DD204100A5 - DICHROITIC ANTHRACHINONE DYES CONTAINING LIQUID CRYSTALLINE DIELECTICS - Google Patents

Abstract

Pleochroic anthraquinone dyes of the formula (I) in which W, X, Y and Z are hydrogen, NH deep 2, OH, NHCH deep 3 or NHC deep 2 H deep 5, but not more than 3 of these substituents are the same, R deep 1 4- (R deep 3) -phenyl, when R 2 is lower H, alkyl or alkoxy having in each case up to 8 C atoms, CN or 4- (R-low 3) -phenyl, and 4-alkylcyclohexyl or 4-alkoxyphenyl, when R 2 is lower alkyl or alkoxy each having up to 8 carbon atoms, and R 3 is lower alkyl or alkoxy having up to 8 carbon atoms, wherein the carbon chain is not 1-, 2- or 3-times interchangeable adjacent oxygen atoms is interrupted, are suitable for doping liquid-crystalline dielectrics for electro-optical display elements based on the guest-host effect. They have good dichroic values and are sufficiently soluble in the common liquid-crystalline base materials.

Description

') O O π 0

* »W w U <&.

Dichroic anthraquinone containing liquid crystal dielectrics

Field of application of the invention:

This invention relates to novel dichroic anthraquinone-containing liquid-crystalline dielectrics for electro-optic display elements based on the guest-host effect.

In the case of electro-optical display elements with liquid-crystalline dielectrics, it is known to generate the electro-optical effect of the display by incorporation of dichroic or pleochroic dyes as so-called "guest phase" in a liquid-crystalline matrix as a so-called "host phase" (GH Heilrneier et al, Molecular Crystals and Liquid Crystals, Vol. 8 (1969), pages 295-304). The dye molecules of the guest phase are in this case oriented by the embedding host phase in which they are dissolved or distributed according to the applied electric field. show their pleochroic properties according to their orientation

0 "U." ^ "^ * ¹ ^ ^" SC ^ * " ¹ ^ ^ ^ J_ ^ Γ ¹ Ή α Γ _ -. R- Η t" p- H ^ '~ \ "^ T"" ¹ 7 "." i Q " T Tr < _: T 7 7- *. -arcrjhl ^. ^. T "',

normal nionochro.i ti see dyes hänct of

pleochroic dyes. Absorbed amount of light from the orientation of their molecules Z ¹ Om electric field vector of the incident light. By applying an electric field to the dielectric dispersed in a cell as a thin layer, the nematic liquid crystals of the host phase and, together with these, the pleochroic dyes incorporated as the guest phase are reoriented, resulting in a change in light absorption. The practical application of this technique, which is referred to in the literature as a guest-host effect, is described, for example, in DE-OS 1 92 S 003. As examples of pleochroic or dichroic dyes, indophenol blue, indigo derivatives, azo dyes and the like are described there. The achievable contrasts are only sufficient when using a polarizing film for a good readability.

ι . 2 % qn '? ι

According to a recent development, as z. As described in DE-OS 2 410 557, can be dispensed with polarizers, if the len of nematic Flüssigkristal len with positive dielectric anisotropy (as the host phase) and therein (as a guest phase) embedded pleochroic a dye composite dielectric Quantity, e.g. B. 0.1-15 wt.% Of an optically active material is added, which causes the formation of a helical structure (cholesteric structure in the liquid crystal). Examples of such compositions, as well as the physical principles of light absorption therein, are described in the work of DL White and GN Taylor entitled "New Absorptive Mode Reflective Liquid Crystal Display Devices ^11" (J. Appl. Physics, Vol. 45 (1974), pages 4718-4723 Examples of the structure and operation of electro-optical display elements based on this effect are described in DE-OS 2 63 9 5 75 and 2 658 563.

In the literature, the cholesteric host-phase liquid crystal display element and the guest-embedded dye therein are often referred to as cholesteric guest-host displays. These CGH display elements have proven to be advantageous because they provide a good display contrast without polarizing films 5 and also have a greater brightness of the imaged timers.

It has been found that the selection of suitable dyes for CGH display elements is very difficult. First, the dichroic ratios of such host-phase systems and dye embedded therein as the guest phase must be sufficiently large to provide the display cell with sufficient brightness and ample Give contrast ratio. The achievable contrast depends on the degree of order S of the dye in the liquid-crystalline matrix. The order applies to the relationship

S = -. <3 cos ² θ -1> = ^E II ~ ^E I 2, Ξ, - + 2Ξ_

Ii 1

wherein θ is the angle between the molecular longitudinal axis of the dye molecule and the optical axis of the liquid crystal; Ξ_ _τ and E- are the values of the extinction 'of the display element when the measurements are made with parallel orientation (E ₇ -) or perpendicular orientation (Ξ-) of the liquid crystal microwells.

A value that is easier to handle for everyday practice and that allows a statement about the degree of order S and thus the technical usefulness of a dye-liquid-crystal combination is the so-called dichroic ratio V, which is the quotient of the abovementioned extinction values represents:

V =

In commercially useful dye-liquid crystal combinations, the value of V is 5 or above.

Practically, the degree of order of a dye depends primarily on its chemical structure and on the nature of the liquid-crystalline matrix. A number of examples are described by R. 1. Cox in "Molecular Crystals and Liquid Crystals, Vol. 55 (1979), pp. 1-33".

In addition to the degree of order or the dichroic ratio, however, other parameters are important for the use of a dye in CC-H display elements: an absorption maximum of the dye must be in the range of

IQ ren wavelengths, ie lie between 400 and 700 nm and the dye must in the doped host phase up to a temperature of about 100 ⁰ C resistant to AC voltages of up to 20 V, against radiation in the infrared, visible and ultraviolet range and against be the components of the liquid crystalline host phase. Furthermore, good solubility in the host phase and high optical density are desirable.

Characteristic of the known technical solutions:

However, the previously proposed for CGH Anzeigeeleir.ente dyes do not meet these requirements sufficiently. In particular, the azo dyes useful in terms of the dichroic ratio and the absorption maximum per se and usually proposed for use in CGE display elements have insufficient resistance to light or ultraviolet radiation (too low photochemical stability) and, in part, also to proved chemically unstable. On the other hand, the generally higher photochemical and chemical stability of anthraquinone dyes compared to azo dyes is well known. In fact, proposals have also been made in the literature for the use of anthraquinone dyes for CGH display elements. Most of the previously proposed anthraquinone dyes, "but have. Too small a dichroic ratio V to allow for technically employable CGH displays.

In the published British Patent Application No. 20 11 940 substituted anthraquinone dyes of the formula (A) are described,

wherein R, an optionally substituted in the ring, bound via the nitrogen atom aniline, R _{9 is} H or OH

and R-H or, when R 1 is K, also represents an optionally substituted anilino group. The dichroic ratio of these anthraquinone dyes, measured in commercial cyanobiphenyl / cyanoterphenyl liquid crystal mixtures, is between 3, S and 8.4, with most values between 5 and 6. However, the aniline groups reduce the solubility of the dyes in most common liquid crystalline host phases. In particular, in today flüssigkristaili- base materials from the class of phenylcyclohexanes largely used, the solubility of these dyes of the formula (A) for the needs of practice is too low.

Object of the invention:

The invention is the. It is an object to provide dichroic dyes which are sufficiently soluble in the commercially available liquid crystal base materials, for example to a minimum concentration of 0.5% by weight. Moreover, these dyes should have a ratio of at least dichroitiscb.es V ^ 5 and - be chemically and ^D ohotochemisch weitesrcehend resistant.

ο * - w ^ Vj a. '^ U

Explanation of the essence of the invention:

It has now been found that the anthraquinone dyes of the formula (I)

(D

worm

W, X, Y and. Z hydrogen, NE _? . OH, NHCH, or NHC ₇ H ₅ , but at most 3 of these groups are Gleich.sind

R ₁ 4- (R ") - phenyl, when X _{9 is} H, alkyl or alkoxy each having up to 8 C atoms, CN or 4- (R ₃ ) -phenyl, and 4-alkyl IQ cyclohexyl or 4- Alkoxyphenyl, when R _{9 is} alkyl or alkoxy each having up to 8 carbon atoms, means, and R ^ is alkyl or alkoxy having up to 8 carbon atoms, wherein the carbon chain 1-, 2- or 3 times by each other non-adjacent oxygen atoms is interrupted,

/ IMI! / 1

2390

are surprisingly soluble in the common liquid-crystalline base materials and have therein good dichroic ratios.

The invention thus relates to a liquid-crystalline dielectric containing one or more dichroic dyes for electro-optical display elements based on the guest-host effect, which contains at least one Anthrachinonearbstoff of formula (I).

In the compounds of the formula (I), the substituents W, X, Y and Z are hydrogen, hydroxyl, amino, methylamino or ethylamino, where not more than three of these substituents are identical to one another. Among these, the compounds of the formula (I) are preferred containing not more than two, preferably only one of the strongly polar groups OH or NH .., as these are better soluble in the usual, liquid crystal basic materials, in particular those with Phenvlcyclohexanstruktur.

3 30

ό U

The nature and position of these substituents W, X, Y and Z essentially determines the base color of the dye according to the invention, with gradations being influenced by the radicals R and R. The basic colors for some substituent combinations are given in the following Table I:

Table I: Basic Colors of the Antb.rach.inon Dyes of the Invention in Different Substitution Patterns

10 substitution pattern No.

farce

2 3 4

5 6 7 8 9

IO 11 12 13 1 Δ.

NE,

NH,

NH.

NH,

OH

OH

OH

OH

OH

OH

OH

NH ₂ NHC ₂ H ₅

NH

NH ₂ OE H NHCH ₃ OH H NH ₂ OH OH NH _ OH

OH NH,

NH, OH

NH

OH OH NC ₂ ^ ₅

vioiett

orange

red

b 1 au

b 1 au

yellow

orange

yellow

orange

yellow

yellow

Au 1 au

blue

Apart from the color-shade, the radicals R ^ and R ^ determine

Lz.

the solubility of the dyes in the conventional liquid crystal dielectrics

trika and d.sn. Ordnuncsgrad S.

/ IP

The radical R ₁ in the compounds of the formula. (I) regularly represents a phenyl or trans-cyclohexyl radical which is substituted in the 4-position. For example, it may be 4-alkylcyclohexyl or 4-alkoxyphenyl if R 1 is simultaneously alkyl or alkoxy. All alkyl and alkoxy groups in the radicals R ₁ and R "can contain up to 3 carbon atoms; if they contain more than 2 carbon atoms, they may be arranged in a straight or branched chain. Compounds of formula (I) having branched carbon chains are often i ⁿ the conventional liquid-crystal materials more soluble than those with straight chains, but the degree of order S is occasionally it lower again. For this reason, among the compounds of the formula (I), those having at most one branched carbon chain are present.

-15 gives.

When R_ is H, CN, alkyl or alkoxy, R_ can also

· <- J-

a 4-alkoxyalkylphenyl radical or a 4-alkoxyalkoxyphenyl radical. Suitable alkoxyalkyl or alkoxyalkoxy radicals R are, for example: 2-oxapropyl, 2- or 3-oxa-n-butyl, 3-oxa-n-butyloxy, 2-, 3- or 4-oxapentyl, 3- or 4- Oxapentyloxy, 3-, 4- or 5-oxahexyioxy , 2-, 3-, 4-, 5- or 5-oxaheptyl, 3-, 4-, 5- or o-oxaheptyloxy, 2,4-dioxapentyi, 2,4 -, 2,5- or 3,5-dioxahexyl, 3,5-dioxahexyloxy, 2,4-, 2,5-, 2,6-, 3,5-, 3,6- or 5,4,6-dioxaheptyl , 3,5-, 3,6- or 4,6-dioxoheptyloxy, 2,4-, 2,5-, 2,6-, 2,7-, 3,5-, 3,5-, 3,7 -, 4,5-, 4,7- or 5,7-dioxaoctyl, 3,5-, 3,6-, 3,7-, 4,6-, 4,7- or 5,7-dioxaoctyloxy, 2 Methoxypropyl, 2- or 3-methoxybutyl, 2-, 3- or 4-methoxypentyi, 2-ethyl-3-oxapentyi, 2-ethoxy

_o- pentyl, 2- or 3-methyl-4-oxahexyl, 2-ethoxypentyloxy, 2-, 4-, 5- or 7-methyl-3, S-dioxo-octyl and 2-, 4-, 5-oxy-7-methyl -3,6-dioxa-octyioxy. Finally, in

-ί -ι λ η L ύ 3 U

the compounds of the formula (I) according to the invention also both radicals R ₁ and R _{7 is} 4-alkoxyalkylphenyl or 4-alkoxyalkoxyphenyl. Preferred among these compounds are those in which R ₁ and R _{0 are the} same and the substituents R_ contained therein contain unbranched chains.

The dyes of the formula (I) are prepared in a manner customary for anthraquinone dyes. Sin preferred synthesis method consists in the reaction of a substituted "phthalic anhydride derivative of the formula (II)

'2 y

with a benzene derivative of the formula (II)

in the manner of a Friedel-Crafts reaction in the presence of an acidic catalyst. In the formulas (II) and (III), R ₁ and R _{9 have} the meaning given in the formula (I);

Seduction like W, X,

'have

Y and 2 or place by facsimile

Berf

e a j <-

• Tv / i Μ Π / 1 π

The reaction conditions for the Friedel-Crafts reaction (solvent, catalyst, temperature, duration) are selected in analogy to literature production methods of constitutionally similar anthraquinone dyes, depending on the structure and reactivity of the starting materials. The starting materials are generally known or can be prepared without difficulty in analogy to the known methods of standard synthetic organic chemistry.

Furthermore, dyes of the formula (I) according to the invention can be synthesized by substitution, reduction, oxidation or rearrangement reactions customary in this compound class, as described, for example, in Bayer 0, Chinone ,. Part III, in Houben-Weyl-Müller, Methods of Organic Chemistry, Volume VI1 / 3 c, Georg-Thieme-Verlag Stuttgart, 4th edition 1979 are described in detail.

The dielectrics according to the invention consist of 2 to 15 ', preferably. 3 to 12 components, including at least one Anthrachinonfarbstoff of formula (I). The other ingredients are selected from the nematic or nematogenic substances from the classes of the azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, phenyl or cyclohexyl benzoates, cyclohexanecarboxylic acid phenyl or cyclohexyl esters, pnenylcyclohexanes, cyclohexylbenzenyls, cyclohexyicyclohexanes, cyclohexylnaphthaiines, 1,43iscyclohexy ! benzenes, 4,4'-bis-cyclohexylbiphenyls, phenyl- or cyclohexyl-pyrimidines, phenyl- or cyclohexyl-dioxanes, optionally halogenated stilbenes, benzylphenyl ethers, tolans

τQ and substituted cinnamic acids. The most important compounds which may be considered as constituents of liquid crystalline host materials are characterized by the formula (IV).

R ₌ (IV)

V '- J

/ 3

> r -

wherein A and C are each a carbon or heterocyclic ring system of the 1,4-disubstituted benzene and cyclohexane rings, 4,4'-disubstituted biphenyl, phenylcyclohexane and cyclohexylcyclohexane systems, 2,5-disubstituted pyrimidine and 1, 3-dioxane rings, 2,6-disubstituted naphthalene, di- and tetrahydronaphthalene, quinazoline and tetrahydroquinazoline,

-CH = CH-

-CH = CD

-Q = C-

-CO-O-

-CO-S-

-CH = N-

-N = N-

-N (O) = N- -CH = N (O) -

-CH ₂ -O-CH ₂ -S-

-COO- or a C-C-Sinfachbindung,

D is halogen, preferably chlorine, or -CN, and

R ₄ and R _{5 are} alkyl, alkoxy, alkanoyloxy or Aikoxycarbonylox] with up to IS, preferably up to 8.Kohlenstoffatomen, or'einer of these radicals also -CN, -NC, -NO ₀ , -CF-, F, Cl or 3r mean. In most of these compounds, R ₄ and R ₁ - are different from each other, with one of these radicals; usually an alkyl or alkoxy group is ~ c. But other variants .der intended Substitueriten are common Many such substances or mixtures thereof are in the

9 q Handel ·, - available.

30

As a rule, the dielectrics according to the invention contain from 0.1 to 15, preferably from 0.5 to 10, in particular from 1 to 5, percent by weight of one or more compounds of the formula (I). The preparation of the dielectrics according to the invention is carried out in a conventional manner. In general, the

23 3 02 3

desired amount of the components used in lesser amount dissolved in the main constituent component, useful at elevated temperature. If . While a temperature above the clearing point of the main component is selected, the completeness of the dissolution process can be particularly easily observed.

By means of suitable additives, the liquid-crystalline dielectrics according to the invention can be modified so that they can be used in all hitherto known types of guest

q Host display elements can be used. Such additives are known to the person skilled in the art and are described in detail in the relevant literature: For example, substances for changing the dielectric anisotropy, the viscosity, the conductivity and / or the

c orientation of the nematic phases can be added. Such substances are described for example in DE-OS 22 09 127, 22 40 864, 23 21 632, 23 38 281 and 24 50 088.

Exemplary embodiments :

The following examples are intended to illustrate the invention without limiting it. In the examples, F. is the melting point and K. is the clearing point of a liquid crystalline substance in degrees Celsius; Boiling temperatures are designated by Kp. Unless otherwise indicated, parts or percentages are by weight or weight.

390

example 1

12 g of 1,5-dihydroxy-4,8-dinitro-anthraquinone are dissolved with stirring in a solution of 170 g of 96% sulfuric acid and 20.0 g of boric acid. The resulting solution is cooled to OC and treated with 20.0 g of 3-Oxapentyloxybenzol. After 4 hours of intensive stirring at this Tenvoera door is poured on 4OO σ ice. The mixture formed after the melting of the ice is heated to boiling overnight and then filtered. The neutral-washed residue is brought into a solution prepared from 50 g of sodium sulfide and 300 ml of water, the mixture is heated to boiling for 5 hours and filtered after cooling.

The filtered precipitate is taken up in 100 ml of 2N hydrochloric acid and the slurry is boiled. The residue remaining after filtration is washed neutral, dried and purified by column chromatography (mobile phase toluene / methanol 9: 1, silica gel).

The remaining as a blue dye 1,5-diamino-4,8-dihydroxy-3,7-bis- [4- (3-oxapentyloxy) phenyl] anthraquinone

In a liquid-crystal mixture of 71% of 4- (trans-4-alkylcyclohexyl) benzonitriles, 15% of 4- (trans-4-alkylcyclohexyl) -4'-cyanobiphenyl and 14% of 4, jQ has an absorption maximum at 517 m -Aikyl-4 '' - cyanoterphen ^ the dye is 3.2% soluble and has a degree of order S of 0.73.

Analog are produced:

1,5-diamino-4,8-dihydroxy-3,7-bis- [4- (3-oxapentyijphenyl] -anthraquinone.

1, 5-diamino-4, S-dihydroxy-3,7-bis- [4- (3-oxabutyloxy) -phenyl] -anthraquinone.

/ f6 ο * v

£ J

1, 5-diamino-4,8-dihydroxy-3,7-bis [4- (3, 6-dioxaoctyloxy) phenyl] anthraquinone,

1,5-diamino-4,8-dihydroxy-3,7-bis [4- (4-oxahexyloxy) -phenyl] -anthraquinone.

Example 2

18, Og 1,5-dihydroxy-4,8-dinitro-2-methylanthraquinone are dissolved with stirring in a solution of 200 g of 96% sulfuric acid and 28 g of boric acid- and reacted analogously to Example 1 with 3-Oxapentyloxybenzol. After working up as described in Example 1, 1,5-diamino-4,3-dihydroxy-3- [4- (3-oxapentyloxy) -phenyl] -7-methylanthraquinone is isolated as a blue dye (absorbence maximum in chloroform at 615 run). This dye is in the liquid crystal mixture mentioned in Example 1 to 3.7% löslieh and has a degree of order S of 0.58,

Analog'When manufactured:

l _/ 5-diamino-4,8-dihydroxy-3- [4- (4-oxaheptyloxy) -phenyl] -7-methylanthraquinone .

1,5-diamino-4,8-dihydroxy-3- (4-n-butyloxyphenyi) -7-ethyl anthraquinone.

1,5-diamino-4,8-dihydröxy-3- (4-n-hexyloxyphenyl) -7-isoOrooylanthrachinon.

ίο- f 3 ¹ ^ l * I #% 3 s

Example 3

15.0 g of 1,5-dihydroxy-4,8-diamino-anthraquinone-2 _/ 6-disulfonic acid are added at 85 ° in a solution of 7.5 g of boric acid in 120 ml of 96% sulfuric acid. Subsequently, the mixture is cooled to 0 ⁰ C, and stirred after addition of 11.6 g of 3-Oxapentyloxybenzol 3 hours at this temperature. The. The reaction mixture is poured into 500 ml of water and the resulting mixture is heated to boiling for 3 hours. After cooling, the violet precipitate is filtered off, washed with water and 100 m. ' Dissolved 15% ammonia solution. 9.0 g of sodium dithionite are added to the solution, and the reaction mixture is stirred at 95 for 2 hours. The precipitated 1,5-dihydroxy-4,8-diamino-3- [4- (3-oxapentyloxy) -phenyl] -anthraquinone is filtered off and recrystallized from ethanol; Absorption maximum in chloroform 615 nm. In the liquid crystal mixture indicated in Example 1, 4.1 percent by weight are soluble; the degree of order S in the solution is 0.71.

Example 4

To. a solution of 81 g of 4-methylphthalic anhydride in 200 ml of dichloromethane is added at -5 with stirring a suspension of 70 g of aluminum chloride in 600 ml Di and then slowly in the course of 2 hours, a solution of 101 g of trans-4-n- Propyi-i-phenylcyclohexane was added dropwise in 200 ml of dichloromethane, keeping the temperature at -5. Subsequently, the reaction mixture is stirred for a further 2 hours, the temperature rising to Ziramertemperatu. Thereafter, the reaction mixture is stirred into 4 l of ice-water acidified with hydrochloric acid, the organic

3Q phase separated and the aqueous extracted twice with 3.00 ml dichloromethane. The combined organic phases are 'dried over calcium chloride and

39023

evaporated. The Ruck.st.and is recrystallized from ethanol, thereby obtaining 95 g of 2- [4- (trans-4-n-propylcyclohexyl) benzoyl] -4 ~ methylbenzoic acid. The well-dried product is finely triturated with 50 g of diphosphorus pentoxide and the mixture heated to 150-180 ° for 2 hours. After cooling, the melt obtained is finely triturated and extracted with 250 ml of toluene at boiling heat. The resulting toluene solution is purified by chromatography on a silica gel column and evaporated. The remaining 2- (trans-4-n-propylcyclohexyl) -6-methylanthraquinone is added to a mixture of 90 ml of 96% sulfuric acid and 40 ml of fuming nitric acid and stirred therein at 45 ° for 1.5 hours. The reaction mixture is stirred into 800 ml of ice-water and from the obtained 1,5-dinitro-5 2- (trans-4-n-propylcyclohexyl) -6-methylanthraquinone by shaking with chloroform. After evaporation of the solvent, the residue is heated to boiling in a solution of 120 g of sodium sulfide in 500 ml of water and 200 ml of ethanol for 5 hours; then the ethanol is distilled off, the aqueous reaction mixture cooled to 0 ° and the yellow finely crystalline 1,5-diamino-3- (trans-4-n-propylcyclohexyl) -δ-methylanthraquinone filtered off, absorption maximum in chloroform 500 mn; Solubility in the liquid crystal mixture indicated in Example 1 4.7%, order degree O ₇ 58.

Analog are produced:

1,5-diamino-2- (trans-4-n-pentylcyclohexyl) -6-methylanthraquinone,

1,5-diamino-2- (trans-4-n-heptylcyclohexyl) -6-methoxyanthraquinone,

1,5-diamino-2- (trans-4-n-butylcyclohexyl) -o-n-butylanthraquinone,

1, 5-di-airulo-2- (trans-4-ethylcyclohexyl) -6-n-pentylanthraquinone.

023

Example b

To a solution of 7.5 g of 1,5-diamino-2- (trans-4-n-propylcyclohexyl) -6-methylanthraquinone in 100 ml of 15% sulfuric acid at 5 °, a solution of 2.5 g of sodium nitrite in 20 ml of water dripped. The reaction mixture is heated to boiling for 2 hours. After cooling, the formed 1,5-dihydroxy-2- (trans-4-n-propylcyclohexyl) -6-methylanthraquinone is extracted with chloroform, the organic phase dried over calcium chloride, evaporated and the remaining yellow dye - recrystallized from ethanol; Absorption maximum in chloroform 437 nm, solubility in the liquid-crystal mixture according to Example 1 3.4%, degree of order S = 0.65.

The following are prepared analogously: 1,5-dihydroxy-2- (trans-4-n-pentylcyclohexyl) -6-methylanthraequinone,

1,5-dihydroxy-2- (trans-4-n-butylcyclohexyl) -6-n-butylanthroquinone,

1,5-dihydroxy-2- (trans-4-ethyicyclohexyl) -5-n-pentylanthraquinone.

Example 6

5 g of 1,5-dihydroxy-2- (trans-4-n-propylcyclohsxyl) -6-methylanthraquinone are dissolved at 50 in a solution of 5 g of boric acid in 50 ml of 96% sulfuric acid with stirring and stirred at this temperature for 2 hours , It is then cooled to 15 ° and 3 ml of 65% nitric acid was added. The reaction mixture is stirred at room temperature for 3 hours and then poured into 250 ml of sis water. The filtered-1,5-dihydroxy-4,3-dinitro-2-

3.Q (trans-4-n-prapylcyclohexyl) -6.-me.t. ethyl.anthraquinone is dissolved in a solution of 25 g of sodium sulfide in 100 ml of water

90

Heated to boiling for 5 hours. The resulting 1,5-dihydroxy-4,8-diamino-2- (trans-4-n-propylcyclohexyl) -6-methylanthraquinone is dissolved in a little toluene and purified by chromatography on silica gel (eluent: toluene); Absorption maximum in chloroform 616 nm; Solubility in the liquid-crystal mixture according to Example 1 3.7%, degree of order S = 0.75. , ,

Analog are produced:

1,5-dihydroxy-4,8-diamino-2- (trans-4-n-pentylcyclohexyl) -jO 6-methylanthraquinone,

1,5-dihydroxy-4,8-diamino-2- (trans-4-n-heptylcyclohexyl) -6-methylanthraquinone,

1,5-dihydroxy-4,8-diamino-2- (trans-4-n-butylcyclohexyl) -6-n-butylanthraquinone, 1,5-dihydroxy-4, S-diamino-2- ^ {trans-4- ethyl-cyclohexyl) -6-n-OentYlanthrachinon.

Claims (1)

claim wherein W, X, Y and Z are hydrogen, NH-, OH, NI-iCEL, or NHC ₉ H ₁ -, but not more than 3 of these substituents are identical to one another, R ₁ 4- (R ₀ ) -phenyl, if H,. Alkyl odi xit respectively 8 C atoms, CN or 4- (R ") - phenyl, and 4-? Alkvlcyclohexvi or ^: 4-Alkcxyt'h- = nvl ₇ Wh which R _{7 is} alkyl or alkoxy each having up to S C atoms, and R _{0 is} alkyl or alkoxy having up to S C atoms, in which the <carbon chain is 1-, 2- or 3-times is interrupted, contains