US 4,358,393 AGrant
Nematic Liquid Crystals of 5-Cyano-2-[4-Acyloxyphenyl]-Pyrimidines and Mixtures Containing the Same
Issue Date:1982-11-09
•10 Claims
Abstract
Nematic liquid crystals are employed in electro-optical devices for the modulation of the transmittant or incident light and for the black and white or colored rendition of numerals, symbols and pictures. The object of the invention is the use of nematic liquid crystals having a high positive dielectric anisotropy, a low threshold and operating voltage and high clear points and a process for making these compounds. It was found that as liquid crystals for electro-optical devices mixtures are useful which, as an essential component, contain one or several compounds from the class of 5-cyano-2-[4-acyloxyphenyl]-pyrimidines of the formula ##STR1## wherein R.sup.1 is ##STR2## C.sub.5 H.sub.11 -- or C.sub.n H.sub.2n+1 O-- R.sup.2 is C.sub.n H.sub.2n+1 ; C.sub.n H.sub.2n+1 O; C.sub.n H.sub.2n+1 S; F; Cl; Br; CF.sub.3 ; C.sub.n H.sub.2n+1 COO; C.sub.n H.sub.2n+1 OCOO; CN; NO.sub.2 ; C.sub.n H.sub.2n+1 NH; or C.sub.n H.sub.2n+1 (CH.sub.3)N, n is 1 to 10, and R.sup.3 is C.sub.n H.sub.2n+1, n is 1 to 10.
Metadata
Assignee
- VEB Werk fur Fernsehelektronik im VEB Kombinat Mikroelektronik
Inventors
- Horst Zaschke
- Dietrich Demus
- Sylvia Deresch
Application Information
Application Number:US 1450603
Filing Date:1980-04-30
Priority Date:1979-05-15
Art Unit:223
Classifications
IPC:
C09K 334G02F 113C07D23932
Field of Search:
252544299.5;299.61;299.63242;335
Patent Drawings
This patent does not have any drawings.
Description
Background of the Invention
The invention relates to nematic liquid crystals constituted by 5-cyano-2-[4-acyloxyphenyl]-pyrimidine can be used in electro-optical devices for the modulation of the transmitted or incident light and for the black and white or colored rendition of numerals, symbols and pictures.
Nematic liquid crystals having a positive dielectric anisotropy are used for electro-optical devices on the basis of the field effects, particularly of the Schadt-Helfrich effect. The compounds heretofore used which always consisted of mixtures of several compounds partially having too high a threshold and operating voltage and on the other hand too low a clear point so that they are not suited for use at higher temperatures.
An object of the invention is the use of nematic liquid crystals having a high positive dielectric anisotropy, a low threshold at operating voltage, and a high clear point, and a process for making the same.
Summary of the Invention
This object is accomplished according to the invention by forming new liquid crystals and providing processes for preparing them which were previously not known. It was found that liquid crystals in the form of 5-cyano-2-[4-acyloxyphenyl]-pyrimidine of the formula ##STR3## wherein ##STR4## or C.sub.n H.sub.2n+1 O-,
R.sup.2 =C.sub.n H.sub.2n+1, C.sub.n H.sub.2n+1 O, C.sub.n H.sub.2n+1 S, F, Cl, Br, CF.sub.3, C.sub.n H.sub.2n+1 COO, C.sub.n H.sub.2n+1 OCOO, CN, NO.sub.2, C.sub.n H.sub.2n+1 NH, C.sub.n H.sub.2n+1 (CH.sub.3)N,
and n=1 to 10 as well as
R.sup.3 =C.sub.n H.sub.2n+1, with n=1 to 10.
can be employed for electro-optical structural elements for the modulation of the transmitted or incident light as well as the black and white or colored rendition of numerals, symbols and pictures in the form of mixtures containing at least one compound of the invention. The advantages of the compounds of the invention are in their high dielectric anisotropy, the high clear point and the low threshold at operating voltages. An advantage is also in their black and white or colored rendition of numerals, letters or symbols in electro-optical devices.
Detailed Description of Preferred Embodiments
The invention will be explained as follows by way of five examples:
Example 1
The following Table shows Examples for the 5-cyano-2-[4-acyloxyphenyl]-pyrimidines.
Example 2
A mixture of the composition
is suitable for electro-optical structural elements of the basis of the Schadt-Helfrich effects and has the following properties:
Example 3
Preparation of 5-cyano-2-[4-hydroxy-phenyl]pyrimidine.
50 ml abs. triethylamine, 50 ml abs. pyridine, 17.3 g (0.1 mol) 4-hydroxybenzamidine-hydrochloride and 11 g (0.1 mol) .alpha.-cyano-.beta.-dimethylamino-acroleine are heated upon stirring for 6 hours to 80.degree. C. Dark brown colored reaction mixture is poured on ice/concentrated H.sub.2 SO.sub.4 (500 g/50 ml), the precipitate is removed by suction, washed thoroughly with water and recrystallized from methanol/activated carbon. The yield is 12.8 g (65% of the theoretical value). m.p.: 160-262 (sublimed).
Example 4
The preparation of the 5-cyano-2-[4-acyloxy-phenyl]-pyrimidines
The preparation of these compounds is effected by reacting the 5-cyano-2-[4-hydroxy-phenyl]-pyrimidine with acid chlorides according to the modification of Einhorn or Schotten-Baumann according to the general scheme: ##STR10## 1.97 g (0.01 mol) of 5-cyano-2-[4-hydroxy-phenyl]-pyrimidine and 0.015 mol of a corresponding acid chloride are stirred into 25 ml absolute pyridine for 6 hours at room temperature whereupon the mass is heated for 5 minutes at reflux and is permitted to stand overnight.
The reaction product is poured onto ice/concentrated H.sub.2 SO.sub.4 (300 g/20 ml), is taken up in ether and the ether and the ether phase is washed with 1 n KOH solution and water. Subsequently it is dried with Na.sub.2 SO.sub.4, the solvent is distilled off at a rotary evaporator and the residue is recrystallized several times from n hexane. The yield is 70 to 90% of the theoretical.
Example 5
Making of the 5-cyano-2-[4-alkyl or alkyloxy-phenyl]-pyrimidines.
This production is effected according to the general scheme I in which R'=C.sub.n H.sub.2n+1 -- or C.sub.n H.sub.2n+1 O--.
40 ml of absolute triethylamine, 1,1 g (0.01 mol) .alpha.-cyano-.beta.-dimethyl-amino-acroleine and 0.01 mol substituted benzamidine-hydrochloride or the free base thereof were heated upon stirring for 6 hours to 80.degree. C. The cooled reaction gas was poured onto 150 g ice/30 ml concentrated H.sub.2 SO.sub.4, the precipitate was removed by suction, washed thoroughly with water and subsequently recrystallized several times in n-hexane. The yield was 75 to 95% of the theoretical value. Examples are found in Table 2.
Claims
We claim:
1. A 5-cyano-2-[4-acyloxyphenyl]-pyrimidine of the formula ##STR12## wherein R.sup.1 is ##STR13## and n=1 to 10.
2. The compound of claim 1 wherein R.sup.1 is ##STR14##
3. The compound of claim 1 wherein R.sup.1 is ##STR15##
4. The compound of claim 1 wherein R.sup.1 is ##STR16##
5. The compound of claim 1 wherein R.sup.1 is ##STR17##
6. A nematic, liquid crystal composition comprising at least one nematic, liquid crystal compound and a compound of claim 1.
7. The composition of claim 6 comprising said at least one nematic liquid crystal compound of different structure from said compound.
8. The composition of claim 7 wherein said at least one compound of different structure is selected from the group consisting of 4-n-propylcyclohexanecarboxylic acid-4-cyanophenylester, 4-n-butylcyclohexanecarboxylic acid 4-cyanophenylester, 4-n-pentylcyclohexanecarboxylic acid 4-cyanophenylester, and mixtures thereof.
9. 5-cyano-2-(4-hexyloxycarbonyloxy phenyl) pyrimidine.
10. A nematic liquid crystal mixture composed of 4-n-propylcyclohexanecarboxylic acid-4-cyanophenylester 30% 4-n-butylcyclohexanecarboxylic acid-4-cyanophenylester 30% 4-n-pentylcyclohexanecarboxylic acid-4-cyanophenylester 30% 5-cyano-2-[4-hexyloxycarbonyloxy-phenyl]-pyrimidine 10%. ______________________________________
Patent Citations (21)
| Patent | Date | Inventor | Cited By |
|---|---|---|---|
| US3947375 | 1976-03-01 | Gray et al. | |
| US3951846 | 1976-04-01 | Gavrilovic | |
| US3952046 | 1976-04-01 | Scherrer et al. | |
| US3997536 | 1976-12-01 | Boller et al. | |
| US4062798 | 1977-12-01 | Boller et al. | |
| US4112239 | 1978-09-01 | DuBois et al. | |
| US4113647 | 1978-09-01 | Coates et al. | |
| US4136053 | 1979-01-01 | Steinstrasser | |
| US4200580 | 1980-04-01 | Hsu | |
| US4229315 | 1980-10-01 | Krause et al. | |
| US4256656 | 1981-03-01 | Beguin et al. | |
| US4311610 | 1982-01-01 | Zaschke et al. | |
| DEX2257588 | 1973-06-01 | ||
| DEX2846409 | 1979-06-01 | ||
| DEX2854310 | 1979-06-01 | ||
| DDX105701 | 1974-05-01 | ||
| DDX132591 | 1978-10-01 | ||
| DDX139852 | 1980-01-01 | ||
| DDX143625 | 1980-09-01 | ||
| JPX54-6884 | 1979-01-01 | ||
| JPX54-11887 | 1979-01-01 |
Non-Patent Literature (6)
- Boller, A. et al.; Mol. Cryst. Liq. Cryst., vol. 42, No. 1-3, pp. 215-231 (1977).
- Nash, J. A. et al., Mol. Cryst. Liq. Cryst., vol. 25, pp. 299-321 (1974).
- Zaschke, H., J. Prakt. Chemie., vol. 317, No. 4, pp. 617-630 (1975).
- Schubert, H. et al.; J. Prakt. Chemie, vol. 312, pp. 494-506 (1970).
- Demus, D., "Nonemissive Electrooptic Displays", pp. 83-119 (1975).
- Zaschke, H., Advances in Liquid Crystal Research and Applications, Bata, Lajos, Pergamon Press, Oxford, pp. 1059-1074 (1980), Proceedings of the Third Liq. Cryst. Conf. of Socialist Countries, Budapest, 27-31, Aug. 1979.