NL8400195A - 2,5-DISUBSTITUTED PYRIDINS, METHOD FOR PREPARING THE SAME, MESOMORF MATERIAL AND ELECTRO-OPTICAL DEVICE. - Google Patents

Description

* · /., 1 <> .0. 322i2 2,5-Dubstituted pyrldines, method of preparation, mesoworph Material and electro-optical device.

The invention relates to heterocyclic compounds, in the lifting sub 2,5-disubstituted pyrldines, to a method for preparing them as a second on an aesonorphic water language and a system electro-optical device for displaying and processing information · 2,5 Substituted pyrldines can be used as intermediates of organic synthesis, liquid crystals, pharmaceutical sawing counts and for a number of other applications.

The main application of liquid crystals is their use as active parts in electro-optical devices for displaying and processing information. A large number of requirements are imposed on liquid crystal materials used for this purpose, the most important of which are the range of operating temperatures and dielectric constants. These properties must first of all be taken into account when choosing the components of mesomorphic materials.

The best known electro-optical device with liquid crystals is a twist indicator (a display device, the operation of which is based on the rotation of liquid crystals), which uses nematic wesomorphic materials with a positive dielectric anisotropy (δ £ } 0). This property is obtained by introducing into the water language components containing a nitrile group, the constant dipole moment of which is oriented along the axis of the molecule. Examples of such compounds are, for example, cyanyl phenyls of formula 1 (British Patent 1,452,826) and cyanophenylcydohezanes of formula 2 (Russian Patent 738,516), wherein R represents Ct ^ nfl v ° and n an integer from 3-8 means.

4,4-dialkyl-2,5-diphenylpyridines of the general formula (3) are also known as liquid crystal blends: wherein R 1, R 2 - C 1 - 2 - 1 - 6.

35 (compare D. Demus et al. Flttssige Kristale in Tables, 1974, MVEB Deutscher Verlag fttr Grundstoffindustrle "Publishing House, Leipzig, p. 254).

The use of these compounds to provide meso-fluff materials with positive dielectric anisotropy is limited by very high melting points (100 - 213 ° C) and low dielectric 8400195

1 I

* 4 2 constants.

A number of mesomorphic nitrile group containing 2,5-disubstituted pyridines are also known: compounds of the formula 4, wherein R = ^ η®2η + 1 »^ 6-9; compounds of the formula 5, wherein R = cnH2n + i »®“ 4-8; compounds of the formula 6, wherein R = ηη 2π + 1 * n ^ 4-8; compounds of the formula 7, wherein R · * · «^ t ^ 2n + l *

The phase transition temperatures of compounds of formulas 4-6 do not fully meet the requirements of the components of mesomorphic materials. For example, a compound of formula 4 (n = 6) has a relatively high melting point (52 ° C) at a low clearance point (26 ° C) (compare AI Pavljuchenko, EI Kovshev, VV Titov, "Khimija geterocyklicheskikh soedineny" (chemistry of Heterocyclic Compounds - Magazine, in Russian), Zinatne Publishing House, Riga, 1981, 15 No. 1, pp. 85-88). Compounds of formulas 5 and 6 also have high melting points (58-97 ° G); no compounds of formula 5 have e-nantiotropic liquid crystals found, while the clearance temperatures of compounds of formula 6 are in the range of 80-90 ° C (compare Al Pavljuchenko, VV Titov, NI Smirnova, VT Grachev, Chemistry of Heterocyclic Compounds Journal, "Zinatne" Publishing House, Riga, 1980, No. 7, pp. 888-891).

Compounds of formulas 4-6 have a dielectric constant which is not too high.

Compounds of formula 7 have only been mentioned to be mesomorphic, but. the properties or the process for their preparation have not been described in the literature so far (compare VT Grachev, BE Zaitsev, EM Itskovich, AI Pavljuchenko, VV Titov, KM Dju-maev, Molecular Crystals and Liquid Crystals, 1981, volume 65, No. 1/2, pp. 133-142).

Cyanobiphenyl derivatives of the formula 1 and cyanophenylcyclohexane derivatives of the formula 2 ° are used to provide nematic mesomorphic materials. For example, a mesomorphic material is known, consisting of 50 moles of Z 4-pentyl-4'-cyanobiphenyl, 25 mole% of 4-heptyl-4'-cyanobiphenyl, 16 moles of Z 4-octyloxy-4'-cyanobiphenyl and 9 moles % 4-35 pentyl-4'-cyanoterphenyl, which has the following characteristic properties: a s 14, the range of the existence of the mesophase: from -9 to + 60 ° C, threshold voltage of the turning effect (Uthr) 1.5 V, saturation voltage (Ugat) * 1.96 V. This mixture is widely used in the manufacture of indicators and is known under the trademark E7 (available from BDH Co., Great Britain). At 8400195

If * "W

Mixtures of cyanophenylcydohexanes of formula II have even lower lagereZ arden groundings and correspondingly higher vanths of threshold and control voltages.

The object of the invention is to provide 2,5-disubstituted pyridines which have a positive dielectric anisotropy and which are suitable for effective use as components of a mesoorphic material.

The object of the invention is to provide such a process for the preparation of 2,5-disubstituted pyridines which is one-fold and does not require high material costs and can be easily carried out on a technical scale.

Another object of the invention is to provide a mesomorphic material having a positive dielectric anisotropy, which has a wide range of operating temperatures and low grounding of the threshold and control voltages.

Another object of the invention is to provide an electro-optical device for displaying information in black and white or in color, which can be effectively applied under both static and complex control conditions. These objects are achieved according to the present invention. by providing new 2,5-disubstituted pyridines corresponding to the general formula 8 wherein R represents Cn? * 2irtl or and n represents an integer of 4-8.

The compounds of formula (8) normally comprise colorless crystals, which are stable in electro-optical devices under storage and operating conditions. The melting and curing temperatures of these compounds and their dielectric constants are ideally suited for their use as components of mesomorphic materials.

According to the invention, 2,5-disubstituted pyridines of the formula 8 are prepared by reacting pyrllium salts of the formula 9 with ammonium acetate in an organic medium according to the reaction scheme of Figure 1, wherein R represents C 1 or 2n + -10 and n means n .

A pyrllum salt of formula 9 can be prepared from substituted phenylacetic acid and 4-cyanoacetophenol according to the reaction scheme of flg. 2, where R and n have the above meaning *

As can be seen from the above reaction scheme, the preparation of the compounds of formula 8 is based on relatively inexpensive and readily available starting materials; the method 8400195 I 'v 4 consists of a small number of stages, the execution of which does not require highly refined equipment, and can be easily carried out on a technical scale ·

The invention also relates to a mesomorphic material comprising at least a 2,5-disubstituted pyridine of the general formula 8, wherein R = »C ^ n + 1 or ^ n2n + l® νοοΓδε®ΐ £ and n 4- 8, and / or contains a 2,5-disubstituted pyridine of the general formula 7 wherein R * represents and n represents 1-9.

According to the invention, this material can additionally contain an organic dielectric dye, as well as a dichroic dye for the purpose of displaying information in color.

The mesomorphic material contains 2,5-disubstituted pyxidines of the formula 7, which are already known from the literature (compare V.T.

*

Grachev, B.E. Zaitsev, E.M. Itskovich, A.I. Pavljuchenko, V.V. Titov, 15 K.M.Jumaev, Molecular Crystals and Liquid Crystals, 1981, vol. 65, no 1/2, biz. 133-142). However, neither its properties nor the method of preparing such compounds have been described heretofore. These compounds can be prepared from the corresponding pyrilium salts according to the reaction scheme of Fig. 3, where R 1 represents -20 and n represents 1-9.

In both cases, the main stage of the synthesis is the conversion of pyrilium salts to a 2,5-disubstituted pyridine derivative. * A bromo derivative of the formula 10 is converted into the desired product with the for-25 by the usual method, namely treatment with copper cyanide. mule 7 converted.

The phase transition temperatures and dielectric constants of compounds of formula 7 are very favorable for their use as components of liquid crystal materials.

According to the present invention, it is possible to prepare meomorphous materials from a wide range of operating temperatures, a high value of the positive dielectric anisotropy and it is possible to manufacture electro-optical devices operating efficiently under both static and dynamic steering conditions.

The present invention also relates to an electro-optical device containing a liquid crystal-containing active moiety, containing at least 2,5-disubstituted pyridine of the general formula 8 and / or 7, which is located between two optically transparent, electrically non-conductive plates, with transparent electrodes arranged on the inside thereof · Polarizing material can be applied to the outer sides of the transparent plates.

8400 195 r, ........

* \ 5

This electro-optical device according to the present invention is illustrated by the drawing of Fig. 4, in which the principle is indicated. The device comprises an active part 1 (a layer of mesomorphic material) which is arranged between two glass plates or two other transparent, electrically non-conductive plates 2, which are arranged opposite each other. Transparent electrodes 3 are provided on the inner sides of the plates 2 and are provided with conductors 4 which are connected to a current source (not shown).

In the case of the use of a mesomorphic material containing a 10-chromic dye, the device may have no polarizing material or just a single plate of polarizing material 5 applied to the outside of one of the plates 2, are applied.

When operating the device under the twist inductor conditions, the device must contain two plates of polarizing material 5 mounted on the outer sides of both plates 2.

In the device according to the invention, the molecules of the liquid crystal material in the initial state (using an electric field) are oriented parallel to the transparent plates, so that in the twist indicator the direction of the orientation in one plate is under a angle of 90 * to the orientation direction in the other plate.

When using an electric field, the liquid crystal molecules are reoriented so that their longitudinal axis is perpendicular to the plates. This is manifested visually by color change (in the case of the use of a mesomorphic material of a chemical dye) or darkening (under the turning conditions) of the cell.

The invention is further illustrated by the following Examples I-XLII1, wherein Examples I-IX indicate the process for the preparation of the compounds of Formula 8 and their properties; Examples X-XVI illustrate the process for the preparation of the compounds of Formula 7 and their properties, while Examples XVII-XLIII illustrate the process for the preparation of mesomorphic materials and their properties for use in twist indicators ( Examples XVII-XL) and the materials containing dichroic dyes (Examples XLI-XLIII) are described.

Example I

In this example and Examples II-IX below, the preparation of compounds of formula 8 is illustrated.

40 Preparation of 5- (4-butylphenyl) -2- (4-cyanophenyl) -pyrldlne 8400195 * "6

0.3 mol of phosphorus oxychloride is added dropwise to 0.5 mol of anhydrous methyl formamide at 0 ° C and then 0.1 mol of 4-butylphenylacetic acid is added at a temperature of -10 ° C. The mixture is stirred at 20 ° C for 1 hour, at 6GeC for 2 hours and at 80 ° C for 5 hours. Dimethylformamide is distilled off under reduced pressure, the residue is cooled and mixed with 20 ml of water and 0.1 ml of magnesium perchlorate in the form of a saturated aqueous solution at a temperature of -10 ° C. The precipitated salt is filtered off, washed with ether to give 21.5 g of a salt which melts at 102 ° C.

0.0182 mol of 4-cyanoacetophenone is added to a solution of 6.5 g of the salt thus prepared in 10 ml anhydrous pyridine and then 0.0182 mol of a 2.5 M solution of sodium methanolate at a temperature of 20 ° C slowly added dropwise. Stirring is carried out at 20 ° C for 24 hours, pyridine is distilled off, the residue is treated with water and extracted with benzene. Benzene is distilled off, the residue is recrystallized from methanol and dissolved in 30 ml of methanol. 5 ml of 2N hydrochloric acid are added to the resulting solution, the mixture is stirred for 30 minutes, the residue is filtered off, washed with methanol and dissolved in 10 ml of acetic acid and 5 ml of a 70% strength perchloric acid solution are slowly added. added dropwise. The mixture is diluted with diethyl ether, the residue is filtered off, dissolved in a mixture of 30 ml of acetic acid and 8 g of ammonium acetate. The mixture is stirred for 2 hours, cooled, poured into water, the residue is filtered off, and recrystallized from methanol to give 5- (4-butyl-phenyl) -2- (4-cyanophenyl) -pyridine which melts at 95 ° C; the clearance point is 233eC. Dielectric constants (measured at 95 ° C): 23.6; £ ± - 6.3; Δ £ - + 17.3.

Examples IX-XI are shown in Table A, which also indicates the properties of the compounds of Formula 8. The compounds listed in Table A are obtained by a similar method as described in Example 1 above.

8400195 w ^ 7 "

Table A

Properties of 5- (4-alkyl- or alkoxyphenyl) -2- (4-cyanophenyl) pyrldines with photnule 8 5

Example No. R Melting temperature - temperature, eC tempera

ture, eC

10 II C5H11 76 232 III 0 $ Ηι3 72 221 IV C7H15 69 217 V CgHi7 67 210 VI C4H9O 117 165 15 VII C6H13O 80 251 VIII C7H15O 83 243 IX C8H17O 89 235

Example X

This example illustrates the preparation of compounds of formula 7.

Preparation of 5-Butyl-2- (4-cyanophenyl) pyrldine

To a solution of 10.2 g of N- (hexenyl-1) -piperldine and 8.34 al of 25 trlethylaaine in 10 al of ethyl ether is added dropwise, with stirring, a solution of 14.7 g of p-bromophenyl-0-chlorophenyl ketone in 20 ml of di ethyl ether is added and the reaction mixture is allowed to stand at room temperature for 12 hours. The reaction mass is diluted with water, ether is distilled off and the residue is filtered off, washed twice with water and mixed with a solution of 25 ml of a 54% perchloric acid solution in 20 ml of water. The mixture is heated at reflux for 15 minutes. The precipitant formed is filtered after cooling, washed with ether and mixed with a solution of 40 g of amamonum acetate in 150 ml of acetic acid. The mixture is heated under reflux for 4 hours, poured into 300 ml of water and extracted with benzene. The benzene extract is washed with water, dried over sodium sulfate and benzene is distilled off. The residue is recrystallized from hexane to give 5-butyl-2- (4-brooafenjrl) pyridine, which accelerates at 76 ° C.

40 A mixture of 6 g of 5-butyl-2- (4-brooaphenyl) -pyridine, 5.5 g of copper-8400195 *, V g of cyanide and 20 ml of N-methylpyrrolidone is refluxed for 2 hours, cooled, poured into a mixture of 25 ml of a 25 wt% aqueous ammonia solution and 100 ml of water and extracted with benzene. The benzene extract is washed with water until the washing liquid reacts neutral, dried over sodium sulfate, passed through a bed of activity grade II alumina, the elution being carried out using benzene. Benzene is distilled off, the residue is recrystallized from hexane to give 5-butyl 2- (4-cyanophenyl) pyridine, mp 3 ° C and clarification temperature of 27.5 ° C; £. / Ƒ = * 29, “15.5, +13.5.

Examples XI-XVI

Similarly, other compounds of the general formula 7 are obtained. Its properties are shown in Table 15B.

Table B

Properties of 5-alkyl-2- (4-cyanophenyl) -pyridines of the Formula 7, wherein R 1 - C 1 2afl 20 Example n Melting Temperature Dielectric Constants 25 ° C

No. temperature tempera. £ ^ Δ __C_ 12 3_4_5_6_7 XI 2 68.0 35.5 37 14 + 23 25 XII 3 42.3 43.7 36 9.5 + 26.5 XIII 5 32.2 43.5 29 11 + 18 XIV 6 27.2 32.6 25.5 12 + 13.5 XV 7 28.5 47 24 9.5 + 15.5 XVI 8 39.5 43 - 30 _

Example XVII

Preparation of a mesomorphic material 39.0 mol% 5-butyl-2- (4-cyanophenyl) -pyridine, 40.5 mol% 5-hexyl-2- (4-cyanophenyl) -pyridine and 20.5 mol% 5 - (4-Amylphenyl) -2- (4-cyanophenyl) -pyridine are placed in a beaker, heated to 90 ° C with stirring and cooled to room temperature. In this way a ready-to-use mesomorphic material is obtained, which has the following characteristic properties: the range of the occurrence of the meso phase: from -7 to + 78eC; 8400195

IP "·" "W

9 1 Δ £ - + 18.5; UthT - 1.1 V, U8at - 1.5 V; the viscosity at 25 * C is 27 mPa.s.

Examples XVIII-mill 5 In a manner similar to the method described in Example XVII above, other mesomorphic materials are obtained by mixing compounds of formulas 7 and 8. The mesomorphic materials obtained have compositions and properties, which are indicated in Table C * 8400195 '10

Table C

Mesomorphic materials containing compounds of formulas 7 and 8

Example Composition of the mesomorphic material. Compound with the R mol% formula 1_2 _3 _4_ XVIII 8 C5Hh 22.8 7 C3H7 33.0 10 7 C4H9 44.2 XIX 8 C5Hn 25.5 7 C2H5 26.0 7 C4H9 15.8 15 7 C6H13 32.7 XX 8 C6ÏX3 27.2 7 C4H9 41.7 7 C6H13 31.1 20 ------------ XXI 8 C4H9 18.2 7 C4H9 39.2 7 C5H11 28.9 7 C8Hi7 13.7 25 ----------- XXII 8 C7H15 16.8 7 C4H9 30.4 7 C5HH 21.5 7 C6H13 31.3 30 ------------ XXIII 8 C5Hn 14, 2 7 C3H7 19.2 7 C4H9 24.7 7 C5H11 16.9 35 7 CgH ^ 3 25.0 XXIV 8 C8H170 18.3 7 CH3 25.7 7 C5H11 24.4 40 7 c7H15 20.8 8400 195 r- - -Ij 11 7 C9H19 10.8 XXV 8 C6H13 21.5 7 C5HU 21.2 5 7 C6H13 30.7 7 C7H15 17.6 7 C8H17 9.0 mi 8 C5Hn 15.6 10 7 C2H5 13.5 7 C5HU 19 .2 7 C6H13 28.1 7 C7H15 15.7 7 C8H17 7.9 15 - rnii 8 c7h15 1.0 7 C2H5 10.0 7 C3H7 16.6 7 C4H9 21.1 20 7. C5HU 14.1 7 C6H13 21.3 7 C7Hi5 10.8 7 C8H17 5.1 25 XXVIII 8 05Ηη 0.5 7 C2H5 16.5 7 C3H7 26.1 7 C5Hn 24.7 7 C7Hi5 21.1 30 7 C8H17 11 , 1

Table C (continued)

Properties of the nesomorphic material 35 Example Melting temperature - Clearance Threshold - Saturation - Anisotropy

No ra ture * C tempera-voltage voltage of the temperature eC VV electrical constant 1_5__6_7_8_9 40 XVIII - 4 + 79 0.9 1.3 + 20.0 8400195 '12 XIX -13 + 67 1.0 1.4 + 19.2 XX - 5 + 84 1.1 1.5 + 18.6 XXI - 7 + 70.6 1.15 1.6 + 18.0 XXII -15 + 67 1.2 1.6 + 18.0 10 XXIII -22 + 63 1.1 1.5 + 18.2 XXIV -12 + 78 1.15 1.65 + 18.0 XXV -16 + 78.6 1.2 1.65 + 18.0 15- ---------- XXVI -25 + 62 1.3 1.7 + 17.2 XXVII -16 + 40 1.05 1.5 + 19.0 20 XXVIII -12 + 45 1.05 1 , 45 + 19

Examples XXIX-XXXV

In these examples, the preparation and properties of a mesomorphic material containing an organic dielectric are described *

In accordance with the procedure described in Example XVIII, reaction of compounds of the formulas 7 and 8 and the organic dielectric cyanobiphenyl derivatives of the formula 1 and cyanophenylcydohexane derivatives of the formula 2 yields other liquid crystal materials which Table D have compositions and properties indicated.

8400 195 w 13

Table D

Mesomorphic materials containing compounds of formulas 1 »2, 7 and / or 8 · 5__

Example No. Composition of the mesomorphic material_

Connection with the R Mass percentage formula 10 1 2 3 4 XXIX 2 C3H7 36.1 2 05Ηχχ 30.8 2 C7H15 21.1 15 8 C5H11 12.0 XXX 1 C5H11 34.5 1 C7H15 39.3 8 C6H13 12.0 20 7 C5HU 6.0 XXXI 2 C3H7 33.6 2 C5H11 28.7 2 C7H15 19.7 25 8 C7H15 8.9 7 C5HU 9.1 XXXII 1 C5H11 55.0 1 C7H15 21.0 30 1 CgH 17O / -V 14.0 1 9 ° ° 7_C5HU W 1.0_ XXXIII 1 Ο ^ χχ 10.0 35 8 C4H9O 17.9 7 C4H9 25.3 7 C5Hxx 17.5 7 C6H13 29.3 40 XXXIV 2 C3H7 31.5 2 05Ηχχ. 20.5 8 C7HX5 12.1 7 C5Hxx 14.4 7 C6®13 21 * 7 45 ----------------------------- -------------------------------------------— XXXV 1 C3H7O 11.8 1 C4H9O 7.0 1 C5HXXO 10.3 1 0 ^ x30 7.3 50 1 C7H15O 9.4 1 C7H17O 13.6 1 c8h17 5.8 8 C5Hxx 5.1 7 ^ 5®11 19.6 55 ___

Table D (continued)

Example Properties of the mesomorphic material__

No. Melting Temp- Clearance Threshold- Saturated! Ngs-

temperature aC temperature * C voltage V voltage V

8 4 00 1 9 5 * r '. ”14 1 5 6 7 8 XXIX - 6 + 74 1.6 2.35 5 XXX - 3 + 60 1.4 1.8 XXXI -12 78 1.6 2.2 XXXII -10 + 60 1.4 1, 8 10 -------- XXXIII -18 +72 1.1 1.5 XXXIV -22 + 66 1.4 1.9 15 XXXV - 7 + 70 1.2 1.7

Example XXXVI

In a manner corresponding to the method described in Example XVIII, a mesomorphic material is obtained, which consists of 9.0 wt.% 4-butylbenzoic acid-4-cyanophenyl ester, 21.6 wt.% 4-hexylbenzoic acid-4-cyanophenyl ester , 16.5 wt. Z 4-heptylbenzoic acid-4-cyanophenyl ester, 5.0 wt. Z 5-methyl-2- (4-cyanophenyl) -pyridine, 7.2 wt. Z 5-ethyl-2- (4- cyanophenyl) -pyridine, 8.4 wt. 5-propy1-2- (4-cyanophenyl) -pyridine, 13.6

25 parts by weight 5-heptyl-2- (4-cyanophenyl) -pyridine, 6.1 parts by weight 5-octyl -2- (4-cyanophenyl) -pridine, 3.8 parts by weight 5-nonyl- 2- (4-cyanophenyl) -pyridine and 8.8 wt

5- (4-hexylphenyl) -2- (4-cyanophenyl) -pyridine. Melting point * -12 ° C, clarification point - + 72eC; üthr = 1.0 V; Ugat - 1.5 V.

Example XXVII

According to the procedure of Example XVIII, a mesomorphic material is obtained, which consists of 25.0% by weight of 5-propyl-2- (4-cyanophenyl) -pyridine, 35.0% by weight of 5-amyl-2- (4- cyanophenyl) -pyridine, 18.0 wt. Z 4-trans-butylcyclohexanecarboxylic acid-4-ethyloxyphenyl ester, 12.0 wt. -butylcyclohexanecarbonyloxy) -4-cyanediphenyl. The material obtained has a melting point of -80 ° C and a clarification point of + 68 ° C; üthr s X »34 V? üsat “^ 81 V ·

40 Example XXXVIII

In a manner corresponding to the method of Example XVIII, a mesomorphic material is prepared, which is particularly suitable for use under multiplex control conditions; the material consists of 30 wt% trans-4-n-butylcyclohexane carboxylic acid, 30.0 wt% 45 trans-4-n-hexyl-cyclohexane carboxylic acid, 10 wt% 2-chloro-4- (4-n-heptyl- 8400195 p '..... * 15 4 benzoyloxy) -benzoic acid-4-cyanophenyl ester, 10.0 wt.% 5-propyl-2- (4-cyanophenyl) -pyridine and 10.0 wt.% 5- hexyl 2- (4-cyanophenyl) pyridine.

The material thus formed has a melting point of -9 ° C and a clearing point of + 64 ° C; 1 »6 V mult iplex ratio 1: 6.

5

Example XXXIX

In a manner corresponding to the method of Example XVIII, a meaomoxf material is obtained, which is particularly suitable for use under the multiple control conditions: the material consists of 25.0 wt.% Trans-4-butylcycloexane carboxylic acid, 25.0 wt% trans-4-hexylcyclohexanecarboxylic acid, 15.8 wt% 4 * octyl-4-cyanedi-phenyl, 9.7 wt% 5-ethyl-2- (4-cyanophenyl) -pyridine, 15 .0 wt.% 5-propyl-2- (4-cyanophenyl) -pyridine, 9.5 wt.% 5-hexyl-2- (4-cyanophenyl) -pyridine.

The material thus formed has a melting point of -5 ° C and a clarification point of + 70 ° C; Üthr “1 · 7 V; multiplex ratio 1: 5.

Example XL

In a manner similar to the procedure described in Example XVIII, a mesomoxic material is obtained, which consists of 24.7 20 wt.% 5-buty1-2- (4-cyanopheny1) -pyridine, 17.1 wt. 5-amyl-2- (4-cyanophenyl) -pyrldine, 28.6% by weight 5-Hexyl-2- (4-cyanophenyl) -pyridine, 17.4% by weight

5- (4-butylphenyl) -2- (4-cyanophenyl) -pyrldine, 10 wt.% 4-amyl-4'-cyanedi-phenyl and 2.2 wt.% Of a red dichroic dye with a positive dlchrolache ratio of 10. The material 25 formed in this way has a melting point of -17 ° C and a clarification temperature of + 72.5 ° C; üthr “l» 1 V * üsat "l» 5 ψ> This material allows the formation of colorless symbols against a red background in a twist indicator.

30 Example XLI

In the manner described in Example XVIII, a mesomorphic material is obtained, which consists of 25.0% by weight of 5-butyl-2- (4-cyanophenyl) -pyrldine, 17.3% by weight of 5-amyl-2- (4-cyanophenyl) -pyridine, 29.1% by weight 5-hexyl-2- (4-cyanophenyl) -pyridine, 17.4% by weight 5- (4-butylphenyl) -2- (4-cyanophenyl) - Pyridine, 10.2 wt.% 4-amyl-4'-cyanediphenyl and 1.0 wt.% Of a golden yellow dye. The obtained material has a melting point of -18 ° C and a clarification point of 72 ° C; Uthr - 1.1 V; Ugat - 1.5 V; with this material la the formation of black symbols against a golden-yellow background in a twist indicator is possible.

40 8400195

- 16 Example XLII

In a manner similar to the method described in Example XVIII, a mesomorphic material is obtained, consisting of 26.8 wt.% Trans-4-propyl- (4-cyanophenyl) -cyclohexane, 18.0 wt.% Trans- 4-a-5 myl- (4-cyanophenyl) -cyclohexane, 12.7% by weight of 5-amy 1-2- (4-cyanophenyl) -pyridine, 19.1% by weight of 5-hexyl-2- (4 cyanophenyl) pyridine, 11.4 wt.% 5- (4-hep-phenylphenyl) -2- (4-cyanophenyl) -pyridine, and 12.0 wt.% of a red dye having a negative dichroism. The material thus formed has a melting point of -18 ° C and a clearing point of + 63 ° C; Ut ^ r * 1.5 10 V; ügat “2.0 V; this material allows the formation of pink-red symbols against a colorless background.

Example XLIII

Following the procedure of Example XVIII, a mesomorphic material is obtained, which consists of 30.0 wt.% Trans-4-propyl- (4-cyanophenyl) -cydohexane, 20.2 wt.% 4-amyl- (4-cyanophenyl) -cyclohexane, 14.2% by weight of 5-amyl-2- (4-cyanophenyl) -pyridine, 21.4% by weight of 5-hexyl-2- (4-cyanophenyl) -pyridine, 12.7 wt 5- (4-octylphenyl) -2- (4-cyanophenyl) -pyridine and 1.5 wt 2 of a dye showing a positive dichroism at an absorbance band of 430 nm and a negative dichroism at an absorbance band of 540 nm. The material thus formed has a melting point of -20 ° C and a clearing point of + 66.5 ° C; Uthr * 1.4 V; Ugat = 1.9 V; this material allows the formation of violet-colored symbols against a yellow background.

25 8400195

Claims (7)

5 R - CnPjafi »Cna2irl-10 n 4-8 * 2. Process for preparing 2,5-disubstituted pyridines according to claim 1, characterized in that a pyrilium salt is used with the general formula 9, in which 10 R - CJ! 2nH0 n 4-8 react in an organic environment with ammonium acetate * 3. Mesomorphous material, characterized in that it contains at least one 2,5-disubstituted pyridine of the general formula 8 and / or 7, wherein in the formula 8 R "Cn? 2ttfl» ^ n®2n + l0 * n 4-8 and in the formula 7 R '“C ^ 2nfl» n “1-9 · 4. Mesomorphic material according to claim 3, characterized in that it contains an organic dielectric in an amount of up to 99% by mass * Mesomorphic material according to claim 3 or 4, characterized in that it contains 1.0 - 12 parts by weight of a dichrolic dye * 6. Electro-optical device, which comprises a liquid crystal-enclosing active part located between optically transparent plates (2), transparent electrodes (3) being provided on the inner sides of these plates, and provided with conductors (4) for connection to a current source, characterized in that this device contains as the active part the mesomorphic material according to claims 30 3-5 * ******* 8400195