CH644574A5 - ANISOTROPE CYCLOHEXEN COMPOUNDS AND LIQUID CRYSTAL MIXTURES. - Google Patents

Description

The invention relates to new anisotropic cyclohexene-55 compounds and liquid crystal mixtures (LC mixtures) which contain these new compounds as components.

It is known that the binuclear or trinuclear compounds which are suitable for LC mixtures in LC displays can advantageously be modified by replacing some or all of the aromatic nuclei of such compounds with trans-cyclohexyl rings (see e.g. DE-OS 2 636 684.2 800 553 and DE-AS 2 429 093). With such trans-cyclohexyl compounds, LC mixtures with a comparatively low optical anisotropy and reduced viscosity can be obtained.

A disadvantage of the anisotropic trans-cyclohexyl compounds is that the production of these compounds

3rd

644 574

fertilization is made considerably more difficult by the generally required separation of the desired trans isomers from the normally non-anisotropic cis isomers or the separation of the isomer mixtures usually obtained in the synthesis and is therefore comparatively expensive.

From EU patent application No. 78 300 649.7 (publication no. 0 002 136) it is known that this disadvantageous isomer separation does not apply if the analogous 1,4-disubstituted cyclohexene compounds of the LC mixtures are used instead of the trans-cyclohexane compounds Formula (V)

CN (V)

can be used in which R is an alkyl group and n is 1 or 2. In these cyclohexene derivatives (V), the double bond of the cyclohexene ring is in the y position to the electron-repelling (electrophobic) alkyl group R.

Also in the compounds of the formula (X) known from JP-OS 54-41 840 (No. 7 941 840)

eoo is the double bond of the cyclohexene ring in the y position or 3 position to the electron-impacting group R.

It has been found that compounds (V) and (X) have a high sensitivity to actinic radiation, e.g. Ta-geslicht-UV, which is usually disadvantageous for the operation of LC displays, because the effect of such radiation on the LC display then z. B. must be switched off by appropriate filters or the LC mixture changes chemically as a result of the radiation effect.

The aim of the invention is to provide new anisotropic cyclohexene compounds which are suitable for LC mixtures and have better resistance to actinic radiation, in particular daylight UV, than the known compounds of the formulas (V) and (X).

The invention relates to new anisotropic cyclohexene compounds of the formula (1)

(1)

In this formula (1), X1 and X2 are the same or different and represent hydrogen atoms, nitrile groups or halogen atoms;

Z1 is a simple covalent bond (-), the carboxyl - (- COO-), oxycarbonyl- (-OOC-), methyleneoxy- (-CH20-) or oxymethylene- (-OCH2-) grappe and

Y1 and Y2 are the same or different and mean AI-

Scheme I

kyl, alkoxy, monoalkylamino, alkylcarbonyloxy, alkyloxycarbonyloxy or nitrile groups.

According to a preferred embodiment, Y2 denotes the nitrii, alkyl or alkoxy group.

5 The alkyl portions of the groups mentioned for Y1 and Y2 each contain 1-12 C atoms in a preferably straight chain.

One of the two groups Y1, Y2 and preferably the group Y2 can also contain a monovalent radical of the For-io mein (la), (lb) or (lc)

15

-Z

-0-

(trans)

(la)

(lb)

(lc)

mean in which Y3 has the meaning given for Y1 and Y2, X3 and X4 have the meaning given for X1 and X2 and Z2 has the meaning given for Z1.

In a preferred embodiment, Y3 then means the nitrii, alkyl or alkoxy group.

The reason for the higher UV stability of the compounds of the formula (1) according to the invention compared to the 35 known cyclohexene compounds (V) or (X) is not yet fully clarified; however, it is assumed that the a position of the double bond in the cyclohexene ring in the compounds 40 (1) according to the invention, in contrast to the known compounds (V) and (X), means that no conjugated double bonds with the phenyl ring or the bridge members Z1 , Z2 - if these do not mean a simple covalent bond - and that the lack of conjugation of the a-cyclohexene double bond with other double bonds in the molecule of the compounds (1) is the main reason for the surprisingly better UV stability of these compounds (1) is.

According to the invention, the advantage of the known compounds (V) or (X) can thus be achieved without their disadvantage.

The invention also relates to LC mixtures which contain at least one compound of the formula (1). Such mixtures according to the invention are preferably eutectic mixtures which consist partly or wholly of compounds of the formula (1) and optionally also contain anisotropic compounds known per se.

A mixture according to the invention preferably contains at least about 5 mol% of at least one compound (1). 60 The new compounds (1) can be obtained, for example, according to the following synthesis schemes:

(1) R MgX

(2) -H20

(10)

644574

Scheme II

4th

(IIa)

Scheme III

(IIb)

2-HX

\ -2

(11)

H2oh + X

(purple)

(Illb)

2 -HX 1 R »R

(12)

In the formulas I-III above, R1 and R2 have the meanings given above for Y1 and Y2, respectively; X is halogen, such as bromine, or a similar leaving group.

In detail:

(I) This synthesis, which leads to compounds (10) according to the invention, is based on a Grignard reaction for the introduction of R1 on the keto carbon of cyclohexanone (I) with conversion of the keto oxygen into hydroxyl and subsequent elimination of water to form the a double bond. Reactions of this type are part of the technical knowledge and the cyclohexanones (I) used as starting compounds can be obtained from commercially available compounds (R2 in (I) is H) by introducing the desired R2 group by methods known per se.

(II) This synthesis, which leads to compounds (11) according to the invention with a carboxyl group as a bridge member (Z1 in formula (1)), can also lead, analogously with correspondingly modified starting compounds, to compounds according to the invention with the oxycarbonyl group as bridge member; the synthesis is a condensation which is customary per se and suitable starting compounds (IIa), (IIb) are either known or can be obtained from known compounds within the scope of the technical knowledge, for example by converting known cyclo-hexenecarboxylic acids into the acid halides.

(III) This synthesis can also be carried out for the compounds (12) according to the invention with Z1 = -CH20- as shown or for the corresponding compounds according to the invention with an inverted bridge member, i.e. Z1 = -OCH2-, lead if the substituents involved in the condensation of the starting compounds (purple), (Illb) are exchanged. Again, the starting compounds for synthesis scheme (III) are either known or are available from known compounds, e.g. by reducing the cyclohexenecarboxylic acids according to (IIa) to the alcohols (purple).

Specific examples of compounds (1) according to the invention and their preparation are given below.

The novel compounds of formula (1) according to the invention are anisotropic, i.e. either enantiotropic liquid crystalline or monotropic liquid crystalline; in the case of monotropic liquid-crystalline substances, the clearing point (Tc) of the pure substance is lower than its melting point (Tm). B. measured by supercooling the pure monotropic substance or by examining an enantiotropic mixture containing the monotropic substance and calculating the mesomorphic contribution of the monotropic substance.

20 Examples of the new anisotropic cyclohexene compounds of the formula (1) are given below.

example 1

2s 4- (4'-cyanophenyl) cyclohexanone (20 g) were placed in 90 ml THF at 0 ° C and with heptyl magnesium bromide (from 2.9 g Mg and 17.8 g bromheptane) in 60 ml ether at 0-5 ° C with stirring. The reaction mixture was 2h. stirred at room temperature, then poured onto ice and extracted with methylene chloride. The organic phase was washed, dried and evaporated. The crude product (cis / trans mixture) (22 g) was dissolved in 25 ml of pyridine for elimination of water, and 5 ml of thionyl chloride were added at −20 ° C. The reaction mixture was stirred at 0 ° C. for 30 35 min, then poured onto ice and washed with

Extracted methylene chloride. The organic phase was washed, dried and evaporated. The crude product was chromatographed on silica gel.

The cyclohexene-40 compound according to the invention thus obtained (Example 1) corresponds to the formula (10)

(10)

for R1 = n-heptyl and R2 = CN and can therefore be called 4-Cy-50 ano-4'-heptyl-r, 2 ', 3', 6'-tetrahydrobiphenyl:

K35, l N (5.0) 1

55 The comparison with the analogous known compound of the formula (V) given above (R = n-heptyl, n = 1; K 47.5 N 611) showed an improved UV resistance of the new compound according to Example 1.

60

Example 2

In an analogous manner as in Example 1, but using n-nonyl magnesium bromide, the compound was prepared according to the formula (10) for R1 = n-C9H19 and R2 = 65 CN, i.e. das4-cyano-4'-nonyl-r, 2 ', 3', 6'-tetra-hydrobiphenyl:

K 29.8 N (15.5) 1

5

644574

Examples 3-4

In a manner analogous to that in Example 1, the corresponding compounds can be used using n-propyl or n-pentyl magnesium bromide

(3): Formula (10), R1 = n-propyl, R2 = CN and

(4): Formula (10), R1 = n-pentyl, R2 = CN can be obtained.

Examples 5-8

According to the procedure described in Example 1, but using 4- (4'-butoxyphenyl) cyclo-hexanone instead of the corresponding cyanophenylcyclo-hexanone compound, the corresponding 4-butyloxy-4 'can be obtained using the alkylmagnesium compounds mentioned in Examples 1-4. -alkyl-r, 2 ', 3', 6'-tetrahydrobiphenyls can be obtained, ie the compounds of formula (10) with

(5): R1 = n-C3H7-, R2 = n-C4H90-

(6): R1 = n-C5H „-, R2 = n-C4H90-

(7): R1 = n-C7H13-, R2 = n-C4H90-

(8): R1 = n-C9H17-, R2 = n-C4HsO

Examples 9-12 In analogy to the procedure described above with a corresponding change in the 4'-substituent of the phenylcyclohexanone compound and the alkylmagnesium bromide, the 4-butylthio-4'-alkyl-r, 2 ', 3', 6'- tetrahydrobiphenyls can be obtained, ie the compounds of formula (10) with (9): R1 = n-propyl, R2 = n-H9C4S-

(10): R1 = n-pentyl, R2 = n-H9C4S-

(11): R1 = n-heptyl, R2 = n-H9C4S-

(12): R1 = n-nonyl, R2 = n-H9C4S-

Examples 13-16 In an analogous manner as above, the 4-butylamino-4'-alkyl-1 ', 2', 3 ', 6'-tetrahydrobi-phenyls according to the invention can be obtained, i.e. the compounds of formula (10) with

(13): R1 = n-propyl, R2 = n-H9C4N (H> -

(14): R1 = n-pentyl, R2 = n-H9C4N (H) -

(15): R1 = n-heptyl, R2 = n-H9C4N (H) -

(16): R1 = n-nonyl, R2 = n-H9C4N (H) ~

Examples 17-20 The following 4-cyano-4'-alkoxy-r, 2 ', 3', 6'-tetrahydro-biphenyls are examples of compounds of the formula (10) according to the invention for

(17): R1 = ethyloxy, R2 = CN

(18): R1 = butyloxy, R2 = CN

(19): R1 = n-hexyloxy, R2 = CN

(20): R1 = n-octyloxy, R2 = CN

Examples 21-24 The following 4-pentyl-4'-alkoxy- or alkyl-1 ', 2', 3 ', 6'-tetrahydrobiphenyls are examples of compounds of the formula (10) according to the invention for

(21): R1 = ethyloxy, R2 = n-pentyl

(22): R1 = n-butyloxy, R2 = n-pentyl

(23): R1 = n-propyl, R2 = n-pentyl

(24): R1 = n-pentyl, R2 = n-pentyl

Examples 25-28 The following 4-butylamino-4-alkoxy-r, 2 ', 3', 6'-tetra-hydrobiphenyls are examples of compounds of the formula (10) according to the invention for

(25): R1 = ethyloxy, R2 = n-H9C4N (H) -

(26): R1 = n-butyloxy, R2 = n-H9C4N (H) -

(27): R1 = n-hexyloxy, R2 = n-H9C4N (H) -

(28): R1 = n-octyloxy, R2 = n-H9C4N (H) -

Examples 29-32 The following 4-butylthio-4'-alkoxy-r, 2 ', 3', 6'-tetra-hydrobiphenyls are examples of compounds of the formula (10) according to the invention for:

(29): R1 = ethyloxy, R2 = n-H9C4S-

(30): R1 = n-butyloxy, R2 = n-H9C4S-

(31): R1 = n-hexyloxy, R2 = n-H9C4S-

(32): R1 = n-octyloxy, R2 = n-H9C4S-

Examples 33-35 The following 4-cyano-4'-alkylamino-r, 2 ', 3', 6'-tetra-hydrobiphenyls are examples of compounds of the formula (10) according to the invention for

(33): R1 = ethylamino, R2 = CN

(34): R1 = n-hexylamino, R2 = CN

(35): R1 = n-octylamino, R2 = CN

Examples 36-39 The following 4-pentyl-4'-alkylamino-r, 2 ', 3', 6'-tetra-hydrobiphenyls are examples of compounds of the formula (10) according to the invention for

(36): R1 = ethylamino, R2 = n-pentyl

(37): R1 = n-butylamino, R2 = n-pentyl

(38): R1 = n-hexylamino, R2 = n-pentyl

(39): R1 = n-octylamino, R2 = n-pentyl

Examples 40-43 The following 4-butyloxy-4'-alkylamino-r, 2 ', 3', 6'-tetra-hydrobiphenyls are examples of compounds (10) according to the invention for

(40): R1 = ethylamino, R2 = n-butyloxy

(41): R1 = n-butylamino, R2 = n-butyloxy

(42): R1 = n-hexylamino, R2 = n-butyloxy

(43): R1 = n-octylamino, R2 = n-butyloxy

Examples 44-47 The following 4-butylthio-4'-alkylamino-r, 2 ', 3', 6'-tetra-hydrobiphenyls are examples of compounds of the formula (10) according to the invention for

(44): R1 = ethylamino, R2 = butylthio

(45): R1 = n-butylamino, R2 = butylthio

(46): R1 = n-hexylamino, R2 = butylthio

(47): R1 = n-octylamino, R2 = butylthio

Examples 48-67 The following 4-cyano-4 "-YM", 2 ", 3", 6 "-tetrahydroter-phenyls substituted in the 4" position by the groups specified in each case according to the definition of Y1 in formula (1) of the formula (20)

are further examples of compounds according to the invention:

Example No .: Meaning of R3 in formula (20):

(4) n-propyl

(49) n-pentyl

(50) n-heptyl

(51) n-nonyl

(52) ethoxy

(53) n-butoxy

(54) n-hexyloxy

(55) n-octyloxy

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

644 574

Example No .:

Meaning of R3 in formula (20):

(56)

Ethylthio

(57)

n-butylthio

(58)

n-hexylthio

(59)

n-octylthio

(60)

Ethylamino

(61)

n-butylamino

(62)

n-hexylamino

(63)

n-octylamino

(64)

n-propionyloxy

(65)

n-pentanoyloxy

(66)

n-heptanoyloxy

(67)

n-nonanoyloxy io

(R3) -l ", 2", 3 ", 6" -tetrahydroterphenyls of the formula (50)

O

occ2h5

(50)

are further examples of compounds according to the invention.

EXAMPLES 128-147 The 4-ethylthio-4 "- (R3) -l", 2 ", 3", 6 "-tetrahydroterphenyls of the formula (substituted by the groups given in Examples 48-67 for R3 in the 4" position 60)

Examples 68-87 The 4-position substituted by the groups given for R3 in Examples 48-67 above according to the definition of Y1 in formula (1) 4-propyl-4- (R3) -l ", 2", 3 ", 6" tetrahydroterphenyls of the formula (30)

(60)

are further examples of compounds according to the invention.

Examples 148-167 The 4-position substituted by the groups given for R3 in Examples 48-67 for 4-ethylamino-4 "- (R3) -l", 2 ", 3", 6 "-tetrahydroterphenyls of the formula ( 70)

25th

(30)

are further examples of compounds according to the invention.

Examples 88-107 The 4-position substituted by the groups given for R3 in Examples 48-67 for 4-ethyloxy-4 "- (R3) -l", 2 ", 3", 6 "-tetrahydroterphenyls of the formula ( 40)

° c2h5

= -> (40)

are further examples of compounds according to the invention.

Examples 108-127 The 4-position substituted by the groups specified for R3 in Examples 48-67 for 4-propionyloxy-4 "

n (h) c2h5

(70)

30 are further examples of compounds according to the invention.

It is understood that the above examples are not exhaustive and that further modifications fall within the scope of the formula (1) according to the invention cyclohexene compounds.

35 Compounds of the formula (1) according to the invention can be used in a conventional manner individually or in a mixture for LC mixtures. Depending on the operating mode of the cell, the LC mixtures can be used in accordance with the required values of the mixture (e.g. with regard to the dielectric

40 see and optical anisotropy, viscosity and the like) are adjusted. The LC mixtures can also e.g. for guest / host operation usual additives such as dyes or cholesteric substances. As a rule, eutectic mixtures are preferred.

Claims (7)

644 574 2nd PATENT CLAIMS 1. Anisotropic cy'clohexene compounds, characterized by the formula (1) x1 x2 in which X1 and X2 are identical or different and denote hydrogen atoms, nitrile groups or halogen atoms, Z1 is a simple covalent bond which represents carboxyl, oxycarbonyl, methyleneoxy or oxymethylene group and Y1 and Yz are the same or different and are alkyl with 1-12 C atoms, alkoxy with 1-12 C atoms, monoalkylamino with 1-12 C atoms in the alkyl part, alkylcarbonyloxy with 1-12 C atoms in the alkyl part, Alkyloxycarbonyloxy with 1-12 C atoms in the alkyl part, alkylthio groups with 1-12 C atoms in the alkyl part, nitrile groups or residues of the formulas (la), (lb) or (lc) (la) in the X1 and X2 are identical or different and denote hydrogen atoms, nitrile groups or halogen atoms, Z1 is a simple covalent bond which represents carboxyl, oxys carbonyl, methyleneoxy or oxymethylene group * and Y1 and Y2 are the same or different and alkyl with 1-12 C atoms, alkoxy with 1-12 C atoms, monoalkylamino with 1-12 C atoms in the alkyl part, alkylcarbonyloxy io with 1-12 C atoms in the alkyl part , Alkyloxycarbonyloxy with 1-12 C atoms in the alkyl part, alkylthio groups with 1-12 C atoms in the alkyl part, nitrile groups or radicals of the formulas (la), (lb) or (lc) 15 20th 30th (la) (lb) (lc) (trans) -Z " < H (lb) (lc) (trans) mean in which Y3 has the meaning given for Y1 and Y2, X3 and X4 have the meaning given for X1 and X2 and Z2 has the meaning given for Z1, with the proviso that Y1 and Y2 do not simultaneously represent a group of the formulas (Ia ), (lb) or (lc) mean. 2. A compound according to claim 1, characterized in that only Y2 in the formula (1) means one of the radicals of the formulas (la), (lb) and (lc). 3. A compound according to claim 1 or 2, characterized in that Y2 or Y3 is the nitrite, alkyl or alkoxy group. 4. A compound according to claim 1, characterized in that Y2 is the nitrile group and Y1 is not the nitrile group. 5. Liquid crystal mixture, characterized in that it contains at least one compound of the formula (1) as a component (1) mean in which Y3 has the meaning given for Y1 and Y2, X3 and X * have the meaning given for X1 and X2 and Z2 has the meaning given for Z1, with the proviso that Y1 and Y2 are not simultaneously a group of the formulas (la), (lb) or (lc). 6. Mixture according to claim 5, characterized in that only Y2 in the formula (1) is one of the residues of Formulas (la), (lb) and (lc) mean. 7. Mixture according to claim 4 or 5, characterized in that Y2 or Y3 means the nitrite, alkyl or alkoxy group. 45 8. Mixture according to patent claim 7, characterized in that Yz is the nitrile group and Y1 is not the nitrile group. 50