cholesteric positive material, preferably also containing a pleochroic dye; a cholesteric-nematic material whose molecular arrangement is converted by an electric field from a scattering focal conic structure (OFF state) to a clear homeotropic structure (ON state); Used for phase change effect devices (negative contrast type). (vii) Negative nematic material with appropriate resistivity (approximately 10 ⁹ ohm-cm); dynamic scattering effect where the molecular arrangement changes from a clear homeotropic organization (OFF state) to a scattering organization (ON state) depending on the electric field. Used for devices. (vii) Used in two-frequency switching effect devices (which may be twisted nematic effect devices) where the induced anisotropy of the material changes (at low frequencies) from positive (OFF state) to negative (ON state) by application of a high frequency electric field. (ix) a material suitable for the device described in co-pending British Patent Application No. 8317355; The construction and operation of the devices described above and the general types of materials suitable for their use are known per se. When liquid crystal materials are used in twisted nematic effect devices, cholesteric-nematic phase change effect (negative contrast type) devices or Frequency effect (positive nematic type) devices, these materials preferably contain the following components: do. That is, one or more compounds of the formula (component A) and one or more compounds of formulas a to i (component B) and optionally one or more of the following: Component C: one or more compounds of formulas a to n; component D: one or more compounds of formulas a to l; component E: one or more chiral additives. For the twisted nematic effect and the normal nematic effect, the percentages of the various components of the material are as follows (totaling to 100%): Component A: 5-95% by weight (typically 5-75% by weight) Component B: 5-95% by weight (typically 10-50% by weight) Component C: 0-90% by weight (typically Component D: 0-30% by weight (typically 0-20% by weight) Component E: 0-5% by weight (typically 0-1% by weight) Phase change (negative contrast type) the following proportions may be used: Components A to D: Above proportions Component E: 2 to 20% by weight (typically 4 to 5% by weight). For Frequency (positive nematic) and phase change (negative contrast type) effects, it is preferred to add pleochroic dyes to the liquid crystal material forming 1.5 to 15% of the total mixture. Suitable dyes include British Patent Application Publication Nos. 2081736A, 208219A and
Described in No. 2093475A. Typically, each dye compound added forms 1-3% by weight of the total mixture. Liquid crystal mixtures containing compounds of formula may be formed by known methods. For example, appropriate weight proportions of the components may simply be heated together to form a generally isotropic liquid (eg, at about 100° C.). To provide one example of a more general mixture that is an embodiment of the invention, at least one compound of the above formula
The seeds may be mixed with one or more of the following known classes of compounds suitable for use in one or more of the above applications (the actual application will depend on the properties of the mixture): here

[Formula] is trans-1,4-di substituted cyclohexane ring,

[Formula] is a 1,4-disubstituted bicyclo(2,2,2)octane ring,
is 1,4 phenylene group

[Formula] 4,4'- biphenyl group

[Formula] 2,6- naphthyl group

[Formula] or trans-1,4-disubstituted cyclohexane ring, Y ₁ is CN,
R', halogen or CO, O-X-Y ¹ (Y ¹ is CN,
R' or OR', and R and R' are alkyl groups. Further, derivatives of the above compounds in which H in one benzene ring is substituted with a halogen such as F may also be used. Preferably, one or more compounds of formula constitute from 5 to 95% by weight of the mixture. In a second aspect of the invention, the liquid crystal device includes:
two dielectric substrates, at least one of which is optically transparent, a layer of liquid crystal material sandwiched between the substrates, and an electric field applied to the inner surface of the substrates and across the layer of liquid crystal material to produce an electro-optic effect therein. The liquid crystal material is characterized in that it consists of or contains a compound of the above formula. This second plane device may be a twisted nematic effect device, a cholesteric-nematic phase change effect device, a Frequency switching effect device, or a two-frequency switching effect device, which may or may not be operated in a multiplexed manner. ,
These may be constructed in a known manner and may also be any of the other devices described above. Various methods of using compounds of formula in these devices are outlined above and will be apparent to those skilled in the art. Examples regarding the preparation and properties of compounds having the formula are described below. The following abbreviations are used in the examples. mp = Melting point K-N = Transition temperature from crystal to nematic liquid crystal N-I = Transition temperature from nematic to isotropic liquid bp = Boiling point S = Smectic S _A = Smectic A S-N = Transition from smectic to nematic Temperature K-S = transition temperature from crystalline solid to smectic ch-I = cholesteric (chiral nematic)
transition temperature from crystalline solid to isotropic liquid k-ch = transition temperature from crystalline solid to cholesteric s-ch = transition temperature from smectic to cholesteric △n = birefringence at 20 °C measured at 589.6 nm η = material Extrapolated nematic viscosity at 20°C measured in solution with ZLI1132 (manually available from Emerck) glc = gas-liquid chromatography Example 1 1-(trans-4-n-
pentylcyclohexyl)-2-(4-ethyl-
Steps for producing 2-fluoro-4-biphenyyl)-ethane 1 of 1: Production of 4-(trans-4-n-pentylcyclohexylacetyl)-2'-fluoro-4'-ethyl-biphenyl by Friedel-Crafts acylation 4-ethyl-2-fluorobiphenyl (13.0
g) was added once to a stirred suspension of aluminum trichloride (9.54 g) in methylene chloride (30 ml), followed by a solution of trans-4-n-pentylcyclohexylacetyl chloride (15 g) in methylene chloride (30 ml) for 30 min. It dripped. After stirring at room temperature for 3.5 hours,
The reaction mixture was poured into ice (250 g) and hydrochloric acid (25 ml) and the product was extracted with 350 ml then 250 ml petroleum ether (bp 60-80°C). The extracts were combined and
It was washed with water (150 ml), dried over anhydrous sodium sulfate, and evaporated to solidification. The residue (26.8 g) was crystallized from industrial methylated spirits at 0°C.
4-(trans-4-n-pentylcyclohexylacetyl)-2'-fluoro-4'- at mp72-73℃
13.2 g (yield 51.5%) of ethylbiphenyl was obtained. Analogues of the product of Step 1a1 shown in Table 3 were prepared in a similar manner from similar starting materials.

[Table] Step 1b1: 1-(trans-4
-n-pentylcyclohexyl)-2-(4'-ethyl-2'-fluoro-4-biphenylyl)-
Production of ethane The ketone produced in step 1 (13.0g),
99% hydrazine hydrate (13 ml), potassium hydroxide (7 g) and digol (100 ml) were heated to 120-125°C under a reflux condenser with stirring for 4 hours, then excess hydrazine hydrate was removed. The temperature was increased to 175°C by distillation. The mixture was heated to reflux for 16 hours, then cooled and poured into 500 g of ice water. The organic product was dissolved in petroleum ether (bp60-80゜, 2 x 250ml)
The extract was washed with water, dried over anhydrous sodium sulphate and evaporated to give a yellow oil (13.8g). The oil is converted into petroleum spirits (bp60~80℃)
(60 ml) and adsorbed onto a column of basic alumina (40 g) on silica gel (28 g). Elution with petroleum spirits (550ml) gave the product (10.gg) as a nematic oil, which was crystallized at -25°C from industrial methylated spirits (30ml). 1-(trans-4-n-pentylcyclohexyl)-2-(4'-ethyl-2'-fluoro-4-biphenylyl)-ethane has K-N (melting point), N-
The result was a colorless crystalline solid (8.3 g, 67% yield) with a clearing point of 103.50°C. Furthermore, the viscosity and birefringence at 589.6 nm measured at 20° C. in a supercooled liquid were 32.6 cSt and 0.145, respectively. Analogues of the products of Step 1b1 shown in Table 4 were prepared by the Huangminlon reduction of the appropriate ketones in the manner described in Step 1b1.

Table: 4-Ethyl-2-fluorobiphenyl, one of the starting materials used in step 1a1, was prepared as follows: 4-acetyl-2-fluorobiphenyl (150 g), 99% hydrated. hydrazine (150ml),
Potassium hydroxide (105g), digol (900ml) and xylene (150ml) were heated with stirring to 125°C for 16 hours, then the xylene and excess hydrazine hydrate were distilled off until an internal temperature of 165°C was reached.
The mixture was heated to reflux for 3 hours, cooled to 40°,
Pour into water 5. The product was extracted with petroleum ether (bp 60-80°, 2x2), the extracts were washed with water, dried over anhydrous sodium sulfate and evaporated. 4-ethyl-2-fluorobiphenyl (95
g, 68% of theory) was a colorless oil of bp 130°/0.8 mm. Other 4-alkyl-2-fluorobiphenyls were prepared by the reaction of 2-fluoro-4-biphenylylmagnesium bromide with n-alkyl bromides, which were produced as colorless oils with the properties shown in Table 5. It was hot.

TABLE The following mixture containing the product of step 1b1 illustrates the usefulness of the product. (a) For cyanobiphenyl components 51% 4-cyano-4'-n-pentylbiphenyl 25% 4-cyano-4'-n-hebutylbiphenyl 16% 4-cyano-4'-n-octyloxybiphenyl Formation of Step 1b1, herein designated as Compound A, using the commercially available liquid crystal material E7, sold by BDH Chemical Company, containing 8% 4-cyano-4''-n-pentyl-p-terphenyl. The resulting solution (mixture A) consisted of 20% by weight of compound A and 80% by weight of E7. Various properties of the resulting solution were determined and these were compared with the corresponding properties of E7 alone. The abbreviations in the properties column shown in Table 6 are as above or below: T _F = temperature at which the liquid crystal material can be maintained for 72 hours without freezing.

[Table] All four properties shown in Table 6 apply to compound A.
It has been improved by adding it to E7. Furthermore,
As mentioned above, the mixture of Compound A and EA (like E7) did not exhibit a smectic phase even when the temperature was lowered to -20°C. (b) In the case of PCH component: A commercially available product (sold by E. Merck) having the following weight composition of 20% by weight of Compound A and 80% by weight.
A mixture (mixture B) was prepared using ZLI1132. 24% trans-4- n -propyl-1-(4
-cyanophenyl)cyclohexane 36% trans-4- n -pentyl-1-(4
-cyanophenyl)cyclohexane 25% trans-4- n -heptyl-1-(4
-cyanophenyl)cyclohexane 15% trans-4- n -pentyl-1-
(4'-cyano-4-biphenylyl)cyclohexane ZLI1132 with and without compound A
The properties with ZLI1132 were measured and compared using the same method as above. The results are shown in Table 7.

[Table] According to Table 7, the above three properties of ZLI1132 are improved by the addition of Compound A, and the fourth property, birefringence, is at the same level. Furthermore, the mixture of Compound A and ZLI1132 did not exhibit a smectic phase even when the temperature was lowered to -20°C. (c) Mixture with wide fast-switching range A mixture (Mixture C) was prepared with the following weight composition. 9.95% 4-cyano-4'-ethylbiphenyl 4.98% trans -4- n -propyl-1-
(4-Cyanophenyl)-cyclohexane 4.98% 4-cyano-4'- n -propylbiphenyl 6.96% 1-( trans -4- n -propylcyclohexyl)-2-(4'cyano-4-biphenyl)-ethane 2.98 % 4'-cyano-4-biphenylyl-4
- n -heptyl-4-biphenylcarboxylate 18.11% 1-( trans -4- n -propylcyclohexyl)-2-(4'- n -propyl-
2'-Fluoro-4-biphenylyl)-ethane 24.38% 1-( trans -4- n -propylcyclohexyl)-2-(4'-n-pentyl-
2'-Fluoro-4-biphenylyl)-
Ethane 27.17% 1-( trans -4- n -pentylcyclohexyl)-2-(4'-ethane-2'-fluoro-4-biphenylyl)-ethane 0.48% (+)-4-cyano-4'-(2 -Methylbutyl)-biphenyl The mixture was found to have the following properties: K-N: does not freeze even when stored at -35°C for 1 month N-I: 102°C Birefringence: 20°C, 589.6 0.1735 in nm Threshold voltage: 2.85 volts {Ton 400ms Toff 540ms} Measured by driving a twisted nematic electro-optic cell with a 7 μm thick liquid crystal layer at 8 volts RMS at -20°C Ton and Toff are the cell ON and OFF respectively. This is the time required for the cell to switch to 10% and 90%. (d) Mixtures with minimal temperature change in threshold voltage The mixtures shown in Table 8a were prepared and their properties were determined in a twisted nematic electro-optic cell with a 7 μm thick liquid crystal layer.

[Table] In Table 8a, E represents a ternary eutectic mixture of the compound of the above formula, K6 represents 4-cyano-4'-n-ethylbiphenyl obtained from BDH Chemical Company, and DCH3 represents E. Merck. Trans-4-n-propyl-(4
-cyanophenyl)cyclohexane. The parameter -1./V dV/dT _-50 °C is the temperature change of the threshold voltage in the range 0 to 50 °C, and V is the temperature change at 20 °C (required for 90% cell transmittance). is the threshold voltage at which T is the temperature. Example 2 1-(trans-4-n-
propylcyclohexyl)-2-[4'-(4-trans-n-propylcyclohexyl)-2'-
Production process of fluoro-4-biphenylyl]-ethane 2-1: 1-2-(fluoro-4-biphenylyl)-4
-n-propylcyclohexan-1-ol 4-
A few ml of a solution of bromo-2-fluorobiphenyl (50 g) in diethyl ether (150 ml) was mixed with magnesium shavings (5.3 g) and diethyl ether (25 ml).
under nitrogen. The reaction was started by adding iodine crystals and heating. The remainder of the 4-bromo-3-fluorobiphenyl solution was then added at a rate sufficient to maintain vigorous reflux. After boiling for 1 hour, the Grignard reagent solution was cooled to 20°C, and then a solution of 4-n-propylcyclohexanone (27.9 g) in diethyl ether (75 ml) was added over 30 minutes. After stirring for 1 hour, the mixture was poured onto 15% hydrochloric acid (2) and the product was dissolved in ether (2 x 300
ml). The combined extracts were washed with water, dried and evaporated, and the residue was dissolved in petroleum ether (bp60−
mp45−72° (37.2
g, 61.2% of theory) as pale yellow crystals.
(2-Fluoro-4-biphenylyl)-4-propylcyclohexan-1-ol (isomer ratio by GLC 60.6:39.4) was obtained. Step 2b1: 1-(2-fluoro-4-biphenylyl)-4
-n-propylcyclohex-1-ene phosphorus pentoxide (40 g) to the product of step 2a1 (35.5 g)
to a cooled, stirred solution of toluene (500ml).
The mixture was kept at room temperature for 4 hours, then 1 portion of water was added. After stirring for 30 minutes, the organic layer was separated and the aqueous layer was re-extracted with toluene (300ml). The combined extracts were washed neutral, dried and evaporated to dryness under reduced pressure. The yellow residue was crystallized from ethanol (200 ml) at 5°C to give 1-(2-fluoro-
29.3 g (88% of theory) of 4-biphenylyl-4-n-propyl-cyclohex-1-ene were obtained. The product was 99.5% pure by GLC. Step 2c1 2-fluoro-4-(4-n-propylcyclohexyl)-biphenyl (mixture of isomers) Corresponding cyclohexene from step 2b1 (7 g), 5% palladium on charcoal (0.7 g)
and ethanol were stirred at 40° C. under a hydrogen atmosphere until hydrogen absorption ceased. The catalyst was separated and the solution was evaporated to give a product which was an isomer mixture of 64.5% cis and 34.5% trans as determined by GLC. Step 2d1: Isomer mixture (9 g) prepared as above
A solution of C. in dimethylformamide (50ml) was added to a suspension of sodium hydride (2.4g) in dimethylformamide (50ml). Heat the mixture;
The mixture was stirred at 60°C for 20 hours, then first added to ethanol (100ml) and then added to water (1). The product was extracted with petroleum ether (bp 60-80°, 2 x 200ml), washed with water, dried and evaporated to dryness. The residue (9.1 g) consists of 83% trans isomer and was purified by crystallization from ethanol (30 ml) at 5°C to give the trans product (5.6 g, glc
(purity 99.5%) was obtained. The products of step 2d1 and other examples of compounds of formula K that can be similarly prepared are summarized in Table 8b below.

【table】

[Table] Step 2e1: 4-(trans-4-n-propylcyclohexylacetyl)-2'-fluoro-4'-(trans-4-n-propylcyclohexyl)-biphenyl of step 2d1 in methylene chloride (30 ml). The product (5 g) and trans-4-n-propylcyclohexylacetyl chloride (3.42 g) were dissolved in aluminum trichloride in methylene chloride (15
ml) to the stirred suspension at 10°C. The temperature is room temperature (20
℃), the mixture was stirred for 4 hours. It was then poured into water (150ml). The product was subsequently extracted with petroleum spirits (bp 60-80°, 2 x 200 ml). This was washed with water, dried over anhydrous sodium sulfate, and evaporated to dryness to yield 7.7 g of a yellow solid. The pure product was obtained by recrystallization from petroleum spirits (or petroleum ether (bp. 60-80°)) at 10°C. The yield was 4.9g (63%) and the purity was
It was 99.8% (GLC). The product had the following physical properties. K-S _A = 90°; S _A -N = 179-180°; N-I = 220-223° Step 2f1: 1-(trans-4-n-propylcyclohexyl)-2-[2'-fluoro- 4'-(trans-
4-n-propylcyclohexyl)-4-biphenylyl]-ethane Ketone prepared in step 2a1 (4.8 g), 99%
Hydrazine hydrate (5ml), potassium hydroxide (2g)
and Digol (35 ml) were heated under a reflux condenser with stirring to 120-125°C for 5 hours, then the temperature was raised to 180°C by distilling off the excess hytrazine hydrate.
It was raised to . The mixture was heated to reflux for 20 hours, cooled and poured onto 300 ml of water. The organic product was extracted with a 4:1 solution of petroleum spirits (bp 60-80°)/methylene chloride (2 x 20 ml), the extract was washed with water, dried over anhydrous sodium sulfate and evaporated to give 4.6 g of solid.
I got it. Add this to petroleum spirits (bp60-80℃)
(60 ml) and adsorbed onto a column of basic alumina (10 g) on silica gel (5 g). Elution with petroleum spirits (150ml) gave 4.3g of crude material. Recrystallization from petroleum spirits then yielded 3.4 g of product (99.9% purity) in 73% yield.
K-N=106-108°C, N-I=244°C. Example 3 1-(trans-4-n-
propylcyclohexyl)-2-(2-fluoro-4'-n-propyl-4-biphenylyl)-
Ethane production step 3a1: 2-fluoro-4-(trans-4-n-propylcyclohexyl)biphenyl 4-bromo-2-fluorobiphenyl (38.1
A solution of g) in tetrahydrofuran (60ml) was added over 20 minutes to magnesium turnings (4g) suspended in tetrahydrofuran (20ml) and the reaction was started by addition of iodine crystals and warming as usual. The Grignard reagent was mixed with trans-4-propylcyclohexylacetyl chloride (40 g) and cuprous chloride (0.4 g) in tetrahydrofuran (200 g).
ml) solution over 90 minutes at −60° C. with stirring. After being allowed to warm to room temperature for 2 hours, the mixture was decomposed with water and the product was extracted with petroleum ether (bp 60-80°). The crude material was recrystallized twice from ethanol at 5°C to give a product (20.6g, 40% of theory) with mp 96.5-97.3°C. The product is glc
The purity was 99.6%. Step 3b1: 1-(2-fluoro-4-biphenylyl)-2
-(trans-4-n-propylcyclohexyl)-ethane The ketone prepared in Step 3a was reduced as described in Step 1b1 to give a product with 99.8% purity by GLC in 71% yield. The product had mp=46.5-48° (N-I [37-39.8°]). Step 3c1: 1-(2-fluoro-4'-propionyl-4-
Biphenylyl)-2-(trans-4-n-propylcyclohexyl)-ethane 4'-propionyl group was introduced into the product of Step 3b1 by the procedure using the Friedel-Crafts reaction described in Step 1a1. The desired product was obtained in 90% yield and 99.7% purity by GLC. The product had the following properties: K-N = 74.4-74.8° N-I = 165.4-165.8° Step 3d1: 1-(2-fluoro-4'-n-propyl-4-
Step 1b1
The product was reduced using the Huangminlong method described in 2009 to give a product with a yield of 30% and a purity of 99.8% by GLC. In the product, K-N=59° and N-I=108°. The following analogs were prepared in a similar reaction.

[Table] Example 4 Formula according to route 4: Step 4a1: Friedel-Crafts acylation using 2-fluorobiphenyl in place of 4-ethyl-2-fluorobiphenyl and further converting the molar amount of aluminum trichloride present in methylene chloride into trans- 4-n
- Step 1a1 except double the molar amount of pentylcyclohexylacetyl chloride.
I did the same thing. Step 4b1: Huangminglong reduction was performed essentially as in Step 1b1 above. Compounds of formula f with other alkyl groups may be synthesized in an analogous manner. Example 4′ Formula according to the above root 4′: The following steps 4′a1 to 4′e1 are steps 4′a to 4′e1, respectively.
This is a specific example of 4'e. Step 4'a1: Preparation of Grignard reagent This step was carried out in a similar manner to the preparation of the Grignard reagent in Step 1a1, ie, the starting material 4-bromo-2-fluorobiphenyl. Step 4'b1: This step involves the addition of trans-4-n-butylcyclohexylacetyl chloride and the Grignard reagent produced in step 4'a1 at a temperature of -78°C in the presence of tetrahydrofuran.
Inoue, K Oguro and M Sato Tetrahedron
The reaction was carried out according to the method described in Letters (1979) pages 4303-4306. Step 4a1: Reduction This step was performed in a similar manner to the reduction in step 1b1. formula: The compound had the following properties: C-I = 44°C N-I = (36.6°C). Step 4'd1: Friedel-Crafts acylation reaction This step was carried out in the same manner as Step 1a1. formula: The compound had the following properties: C-S=110°C S-N=185.7°C N-I=190.1°C. Step 4'e1: Reduction This step was performed in a similar manner to step 1b1. The product has the formula: It was a compound of Compounds of formula f with other alkyl groups may be synthesized in an analogous manner. Compounds that can be synthesized by the methods described in Examples 1 to 4 and 4' are summarized in Tables 10 to 13, respectively. Table 10: Formula: The compound R ₁ R ₂ C _n H _2n+1 C _p H _2p+1 C _n H _2n+1 OC _p H _2p+1 C _n H _2n+1 H where m is an integer from 0 to 12, p is an integer from 1 to 12.

[Table] Table 12: Formula: Compound R ₁ R ₂ C _n H _2n+1 C _p H _2p+1 C _n H _2n+1 OC _p H _2p+1 C _n H _2n+1 H

[Table] Example 5 1-(trans-4-n-
(propylcyclohexyl)-2-(2'-fluoro-4''-n-propyl-p-terphenylyl)
Ethane production step 5a1: 3'-fluoro-4-propyl-p
-Production of terphenyl 4-(4-n-propylcyclohexenyl)-2
- Fluorobiphenyl (20g) toluene (120g)
ml) solution was added to a suspension of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) (34 g) in toluene (200 ml) with stirring over 25 minutes. The temperature rose from 19°C to 24°C during the addition, after which the reaction mixture was heated to reflux (114°C) for 2 hours.
℃). The reaction mixture was cooled, filtered, and the liquid and toluene washes (100ml) were combined, then washed with saturated isomeric sodium bisulphite solution (250ml).
The organic extract was further washed with water (2 x 250 ml), dried,
Evaporation to dryness gave a brown residue (20.1 g). The residue was dissolved in methylene chloride (120ml) and adsorbed onto a column of basic alumina (60g) on silica gel (60g). Elution with methylene chloride (450 ml) and evaporation of the solvent gave an off-white solid (14
g) was obtained. This was recrystallized from ethanol (80 ml) to produce a white crystalline substance (mp 75-77°C) (12.8
g) was obtained. Step 5b1: 4-(trans-4-n-propylcyclohexylacetyl)-2'-fluoro-
Preparation of 4″-propyl-p-terphenyl 3′-fluoro-4- in methylene chloride (15 ml)
A mixture of propyl-p-terphenyl (4 g) and trans-4-n-propyl-cyclohexylacetyl chloride (2.8 g) was added to anhydrous aluminum chloride (2.02 g) in methylene chloride (10 ml) under cooling (10°C) under stirring. It was added to the suspension over 20 minutes. After addition,
The reaction mixture was warmed to 23°C and stirred for 18 hours. The resulting solution was added to 10% hydrochloric acid solution (100 ml), followed by petroleum spirits (bp60-80°, 2 x 100
ml). The organic extract was then washed with water (120
ml), dried over anhydrous sodium sulfate, filtered and evaporated to dryness. Yellow oily solid (7
g) was dissolved in methylene chloride (50ml) and adsorbed onto a column of basic alumina (20g) on silica gel (10g). Elution with methylene chloride and evaporation of the solvent gave a yellow solid (5g). Recrystallization from methylene chloride (10 g) gave a crystalline material (2.5 g) with properties: K-S = 120-126 S-N = 200-204°C N-I = 225-227°C had. Step 5c1: Preparation of 1-(trans-4-n-propylcyclohexyl)-2-(2'-fluoro-4''-propyl-p-4-terphenyl)ethane Ketone prepared in Step 5b1 (1.8 g) 99% hydrazine (2 ml), potassium hydroxide (1 g) and digol (30 ml) were heated to 120°C with stirring for 17 hours, then the temperature was raised to 180°C by distillation of the excess hydrated hydrazine/digol mixture. .
The resulting solution was heated to reflux at 180-182°C for 5 hours,
It was then cooled to 60°C and poured onto ice water (100g).
Organic products are converted into petroleum spirits (bp60−80, 150
ml) and methylene chloride (30 ml), washed with water (2 x 50 ml), dried and the solvent was evaporated. The yellow residue (1.7 g) was dissolved in 20 ml of a 1:1 mixture of methylene chloride and petroleum spirits (bp60-80).
and adsorbed onto a column of basic alumina (6 g) on silica gel (4 g). Elution with the same solvent mixture (70ml) and evaporation of the solvent gave a crystalline material (1.3g). Recrystallization from petroleum spirits (bp60-80, 7 ml) at 10°C gives a white solid ( 1 g) was obtained. Examples of other compounds that can be prepared by one or more of the routes described above or by analogous routes are shown in Table 13a below.

【table】

[Table] In the following examples, namely Examples 6 to 8, the terminal group
The preparation of compounds of formula where one of R ₁ and R ₂ is chiral is described. Example 6: (+)-1-(trans-4
-n-butylcyclohexyl)-2-[2'-fluoro-4'-(2-methylbutyl)-4-biphenylyl]-ethane production step P: (+)-2-fluoro-4-(2-methylbutyl- Preparatory production of biphenyl 4-bromo-2-fluorobiphenyl (90g)
10 ml of a solution of 100 ml in tetrahydrofuran (90 ml) was added to the magnesium turnings (9.6 g) and tetrahydrofuran (20 ml) under nitrogen. The reaction was started by adding a single crystal of iodine and heating. Then, the remainder of the 4-bromo-2-fluorobiphenyl solution was added dropwise over 1/2 hour. After heating under reflux for 1 hour, the Grignard reagent solution was cooled to 25°C.
2-Methylbutylphenyl sulfonate (150g)
10 ml of a solution of in tetrahydrofuran (140 ml) was added to the reaction mixture followed by cuprous chloride (3 g) and the remainder of the phenyl sulfonate solution over 40 minutes. The temperature of the resulting gray/green reaction mixture rose to 45°C and was then heated for 1 hour to raise the temperature to boiling point. The reaction was allowed to cool to room temperature, then 20% by volume hydrochloric acid (2.5) was added and the product was extracted with methylene chloride (2 x 500ml). The organic layer was washed with water (2 x 500 ml) and diluted with anhydrous sodium sulfate (15
g) and evaporation of the solvent to obtain an organic liquid residue. Upon cooling, a white solid crystallized from the residue. After filtration, the residue (88.6 g) was fractionally distilled under reduced pressure (0.5 torr) to obtain a colorless liquid (65 g). this is
According to GLC, the purity was 98.8%. bp is 0.5torr
It was 120℃. The optical rotation was +14.62° (solvent). Step 1a2: (+)-4-(trans-4-n-
Preparation of (+)-2-fluoro-4-(2-methylbutyl)biphenyl (10 g) in methylene chloride (20 ml)
and trans-4-n-butylcyclohexylacetyl chloride (9.4 g) was added over 20 minutes to a stirred suspension of anhydrous aluminum chloride (6.1 g) in methylene chloride (20 ml) cooled (5-10°C). . After the addition, the reaction mixture was allowed to warm up to 23°C and stirred for 17 hours. Add the resulting solution to water (200ml)
followed by petroleum spirits (bp60~80°180
ml + 100 ml). The organic extract was then washed with water (200ml), dried over anhydrous sodium sulphate (5g) and evaporated to a yellow crystalline residue (17.9g).
was recrystallized from ethanol (35 ml) at 25°C,
The product (14.8 g, yield 85%) was obtained. The product is
mp71.4-72.1℃, actual Ch-I (68.5-68.8℃)
The purity by GLC was 99.5. Step 1b2: (+)-1-(trans-4-n-
butylcyclohexyl)-2-[2'-fluoro-
Production of 4'-(2-methylbutyl)-4-biphenylyl]-ethane The previously produced ketone (14.4 g), 99% hydrazine hydrate (14.4 ml), potassium hydroxide (7.2 g) and digol (120 ml) were added. It was heated to 125°C under a reflux condenser with stirring for 4 hours, after which the excess hydrazine hydrate was distilled off and the temperature was raised to 175°C.
The mixture was then heated to reflux for 17 hours, cooled to 60°C and poured onto ice water (500g). The organic products were extracted with petroleum spirits (bp 60-80°, 2 x 200 ml) and the extracts were washed with water (2 x 200 ml) and dried over anhydrous sodium sulfate. Evaporation of the solvent gave a yellow oil (41.1g). Add this to petroleum spirits (bp60
~80°, 100 ml) and adsorbed onto a column of basic alumina (50 g) on silica gel (20 g). Elution with petroleum spirits (320ml) and evaporation of the solvent gave a colorless oil (11.7g). −
Crystallization from propan-1-ol (70 ml) at 50°C yields 9.4 g (68% yield) of chiral nematic material.
was gotten. This material was 99.8% pure by GLC. The properties of the product were as follows: S-Ch = 6°C Ch-I = 72°C Helical molecular pitch = 0.23 microns Example 7 1-(trans-4-ethylcyclohexyl)- by Route 1 above 2-[2'-Fluoro-4'-
(2-methylbutyl)-4-biphenylyl]-
Ethane production step 1a3: 4-(trans-4-ethylcyclohexylacetyl)-2'-fluoro-4'(2-
Preparation of methylbutyl)biphenyl This step uses 4-ethylcyclohexylacetyl chloride as the starting material.
It was done in the same way as 1a2. The product had the following properties: mp = 40-42°C Actual Ch-I = (27.5°C) Step 1b3: 1-(trans-4-ethylcyclohexyl)-2-[2'-fluoro −4′−(2−
Preparation of methylbutyl)-4-biphenylyl]-ethane This step was carried out in a similar manner to step 1b2. The properties of the product are as follows: S-Ch=-11°C Ch-I=45°C Example 8 1-(trans-4-n-
heptylcyclohexyl)-2-[2'-fluoro-4'-(2-methylbutyl)-4-biphenylyl]-ethane Step 1a4: 4-(trans-4-n-heptylcyclohexylacetyl)-2'-fluoro −
Preparation of 4'-(2-methylbutyl)biphenyl This step was carried out in a similar manner to step 1a2. The properties of the products are as follows: K-Ch = 69.8-70.3°C Ch-I = 74.1-74.3°C Step 1b4: 1-(trans-4-n-heptylcyclohexyl)-2-[2'-fluoro −4′−
(2-methylbutyl)-4-biphenylyl]-
Production of ethane This step was carried out in a similar manner to step 1b2. The product had the following properties: S-Ch = 52°C Ch-I = 79°C Examples of chiral nematic compounds that can be synthesized in a similar manner to the above examples are shown in Table 13b below. .

【table】

[Table] In the following experiment, R _A = n-alkyl and R _B = n-
The advantage of compounds of formula a which are alkyl and have less than 10 carbon atoms in R _A and R _B is that R _A and R _B are both n-pentyl, i.e. R _A and
The same formula a where the total number of carbon atoms in R _B is 10
This was done to compare with the compound of 80% by weight of each compound investigated, formula: 10% by weight of cyanobiphenyl, and the formula: was mixed with 10% by weight of cyanobiphenyl ethane to form each mixture. Next, the smectic-nematic (SN) transition temperature of each of the obtained mixtures was measured. From the transition temperature it was found that the compound has a tendency to form an injective smectic phase. It can be said that the lower the SN temperature, the more preferable the compound is. The results obtained are shown in Table 14 below.

[Table] Specific examples of materials and devices embodying the present invention will be described based on the accompanying drawings. The display of Figures 1 to 4 consists of cells formed from front and rear glass slides 2, 3 held apart by spacers 4 at a distance of approximately 7 μm and held together by epoxy adhesive. Consists of 1. The liquid crystal material 12 is placed on the slide 2,
3 and spacer 4 is filled. Front polarizers 5 are arranged in front of the windshield slide 2 so that their polarization axes are horizontal. Reflector plate 7
Place it behind slide 3. A rear polarizer 6 or analyzer is placed between the slide 3 and the reflector 7. a tin oxide electrode 8, typically 100 Å thick;
9 is applied as a complete film to the inner surface of the slides 2, 3 and etched in the shape shown in FIGS.
The display has seven bars per digit 10, with an additional decimal point 11 between each digit. As shown in FIG. 3, the rear electrode structure consists of three electrodes X ₁ , X ₂ , X ₃ . Similarly, the front electrode structure has three electrodes Y ₁ for each number and decimal point,
It consists of Y ₂ , Y ₃ …. By examining the six electrodes for each number and applying the appropriate voltages to the appropriate X, Y electrodes, each of the eight elements is shown to have an independently applied voltage. Before assembling, slide 2 with electrodes attached,
3. After cleaning, soak it in a 0.2% by weight polyvinyl alcohol (PVA) aqueous solution. When dry, the slides are rubbed in a certain direction with a soft cloth, and then assembled so that the rubbing directions are perpendicular to each other and parallel to the optical axes of the adjacent polarizers, that is, the polarizers intersect. Slide the nematic liquid crystal substance 12 2,
When introduced between 3 and 3, the molecules on the slide surface become progressively twisted along the direction of abrasion on each slide and between the slides. When no voltage is applied to the cell 1, the light passes through the front polarizer 5, through the cell 1 (during which the plane of polarization rotates by 90°), through the rear polarizer 6, and through the reflector 7.
is reflected and reaches the observer. See Figure 1. The observer is at an angle of 45° to the Z axis perpendicular to the X and Y axes in the plane of the slides 2 and 3. ) When a voltage higher than the threshold is applied between the two electrodes 8 and 9,
In the liquid crystal layer 12, molecules that do not lose their optical activity are rearranged perpendicularly to the slides 2, 3, that is, along the Z axis. In this state, the light no longer reaches the reflector 7 and therefore does not reach the observer, and the observer only sees a dark display of one or more bars of the number 10. As shown in Figures 5, 6 and 7, 3
The voltage is applied in a line scanning manner at continuous time intervals.
Each X electrode is set to a potential of 3V/2 in turn, while the remaining X electrodes are set to -V/2. Meanwhile, the Y electrode is -
Set it to 3V/2 or V/2. 3V at the crossing point/
When 2 and -3V/2 match, a voltage of 3V will be applied to the liquid crystal layer 12. At other points the voltage is V or -V. In this way, when 3V/2 is scanned to the X electrode, - to the appropriate Y electrode.
By applying 3V/2, the selected crossing point is turned on (indicated by a black circle in the figure). The voltage V is, for example, a 100 Hz square wave alternating current signal, and the sign represents the phase. It will be apparent to those skilled in the art that the devices shown in Figures 1-7 are diversified displays because the electrodes are distributed between on and off cross-points or display elements. Materials embodying the invention suitable for use in material 12 of the device described above include mixture C, described above;
D ₁ , D ₂ , D ₃ or D ₄ and Mixture 1 as shown in Table 15 below.

【table】

Table: Small amounts of optically active substances may be added to the nematic material to create a desired twist in the molecules of the liquid crystal layer. Using this process and appropriate slide surface preparation, UK Patent Application No. 1472247 and
The display patch problem taught in No. 1478592 can be avoided. Suitable optically active materials are: about 0.1-0.5% by weight C15 and about 0.01-0.05% by weight CB15. C15 is CB15 is Small amounts of pleochroic dyes such as British Patent Publication No.
2093475, dye mixture 2 may be added in an amount of 2% by weight to increase display contrast. Other specific mixtures embodying the second aspect of the invention may be used in Fre?edericksz effect cells. The cell consists of a sandwich of liquid crystal material between glass slides having an electrode film on the inner surface, as in the device described above. However, in this case, a polarizer is not necessarily necessary, and the inner surface of the glass slide is coated with lecithin, and the liquid crystal material is a negative substance, and the lecithin coating ensures that all molecules are perpendicular to the slide substrate (homeotropic orientation). Arranged in the off state. When an appropriate electric field is applied to the material in the on state, the molecules rearrange parallel to the slide surface (homogeneous orientation). Pleochroic dyes may be incorporated into the liquid crystal material to enhance the contrast between the on and off states. The Fre〓edericksz effect cell made as described above may incorporate the following mixture 3;
Place at intervals of 10 μm.

【table】

[Table] Compound J: may be added to mixture 3 (up to 3% by weight of mixture 3) as a negative additive. The preparation of compound J is described in GB 2061256. Approximately 1% by weight of a known dye mixture may be added to Mixture 3 to form a colored mixture (Mixture 3A). When a voltage is applied to the cell, the color changes from a weakly absorbing state to a strongly absorbing state. Another embodiment of the invention incorporates the above-described materials into a (cholesteric-nematic) phase change effect device. A cell is prepared containing a long helical pitch of cholesteric material sandwiched between electrodes having a glass slide, similar to the twisted nematic cell described above. However, in this case surface preparation for homogeneous arrays e.g.
Glass slide surface treatment with SiO and polarizers are not used. If the glass slide is untreated and the liquid crystal material has a positive dielectric anisotropy (ΔE), the liquid crystal material has a twisted focal conic molecular orientation in the off state which scatters light. The effect of an electric field applied between a pair of electrodes on the internal surface of each glass slide is to turn the region of liquid crystal material between the electrodes into an on state into a homeotropic nematic orientation with less scattering than an off state. be. This is a negative contrast phase change effect device. If the internal surface of the glass slide is treated with a coating of lecithin, for example, so that the liquid crystal material has a negative ΔE and is oriented perpendicular to the surface, then the off-state material has a homeotropic orientation with a small scattering effect on the incident light. be. Applying an electric field between a pair of electrodes on the interior surface of each glass slide changes the region of liquid crystal material between the electrodes (in the on state) into a twisted homogeneous orientation that scatters light. This is a positive contrast phase change effect device. The contrast between the two states in each case may be increased by adding small amounts of suitable pleochroic dyes to the liquid crystal material (for example 1% by weight of the dye mixture if ΔE is positive). The positive dielectric anisotropic material, mixture 4, embodying the present invention and used in a phase change effect type (negative contrast type) device is as follows.

[Table] Suitable negative dielectric anisotropic materials, mixtures 5 embodying the present invention, used in phase change effect type (positive contrast type) are as follows.

Table 18 Chiral compounds of the formula may be used in place of the chiral substances listed in Table 18.

[Brief explanation of drawings]

Figure 1 is a partial view of a twisted nematic type digital display, Figure 2 is a sectional view of the display in Figure 1, Figure 3 is a diagram of the shape of the rear electrode in Figure 1, and Figure 4 is the figure in Figure 1. Shape diagram of the front electrode, fifth,
Figures 6 and 7 are illustrations of the device of Figures 1-4 showing typical voltages. 1... Cell, 2, 3... Glass slide, 4...
...Spacer, 5, 6... Polarizer, 7... Reflector, 8, 9... Electrode, 12... Liquid crystal material.

Claims (1)

[Claims] 1 formula [wherein R ₁ is alkyl having up to 12 carbon atoms and R ₂ is selected from hydrogen, alkyl having up to 12 carbon atoms, [formula] [formula] and [formula], where R ₃ is alkyl with up to 12 carbon atoms;
[Formula] represents a cyclohexane ring in the trans configuration when it is 1,4-disubstituted,
[Formula] represents a benzene ring, and each of X, Y and Z individually represents hydrogen or fluorine at one or more side positions of the benzene ring, provided that one of X, Y or Z is fluorine; , R ₁ and R ₂ are n-
When alkyl, the total number of carbon atoms in the two groups R ₁ and R ₂ is less than 10. 2 formulas [In the formula, R ₁ is n-alkyl, R ₂ is alkyl, and one of X or Y is fluorine]
A fluorinated compound according to claim 1. 3. Fluorinated compounds according to claim 2, wherein _R2 is n-alkyl. 4. The fluorinated compound according to claim 2, wherein R ₂ is a chiral alkyl group. 5. The fluorinated compound according to claim 2 or 3, wherein Y is fluorine and X is hydrogen. 6 formula A fluorinated compound according to claim 1 having: 7 formula A fluorinated compound according to claim 1 having: 8 formula A fluorinated compound according to claim 1 having: 9 formula [wherein R ₁ is alkyl having up to 12 carbon atoms and R ₂ is selected from hydrogen, alkyl having up to 12 carbon atoms, [formula] [formula] and [formula], where R ₃ is alkyl with up to 12 carbon atoms;
[Formula] represents a cyclohexane ring in the trans configuration when it is 1,4-disubstituted,
[Formula] represents a benzene ring, and each of X, Y and Z individually represents hydrogen or fluorine at one or more side positions of the benzene ring, provided that one of X, Y or Z is fluorine; , R ₁ and R ₂ are n-
When the group is alkyl, the total number of carbon atoms in the two groups R ₁ and R ₂ is less than 10. 10 formula [In the formula, R ₁ is n-alkyl, R ₂ is alkyl, and one of X or Y is fluorine]
10. The liquid crystal composition according to claim 9, comprising at least one compound. 11 formula [In the formula, both R ₁ and R ₂ are n-alkyl, and the total number of carbon atoms in R ₁ and R ₂ is 4 to 8.
The liquid crystal composition according to claim 9, comprising a mixture of different compounds, wherein one of X and Y is fluorine and the other is hydrogen.