EP0773980A1

EP0773980A1 - Process for producing liquid crystal mixtures

Info

Publication number: EP0773980A1
Application number: EP95927740A
Authority: EP
Inventors: Karl Siemensmeyer; Karl-Heinz Etzbach; Paul Delavier; Frank Meyer
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1994-08-05
Filing date: 1995-07-28
Publication date: 1997-05-21
Also published as: WO1996004351A1; KR970704855A; JPH10503541A; CN1158142A; DE4427766A1

Abstract

Disclosed is a process for producing mixtures of liquid crystal compounds, wherein at least one of the starting components consists of a mixture of at least two compounds and this mixture is reacted, using methods that are known per se, with at least one other starting component to form a static mixture.

Description

Process for the preparation of liquid crystalline mixtures

description

The invention relates to a process for the preparation of mixtures of liquid-crystalline compounds, characterized in that at least one of the starting components consists of a mixture of at least two compounds and this mixture is reacted with at least one further starting component to form a statistical mixture by methods known per se .

As a pure substance, liquid-crystalline materials generally do not have the properties desired for the application. It is only by mixing different liquid-crystalline and, if desired, also non-liquid-crystalline compounds that it is possible to extend the property spectrum of the liquid-crystalline material e.g. with regard to the liquid crystal phase temperatures, electro-optical switching times, birefringence or viscosity for the intended application. Mixtures which contain a large number of different compounds, usually significantly more than ten, are generally required for applications in electro-optics, be it in the field of neic or ferroelectric phases. Liquid crystalline compounds exist with very different structures, but the components do not differ very drastically in many mixtures. For example, Mixtures of various alkoxycyanobiphenyls, phenylcyclohexanes or phenyl benzoates are described, which often differ only in the length of the side chains. Nevertheless, for these mixtures each component is first synthesized and purified on its own, and only in a subsequent mixing step is the mixture with the desired property profile produced. Many liquid-crystalline mixtures often also contain components of different homologous series mixed with one another, but almost always there are several components from a homologous series. It is also known that low molecular weight, non-liquid-crystalline materials are added to reduce the flow viscosity.

Since in the known (see DE-OS 2 927 277, DE-OS 2 636 684, DE-OS 2 702 598, DE-OS 2 701 591, DE-OS 2 747 113, DE-OS 2 907 332, EP- B-14840, as well as the German patent applications P 44 08 170.7, P 44 08 171.5 or P 44 05 316.9) Process for the preparation of liquid-crystalline mixtures each individual component must be synthesized separately, the synthetic effort is very high. In particular, the space-time The yield of such a process is naturally low if the synthesis of all components is considered.

It was therefore an object of the present invention to find a new process for the preparation of liquid-crystalline mixtures which is less complex, requires fewer cleaning steps and has a higher space-time yield in the synthesis.

Accordingly, the process according to the invention for the preparation of mixtures of liquid-crystalline compounds has been found.

The process is particularly suitable for the preparation of mixtures of liquid-crystalline compounds of the general formula I.

_(Z 1 _γl) _ _A ι _{y2 M} y3 _A 2 ( _Y 4 _Z ² ) _n I in which

Z ¹ , Z ² polymerizable groups,

Y ¹ , Y ² , Y ³ , Y ⁴ chemical bonds or bridge members

-, —CO— R— or - R — CO—,

R is hydrogen or -CC ₄ alkyl,

m, n O or 1,

A ¹ if m = 0, hydrogen, one

C ₁ -C ₃ o-alkyl group which can be interrupted by oxygen in ether function or by non-adjacent imino or C 1 -C ₄ alkylimino groups or halogen, nitro, cyano, trifluoromethyl, difluoromethyl or in the event that m = 1 , a C -C ₂ _ alkylene group, which can be interrupted by oxygen in ether function or by non-adjacent imino or -CC ₄ -alkylimino groups,

A ^{2 is} a group of the definition of A ¹ , the conditions for m being replaced by corresponding conditions for n and

M is a mesogenic group consisting of 2 to 5 saturated or unsaturated five- to seven-membered carbocyclic or heterocyclic groups, which are represented by the same or different bridge members of the definition of Y ¹ - Y ^{4 are} connected.

These compounds can contain polymerizable radicals Z ¹ or Z ² . Preferred radicals Z ¹ or Z ² are, for example

N ^: N ^: C = S, 0 - CS N,

the residues are particularly preferred

CH ₃

(the end lines indicate free valences)

where the radicals R are hydrogen or -CC ₄ alkyl groups and may be the same or different.

The various groups Z ¹ , Z ² , A ¹ , A ² and M of the compounds I are connected by bridge members Y ¹ , Y ² , Y ³ and Y ⁴ . Preferred

Bridge members are oxygen, —0 — CO— and

In the event that m and / or n = 0, the groups A ¹ or A ^{2 can be} hydrogen or -C-C ₃ o-alkyl groups.

Examples of such radicals A ¹ and A ² are: Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, 2-methylpentyl, heptyl, octyl, 2-E hylhexyl, isooctyl, nonyl, isononyl , Decyl, isodecyl, undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl or eicosyl. (The designations isooctyl, isononyl, isodecyl and isotridecyl are trivial designations and come from the alcohols obtained after oxosynthesis (cf. Ulimann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. AI, pages 290 to 293, and Vol. A 10, pages 284 and 285)).

Of these, alkyl groups with 1 to 18 carbon atoms are preferred, particularly preferably with 4 to 12 carbon atoms.

Linear alkyl groups are also preferred.

The alkyl groups can also be interrupted by oxygen in ether function or by non-adjacent imino or C ₁ -C ₄ alkylimino groups. Examples of such groups A ¹ and A ² are:

2-methoxyethyl, 2-E oxyethyl, 2-propoxyethyl, 2-butoxyethyl, 2- or 3-methoxypropyl, 2- or 3-ethoxypropyl, 2- or 3-propoxypropyl, 2- or 3-butoxypropyl, 2- or 4- Methoxybutyl, 2- or 4-E hoxybutyl, 2- or 4-butoxybutyl, 3, 6-dioxaheptyl,

3, 6-dioxaoctyl, 4, 8-dioxanonyl, 3,7-dioxaoctyl, 3,7-dioxanonyl,

4,7-dioxaoctyl, 4,7-dioxanonyl, 4,8-dioxadecyl, 3, 6,9-trioxadecyl, 3,6, 9-trioxaundecyl, 3,6,9,12-tetraoxatridecyl or 3, 6, 9,12-tetraoxatetradecyl and the corresponding radicals which contain imino, methylimino, ethylimino, propylimino or butylimino groups instead of oxygen.

A ¹ and A ² can furthermore be halogen, preferably fluorine, chlorine and bromine. However, if one of the radicals A ¹ or A ^{2 is} a halogen or another radical of small size such as cyano, nitro, methyl, ethyl or propyl, the other radical A ¹ or A ^{2 is} preferably a longer-chain alkyl or alkylene radical.

In the event that m and / or n = 1, A ¹ or A ^{2 is} a C ₂ -C ₀ alkylene group which can be interrupted by oxygen in ether function or by non-adjacent imino or C ₄ -C ₄ alkylimino groups . Such groups A ¹ or A ² are, for example, all those groups which are derived from the alkyl radicals with 2 to 20 C atoms mentioned for the case of m and / or n = 0 and from the one mentioned there through oxygen, Imino or alkylimino groups interrupted alkyl groups. 96/04351 PC17EP95 / 03002

All known mesogenic groups can be used as residues M. Groups of the formula come in particular

- (—T — Y ⁵ ) —T, in which the variables have the following meaning:

saturated or unsaturated five- to seven-membered carbocyclic or heterocyclic groups,

Y5 bridge members as defined for Yi-Y ⁴ ,

r 1 to 4,

where the radicals T and Y ^{5 may be the} same or different.

R is preferably 1 or 2.

The radicals T can also be ring systems substituted by fluorine, chlorine, bromine, cyano, hydroxy or nitro. Preferred radicals T are:

and Particularly preferred as mesogenic groups M are, for example

where R ¹ , R ² and R ^{3 are} hydrogen, 0CH ₃ , CH ₃ , F, Cl or Br,

among these, the groups are particularly preferred

The process for the preparation of mixtures of liquid-crystalline compounds of the general formula I is characterized, for example, in that

a) one or more of the compounds Ha

HY ² MYH Ha by methods known per se with, if only one compound Ila is used, a plurality of purple compounds or, if more than one compound Ila is used, at least one purple compound

(Z ¹ - ¹ ) —A ¹ —x ¹ nia, where

X ^{1 is} hydroxyl, amino, carboxyl or another condensable group or halogen or another leaving group

or

b) one or more compounds llb

_(z ι— _γ ι _{) 5r} ___ _A ι— _γ2 - _M ι— _X 2 _{H IIb}

according to methods known per se with, if only one compound 11b is used, several compounds IIIb or, if several compounds IIb are used, at least one compound IIIb

X ³ 0C M ² CO X ³ IIib, where

M ¹ and M ² constituents of the mesogenic groups M, consisting of 1 to 2 saturated or unsaturated five- to seven-membered carbocyclic or heterocyclic groups, in the event that M ¹ and / or M ² consists of two such groups, these are connected by a bridge link of the definition of Y ¹ ,

X ² 0, S or NR and

X ^{3 is} halogen or OH

or

c) one or more compounds Ilc

(Z ¹ - Yi) - A ¹ - Y ² - ¹ - CO - χ ³ Ilc by methods known per se with, if only one compound Ilc is used, a plurality of compounds IIIc or, if several compounds Ilc are used, at least one compound IIIc

HX ² M ² X ² H IIIC.

The three variants a), b) and c) have in common that at least one of the starting components consists of more than one compound, but these compounds have the homologous structures indicated. The multiple starting components preferably consist of 2 to 10, particularly preferably 3 to 8, different homologous compounds.

The quantitative ratios of the compounds within a multiple component depend on the properties that are to be achieved for the liquid-crystalline mixture. It is advantageous to optimize the desired properties by varying the proportions. The individual compounds are generally used in amounts of 1 to 99 mol%, preferably 5 to 95 mol%, particularly preferably 10 to 90 mol%, based on the sum of the compounds of a component.

The components Ila and lila, IIb and Illb or Ilc and IIIc are generally used in a ratio of 20: 1 to 1:20, preferably in a ratio of 5: 1 to 1: 5, particularly preferably in an approximate range stoichiometric ratio.

The reactions are generally carried out in the presence of a solvent. Particularly suitable solvents are moderately polar aprotic solvents such as pyridine, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, acetone, methylethyl ketone or propyl ethyl ketone.

The reactions are advantageously carried out at temperatures from 10 ° C. to 150 ° C., preferably between 30 and 100 ° C., particularly preferably between 40 and 80 ° C. In general, atmospheric pressure is used.

The properties of the resulting liquid-crystalline mixtures are shaped by the number, the proportions and the structural differences of the compounds used. A particularly suitable structural variation is, for example, the use of compounds with different lengths of groups A ¹ or A ² or different substitution patterns. Variants a), b) and c) differ in that synthesis step in which a statistical mixture of different compounds is generated by using multiple starting components.

According to variant a), the statistical mixture is obtained by reacting the mesogenic group substituted by Y ² H and Y ³ H with a compound IIIa

( _Z ι — γi) —A ¹ —X ¹ purple. X ¹ is a condensable group such as, for example, hydroxyl, amino or carboxyl, or a group which easily escapes in a nucleophilic substitution reaction, such as Br, J or tosylate. A condensation reaction can be carried out according to generally known methods, for example with the aid of carbodiimides or other condensation agents, and is particularly suitable for producing an ester or amide bond.

According to variant b), the statistical mixture is generated when the mesogenic group M is built up, a central part M ^{2 of} the mesogenic group M, which is doubly substituted with carboxyl or acid halide groups, serving as a starting component. The second component carries on the molecular parts M ¹ hydroxyl, mercapto, amino or alkylamino groups, which can react in a known manner with the carboxyl or acid halide groups of M ² .

According to variant c), the statistical mixture is also generated when the mesogenic group M is built up, but the reactive groups of M ¹ and M ² are interchanged in comparison to variant b).

Furthermore, the method according to the invention is suitable e.g. for the preparation of the compounds IV

in which for 96/04351 PC17EP95 / 03002

11

Z ¹ , Y ¹ , Y ² , Y ³ , A ¹ , M and m the definitions given above apply and

s 0 or 1 and

A ^{3 is} a C ₁ -C ₂ -alkylene group which can be interrupted by oxygen in ether function or by non-adjacent imino or C 1 -C ₄ -alkyl imino groups,

where the radicals Z ¹ , Y ¹ , Y ² , Y ³ , A ¹ , A ³ and M and the variables and s, since they occur 6 times in the formula, can be the same or different.

As group A ³ , the same groups come into consideration as were mentioned for A ¹ and A ² in the case where m = 1.

In addition to the mesogenic groups mentioned for the compounds I, group M which is particularly preferred here is substituted triphenylene radicals.

A statistical mixture of different compounds IV is produced by mixing several compounds IVa

_(Z 1 γl) —AI (Y ² MY ³ A ³ ) _S X1 IVa where X ^{1 has} the meaning given above

according to known methods with 2,3,6,7, 10,11-hexahydroxy triphenylene (IVb)

implements.

The reaction can be carried out according to the same methods as described for the reaction of Ila with purple.

Another possibility for influencing the properties of the liquid-crystalline mixtures is the hydrogenation of the statistically generated mixture. The hydrogenation can be carried out according to generally known methods. Hydrogenation is particularly suitable for Transformation of aromatic ring structures within the mesogenic group M into saturated ring structures.

Surprisingly, it was found that the mixtures produced according to the invention have no disadvantages compared to conventionally produced mixtures, since they also behave practically like individual compounds with regard to the cleaning options, in particular in chromatography processes such as HPLC and MPLC.

The great advantage over the production of individual compounds for the production of the mixtures consists in the simplified synthesis, since as a rule only one mixture has to be produced instead of many individual compounds. Space-time yield and solvent consumption are therefore significantly cheaper in the process according to the invention.

The process according to the invention also makes it possible to produce mixtures which are not accessible by conventional means or can only be obtained with great effort, since the synthesis effort according to the conventional process of single-component synthesis, e.g. with the variation of several feed components increases exponentially with the complexity of the mixture.

On the other hand, the method according to the invention enables easily complex mixtures with properties optimized for the application, e.g. with regard to viscosity, switching time, phase state ranges, birefringence or dielectric anisotropy.

Examples

Some commonly used abbreviations are listed below:

K crystalline phase,

S smectic phase,

N nematic phase,

I isotropic phase.

The phase transition temperatures were determined in a Mettler microscope heating table (FP800 / 84) in connection with a Leitz polarizing microscope (Ortholux-Pol-II). The percentages for the compositions of the mixtures all relate to percentages by mass. Any deviating information is given as a unit.

5 All starting materials are described in the literature, so that there is no need to go into their synthesis here. The stages of the synthesis in which the mixtures are produced are explicitly described.

10 Example 1

Synthesis of mixture 1 consisting of

66.7% 4-hexoxybenzoic acid (4'-pentylphenyl) ester 15 33.3% 4-methoxybenzoic acid (4'-pentylphenyl) ester

1.64 g (0.01 mol) of 4-pentylphenol were dissolved in 50 ml of toluene and

0.95 g (0.012 mol) pyridine dissolved. A solution of 1.60 g (0.00667 mol) of 4-hexoxybenzoic acid chloride and 0.566 g is then at 50 ° C.

20 (0.00333 mol) 4-methoxybenzoic acid chloride dissolved in 40 ml of toluene were added dropwise. After the reaction has ended, the reaction mixture is added to 50 ml of water and the organic phase is separated off. After shaking with concentrated potassium hydroxide solution and then neutralizing, the organic phase becomes again

25 separated, dried with anhydrous magnesium sulfate and the solvent removed. The yield of mixture 1 is 2.8 g (87% of theory).

Phase behavior: N 49.1 I

30

Example 2

Synthesis of mixture 2 consisting of

35 29% 4- [trans-4-propylcyclohexyl] benzonitrile 41% 4- [trans-4-pentylcyclohexyl] benzonitrile 30% 4- [trans-4-heptylcylohexyl] benzonitrile

a) 3.61 g (0.0258 mol) of 4-propylcyclohexanone, 5.5 g (0.03272 mol) of pentylcyclohexanone are added to a solution of 18.1 g (0.1 mol) of phenylmagnesium bromide in 40 200 ml of diethyl ether with stirring and 4.22 g (0.022 mol) of heptylcyclohexanone, dissolved in diethyl ether, were added dropwise. The mixture is heated for 2 hours on a water bath, then allowed to cool and hydrolyzed by adding 200 g of 45 crushed ice. Then you give so much saturated

Ammonium chloride solution that the precipitate is just dissolving. The ethereal layer is separated and the aqueous one Phase extracted twice with diethyl ether. The combined ethereal solutions are dried with sodium sulfate and then concentrated in vacuo. The cis / trans-isomeric 4-alkyl-1-phenylcyclo-5 hexanols formed approximately in a ratio of 1: 1 are separated on a column filled with silica gel 60 (eluent: petroleum ether, boiling range 50 to 70 ° C., which has up to 15% increasing proportion of diethyl ether ent). The cis product is hydrogenated with H ₂ / Raney nickel in ethanol with retention and the trans product with palladium / activated carbon (10% Pd) in ethanol with inversion. Yield: 12.51 g

b) The product mixture from a) is combined and then after

Friedel-Crafts acetylated. For this, 1,2-dichloroethane is mixed with 5 7.21 g (0.054 mol) of aluminum chloride. While cooling with ice water, 3.7 g (0.047 mol) of acetyl chloride and then the hydrogenation product dissolved in dichloroethane are carefully added dropwise to this suspension in such a way that the internal temperature always remains at approximately 20 ° C. After stirring at room temperature overnight, the contents of the flask are carefully poured onto ice water and dissolved aluminum hydroxide is brought into solution with a little concentrated hydrochloric acid. The organic layer is then separated off and the aqueous phase is extracted twice more with 1,2-dichloroethane. The combined 5 extracts are washed first with dilute sodium hydroxide solution and then with water. After drying over potassium carbonate, the solvent is stripped off and the residue is purified by column chromatography (silica gel 60, toluene / ethyl acetate 3: 1). 0

The product mixture formed is converted into the carboxylic acid by a subsequent haloform reaction. The carboxylic acid function is then converted into the nitrile group via the amide and subsequent dehydration with P0C1 ₃ . 5 Yield: 7.8 g

Phase behavior: N 37 I

Example 3 40

Synthesis of mixture 3 consisting of

30% 2- (4-hexoxyphenyl) -5-octyl-pyrimidine 30% 2- (4-heptoxyphenyl) -5-octyl-pyrimidine 45 40% 2- (4-octoxyphenyl) -5-octyl-pyrimidine 70.75 g (0.25 mol) of 2- (4-hydroxyphenyl) -5-octylpyrimidine, 9.88 g (0.082 mol) of 1-chlorohexane, 10.63 g (0.079 mol) of 1-chloroheptane, 14.85 g (0.1 mol) 1-chloroctane, 41.5 g (0.3 mol) potassium carbonate and 1 g potassium iodide are dissolved in 500 ml DMF and stirred for 4 h at 80 ° C 5. For working up, the reaction mixture is poured onto water and the organic phase is separated off. The organic phase is shaken out with half-concentrated HCl and then with sodium carbonate solution and then dried with sodium sulfate. After chromatography on silica gel with toluene / 10 ethyl acetate (3/1) as the eluent, 94.7 g of mixture 3 were obtained after concentration.

Example 4

15 Synthesis of mixture 4 consisting of

11.12% 1- [4'- (4 "-Acryloxyethoxy) -benzoyloxy] -4-4'- (2" -acryloxy-butoxy) -benzoyloxy] -3-chlorobenzene 11.11% 1- [4 '- (4 "-Acryloxybutoxy) benzoyloxy] -4-4 '- (2" -acryloxy-20 butoxy) benzoyloxy] -3-chlorobenzene

11.11% 1- [4 '- (4 "-Acryloxyethoxy) -benzoyloxy] -4-4'- (2" -acryloxy-hexoxy) -benzoyloxy] -3-chlorobenzene 11.11% l- [4'- (4 "-Acryloxyhexoxy) -benzoyloxy] -4-4'- (2" -acryloxy-ethoxy) -benzoyloxy] -3-chlorobenzene 25 11.11% 1- [4'- (4 "-Acryloxybutoxy) -benzoyloxy] -4-4'- (2 "-acryloxy-hexoxy) -benzoyloxy] -3-chlorobenzene 11.11% 1- [4 '- (4" -acryloxyhexoxy) -benzoyloxy] -4-4'- (2 "- acryloxy-butoxy) -benzoyloxy] -3-chlorobenzene 11.11% bis-l, 4- [4'- (4 "-Acryloxybutoxy) -benzoyloxy] -3-chlorobenzene 30 11.11% bis-1,4- [ 4'- (4 "-Acryloxyhexoxy) -benzoyloxy] -3-chlorobenzene 11.11% bis-1,4- [4'- (4 * -Acryloxyethoxy) -benzoyloxy] -3-chlorobenzene In 100 ml of pyridine 14, 4 g (0.1 mol) of 2-chloro-hydroquinone dissolved. A solution of 19.92 g (0.0666 mol) of 4- (o-acryloxethoxy) benzoic acid chloride, 35 18.78 g (0.0666 mol) of 4- (o-acryloxybutoxy) benzoic acid chloride and 20 , 65 g (0.0666 mol) of 4- (o-acryloxyhexoxy) benzoic acid chloride in 100 ml of toluene was added dropwise. After the addition is complete, the reaction mixture is heated to 60 ° C. and stirred at this temperature for 4 h. The progress of the reaction is monitored by thin layer chromatography. After the reaction is over, it will

The reaction mixture is added to a mixture of ice and concentrated hydrochloric acid and the organic phase is separated off. This is neutralized and then shaken out several times with a potassium hydroxide solution. Finally, the organic phase 45 is neutralized, dried with sodium sulfate and the solvent deducted. The yield of mixture 4 was 54.1 g (= 85% of theory).

Phase behavior: N 91 to 98 ° C I

5

Example 5

Synthesis of mixture 5 consisting of

10 15% 4'-n-propyl-4-cyanobiphenyl 53% 4'-n-pentyl-4-cyanobiphenyl 32% 4'-n-hepty1-4-cyanobiphenyl

23.31 g (0.1 mol) of 4-bromobiphenyl and 17.5 g (0.125 mol)

15 aluminum trichloride were dispersed in dry nitrobenzene. A mixture of 1.57 g (0.017 mol) of propanoyl chloride, 6.5 g (0.054 mol) of pentanoyl chloride and 4.31 g (0.029 mol) of heptanoyl chloride is added dropwise to the mixture in such a way that the temperature does not exceed 20 ° C. increases. The reaction mixture is

20 stirred for 18 h at room temperature, then poured onto a mixture of ice and water. The resulting suspension is stirred for 30 minutes and the nitrobenzene layer is separated off after the addition of chloroform. The solvents are removed by distillation or steam distillation. The residue is in toluene

25 added and dried over sodium sulfate. The toluene is distilled off under reduced pressure. The product is purified by column chromatography on silica gel 60 using petroleum ether / ethyl acetate 9: 1. The yield is 18 g. The spectroscopic data correspond to the mixture of the compound.

30

15 g of the mixture thus synthesized are dissolved in diethylene glycol, mixed with 7 ml of 90% hydrazine hydrate and 9 g of potassium hydroxide and heated to 100.degree. After heating under reflux for one hour, the reaction mixture is distilled off

35 Solvent heated to 180 ° C until the volume is approximately 14 ml. While cooling, the organic material is taken up in toluene, washed with water and the organic phase dried with sodium sulfate. The solvent is distilled off under vacuum and the residue is taken up in ethanol. For the

40 removal of yellowish impurities is filtered hot, the ethanol is then removed in vacuo. Yield: 12.1 g.

11 g of the mixture thus synthesized, dissolved in DMF, are refluxed with 45 5.57 g of copper (I) cyanide for 12 h. While cooling, the reaction mixture is mixed with iron chloride, concentrated hydrochloric acid and water and the resulting one Mixture stirred at 60 to 75 ° C for about 20 min. The organic phase is extracted with CH ₂ C1 ₂ . The resulting organic phase is washed several times with water and then dried with sodium sulfate. The mixture is purified by chromatography on silica gel 60 (chloroform as eluent). A high purification is carried out by subsequent vacuum distillation. A fraction is isolated which changes at bath temperatures between 120 and 130 ° C. The yield of colorless product is 6.1 g.

Phase behavior: N 51.7 I

Example 6

Synthesis of mixture 6 consisting of:

CH ₃

4.86 g (0.015 mol) of hexahydroxytriphenylene were dissolved in oxygen-free, absolute DMF. 8.66 g (0.0525 mol) of bromohexane, 9.4 g (0.0525 mol) of bromoethyl acrylate, 14.4 g (0.105 mol) of potassium carbonate and 0.19 g of phenotiazine were added to this solution and 6 h at 80 ° C stirred. After the reaction had ended, the mixture was precipitated into cold, dilute hydrochloric acid, filtered off with suction and dried in a desiccator. The mixture was then purified by chromatography and the solvent was stripped off in a high vacuum.

Yield: 10.9 g

According to NMR analysis, the mixture contains, statistically linked, 43% hexyloxy and 57% ethyl acrylate side chains.

The mixture has a discotically arranged hexagonal phase. Example 7

Synthesis of mixture 7 consisting of:

6.6 g (0.02 mol) of hexahydroxytriphenylene were dissolved in oxygen-free toluene. 0.12 mol of pyridine and a solution of 14.4 g (0.066 mol) of undecanoic acid chloride and 11.6 g (0.066 mol) of octanoic acid chloride dissolved in 100 ml of toluene were added to this solution. After completion of the reaction, the reaction mixture was carefully poured into ice water and the resulting precipitate was suction filtered. After chromatographic purification, 16.4 g of mixture were obtained (yield: 63%).

The mixture has a discotically liquid-crystalline phase.

Claims

claims

1. A process for the preparation of mixtures of liquid-crystalline compounds, characterized in that at least one of the

Starting components consist of a mixture of at least two compounds and this mixture is converted into a statistical mixture with at least one further starting component according to methods known per se.

2. A process for the preparation of mixtures of liquid-crystalline compounds, characterized in that at least one of the starting components consists of a mixture of at least two compounds and this mixture is reacted with at least one further starting component to form a statistical mixture according to methods known per se and which ent Subsequent mixture is then subjected to a hydrogenation action.

3. The method according to claim 1 or 2 for the production of

Mixtures of liquid crystalline compounds of the general formula I

(Z ¹ Y ¹ ) —AI Y ² MY ³ A ² (Y ⁴ Z ² ) _n in which

Z ^X , Z ² polymerizable groups,

Y ^ Y ^ Y ^ Y ⁴ chemical bonds or bridge members

—S—, —CO — NR— or —NR — CO—,

R is hydrogen or C_-C ₄ -alkyl,

m, n 0 or 1,

A ¹ in the event that m = 0, hydrogen, a C_-C_o-alkyl group which can be interrupted by oxygen in ether function or by non-adjacent imino or C ₁ -C ₄ -alkylimino groups, or halogen, nitro, cyano, Trifluoromethyl, difluoromethyl or, if m = 1, a C ₂ -C ₂₀ alkylene group, which by ether function or by non-neighboring

Imino or C 1 -C ₄ alkylimino groups can be interrupted, A ^{2 is} a group of the definition of A ¹ , the

Conditions for m are replaced by corresponding conditions for n and

M is a mesogenic group consisting of 2 to

5 are saturated or unsaturated five- to seven-membered carbocyclic or heterocyclic groups which are connected by identical or different bridge members of the definition of Y ¹ - Y ⁴ ,

characterized in that one

a) one or more of the compounds Ila

HY ² - —Y ³ H Ila according to methods known per se with, if only one compound Ila is used, several compounds purple or, if several compounds Ila are used, at least one compound purple

implements whereby

X ¹ denotes hydroxy, amino, carboxyl or another condensable group or halogen or another leaving group

or

one or more compounds llb

X ³ OC M ² CO X ³ Illb ^* , where M ¹ and M ^{2 are} constituents of the mesogenic groups M, consisting of 1 to 2 saturated or unsaturated five- to seven-membered carbocyclic or heterocyclic groups, in the event that M ¹ and / or

M ² consists of two such groups, which are connected by a bridge member of the definition of Y ¹ - Y ⁴ ,

X ² 0, S or NR and

X ^{3 is} halogen or OH

or

c) one or more compounds Ilc

_(z ι— _γ ι ₎ __._. _A ι— _γ2 - _M ι — co— χ3 He

by methods known per se with, if only one compound Ilc is used, a plurality of compounds IIIc or, if several compounds Ilc are used, at least one compound IIIc

HX ² M ² X ² H IIIc.

4. The method according to claim 3, characterized in that mixtures are prepared which contain liquid-crystalline compounds of the general formula I in which M denotes one of the following structures:

where R ¹ , R ² and R ^{3 are} hydrogen, 0CH ₃ , CH ₃ , F, Cl or Br.

Process according to Claim 3, characterized in that mixtures are prepared which contain liquid-crystalline compounds of the general formula I in which Z ¹ and / or Z ^{2 represent} one of the following structures:

CH.

6. The method according to claim 1 or 2 for the production of

Mixtures of liquid crystalline compounds of the general formula IV

in which for

Z ¹ , Y ¹ , Y, Y ³ , A ¹ , M and m the definitions of claim 3 apply and

s 0 or 1 and

A ^{3 is} a C ₂ -C ₂ o-alkylene group which can be interrupted by oxygen in ether function or by non-adjacent imino or C ₁ -C ₄ -alkylimino groups,

where the radicals Z ¹ , Y ¹ , Y ² , Y ³ , A ¹ , A ³ and M and the

Variables m and s, since they appear 6 times in the formula, can be the same or different,

characterized in that several of the compounds IVa

_{Z 1 γl) —A ¹ (Y ² MY ³ A ³ ) _S X1 IVa where X ^{1 has} the meaning given in claim 3,

by methods known per se with 2,3, 6, 7, 10,11-hexa-hydroxy-triphenylene (IVb)

implements.