DE4113342A1 - New 2,5-di:substd. 1,3-dioxan cpds. with (phenyl-)cyclohexyl gp. - are components of liq. crystal media for twisted cell devices, with high stability, good solubility, etc. - Google Patents

Abstract

1,3-Dioxan derivs. of formula (I) are new: Q = CHal H(3=l); OCnH(2n+1) or CH=CH CnH(2n+1); Hal = F or Cl; l = 1-3; n and r = 0-5; Xa = Xb = O and Ya = Yb = Ch2; Xa = Xb = CH2 and Ya = Yb = 0; Z1 and Z2 = C2H4 or single bond; A1 = trans-1,4-cyclohexylene or 1,4-phenylene (or its 3-fluoro or 3,5-difluoro- deriv.); m = 0-2; X = F, Cl, CF3, CN, OCF3 or OCHF2; Y and Z are each H or F. Z1 and Z2 = bond, Ya and Yb = 0; and Q = CH2Hal, OMe or CH = CH2. Pref. X = F, Cl, CF3 or OCF3; (a) Y = H or F and Z = H; (b) Y = F and Z = 6-F; m = zero; r = 2-4 or also 1 when Q is CH = CH2. USE/ADVANTAGE - (I) are useful as components of liq. crystals media for electrooptical displays, esp. those operating on the twisted cell principle. They provide media which remain nematic down to low temps., have excellent chemical stability and elastic properties; low threshold voltage (and its temp. dependence), and/or low optical anisotropy. (I) are colourless; readily soluble in other media components; have high positive dielectric anisotropy and favourable viscosity properties. They provide super twist devices having a very steep slope to the electrooptical characteristic.

Description

The invention relates to novel 1,3-dioxane derivatives of the formula I.

wherein

Q CHalogen ₁ H _3-1 , CnH _{2n + 1} -O- or C ₂ H _{2n + 1} -CH = CH-, where halogen is F or Cl,
1 1, 2 or 3 and
n is 0 to 5,
r 0 to 5,
X = X '= 0 and Y' = CH₂ or
X = X '= CH₂ and Y = Y' = O,
Z¹ and Z² are each independently of the other -C₂H₄- or a single bond,
A¹ is trans-1,4-cyclohexylene, 1,4-phenylene, 3-fluoro-1,4-phenylene or 3,5-difluoro-1,4-phenylene,
m 0, 1 or 2,
X is F, Cl, -CF₃, -CN, -OCF₃ or -OCHF₂ and
Y and Z each independently represent H or F.

From DE-OS 29 44 905 liquid crystals of the formula

known (R = C₆H₁₃, C₈H₁₇).

However, such compounds are not the high requirement The electrical resistance is just as good as it is For example, be required for ads with active matrix. Moreover, such compounds show in liquid-crystalline media quite high values for the Schwel lenspannung.

The compounds of formula I may be similar to, for. B. off DE-OS 26 36 684 known compounds as components liquid-crystalline media are used, in particular for Ads based on the principle of the twisted cell.  

The substances previously used for this purpose own All certain disadvantages, such as too high enamel 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 of the Threshold voltage or lead to too high threshold voltage gene.

Especially when displaying Supertwisttyp (STN) with Ver drift angles of significantly more than 220 ° C or at display active matrix systems have the previously used mate disadvantages.

The invention was based on the object, new liquid crystalline Find connections as components liquid-crystalline media are suitable, in particular 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 particularly suitable as components of liquid-crystalline media. In particular, with their help flüssigkristalli ne media with wide nematic ranges, excellent nematogeneity down to low temperatures, excellent chemical stability, outstanding elastic properties th, pronounced ε ^┴ in positive dieelektrische Anisotropy pie, low threshold voltage, low temperature dependence of the threshold voltage and / or smaller optical anisotropy available. The new compounds also show good solubility for other components of such media and high positive dielectric anisotropy while maintaining favorable viscosity.

The compounds of formula I allow both STN displays with very high slope of the electro-optical characteristic as also ads with active matrix with excellent long-term stability. By a suitable choice of around n can be with both display types, the threshold voltages ernied ernied engined.

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 Temperaturbe rich.

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-crystal line media containing at least one compound of the formula I and electro-optical displays, the like Media included.

Above and below have Q, r, X, Y, X ', Y', Z¹, Z², A¹, X, Y, m and Z are as defined, if not expressly stated otherwise.  

In the compounds of the formula I, the alkylene groups (CH ₂ ) _{r are} preferably straight-chain. Accordingly, (CH ₂ ) _{r is} preferably methylene, ethylene, n-propylene, n-butylene or n-pentylene. Preferably, m is 0 or 1, more preferably 0. Preferably, r is 2, 3 or 4. More preferably, r = 1, especially when Q = C _n H _{2n + 1} -CH = CH-.

The rest

is preferable

X is preferably F, Cl, -CG₃ or -OCF₃.

In the following preferred sub-formulas of the Invention given according to the following compounds:

Z 1 and Z 2 are preferred single bonds or one of these Groups also -C₂H₄-. m is preferably 0 or 1. Further are but also compounds with m = 2 (where A¹ and Z² are the same or different from one another), in particular those of the following subformulae

Particularly preferred are the compounds of the sub-formula Ia

wherein Q, r, A¹, m, X, Y and Z are those given in formula I. Have meaning. Preferably, Z is ortho to X, In a particularly preferred embodiment, Y = Z = F. A¹ is preferably trans-1,4-cyclohexylene. Q is preferred as CF₃, CHF₂, CH₂F, CH₂CL, CH₃O-, CH₂ = CH- or CH₃- CH = CH- (trans). Halogen is preferably F.

In the above formulas, Dio

and
is preferable

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) ben, under reaction conditions that for the mentioned reactions are known and suitable. It can one also from known, not mentioned here Make use of variants.

If desired, the starting materials may also be in situ be formed, such that they are from the reaction mixture not isolated but immediately further to the compounds of Formula I implements.  

The 1,3-dioxane derivatives according to the invention are in themselves usually by condensation of 1,3-diols of For mel IIa with aldehydes of the formula IIIa or of 1,3-diols of Formula IIb prepared with aldehydes of the formula IIIb:

The precursors of the formulas IIa, IIIa, IIb and IIIb are part wise known. All these connections can be routineme methods are produced, for example, according to the following Synthesis scheme:  

The compounds of the formulas IIIa and IIb can be analogous getting produced. The synthesis of some particularly Favor The compounds of the formulas IIIa and IIb are as follows explained in more detail

Compounds of formula IIIa are further characterized by Transition metal-catalyzed cross-coupling reactions (E. Poetsch, contacts (Darmstadt) 1988 (2), p. 15) available, such. B .:

For the synthesis of the compounds of the formula I2 according to the invention suitable precursors are, for example, according to the following Syn available:  

The obtained from the corresponding bromobenzene derivative Grignard-Verbidnung is with Chlortrialkylorthotitanat or zirconate according to WO 87/05599 to the tertiary cyclohexanol implemented. After elimination of water, hydrogenation of the dop pelbindung and isomerization is obtained by conventional methods the trans-cyclohexane carboxylic acid ester. From the latter one obtains the suitable ones by usual standard procedures Aldehydes for the compounds of the invention, from this by Wittig synthesis and subsequent hydrogenation of Double bond are available.

The Brombenzolderivate used as starting materials are for Part known, in part, they can without difficulty Standard methods of organic chemistry from the literature th compounds are made. For example, the OCF₃- or OCHF₂ compounds by known methods from the corresponding phenols or the CF₃ or CN compounds obtainable from the corresponding benzoic acids. links the formula

or also corresponding monofluorinated compounds for example, from the known precursors with X = H by Lithiation at low temperatures and subsequent conversion Available with a suitable electrophile.  

The synthesis of a particularly preferred starting material Formula IIIa 'is described below:

The condensation of this intermediate with compounds of Formula IIa provides preferred dioxane derivatives. Q is preferred wise CH₂ = CH-. The corresponding compounds of formula IIa is preferably obtained according to the following scheme:

Particular preference is also given to compounds of the sub-formula

which can be prepared according to the following scheme:

The alkylation of the malonic ester succeeds in a known manner through the generation of its anion and its implementation with the Alkenyl bromides. The reduction to the diols takes place in usual way by reduction with LiAlH₄. The condensation the obtained diols with the aldehyde IIIa 'is also carried out in an analogous manner to the formation of already known dioxane systems by boiling equimolar amounts of the diol with the aldehyde in Toluene on a water separator with the addition of p-toluenesulfone acid. The reaction is completed after 4 hours.

The reaction product is purified by chromatography Silica gel and crystallization from hexane purified. Also the synthesis of the required aldehyde IIIa 'is carried out according to known methods.  

Thus, 1-trisopropyloxytitanyl, 3,4,5-trifluorobenzene - prepared by transmetallation of 3,4,5-trifluorobenzene magnesium bromide with chloro triisoproxytitanium - with cyclohex Anon- (4) -carboxylic acid ethyl ester- (1) chemoselective at the Carbonyl group to 4-hydroxy-4 (3,4,5-trifluorophenyl) cyclo reacted hexanecarboxylic acid ethyl ester. By dehydration, catalytic hydrogenation via Pd / C, saponification and epimerization with KOH / methanol, the pure trans 4- (3,4,5- Trifluorophenyl) -cyclohexanecarboxylic acid (1). This is with Pivaloyl chloride converted into the mixed anhydride and with N, O-dimethylhydroxylamine in the corresponding amide überge leads. This is in high yield to the aldehyde IIIa 'with LiAlH₄ reduced.

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. This further inventory Parts are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, esp substances from the classes of biphenyls, terphenyls, Phenyl or cyclohexyl benzoates, cyclohexane-carboxylic acid phenyl or cyclohexyl esters, phenyl or cyclohexyl esters the cyclohexylbenzoic acid, phenyl or cyclohexyl ester of Cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl ester of Benzoic acid, the cyclohexane carboxylic acid, or the cyclohexyl cyclohexanecarboxylic acid, phenylcyclohexanes, cyclohexyl biphenyls, phenylcyclohexylcyclohexanes, cyclohexylcyclohexanes, Cyclohexylcyclohexenes, cyclohexylcyclohexylcyclohexenes,  1,4-bis-cyclohexylbenzenes, 4,4'-biscyclohexylbiphenyls, Phenyl or cyclohexylpyrimidines, phenyl or cyclohexylpy chloride, phenyl or cyclohexyldioxane, phenyl or cyclo hexyl-1,3-dithiane, 1,2-diphenylethane, 1,2-dicyclohexylethane, 1-phenyl-2-cyclohexylethane, 1-cyclohexyl-2- (4-phenyl cyclohexyl) -ethanes, 1-cyclohexyl-2-biphenylylethanes, 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'-L-E-R '' (1)

R'-L-COO-E-R '' (2)

R'-L-OOC-E-R '' (3)

R'-L-CH₂CH₂-E-R '' (4)

R'-L-CC-E-R '' (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, where Phe unsubstitu substituted or fluorine-substituted 1,4-phenylene, Cyc trans-1,4-cyclohexylene or 1,4-cyclohexenylene, Pyr pyrimi din-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.  

Preferably, one of L and E is Cyc, Phe or Pyr. e is preferably Cyc, Phe or Phe-Cyc. Preferably ent 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 L and E is selected from the group Cyc, Phe and Pyr and the other radical is selected 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' 'different from each other, wherein one of these radicals usually alkyl or alkenyl. In the links the part Formulas 1b, 2b, 3b, 4b and 5b is R "-CN, -CF₃, -OCF₃, F, Cl or -NCS; R has the part of the compounds Formulas 1a to 5a and is preferably Alkyl or alkenyl. More preferably, R "is selected from the group consisting of -F, Cl, CF₃ and -OCF₃. But also other variants of the proposed substituents in the Ver Compounds of formulas 1, 2, 3, 4 and 5 are in use. Many such substances or mixtures thereof are in the Trade available. All these substances are according to literature known methods or in analogy 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 the verb 1b, 2b, 3b, 4b and 5b (group 2), their shares before 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 Verbindun the invention and compounds of groups 1 and 2 up to 100% result.

The media according to the invention preferably contain 1 to 40%, in particular preferably 5 to 30% of erfindungs proper connections. Further preferred are media, ent holding more than 40%, in particular 45 to 90% of fiction proper connections. The media contain vorzgusweise 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 liquid crystal display elements can be used. Such additives are those skilled in the art known and described in detail in the literature (H. Kelker / R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980). For example, pleochroic color materials for producing colored guest-host systems or  Substances for changing the dielectric anisotropy, the viscosity and / or the orientation of the nematic Phases are added.

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 given in degrees Celsius. "Usual Aufar processing "means: add water, extract with Methylene chloride, separates, the organic phase dries, Evaporates and purifies the product 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 gives the transformation temperature in degrees Celsius.

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

Example 1

A mixture of 0.1M 2- (3-fluoropropyl) -1,3-propanediol, 0.1m p- (3,4-difluorophenyl) benzaldehyde (prepared by Crosstalk as described above), 1 g of p-toluenesulfonic acid and 200 ml of toluene is boiled for 1 hour on a water. After extractive work-up and purification by Kristal Lization and chromatography gives trans-2- (3,4-difluoro biphenyl-4'-yl) -5- (3-fluoropropyl) -1,3-dioxane.

example 2

Analogously to Example 1, reaction of 2- (3,3,3- Trifluoropropyl) -1,3-propanediol with p- (p-fluorophenyl) benzal dehyd [from p- (p-fluorophenyl) bromobenzene by reaction with BuLi, N-formylpiperidine and acid] trans-2- (4-fluoro biphenyl-4'-yl) -5- (3,3,3-trifluoropropyl) -1,3-dioxane.

example 3

Analogously to Example 1 is obtained by reacting 2- (4-oxa pentyl) -1,3-propanediol with p-fluorobenzaldehyde trans-2- (4-Flu orphenyl) -5- (4-oxapentyl) -1,3-dioxane.

Analogously or according to the above synthesis schemes, the following preferred compounds prepared (X = X '= CH₂, Y = Y '= O, Z¹ = Z² = single bond, A¹ = trans-1,4-cyclo hexylene, m = 1):  

Claims (6)

1. 1,3-dioxane derivatives of the formula I. wherein
Q CHalogen ₁ H _3-1 , CnH _{2n + 1} -O- or C ₂ H _{2n + 1} -CH = CH-, where
Halogen F or Cl,
1 1, 2 or 3 and
n is 0 to 5,
r 0 to 5,
X = X '= 0 and Y = Y' = CH₂ or
X = X '= CH₂ and Y = Y' = O,
Z¹ and Z² are each independently of the other -C₂H₄- or a single bond,
A¹ is trans-1,4-cyclohexylene, 1,4-phenylene, 3-fluoro-1,4-phenylene or 3,5-difluoro-1,4-phenylene,
m 0, 1 or 2,
X is F, Cl, -CF₃, -CN, -OCF₃ or -OCHF₂ and
Y and Z each independently represent H or F. 2. 1,3-Dioxanderivate according to claim 1, characterized by the formula Ia 3. 1,3-dioxane derivatives according to claim 2, characterized gekennzeich net, that Q is CH₂Halogen, OCH₃ or -CH = CH₂. 4. Use of the 1,3-dioxane derivatives of the formula I according to Claim 1 as a component of liquid-crystalline media for electro-optical displays.   5. Liquid-crystalline medium for electro-optical displays with at least two liquid crystalline components, characterized in that at least one component a 1,3-dioxane derivative of the formula I according to claim 1. 6. Electro-optical display based on a liquid Crystal cell, characterized in that the liquid Crystal cell contains a medium according to claim 5.