GB2220658A

GB2220658A - Liquid crystalline carboxylic esters

Info

Publication number: GB2220658A
Application number: GB8915950A
Authority: GB
Inventors: Dietrich Demus; Hans-Joachim Deutscher; Roger Frach; Horst Kresse; Heiko Stettin; Horst Zaschke
Original assignee: Werk fuer Fernsehelektronik im VEB Kombinat Mikroelektronik VEB; Werk fuer Fernsehelektronik GmbH
Current assignee: Werk fuer Fernsehelektronik im VEB Kombinat Mikroelektronik VEB; Werk fuer Fernsehelektronik GmbH
Priority date: 1988-07-13
Filing date: 1989-07-12
Publication date: 1990-01-17
Anticipated expiration: 2009-07-12
Also published as: CH678858A5; GB2220658B; DE3918884A1; GB8915950D0; JPH0288540A

Description

1 X 1 2220658 Liquid-crystalline 4-(3'-n-alkylcyclopentyl) carboxylic acid

esters The invention concerns liquid-crystalline 4-(3'-n-alkyleyelopentyl) carboxylic acid --"6 esters of the general formula CmH2m+l- X-1 A14'.-COOR and their use in liquid-crystalline mixtures for electro-optical arrangements with low anisotropy of the refraction index for the modulation of the through- passing or reflected light and for coloured or monochrome display of digits characters and moving or non-moving images.

It is known that liquid-crys tal line substances can be used for the modulation of light and for the display of measured values or for the reproduction of information.

These methods are based on the fact that the preferred orientation of thin layers of the crystalline-liquid substances can be modified by application of an electric field. The variation of the preferred orientation of crystal line- liquid substances is connected with a variation of the optical behaviour (double refraction, rotating capacity, light absorption). According to the initial orientation, the dielectric and optical anisotropy, the conductivity, the dichroism and intensity, direction and frequency of the applied electric field achieved by special pre-treatment of the electrodes or by addition of suitable substances, various kinds of electro-optical effects are observed and technically used (M. Tobias:

International Handbook of Liquid Crystal Displays 1975-1976, Ovum Ltd., London; G. Meier, E. Sackmanin, J.G. Grabmeyer:

1 Applications of Liquid Crystals, Springer-Verlag BerlinHeidelberg-New York 1975; N.A. Clark, S.T. Lagerwall: Appl.Phys. Lett. 36. 899 (1980).

By way of example one known method is based upon the fact that by application of an electric field the optical rotating capacity of a coating with twisted structure is eliminated and thus between parallel (crossed) polarisers permeability (extinction) is found for incident light [M. Schadt. W. Helfrich: Applied Physics Letters 18, 127 (1971)].

More recent highly multiplexable displays require the optimalisation of a whole area of substance properties [M. Schadt, Chimia 41, 347 (1987)], which is achieved only by mixing of different liquid-crystalline substances.

In this case important technical parameters are low melting and high clarification temperatures, a positive dielectric anisotropy and an anisotropy of the refractive index adapted to the cell thickness. Here above all the substances are of interest which on addition to a mixture simultaneously increase the clarification temperature, reduce the refraction index anisotropy and produce no change of the sign of the dielectric anisotropy.

It is an object of the invention to find suitable substances which impart a low anisotropy of the refraction index and a higher clarification temperature to a mixture.

The invention provides crys talline- liquid 4-(3-n alkyleyelopentyl)carboxylic acid esters of Formula I CmH2m+l"/'O'-\'X-( _A/\--COOR V the general 1 wherein A, X = CH2)n- n - Oy ly 21 31 m - 0 12 R s. _C>R1;.00 _.R2; _Z - 1-y-Z2; cholesteryl-; RI COU+1 wi th K - 1 12; R2 R1. OR1 CN, Hal. COORly 0COR19 COR1 Z1 0 9 - <C3 4 Y = -COO-9 -OCO2 X; Q R1 2 0 2 W-R R 4 - 4 V.

1 %,." O-X-\/ MH "C 2m+1 or \-C02m+1 R39 R4 - H, CH3 t CNt Fp Cl, Br while H2m+1 0 \.Z2 C when A cannot be X-U m Z2 1 X and when A then cannot be C02m+1 These compounds are added as mixture components to liquid-crystalline mixtures for use in electro-optical components on the basis of liquid- crys tall. ine substances with low anisotropy of the refractive index and high clarification temperatures for the reproduction of digits, characters and images. in quantities of 0.5 - 80 mol%.

Z2.

0 9 Examples of execution The synthesis for compounds in which 0 that is the 4-(3'-n-alkylcyclopentyl)benzoic acid ester., takes place according to the following diagram.

Reaction Diagram 1. 10 -(CH2)n-Hal/Mg/Et20 H =0 2. NH C1/H20 R R 4 1 \//CH2)njO - \i2/ Hal - Br. Cl (CH2)n 1 H2SO4/CH3COOH R' JY 0.

1.11\ ill-/ 1 2 213 Raney-Ni/H2 R1 (CH2)n -0 -i7CH3 4 CH3COC1/A1C13/CS2/0 OC R1-0- (CH2)n - a -(CH2)n-1 0 \-COOH 4 Br21K0H/H20 Rl-,"> 6 1 +Rl(CH2)n- /0 3 6 1 SOC12 -COS R' CH 0 2. R-OHMU3/CH3 _ -COOR -1>- ( 2)n \ / 1 7 The last reaction step is to be explained by the example of 4-(3'-nbutylcyclopentyl) benzoic acid cyanphenyl ester.

0.53 g of 4-(3'-n-butylcyclopentyl) benzoyl chloride and 0.24 g. of 4cyanphenol are heated in 15 ml. of toluene and 1 ml. of triethylamine for 5 h. under reflux. Af ter cooling the reaction mixture is poured on to dilute HCl/ice, the phases are separated and the aqueous phase is extracted 3 times with ether. The united organic extracts are successively washed with dilute HCl, water, 5 % aqueous KOH and water, then dried over Na2S04 and the solvent is removed.

The remaining raw ester is fractionally crystallised 1 1 out of a constancy.

little methanol until clarification point The f 011 owing Table 1 gives examples representatives which were obtained in this way.

C;mH2m+1<(CH2)n-00 -COOR The significances in the Tables are K crystalline-solid S - smectic N - nematic Is - isotropic liquid 1) 80 S 9 98 Se 173 Is Table 1

No. m n R, 1 4 0 0 _CN 2 4 1 -CN 3 4 0 -OC6H13 4 4 1 - 4D -OC6H13 4 0 r H13 6 4 0: O j:C &,-O/-C6Hl3 7 4 1 - RO - 0' -C H A 611.13 1 __ n 8 4 0 0.11- COO \_l OC4H9 9 4 1 - 7 0 COO - 0 -OC4H9 4 0 - COO - 7 -OC4H9 _"CH3 1 - 40- coo ND.O OC4H9 CH3 12 4 0 00C 0 C4'R9 13 4 1 - OOC - SJFO CH2n_ for some K S 0 N 62 28 0 a 52 - - 97. 981 108. (76).

86 43 82 44 43 173 102 212 74 181 83 155 133 141- -.199 99. (95). 147 is 0 0 - t4H9 The synthesis f or compounds in which that is the 4-(3'-n-alkylcyclopentyl) cyclohexane carboxylic acid esters, took place according to the stated diagram:

k A) Raney-Ni/H2 R1-,/Qr(CH2)n"O-COOH--- Rl--(CH2)in -COOH b), i-C5H110H/Na c SOC12 2. R-OH/M3/ CH3-COS (CH2) \-COOR. in \,( The last reaction step is to be explained by the example of 4(3-nbutylcyclopentyl)trans-4'-n-cyclohexane carboxylic acid-C'-cyanphenyl ester.

2m Mol of 4-(3'-n-butylcyclopentyl)cyclohexane carboxylic acid chloride and 0.24 g. (2m mol) of 4cyanophenol are heated in 15 ml. of toluene and 1 ml. of triethylamine for 5 hours under reflux.

After cooling, the reaction mixture is poured on to dilute HCl/ice, the phases are separated and the aqueous phase is extracted 3 times with ether. The united organic extracts are successively washed with dilute HCl, H20y 5 % KOH and H20, dried over Na2S04 The solvent is removed.

The remaining raw ester is fractionally crystallised out of a little methanol, to clarification point constancy.

Examples for substances which were obtained in this way are given by the following Table 2 CmH -COOR 2m+1 -(CH2)n Table 2

No 14 15 16 17 18 19 20 21 22 23 24 m n 4 0 4 1 4 0 4 1 4 0 4 1 4 0 4 1 4 0 4 1 4 0 R W\ W - -W no, -OC6H13 O 1 -OC6H13 -C6H13 -C6H13 OX -QO -C6H13 o', 00 - -Ojx-C6H13 fox - Coo- o.\ -0e4H9. 78. 111 183 WO -Coo- 0) -0e4H9. 92. 118. 165 -Coo- 0 -OC09. 78 (.69) K S1 S2 N 0 53 - - 63 0 76 - - 60) 0 63 81 98 - 73 81 41 --. 103 0 30 - -. 100 0 70. 159. 184 0 30. 155. 163 I 107 97 102 193 176 221 206 167 0 CH3 f H9. 65 153 4 1 1CO:1 -Coo- C1_) -OC4 CH3 26 4 0 - -ooc-C I-C Hq. 86. 168. 176.214.

27 4 1 -ooc- -CH2 "C4H9 42 173 196 The following examples are to substantiate the properties of the compounds according to the invention in mixtures.

mol % of Substance 1 were dissolved in 90 mol % of a basic mixture GM of 24 mol % methoxybenzoic acid -4-n-hexyloxyphenyl ester, 27 mol % 4-n-pentyloxybenzoic acid -4-n-octyloxyphenyl ester, 12 mol % 4-n-hexyloxybenzoic acid 4-n-heptyloxyphenylester and 37 mol % 4-n-hexylbenzoic acid -4-n-butyloxyphenyl ester.

The conversion temperatures from the nematic into the isotropic phase rose from 71 0 C. in the case of basic i mixture to 72.5 0 C. in the mixture Mi. 20 K below the conversion temperature the anisotropies of the refraction index &n(GM) - 0.1246 and 4'n(M') = 0.1228. According to the simple mixture rule 4 E (Mi) = X(GM) Z% r (GM) + X(B)L'\, (B) with the known dielectric anisotropy of the basic mixture (GM) -0.312, 20 K under the clarification temperature, the mol fraction of the basic mixture x(GM), the mol fraction of the dissolved substance 1 X(B) and the dielectric anisotropy 11 (Mi) - 1.6950 measured in the mixture, 20 K below the clarification temperature, for the dielectric anisotropy of the pure substance there results 1AE(B) - 19.8. Example 2 7 mol % of substance 6 were dissolved in 93 mol % of the basic mixture GM (see Example 2).

The conversion temperatures from the nematic into the isotropic phase rose from 710 C. in the case of GM to 750 C in the mixture Mi. 20 K below the conversion temperature the anisotropy of the refractive index of the" mixture was ascertained at&h(Mi) - 0.1003. From the known value for A t\(GM)= 0.1246 it is possible, according to the primitive mixture ruleA h (Mi) = X(GM). & t) (GM) + X(B).4 h (B), to calculate a 4 r\ (B) for the dissolved substance 6 as Aj.,(B) = -0.2225. The negative sign indicates an above-proportional reduction of the anisotropy of the refractive index by substance 6.

Example 3

The solubilities at 200 C. were calculated from the - 10 fusion enthalpies A sch H and the fusion temperatures stated in Table 1.

Subst.no. Asch h xl M/mol-1 1 19.0 0.377 3 24.3 0.375 7 28.9 0.065 8 31.9 0.057 30.6 0.109 11 37.8 0.073.

Very good to good solubilities occur in nematic basic mixtures (X, - mol fraction of the limit solubility of Component i).

Example 4

The good mixing behaviour of the substances according to the invention with one another were tested on a mixture of Subst.No. 1 3 8 10 X, 0.4039 0.4103 0.0643 0.1215.

The said mixture melts at 25' C., changes at 740 C. from the smectic A into the nematic phase and passes over at 1020 C. into the isotropicliquid phase.

Example 5 mol % of substance 18 were dissolved in a mixture (GM) of 24 mol % 4-methoxybenzoic acid -4'-n-hexyloxyphenyl ester, 27 mol % 4-pentyloxybenzoic acid -4'-n-octyloxyphenyl ester, 12 mol % 4hexyloxybenzoic acid 4'-n-heptyloxyphenylester 37 mol % 4-hexylbenzoic acid -4'-n-butyloxyphenyl ester.

The clarification temperature then rose from 710 C. to 720 C. The anisotropy of the refractive index for TNI-T = 20 K amounted for GM to A n(GM) = 0.1246 and for the mixture bn(Mi) to 0.0985. According to the simple mixture rule hLN(Mi) = X(S)An(5)+ x(GM)A n(GM) (1), in the case of known mol fraction of the basic mixture x(GM) and of the dissolved component x(5) results for the refractive index anisotropy of the pure substance 5 & n(5) = -0. 1364. The negative anisotropy is an indication that substance 5 effects an above-proportional reduction of the refractive index anisotropy of the basic mixture GM.

Example 6

The mixtures stated in Example 5 were measured dielectrically. For TNI-T 20 Ky -0.312 was ascertained for GMAE. For 'the mixture 6- -0.385. According to a primitive mixture rule 5) - [,a E (M) - 0. 9.4 E(GM)) /0. 1 we obtain, for the dielectric anisotropy of the dissolved component, with TNI-T = 20 K h(5) = -1.04, which indicates a low influence upon the basic mixtures used in each case.

Example 7

A mixture was produced from 0.320 mol % Substance No. 169 0.324 mol % Substance No. 17 and 0.348 mol % 4-methoxy benzoic acid 4'-nhexyloxyphenyl ester. The mixture melts at 240 C into the nematic phase and converts at 830 C. into the isotropic liquid phase. Even on undercooling to 00 C. it was not possible to record the occurrence of smectic phases which was observed in the cases of Substances 16 and 17.

Example 8

The good solubility of the substances according to the invention at 200 C. and the fusion enthalpies "schmH are illustrated by the following review Subst. No. 16 17 18 23 25 A-schmHMmol-1 22.6 22.4 29.1 173 22.0 X (limit solubility) 0.298 0.294 0.456 0.237 0.300 0 1

Claims

Claims l.) Crystalline liquid 4-(3'-n-alkylcyclopentyl) carboxylic acid

esters of the general Formula I c mH2m+1 X-e' A -COOR I wherein /0 A\= ---ICH2)n- n - 01 11 29 31 4 m = 0 - 12 R \-R' R2; _Zl_y_Z2; cholesteryl-; -1; J:0) - R1 COU+1 with K - 1 - 12; R2 R1. OR19 CN, Hal, COOR1, 0COR1q COR' Z1 0 Y - -COO-Y -OCO-9 X; 1 LR2 jo- Z2 0 _\ _p2 -R -\ or p IZ 1 7 \0 R3 R4 X-CmH2m+1 - -X- -CMH2m+1 R39 R4 = Hq CH3 9 W9 F9 Cl, Br while when A then Z2 c -iG cannot be <D-X- CmH2m+1 and when A --/ 0 then Z2 cannot be)-X- > \1.111, C02m+1 - 2.) Mixtures with low anisotropy of the refractiv index and high clarification temperatures with liquidcrystalline compounds according to Claim 1 in quantities of 0.5 - 80 mol %.

1 1 1 L 3. Liquid crystalline 4-(31-n-alkylcyclopentyl) carboxylic acid esters as claimed in claim 1 wherein n is 0 or 1.

4. Liquid crystalline esters as claimed in claim 1 or claim 3 wherein m is 4.

5. A liquid crystalline ester substantially as described herein with reference to the Examples and Tables.

6. A method of preparing a liquid crystalline ester substantially as described herein.

7. A mixture with low anisotropy of refractive index and high clarification temperature substantially as described herein with reference to the Examples.

8. Use of an ester or mixture as claimed in any one of claims 1, 3, 4, 5 or 7 in liquid-crystalline mixtures for electrooptical arrangements.

Published 1989 atThe Patent Offtee, State Horuse.66171 High Holborn, London WC1R4TP. Purther copies maybe obtaluedfvom ThePatent Office. Sales Branch, St Itary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. 1/87