DE4111765A1 - New penta: and tetra:fluoro-benzene cpds. - useful in liquid crystal medium for electro=optical display esp. super-twist nematic display - Google Patents

Abstract

New penta- or tetrafluorobenzene derivs. (I) are of the formula: n = 0-7; Q = -O-, -CH=CH- or a single bond; r = 0-5; s = 0-2; X = H or F; A = Z, Z-Ar, Ar-Z, Z-Cyc or 1,4-cyclohexenyl- -ene (IIA) or 1-hydroxy-1,4-cyclohexylene (IIB) of the formula: Z = a single bond, -(CH2)2- or -(CH2)4-; Ar = 1,4-phenylene or biphenyl-4,4'-diyl; Cyc = trans-1,4-cyclohexylene. (I) can be prepd. (not claimed) by standard methods, e.g. as described in Houben-Weyl, Methoden der Organischen Chemie, Georg-Thieme-Verlag, Stuttgart. USE/ADVANTAGE - (I) are claimed for use as components of liquid crystalline (LC) media for electrooptical displays. They are esp. useful in nematic media with positive dielectric anisotropy for use in STN and stable active matrix displays. The media have a wide nematic range, excellent nematogenicity down to low temps., excellent chemical stability, excellent elastic properties, little temp. dependence of the threshold voltage and/or small optical anisotropy. (I) also have good solubility for the other components of the media, high positive dielectric anisotropy and favourable viscosity.

Description

The invention relates to novel penta- or tetrafluorobenzene derivatives of the formula I,

wherein
n 0, 1, 2, 3, 4, 5, 6 or 7,
Q is -O-, -CH = CH- or a single bond,
r 0, 1, 2, 3, 4 or 5,
s 0, 1 or 2,
XH or F and
A

Z, Z-Ar, Ar-Z, Z-Cyc, wherein Z is a single bond, - (CH₂) ₂- or - (CH₂) ₄- and Ar is 1,4-phenylene or biphenyl-4,4'-diyl and Cyc trans-1,4-cyclohexylene
means.

From EP-OS 01 84 012 liquid crystals are known following formulas:

However, the compounds described therein are esters which not the high stability requirements for modern display applications satisfy.

The compounds of formula I may be similar to, for. B. off DE-OS 32 11 601 known compounds as components liquid crystalline media are used, in particular for ads based on the principle of the twisted cell based.

The substances previously used for this purpose own all certain disadvantages, for example too high melting points, too low clearing points, too little stability against the action of heat, light or electric Fields, too low electrical resistance, unfavorable elastic properties, too high temperature dependence the threshold voltage, unfavorable elastic and / or dielectric properties.  

Especially with ads of Supertwisttyp (STN) with Twist angles of significantly more than 220 ° or at Active matrix displays show the ones used so far Materials disadvantages.

The invention was based on the object, new liquid crystalline Find compounds that are components of liquid-crystalline Media are suitable, especially for nematic Media with positive dielectric anisotropy, and the disadvantages of the known compounds or not only to a lesser extent. This task was done by the Provision of the novel compounds of the formula I is achieved.

It has been found that the compounds of the formula I are excellent suitable as components of liquid-crystalline media are. In particular, they are liquid crystalline with their help Media with wide nematic ranges, outstanding Nematogeneity down to low temperatures, more outstanding chemical stability, outstanding elastic properties, low temperature dependence of the threshold voltage and / or small optical anisotropy available. The new compounds also show good solubility for other components of such media and high positives dielectric anisotropy with favorable viscosity.  

The compounds of formula I allow both STN displays with very high slope of the electro-optical characteristic as well as active matrix displays with outstanding Long-term stability. By appropriate choice of r and n let For both types of display the threshold voltages clearly humiliate.

The compounds of the formula I are colorless in the pure state and form liquid crystalline mesophases in one for the Electro-optical use conveniently located temperature range.

The invention thus relates to the compounds of Formula I and the use of the compounds of formula I. as components of liquid-crystalline media, liquid-crystalline Media containing at least one compound of the formula I and electro-optical displays, the like Media included.

Above and below, r, s, n, A, X and Q have the indicated Meaning, unless expressly otherwise is noted.

In the compounds of the formula I, the alkyl groups C _n H _{2n + 1 are} preferably straight-chain. Accordingly, C _n H _{2n + 1 is} preferably methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl or n-heptyl. n is preferably 1, 2, 3, 4 or 5, particularly preferably 1, if Q = -O-. In the case of Q = -CH = CH-, n is preferably 0. R is preferably 3 or 4. Further, r = 5 is preferred. In the case of Q = single bond, r is preferably 0.

Compounds of the formula I with branched alkyl groups occasionally because of better solubility in the Of conventional liquid-crystalline base materials of importance but especially as chiral dopants, if they are are optically active. Contain branched groups of this kind usually not more than one chain branch. preferred branched alkyl radicals are isopropyl, 2-butyl (= 1-methylpropyl), isobutyl (= 2-methylpropyl), 2-methylbutyl, Isopentyl (= 3-methylbutyl), 2-methylpentyl, 3-methylpentyl or 2-heptyl (= 1-methylhexyl).

Particularly preferred

• the compounds of the formula Ia, wherein r 2, 3, 4 or 5, s 1 or 2 and A and X have the meaning given in claim 1;
• the compounds of the formula Ib, wherein n is 1 to 7, s 1 or 2 and A and X are as defined in claim 1.

Preferably here s = 2 and A = Z (Z is preferably a single bond or - (CH₂) ₂-) or s = 1 and A = Ar.

Ar is generally preferably 1,4-phenylene. A is preferable 1,4-phenylene or a single bond.

Particularly preferred are also

• the compounds of the formula Ic, wherein n is 1 to 7, s is 0, 1 or 2 and Q, r and X are as defined in claim 1;
• the compounds of the formula Id, wherein n is 1 to 7, s is 0, 1 or 2, Q, r and X are as defined in claim 1;
• the compounds of the formula Ie, wherein n is 1 to 7, Q, r and X are as defined in claim 1;
• the compounds of the formula If, wherein n is 1 to 7, Q.sup.r and X are as defined in claim 1.

Incidentally, the compounds of the formula I are per se prepared methods known in the literature (For example, in the standard works such as Houben-Weyl, Methods of Organic Chemistry, Georg Thieme Verlag, Stuttgart) are, under reaction conditions, for the said reactions are known and suitable. there You can also from known, here not closer make use of the variants mentioned.  

If desired, the starting materials may also be in situ be formed, such that they are from the reaction mixture not isolated, but immediately continue to the connections the formula I implements.

Suitable for the synthesis of compounds of the invention Precursors are for example according to the following synthesis scheme available:

By analogous repetition of this reaction sequence are the compounds with r = 4 or 5 available.

The corresponding aldehydes wherein s = 1, A = 1,4-phenylene means can be prepared analogously to the above synthesis scheme, wherein instead of the Brombenzoderivats a compound

which is catalyzed by transition metal catalyzed Coupling Reactions [E. Poetsch, Contacts (Darmstadt) 1988, P. 15] can be produced.

The obtained from the corresponding Brombenzolderivat Grignard compound is treated with Chlortrialkylorthotitanat or zirconate according to WO 87/05 559 to the tertiary cyclohexanol implemented. After elimination of water, hydrogenation of Double bond and isomerization are obtained according to customary Methods the trans-cyclohexanecarboxylic acid ester. From the latter one obtains the suitable ones by usual standard procedures Aldehydes for the compounds of the invention, which this by Wittig synthesis and subsequent hydrogenation of the double bond are available.  

The bromobenzene derivatives used as starting materials are partly known, in part they can without difficulty according to standard methods of organic chemistry from literature Connections are made.

The homologation given in the above reaction scheme may also be according to other standard methods known to those skilled in the art respectively.

The synthesis of the compounds according to the invention with s = 2 takes place according to the following synthesis scheme:

Another way to make the preferred Compounds with r = 3 and n = 1 are shown below:

The synthesis of some particular preferred compounds is to take the following schemes:  

Scheme 1

Scheme 2

Scheme 3

The liquid-crystalline media according to the invention contain preferably in addition to one or more inventive Compounds as further constituents 2 to 40, in particular 4 to 30 components. Very particularly preferably included these media in addition to one or more inventive Compounds 7 to 25 components. These other ingredients are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, in particular Substances from the classes of biphenyls, terphenyls, Phenyl or cyclohexyl benzoates, cyclohexane-carboxylic acid phenyl or cyclohexyl esters, phenyl or cyclohexyl esters cyclohexylbenzoic acid, phenyl or cyclohexyl esters cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl ester benzoic acid, cyclohexanecarboxylic acid or cyclohexylcyclohexanecarboxylic acid, phenylcyclohexanes,  Cyclohexylbiphenyls, phenylcyclohexylcyclohexanes, cyclohexylcyclohexanes, Cyclohexylcyclohexenes, cyclohexylcyclohexylcyclohexenes, 1,4-bis-cyclohexylbenzenes, 4,4'-biscyclohexylbiphenyls, Phenyl- or cyclohexylpyrimidines, phenyl- or cyclohexylpyridines, phenyl- or cyclohexyl-dioxanes, Phenyl or cyclohexyl-1,3-dithiane, 1,2-diphenylethane, 1,2-dicyclohexylethane, 1-phenyl-2-cyclohexylethane, 1-cyclohexyl 2- (4-phenylcyclohexyl) ethanes, 1-cyclohexyl-2- biphenylylethane, 1-phenyl-2-cyclohexylphenylethanes and Tolans.

The 1,4-phenylene groups in these compounds can also be fluorinated.

The most important as further constituents according to the invention Media eligible connections can be through the Formulas 1, 2, 3, 4 and 5 characterize:

R'-LER "1
R'-L-COO-ER "2
R'-L-OOC-ER "3
R'-L-CH₂CH₂-ER "4
R'-LC≡CER "5

In formulas 1, 2, 3, 4 and 5, L and E are the same or may be different, each independently a bivalent radical from the group consisting of -Phe-, -Cyc-, -Phe-Phe-, -Phe-Cyc, -Cyc-Cyc, -Pyr-, -Dio, -G-Phe- and -G-Cyc-  and their mirror images formed group, wherein Phe unsubstituted or fluorinated 1,4-phenylene, Cyc trans-1,4-cyclohexylene or 1,4-cyclohexenylene, Pyr pyrimidine-2,5-diyl or pyridine-2,5-diyl, Dio 1,3-dioxane 2,5-diyl and G 2- (trans-1,4-cyclohexyl) -ethyl, pyrimidine 2,5-diyl, pyridine-2,5-diyl or 1,3-dioxane-2,5-diyl mean.

Preferably, one of L and E is Cyc, Phe or Pyr. E is preferably Cyc, Phe or Phe-Cyc. Preferably contain the media of the invention one or more Components selected from the compounds of the formulas 1, 2, 3, 4, and 5, wherein L and E are selected from the group Cyc, Phe and Pyr, and at the same time one or more components, selected from the compounds of the formulas 1, 2, 3, 4 and 5, wherein one of the radicals L and E is selected from the group Cyc, Phe and Pyr and the other radical selected is from the group -Phe-Phe, -Phe-Cyc, -Cyc-Cyc, -G-Phe- and -G-Cyc-, and optionally one or more components, selected from the compounds of the formulas 1, 2, 3, 4 and 5, wherein the radicals L and E are selected from the Group -Phe-Cyc, -Cyc-Cyc, -G-Phe and -G-Cyc-.

R 'and R "in the compounds of sub-formulas 1a, 2a, 3a, 4a and 5a are each independently of one another alkyl, Alkenyl, alkoxy, alkenyloxy or alkanoyloxy with up to 8 Carbon atoms. For most of these compounds are R 'and R "are different from each other, wherein one of these radicals  usually alkyl or alkenyl. In the compounds of Partial formulas 1b, 2b, 3b, 4b and 5b is R "-CN, -CF₃, -OCF₃, F, Cl or -NCS; R has the connections of sub-formulas 1a to 5a specified meaning and is preferably alkyl or alkenyl. Particularly preferred is R " selected from the group consisting of -F, Cl, CF₃ and -OCF₃. But also other variants of the proposed substituents in the compounds of formulas 1, 2, 3, 4 and 5 common. Many such substances or mixtures of which are commercially available. All these substances are by literature methods or in analogy thereto available.

The media according to the invention preferably contain in addition Components from the group of compounds 1a, 2a, 3a, 4a and 5a (group 1) also components from the group of Compounds 1b, 2b, 3b, 4b and 5b (group 2), their proportions preferably as follows:

Group 1: 20 to 90%, in particular 30 to 90%,
Group 2: 10 to 80%, in particular 10 to 50%,

wherein the sum of the proportions of the compounds of the invention and the compounds from groups 1 and 2 up to 100% yield.  

The media according to the invention preferably contain 1 to 40%, in particular preferably 5 to 30% of inventive Links. Further preferred are media, containing more than 40%, in particular 45 to 90% of inventive Links. The media preferably contain three, four or five compounds of the invention.

The preparation of the media according to the invention takes place in usual way. In general, the components are dissolved in each other, useful at elevated temperature. By Suitable additives can after the liquid crystalline phases of the invention are modified so that they are in all hitherto have become known types of Flüssigkrsitallanzeigeelementen can be used. Such additives are those skilled in the art known and described in detail in the literature (H.Kalkker / R.Hatz, Handbook of Liquid Crystals, Verlag Chemistry, Weinheim, 1980). For example, pleochroic Dyes for producing colored guest host System or substances for changing the dielectric Anisotropy, viscosity and / or orientation of the nematic phases are added.  

In the present application and in the following examples, the structures of the liquid crystal compounds are indicated by acronyms, wherein the transformation into chemical formulas according to following Tables A and B takes place. All radicals C _n H _{2n + 1} and C _m H _{2m + 1} are straight-chain alkyl radicals with n or m C atoms. The coding according to Table B is self-evident. In Table A, only the acronym for the main body is given. In individual cases, followed by the acronym for the basic body with a dash followed by a code for the substituents R¹, R², L¹ and L².

Table A

Table B

The following examples are intended to illustrate the invention, without to limit them. mp = melting point, cp = clearing point. In front- and below, percentages are by weight; All temperatures are in degrees Celsius. "Customary Workup "means: add water, extract with methylene chloride, separates, the organic Phase, evaporated and the product is purified by crystallization and / or chromatography.

It also means: K: crystalline solid state; S: smectic phase (the index denotes the phase type); N: nematic state; ch: cholesteric phase; I: isotropic phase. The between two Symbols standing number indicates the transformation temperature in Degree Celcius.

DAST diethylaminosulfur DCC dicyclohexylcarbodiimide DDQ dichlorodicyanobenzoquinone DIBALH diisobutylaluminum DMSO dimethyl sulfoxide KOT Potassium tert-butoxide THF tetrahydrofuran pTSOH p-Tolulsulfonsäure

Example 1

There are presented 100 mmol of NaH in the form of an oil dispersion and under N₂ atmosphere added 60 ml of THF. The mixture is stirred vigorously and heated to 45 ° C-50 ° C. Then 120 mmol of methyl iodide are added and then 80 mmol of trans-4- (p-methoxyphenyl) cyclohexylpropyl alcohol (prepared as described above by malonic ester synthesis and reduction with LiAlH₄) in 20 ml of THF within 30 minutes added dropwise. Then it will be at the same Temperature stirred for 30 minutes, then the reaction mixture cooled and carefully hydrolyzed with aqueous THF. After vigorous H₂ development is completed, as usual worked up. This gives trans-4- (4-oxapentyl) - (p-methoxyphenyl) - cyclohexane, K 19 N (15.1) I.

example 2

It is prepared in THF from 0.1 mol of magnesium and 0.1 mol Bromopentafluorobenzene under N₂ atmosphere the corresponding Grignard compound and gives to this 0.1 mol 4- (trans-4- (4- Oxypentyl) cyclohexyl) cyclohexanone (prepared from the Compound of Example 1 by catalytic hydrogenation and Jones oxidation) and the reaction mixture is stirred for 1 hour the boiling heat. Then, as usual, worked up and that  Reaction product on a water by boiling with dehydrated p-toluenesulfonic acid in toluene. Subsequently the reaction product is hydrogenated on a Pd / C catalyst. The isomer separation takes place according to the usual basic isomerization by chromatography or by Crystallization. This gives trans, trans-4- (4-oxapentyl) - 4 '- (p-pentafluorophenyl) bicyclohexyl.

Analogously or by dehydrogenation of the cyclohexene intermediate with chloranil gives the following compounds of the formula

example 3

To a solution of 50 mmol of pentafluorobenzene in 60 ml of THF 37 ml of a 1.6 molar solution of n-BuLi at -70 ° C. added dropwise in hexane. It is stirred for another hour, then at the same temperature, a solution of 50 mmol of 4- (4-n- Propyl-cyclohexyl) cyclohexanone in 40 ml of THF was added dropwise. To Stir overnight at room temperature 100 ml of 1N Hydrochloric acid added.  

Then it is worked up as usual. You get after Chromatography the pentafluorophenylbenzyl alcohol with axial position of the OH group. K 100 N 110 I.

Analogously, the following compounds of the formula are obtained

example 4

50 mmol of 1,2,3,4-tetrafluorobenzene are analogous to Example 3 first with a 1.6 molar solution of n-BuLi in hexane and then with 4- (4-n Propylcyclohexyl) cyclohexanone.

The product from Example 4a) is dissolved in toluene and with p-Tuluolsulfonsäure 5 hours under reflux on Cooked water separator. Then you leave on Room temperature cool, neutralized and works as usually on. K 60 N 77 I.

Analogously, the following compounds of the formula

manufactured.

example 5

0.1 mol pentafluorobenzene are metallized at -70 ° C in THF with 0.1 mol BuLi. Then, at the same temperature, 0.1 mol of N-formylpiperidine is added. After the hydrolysis is worked up as usual and distilled.
0.1 mol / l of the aldehyde thus prepared and 0.1 mol of Wittigsalz dissolved in THF are added in portions with potassium tert.butylat between 0 and 10 ° C. The mixture is then stirred for 24 h at room temperature, poured into water and neutralized and worked up as usual extractive. The resulting alkene is hydrogenated after recrystallization in THF with H₂ / Pd / C at 1 bar. After complete hydrogenation, the solution is concentrated and the residue is purified by recrystallization.

Analogously, the corresponding precursors become compounds the formula

manufactured:

Claims (14)

1. Penta- or tetrafluorobenzene derivatives of the formula I, wherein
n 0, 1, 2, 3, 4, 5, 6 or 7,
Q is -O-, -CH = CH- or a single bond,
r 0, 1, 2, 3, 4 or 5,
s 0, 1 or 2,
XH or F and
A Z, Z-Ar, Ar-Z, Z-Cyc, wherein Z is a single bond - (CH₂) ₂- or - (CH₂) ₄- and Ar 1,4-phenylene or biphenyl-4,4'-diyl and cyc trans 1,4-cyclohexylene
means. 2. Penta- or Tetrafluorbenzolderivate according to claim 1, characterized by the formula Ia, wherein r 2, 3, 4 or 5, s 1 or 2 and A and X have the meaning given in claim 1. 3. Penta- or tetrafluorobenzene derivatives of the formula Ib, wherein n is 1 to 7, s 1 or 2 and X and A have the meaning given in claim 1. 4. Penta- or tetrafluorobenzene derivatives according to claim 3, characterized in that s = 2 and A = Z. 5. Penta- or Tetrafluorbenzolderivate according to claim 3, characterized in that s = 1 and A = Ar. 6. Penta- or Tetrafluorbenzolderivate according to claim 4, characterized in that Z = single bond. 7. Penta- or tetrafluorobenzene derivatives according to claim 4, characterized in that Z = - (CG₂) ₂-.   8. Penta- or tetrafluorobenzene derivatives of the formula Ic, wherein n is 1 to 7, s is 0, 1 or 2 and Q, r and X are as defined in claim 1. 9. Penta- or tetrafluorobenzene derivatives of the formula Id, wherein n is 1 to 7, s is 0, 1 or 2 and Q, r and X are as defined in claim 1. 10. Penta- or tetrafluorobenzene derivatives of the formula Ie, wherein n is 1 to 7, Q, r and X are as defined in claim 1. 11. Penta- or tetrafluorobenzene derivatives of the formula If, wherein n is 1 to 7, Q, r and X are as defined in claim 1. 12. Use of the compounds of the formula I according to claim 1 as components of liquid-crystalline media for electro-optical Show. 13. Liquid-crystalline medium for electro-optical displays with at least two liquid crystalline components, characterized in that at least one component a compound of the formula I according to claim 1. 14. Electro-optical display based on a liquid crystal cell, characterized in that the liquid crystal cell contains a medium according to claim 11.