CA1259628A - Nematic compounds containing cyclohexyl groups - Google Patents
Nematic compounds containing cyclohexyl groupsInfo
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- CA1259628A CA1259628A CA000460292A CA460292A CA1259628A CA 1259628 A CA1259628 A CA 1259628A CA 000460292 A CA000460292 A CA 000460292A CA 460292 A CA460292 A CA 460292A CA 1259628 A CA1259628 A CA 1259628A
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Abstract
"NEMATIC COMPOUNDS CONTAINING CYCLOHEXYL GROUPS"
ABSTRACT OF THE DISCLOSURE
Nematic compounds with a negative DC anisotropy, characterised by the formula I
I
in which m = 1 or 2, r is zero or 1 and m + r = 1 or 2, and R1 and R2 are identical or different and are se-lected from alkyl and alkoxy groups each having 1 - 12 carbon atoms in a straight or branched chain, which may be chiral, Z is a bridge member selected from a single bond and the groups of the formulae -CH2CH2-, -OCH2-, -O-CO- or -CO-O-, one of the groups X and Y is selected from fluorine, chlorine, bromine and cyano and the other of the groups X and Y is selected from hydrogen, fluo-rine, chlorine, bromine and cyano, with the proviso that m = r = 1 if X and Y are both cyano, are suitable as components for liquid crystal mixtures having an overall negative DC anisotropy, such as are re-quired in particular for electro-optical displays of the type of guest/host displays or homotropic-nematic dis-plays.
ABSTRACT OF THE DISCLOSURE
Nematic compounds with a negative DC anisotropy, characterised by the formula I
I
in which m = 1 or 2, r is zero or 1 and m + r = 1 or 2, and R1 and R2 are identical or different and are se-lected from alkyl and alkoxy groups each having 1 - 12 carbon atoms in a straight or branched chain, which may be chiral, Z is a bridge member selected from a single bond and the groups of the formulae -CH2CH2-, -OCH2-, -O-CO- or -CO-O-, one of the groups X and Y is selected from fluorine, chlorine, bromine and cyano and the other of the groups X and Y is selected from hydrogen, fluo-rine, chlorine, bromine and cyano, with the proviso that m = r = 1 if X and Y are both cyano, are suitable as components for liquid crystal mixtures having an overall negative DC anisotropy, such as are re-quired in particular for electro-optical displays of the type of guest/host displays or homotropic-nematic dis-plays.
Description
~L2~9~j28 This invention relates to novel nematic compounds which have a negative anisotropy of the dielectric constant (DC) and are suitable as components for liquid crystal (LC) mixtures. This invention also relates to nematic LC mixtures which contain the novel compounds as components and have an overall negative DC anisotropy.
Nematic liquid crystal mixtures with negative dielectric constant anisotropy (DCA) are required for operating certain displays, for example for the so-called guest/host displays (GHD) and homotropic-nematic d-isplays (HND) with a positive image display or posi-tive contrast. Similar compounds are known~ for example from J. C. Dubois et al., Mol. Cryst. Liq. Cryst. 42 (1977) 139; German Offenlegungschriften No. 2,240,864,
Nematic liquid crystal mixtures with negative dielectric constant anisotropy (DCA) are required for operating certain displays, for example for the so-called guest/host displays (GHD) and homotropic-nematic d-isplays (HND) with a positive image display or posi-tive contrast. Similar compounds are known~ for example from J. C. Dubois et al., Mol. Cryst. Liq. Cryst. 42 (1977) 139; German Offenlegungschriften No. 2,240,864,
2,613,293, 2,835,682, and 2,937,700, and European Patent Application No. 80200464.8.
However, no satisfactory nematic LC mixtures, which have a sufficiently strong negative DCA (for ~259~i~8 example 2 or better) in combination with the further properties, necessary for perfect operation of display cells, of LC mixtures, such as chemical stability in general, photochemical, electrochemical and thermal stability, and a sufficiently wide range of anisotropy as well as sufficiently short response times even at low temperatures, for example at most about one second at the lower end of the anisotropy range, are yet obtainable by means of the compounds hitherto known.
Thus, it is an object of the invention to provide novel nematic compounds which enable LC mixtures with a markedly negative DCA and the further properties mentioned to be prepared.
These objects have been obtained by providing compounds of the formula I
~:a2ci~2~ z {~
in which m = 1 or 2, r is zero or 1 and m + r = 1 or 2, and R1 and R2 are identical or different and are selected from alkyl and alkoxy groups each having 1 - 12 carbon atoms in a straight or branched chain, which may be chiral, Z is a bridge member selected from a single bond ~L~5~628 and the groups of the formulae -CH2CH2-, -OCH2-, -O-CO-or -CO-O-, one of the groups X and Y is selected from fluorine, chlorine, bromine and cyano and the other of the groups X and Y is selected from hydrogen, fluorine, chlorine, bromine and cyano, with the proviso that m =
r = 1 if X and Y are both cyano.
It has been found that the compounds of the formula I are outstandingly suitable as components of liquid-crystalline phases. In particular, stable liquid--crystalline phases with an overall negative dielectric anisotropy and comparat;vely low viscosity can be pre-pared by means of these compounds.
The compounds of the formula I can be used, in the same way as similar compounds,as components of liquid-crystalline phases, such as are required especially for electro-optical displays of the type of guest/hcst displays or homotropic-nematic displays.
Moreover, by the provision of the compounds of the formula (I), the range of liquid-crystalline sub-stances, which are suitable under different application aspects for the preparation of nematic mixtures, is quite generally widened considerably.
The subject of the invention thus concerns the compounds of the formula (I) and the use of the com-pounds of the formula (I) as components of liquid-crystalline mixtures. A further subject of the inven-tion concerns liquid-crystalline mixtures containing at -~S9~i2~3 least one compound of the formula (I) and electro-optical display elements which contain such mixtures.
In these novel compounds, the cyclohexyl rings are each in the trans-configuration, as indicated by dots in formula I.
At least one of the groups X and Y is a substi-tuent having a polarizing action, from the group com-prising fluorine,~chlorine, bromine and cyano.
Particularly preferred are those compounds of the formula (~) in which one of the groups X and Y ;s fluorine, chlorine or cyano, in particular those in which X is fluorine and Y is hydrogen.
If r = 1, the bridge member Z then present can be a single bond or a grouping selected from the groups of the formulae -CHzCH2-, -OCHz-, -O-CO- or -CO-O-.
Preferably, Z is -CH2CH2-, -OCH2- or -O-CO-.
R1 and R2 are ;dentical or different ring groups selected from C1-C12-alkyl and C1-C12-alkoxy groups having a straight or branched chain, ~hich may be chiral, of the alkyl moiety, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl or dodecyl as the alkyl moiety, including the corresponding chiral isomeric alkyl moieties, for example 1-methylpropyl, 1-methylbutyl, 2-methylbutyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1- or 2- or 3- or 4- methylhexyl, 1- or 2- or 3- or 4- or 5-methylheptyl and further alkyl-alkyl groups formed in accordance with this principle and having an asymmetrical carbon atom. Alkyl moieties having 2 - 8 carbon atoms, in particular 3 - 8 carbon atoms, are frequently preferred.
R1 is preferably straight-chain alkyl having 2 - 8 carbon atoms. In the case of r = û, RZ is prefer-ably straight-chain alkoxy having Z - 8 carbon atoms and, ;n the case of r = 1, ;t ;s preferably stra;ght-chain alkyl hav;ng Z - 8 carbon atoms.
Preferred groups of compounds of the formula I
according to the invention are of the follo~ing formulae Ia, Ib, Ic, Id, Ie, and If, in uhich R1, R2, X and Y
have the mean;ngs g;ven above for formula I.:
X Y
Rl~_ CX2CEi2- ;<~ C~2{3~2 Ia X Y
R1{~} CE2CE2~CE2C:12--~ R2 Ib X Y
R1--~ ~} C~2C~I2 ~}R2 Ic X Y
R 1 ~--CE2 CH2~a-CO--Q--R2 Id X Y
Rl {~}CEzCE2~ CO-O--~3 R2 Ie Rl_O--C 12CE2~-- R2 If i28 ,7-Those compounds of the formula If are preferred in which R2 is ~lkoxy and R1 is alkyl.
The novel compounds (I) can be prepared by va-rious processes. A f;rst general process is based on the S condensation of a corresponding carboxylic acid deriva-tive of the formula A-CH2COOH, preferably in the form ~ of the corresponding acid halide, in which A represents the left-hand part of the molecule of the compound (I), that is to say with a corresponding anisole derivative of the formula B
X Y
~ OC~3 3 in order to form the corresponding ketone of the formula X
2 C ~ O-CH3 C
which is then reduced for replacing the ketocarbonyl oxygen by two hydrogen atoms, a compound of the formula X Y
A C~2-CR2 ~ 0-C~3 D
be;ng formed.
For modifying R2 or/and (if r = 1) for introdu-S cing the structure E
~ Z ~ E
the compound D can be converted to a compound F
X Y
. A 2 2 ~ L1 F
in which L1 is a first reactive group, such as hydroxyl, COOH or halogen, and the compound F can then be reac-ted ~ith a compound of the formula G
~2 ~ z ~ ~2 in which L2 is a second reactive group, in order to form 1S the target compound I or a pre-compound which can be converted ;nto the latter.
Alternatiyely~ the compounds I can also be A :~L ;;2 5 9 ~ ~ 8 _9_ prepared from appropriate pre-compounds of analogous structure, but u;thout transversely polari~;ng suhstitu-ents, by halogenation or transhalogenation and, if approp-riate, nitrilation treplacement of halogen by cyano).
S A specific example of the synthesis of preferred compounds I is illustrated by the equation uhich fol-- lous:
R~ ) Rl--O-- (2) oC~2Br X Y
R1 ~ 2 ~ OCa3 ~~~ R ~ H2C02H
~ (S) X Y- X Y
Rl ~ C2H4 ~ (6) ~ 2~4 ~ o~
~7 x Y
R ~ C2H4 ~ ~1)--C~2 ~ R2 9~
t1) reduction, for examp~e with LiAlH4 (2) bromination, for example with elementary bromine in acetonitrile
However, no satisfactory nematic LC mixtures, which have a sufficiently strong negative DCA (for ~259~i~8 example 2 or better) in combination with the further properties, necessary for perfect operation of display cells, of LC mixtures, such as chemical stability in general, photochemical, electrochemical and thermal stability, and a sufficiently wide range of anisotropy as well as sufficiently short response times even at low temperatures, for example at most about one second at the lower end of the anisotropy range, are yet obtainable by means of the compounds hitherto known.
Thus, it is an object of the invention to provide novel nematic compounds which enable LC mixtures with a markedly negative DCA and the further properties mentioned to be prepared.
These objects have been obtained by providing compounds of the formula I
~:a2ci~2~ z {~
in which m = 1 or 2, r is zero or 1 and m + r = 1 or 2, and R1 and R2 are identical or different and are selected from alkyl and alkoxy groups each having 1 - 12 carbon atoms in a straight or branched chain, which may be chiral, Z is a bridge member selected from a single bond ~L~5~628 and the groups of the formulae -CH2CH2-, -OCH2-, -O-CO-or -CO-O-, one of the groups X and Y is selected from fluorine, chlorine, bromine and cyano and the other of the groups X and Y is selected from hydrogen, fluorine, chlorine, bromine and cyano, with the proviso that m =
r = 1 if X and Y are both cyano.
It has been found that the compounds of the formula I are outstandingly suitable as components of liquid-crystalline phases. In particular, stable liquid--crystalline phases with an overall negative dielectric anisotropy and comparat;vely low viscosity can be pre-pared by means of these compounds.
The compounds of the formula I can be used, in the same way as similar compounds,as components of liquid-crystalline phases, such as are required especially for electro-optical displays of the type of guest/hcst displays or homotropic-nematic displays.
Moreover, by the provision of the compounds of the formula (I), the range of liquid-crystalline sub-stances, which are suitable under different application aspects for the preparation of nematic mixtures, is quite generally widened considerably.
The subject of the invention thus concerns the compounds of the formula (I) and the use of the com-pounds of the formula (I) as components of liquid-crystalline mixtures. A further subject of the inven-tion concerns liquid-crystalline mixtures containing at -~S9~i2~3 least one compound of the formula (I) and electro-optical display elements which contain such mixtures.
In these novel compounds, the cyclohexyl rings are each in the trans-configuration, as indicated by dots in formula I.
At least one of the groups X and Y is a substi-tuent having a polarizing action, from the group com-prising fluorine,~chlorine, bromine and cyano.
Particularly preferred are those compounds of the formula (~) in which one of the groups X and Y ;s fluorine, chlorine or cyano, in particular those in which X is fluorine and Y is hydrogen.
If r = 1, the bridge member Z then present can be a single bond or a grouping selected from the groups of the formulae -CHzCH2-, -OCHz-, -O-CO- or -CO-O-.
Preferably, Z is -CH2CH2-, -OCH2- or -O-CO-.
R1 and R2 are ;dentical or different ring groups selected from C1-C12-alkyl and C1-C12-alkoxy groups having a straight or branched chain, ~hich may be chiral, of the alkyl moiety, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl or dodecyl as the alkyl moiety, including the corresponding chiral isomeric alkyl moieties, for example 1-methylpropyl, 1-methylbutyl, 2-methylbutyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1- or 2- or 3- or 4- methylhexyl, 1- or 2- or 3- or 4- or 5-methylheptyl and further alkyl-alkyl groups formed in accordance with this principle and having an asymmetrical carbon atom. Alkyl moieties having 2 - 8 carbon atoms, in particular 3 - 8 carbon atoms, are frequently preferred.
R1 is preferably straight-chain alkyl having 2 - 8 carbon atoms. In the case of r = û, RZ is prefer-ably straight-chain alkoxy having Z - 8 carbon atoms and, ;n the case of r = 1, ;t ;s preferably stra;ght-chain alkyl hav;ng Z - 8 carbon atoms.
Preferred groups of compounds of the formula I
according to the invention are of the follo~ing formulae Ia, Ib, Ic, Id, Ie, and If, in uhich R1, R2, X and Y
have the mean;ngs g;ven above for formula I.:
X Y
Rl~_ CX2CEi2- ;<~ C~2{3~2 Ia X Y
R1{~} CE2CE2~CE2C:12--~ R2 Ib X Y
R1--~ ~} C~2C~I2 ~}R2 Ic X Y
R 1 ~--CE2 CH2~a-CO--Q--R2 Id X Y
Rl {~}CEzCE2~ CO-O--~3 R2 Ie Rl_O--C 12CE2~-- R2 If i28 ,7-Those compounds of the formula If are preferred in which R2 is ~lkoxy and R1 is alkyl.
The novel compounds (I) can be prepared by va-rious processes. A f;rst general process is based on the S condensation of a corresponding carboxylic acid deriva-tive of the formula A-CH2COOH, preferably in the form ~ of the corresponding acid halide, in which A represents the left-hand part of the molecule of the compound (I), that is to say with a corresponding anisole derivative of the formula B
X Y
~ OC~3 3 in order to form the corresponding ketone of the formula X
2 C ~ O-CH3 C
which is then reduced for replacing the ketocarbonyl oxygen by two hydrogen atoms, a compound of the formula X Y
A C~2-CR2 ~ 0-C~3 D
be;ng formed.
For modifying R2 or/and (if r = 1) for introdu-S cing the structure E
~ Z ~ E
the compound D can be converted to a compound F
X Y
. A 2 2 ~ L1 F
in which L1 is a first reactive group, such as hydroxyl, COOH or halogen, and the compound F can then be reac-ted ~ith a compound of the formula G
~2 ~ z ~ ~2 in which L2 is a second reactive group, in order to form 1S the target compound I or a pre-compound which can be converted ;nto the latter.
Alternatiyely~ the compounds I can also be A :~L ;;2 5 9 ~ ~ 8 _9_ prepared from appropriate pre-compounds of analogous structure, but u;thout transversely polari~;ng suhstitu-ents, by halogenation or transhalogenation and, if approp-riate, nitrilation treplacement of halogen by cyano).
S A specific example of the synthesis of preferred compounds I is illustrated by the equation uhich fol-- lous:
R~ ) Rl--O-- (2) oC~2Br X Y
R1 ~ 2 ~ OCa3 ~~~ R ~ H2C02H
~ (S) X Y- X Y
Rl ~ C2H4 ~ (6) ~ 2~4 ~ o~
~7 x Y
R ~ C2H4 ~ ~1)--C~2 ~ R2 9~
t1) reduction, for examp~e with LiAlH4 (2) bromination, for example with elementary bromine in acetonitrile
(3) C2 Grignard
(4) conversion into acid halide and reaction with 2-Y-3-X-anisole (S) reduction (6) demethylation, for example with boron tribromide (7) condensation with (trans-4-R2-cyclohexyl)-methyl bromide.
The starting materials required for the various syntheses of the compounds I are either known or car, be prepared by methods known per se from known starting materials.
The chemistry involved in the reactions described above is fully conventional per se and as applied to this invention. See, e.g., Houben-Weyl, Methoden der Organischer, Chemie (M~thods of Organic Chemistry), Georg-Thieme Verlag, Stuttgart; Organic Reactions, John Wiley ~ Sons, Inc., New York.
In the pure state, the compounds of the formula (I) are colorless and form liquid-crystalline mesophases in a temperature range favorable for electro-optical use. They are very stable chemically, thermally and towards light.
The compounds of the formula (I) have a wide range of application. Depending on the selection of the substituents, these compounds can be used as base ~%~3628 materials, of which liquid-crystalline dielectrics are predominantly composed; however, liquid-crystalline base materials from other classes of compounds can also be added to compounds of the formula (I), for exam~le in order to lower the dielectric and/or optical aniso-tropy of such a dielectric. The compounds of the formula (I) are also suitable as intermediates for the preparation of other substances, which can be used as constituents of liquid-crystalline dielectrics To prepare LC mixtures according to the invention, in each case at least one specific compound I is used as a component and is mixed, if appropriate, with other specific compounds I and/or with compounds known for the preparation of LC mixtures having a clearly nega-tive DCA for use in GHD or HND systems. The compound I, of which there is at least one, here amounts as a rule to at least 5% by weight and, as a maximum, to 30% by weight of the LC mixture. If several compounds I are used, these can represent a predominant proportion, for example 50-90%
by weight, of the mixture, with appropriate conventional selection. Preferably the LC mixtures contain 10-40% by weight of the compounds of formula I.
LC mixtures which virtually consist only of compound I are also included in the invention, up to 95-100% by weight.
One skilled in the art can, using the preceding de-scription, utilize the present invention to its fullest extent. rhe following preferred specific 1;Z5~
embodiments are, therefore, to be construed as merely illustrative.
. In the following examples and in the preceding text, all temperatures are set forth uncorrected in degrees Celsius and all parts and percentages are by weight, unless otherwise indicated.
In the examples, M is the melting point and C is the clear point of a liquid crystal substance.
"Usual working-up" means: water is added, the mixture is extracted with methylene chloride, the phases are separated, the organic phase is dried and evaporated, and the product is purified by crystalli-zation and/or chromatography. The phase transition temperatures quoted relate to degrees centigrade and are in each case given between the corresponding symbols of the phases "C" (crystalline), "N" (nematic)~ "I"
(isotropic), IISA" (A-smectic).
Example 1 (a) Preparation ~of trans-4-pentylcyclohexylacetyl chloride For conversion into the acid chloride, trans-4-pentylcyclohexylacetic ac;d ~12.0 9, 0.0566 mol) was reacted for about 1 hour on an oil bath at 80C w;th thionyl chlor;de (50 ml). The solution obtained was evaporated under reduced pressure, treated with absolute toluene (S0 ml) and once more evaporated under reduced pressure.
(b) Preparat;on of 2-fluoro-4-m~thoxy-~-(trans-4-pentylcyclohexyl)-acetophenone The acid chloride obtained according to section (a) was taken up in absolute dichloromethane (50 ml), 1S without further purification, and added dropwise under virtually anhydrous conditions to a solution of 3-fluoro-an;sole t7.1 9, 0.05S6 mol), aluminum chloride (8.3 9, - 0.0623 mol) and absolute dichloromethane (150 ml). The mixture thus formed uas stirred for 12 hours and then Z0 poured onto ice water wh;ch contained S0 ml of concentra-ted hydrochloric acid. The organic phase was separated off, and the aqueous phase ~as again extracted with di-chloromethane (2 x 10Q ml). The combined organic phases were then washed with ~ater, sodium bicarbonate and water, and dried over magnesium sulfate. The crude pro-duct obtained after evaporation of the dichloromethane under reduced pressure was purified by recrystalli~ation from hexane at 0C. rhis gave 11.5 9 (64~ yield) of pure 2-fluoro-4-metho~y ~ -(trans-4-PentYlcYclohe~Yl)~
- ~259~;~8 ~-14-.
acetophenone, M. 71 to 72C.
(c) Preparation;of 2.(trans-4-pentylcyclohexyl)-1-(2-fluoro-4-methoxYphenyl)-ethane A mixture of the 2-fluoro-4-methoxy-~-(trans-4-S pentylcyclohexyl)-acetophenone (10.0 g, 0~0313 mol) obtained according to sect;on (b), aluminum l;thium hy-dride (Z.1 9, 0.0560 mol)~ aluminùm chloride (15.0 g, 0.1125 mol), absolute ether (70 ml) and absolute chloro-form (70 ml) uas heated to gentle reflux for 5.5 hours under virtually anhydrous conditions.
The reaction solution was then cooled and subse-quently treated with water-containing ether, water and concentrated hydrochloric acid. The aqueous phase ~as separated off and extracted twice more ~ith ether (2 x 100 ml). The combined organic phases uere then washed uith ~ater, sodium bicarbonate and water, dried over mag-nes;um sulfa~e and then concentrated~ The crude product was distilled in a bulb tube at 150C/about 4 x 10 Z
mm ~9. This product (9.û 9, 94% yield) can be used for the following reaction without further purification.
(d) Preparation of 3-fluoro-4-~Z-(trans-4-pentyl-cyclohexyl)-l-ethyl]-phenol A solution of the 2-~trans-4-pentylcyclohexyl)-1-(2-fluoro-4-methoxyphenyl)-ethane (9.0 g, 0.0294 mol) obtained accord;ng to section (c) in absolute dichlorome-thane (100 ml) uas added dropwise to a solution of boron tribromide (11.0 9, 0.0441 ~ol) and absolute dichlorome-thane (100 ml) under virtually anhydrous conditions at 0C. The mixture thus formed uas stirred for 1 hour ~25~62~3 .
and then poured onto ice water. The organic phase was separated off, and the aqueous phase was extracted again with dichloromethane (Z x 50 ml). The combined organic phases were washed with water and dried over magnesium sulfate. The crude product obtained after evaporation was recrystalli~zed from hexane at 0C. 8~5 9 ~9O~
yield) of pure target product were obtained.
~e) Preparation of 1-C2-ttrans-4-pentylcyclo-hexyl)-1-ethyl]~4-(trans-4-propylcyclohexyl)-methoxy-2-1 0 f luorobenzene A mixture of the 3-fluoro-4-CZ-(trans-4-pentyl-cyclohexyl)-1~ethyl]-phenol (2.0 g, 0.00068 mol) ob-tained according to section (d), (trans-4-propylcyclo-hexyl)-methyl bromide (2.0 g, 0.00089 mol), anhydrous potassium carbonate (3.8 g, 0.0274 mol) and absolute di-methylformamide (100 ml) was heated for 24 hours under reflux.
The reaction mixture was worked up as in section (d)~ The crude product was purified by column chromato-graphy on silica gel with toluene as the eluant. Afterevaporation of the toluene, the product was recrystal-li~ed several times from ethanol, until the phase transi-t;on temperatures were constant; the corresponding values are as follows: C 61.5 N 110 I.
Examples 2 to 7 According to the process indicated in Example 1, and using the corresponding (trans-4-alkylcyclohexyl) methyl bromides, the following compounds (I) according to the invention were prepared:
` ~2596~:8 (Example) (2) 1-C2-(trans-4-pentylcyclohexyl)-1-ethyl]-4-(trans-4-pentylcyclohexyl)-methoxy-2-fluorobenzene;
C 72 - SA 7~ N 113 ~ I;
(3) 1-C2-(trans-4-pentylcyclohexyl)-1-ethyl]-4-(trans~4-heptylcyclohexyl)-methoxy-2-fluorobenzene; C 88 ~ SA
- 94 N 110 ~ I;
(4) 1-C2-(trans-4-propylcyclohexyl)-1-ethyl]-4-(trans-4-propylcyclohexyl)-methoxy-2-fluorobenzene; C 64 ~ N
10B I;
(S) 1-C2-(trans-4-propylcyclohexyl)-1-ethyl~-4-(trans-4-pentylcyclohexyl)-methoxy-2-fluorobenzene; C 54.5 N
110.5 I;
(6) 1-C2-(trans-4-propylcyclohexyl)-1-ethyl] 4-(trans-4-1S heptylcyclohexyl)-methoxy-2-fluorobenzene; C 72.5 ~ SA
7~5 ~ N 107.5 ~ I;
~7) 1-C2-(trans-4-heptylcyclohexyl)-1-ethyl~-4-(trans-4-propyLcyclohexyl)-methoxy-2-fluorobenzene; C 45 N
108 ~ I.
Example 8 From 1-(4-trans-heptylcyclohexyL)-2-(3-fluoro-4-hydroxyphenyl)-ethane CM. 70 - 71; obtainable analo-gously to Example 1] and (trans-4-pro~ylcyclohexyl)-methyl bromide 1-C2-~trans-4-heptylcyclohexyl)-1-e~hyl~~
4-(trans-4-propylcyclohexyL)-methoxy-3-fluorobenzene is obtained analogously to Example 1;
C 50.5 ~ SA 90 ~ N 110 ~ I.
~5~ 8 Example From 1-(4-trans-heptylcyclohexyl)-2-(3-bromo-4-hydroxyphenyl)-ethane CM. 50 - 51; obtainable by brom;-nati~n of 1-(4-trans-heptylcyclohexyl)-2-(4-hydroxy-phenyl)-ethane in dichloromethane], 1-C2-trans-4-heptyl-cyclohexyl)-1-ethyl]-4-~trans-4-propylcyclohexyl)-methoxy-3-bromobenzene is obtained analogously to Example 8; C 44 N 85.S I.
Example 10 From 1-(4-trans-4-heptylcyclohexyl)-2-(3-chloro-4-hydroxyphenyl)-ethane CM. 56 - 57, obtainable analo-gously to Example 1] and (trans-4-propylcyclohexyl)-methyl bromide, 1-C2-(trans-4-heptylcyclohexyl)-1-ethyl]-4-(trans-4-propylcyclohexyl)-methoxy-3-chLorobenzene is obtained analogously to Example 1; C 46 N 96 I.
Example 11 From 1-(4-trans-4-heptylcyclohexyl)-~-~3-cyano-4-hydroxyphenyl)-ethane and (trans-4-propylcyclohexyl)-methyl bromide, 1-C2-(trans-4-heptylcyclohexyl)-1-ethyl]-4-(trans-4-propylcyclohexyl)-methoxy-3-cyanobenzene is obtained analogously to Example 1; C 57 SA 90 I.
Example 12 A mixture of 1.0 9 of 1-(4-trans-pentyLcyclo-hexyl)-2-(2-fluoro-4-hydroxyphenyl)-ethane (Example 1), 0.8 9 of 1-bromobutane, 1.9 9 of potassium carbonate and 30 ml of butanone is boiled overnight. The reaction mixture is added to 250 ml of water, and this is extrac-ted with three times 50 ml of chloroform. rhe combined organic phases are washed with twice 500 ml of water and ~L2~962~3 dried over MgS04. Conventional working-up gives 1-(4-trans-pentylcyc~ohex.yl)-2-t2-fluoro-4-butoxyphenyl~-ethane; C 24 - N 26 I.
Examp~.les 13 to 25:
S Follo~ing the procedure indicated in Example 12 the follo~ing compounds I according to the invention ~ere prepared, us;ng the corresponding 1-(4-trans-alkyl-cyclohexyl)-2-t2 fluoro-4-hydroxyphenyl)-ethanes or the corresponding 1-(4-trans-alkylcyclohexyl)-2-t3~fluoro-4-hydroxyphenyl)-e~hanes and the corresponding 1-bromo-alkanes:
tExample) (13) 1-(4-trans-propylcyclohexyl)-2-t2-fluoro-4-ethoxyphenyl)-ethane; M. 22; C. 14 tmonotropic);
(14) 1-t4-trans-propylcyclohexyl)-2-(2-fluoro-4-butoxyphenyl)-ethane; M. 21; C. 12 tmonotropic);
( 1 5 ) 1-(4-trans-propylcyclohexyl)-2-(2-fluoro-4-hexyloxy-phenyl)-ethane; M. 28; C. 22 (monotropic);
t16) - 1-t4-trans-pentylcyclohexyL)-2-(2-fluoro-4-ethoxyphenyL)-ethane; M. 32; C. 28 tmonotropic);
(17) 1-(4-trans-pentylcyclohexyl)-2-(2-fluoro-4-propoxy-phenyl)-ethane; M. 22.5; C. 10 (monotropic);
.(18) 1-(4-trans-pentylcyclohexyl)-2-(2-fluoro-4-pentyloxy-
The starting materials required for the various syntheses of the compounds I are either known or car, be prepared by methods known per se from known starting materials.
The chemistry involved in the reactions described above is fully conventional per se and as applied to this invention. See, e.g., Houben-Weyl, Methoden der Organischer, Chemie (M~thods of Organic Chemistry), Georg-Thieme Verlag, Stuttgart; Organic Reactions, John Wiley ~ Sons, Inc., New York.
In the pure state, the compounds of the formula (I) are colorless and form liquid-crystalline mesophases in a temperature range favorable for electro-optical use. They are very stable chemically, thermally and towards light.
The compounds of the formula (I) have a wide range of application. Depending on the selection of the substituents, these compounds can be used as base ~%~3628 materials, of which liquid-crystalline dielectrics are predominantly composed; however, liquid-crystalline base materials from other classes of compounds can also be added to compounds of the formula (I), for exam~le in order to lower the dielectric and/or optical aniso-tropy of such a dielectric. The compounds of the formula (I) are also suitable as intermediates for the preparation of other substances, which can be used as constituents of liquid-crystalline dielectrics To prepare LC mixtures according to the invention, in each case at least one specific compound I is used as a component and is mixed, if appropriate, with other specific compounds I and/or with compounds known for the preparation of LC mixtures having a clearly nega-tive DCA for use in GHD or HND systems. The compound I, of which there is at least one, here amounts as a rule to at least 5% by weight and, as a maximum, to 30% by weight of the LC mixture. If several compounds I are used, these can represent a predominant proportion, for example 50-90%
by weight, of the mixture, with appropriate conventional selection. Preferably the LC mixtures contain 10-40% by weight of the compounds of formula I.
LC mixtures which virtually consist only of compound I are also included in the invention, up to 95-100% by weight.
One skilled in the art can, using the preceding de-scription, utilize the present invention to its fullest extent. rhe following preferred specific 1;Z5~
embodiments are, therefore, to be construed as merely illustrative.
. In the following examples and in the preceding text, all temperatures are set forth uncorrected in degrees Celsius and all parts and percentages are by weight, unless otherwise indicated.
In the examples, M is the melting point and C is the clear point of a liquid crystal substance.
"Usual working-up" means: water is added, the mixture is extracted with methylene chloride, the phases are separated, the organic phase is dried and evaporated, and the product is purified by crystalli-zation and/or chromatography. The phase transition temperatures quoted relate to degrees centigrade and are in each case given between the corresponding symbols of the phases "C" (crystalline), "N" (nematic)~ "I"
(isotropic), IISA" (A-smectic).
Example 1 (a) Preparation ~of trans-4-pentylcyclohexylacetyl chloride For conversion into the acid chloride, trans-4-pentylcyclohexylacetic ac;d ~12.0 9, 0.0566 mol) was reacted for about 1 hour on an oil bath at 80C w;th thionyl chlor;de (50 ml). The solution obtained was evaporated under reduced pressure, treated with absolute toluene (S0 ml) and once more evaporated under reduced pressure.
(b) Preparat;on of 2-fluoro-4-m~thoxy-~-(trans-4-pentylcyclohexyl)-acetophenone The acid chloride obtained according to section (a) was taken up in absolute dichloromethane (50 ml), 1S without further purification, and added dropwise under virtually anhydrous conditions to a solution of 3-fluoro-an;sole t7.1 9, 0.05S6 mol), aluminum chloride (8.3 9, - 0.0623 mol) and absolute dichloromethane (150 ml). The mixture thus formed uas stirred for 12 hours and then Z0 poured onto ice water wh;ch contained S0 ml of concentra-ted hydrochloric acid. The organic phase was separated off, and the aqueous phase ~as again extracted with di-chloromethane (2 x 10Q ml). The combined organic phases were then washed with ~ater, sodium bicarbonate and water, and dried over magnesium sulfate. The crude pro-duct obtained after evaporation of the dichloromethane under reduced pressure was purified by recrystalli~ation from hexane at 0C. rhis gave 11.5 9 (64~ yield) of pure 2-fluoro-4-metho~y ~ -(trans-4-PentYlcYclohe~Yl)~
- ~259~;~8 ~-14-.
acetophenone, M. 71 to 72C.
(c) Preparation;of 2.(trans-4-pentylcyclohexyl)-1-(2-fluoro-4-methoxYphenyl)-ethane A mixture of the 2-fluoro-4-methoxy-~-(trans-4-S pentylcyclohexyl)-acetophenone (10.0 g, 0~0313 mol) obtained according to sect;on (b), aluminum l;thium hy-dride (Z.1 9, 0.0560 mol)~ aluminùm chloride (15.0 g, 0.1125 mol), absolute ether (70 ml) and absolute chloro-form (70 ml) uas heated to gentle reflux for 5.5 hours under virtually anhydrous conditions.
The reaction solution was then cooled and subse-quently treated with water-containing ether, water and concentrated hydrochloric acid. The aqueous phase ~as separated off and extracted twice more ~ith ether (2 x 100 ml). The combined organic phases uere then washed uith ~ater, sodium bicarbonate and water, dried over mag-nes;um sulfa~e and then concentrated~ The crude product was distilled in a bulb tube at 150C/about 4 x 10 Z
mm ~9. This product (9.û 9, 94% yield) can be used for the following reaction without further purification.
(d) Preparation of 3-fluoro-4-~Z-(trans-4-pentyl-cyclohexyl)-l-ethyl]-phenol A solution of the 2-~trans-4-pentylcyclohexyl)-1-(2-fluoro-4-methoxyphenyl)-ethane (9.0 g, 0.0294 mol) obtained accord;ng to section (c) in absolute dichlorome-thane (100 ml) uas added dropwise to a solution of boron tribromide (11.0 9, 0.0441 ~ol) and absolute dichlorome-thane (100 ml) under virtually anhydrous conditions at 0C. The mixture thus formed uas stirred for 1 hour ~25~62~3 .
and then poured onto ice water. The organic phase was separated off, and the aqueous phase was extracted again with dichloromethane (Z x 50 ml). The combined organic phases were washed with water and dried over magnesium sulfate. The crude product obtained after evaporation was recrystalli~zed from hexane at 0C. 8~5 9 ~9O~
yield) of pure target product were obtained.
~e) Preparation of 1-C2-ttrans-4-pentylcyclo-hexyl)-1-ethyl]~4-(trans-4-propylcyclohexyl)-methoxy-2-1 0 f luorobenzene A mixture of the 3-fluoro-4-CZ-(trans-4-pentyl-cyclohexyl)-1~ethyl]-phenol (2.0 g, 0.00068 mol) ob-tained according to section (d), (trans-4-propylcyclo-hexyl)-methyl bromide (2.0 g, 0.00089 mol), anhydrous potassium carbonate (3.8 g, 0.0274 mol) and absolute di-methylformamide (100 ml) was heated for 24 hours under reflux.
The reaction mixture was worked up as in section (d)~ The crude product was purified by column chromato-graphy on silica gel with toluene as the eluant. Afterevaporation of the toluene, the product was recrystal-li~ed several times from ethanol, until the phase transi-t;on temperatures were constant; the corresponding values are as follows: C 61.5 N 110 I.
Examples 2 to 7 According to the process indicated in Example 1, and using the corresponding (trans-4-alkylcyclohexyl) methyl bromides, the following compounds (I) according to the invention were prepared:
` ~2596~:8 (Example) (2) 1-C2-(trans-4-pentylcyclohexyl)-1-ethyl]-4-(trans-4-pentylcyclohexyl)-methoxy-2-fluorobenzene;
C 72 - SA 7~ N 113 ~ I;
(3) 1-C2-(trans-4-pentylcyclohexyl)-1-ethyl]-4-(trans~4-heptylcyclohexyl)-methoxy-2-fluorobenzene; C 88 ~ SA
- 94 N 110 ~ I;
(4) 1-C2-(trans-4-propylcyclohexyl)-1-ethyl]-4-(trans-4-propylcyclohexyl)-methoxy-2-fluorobenzene; C 64 ~ N
10B I;
(S) 1-C2-(trans-4-propylcyclohexyl)-1-ethyl~-4-(trans-4-pentylcyclohexyl)-methoxy-2-fluorobenzene; C 54.5 N
110.5 I;
(6) 1-C2-(trans-4-propylcyclohexyl)-1-ethyl] 4-(trans-4-1S heptylcyclohexyl)-methoxy-2-fluorobenzene; C 72.5 ~ SA
7~5 ~ N 107.5 ~ I;
~7) 1-C2-(trans-4-heptylcyclohexyl)-1-ethyl~-4-(trans-4-propyLcyclohexyl)-methoxy-2-fluorobenzene; C 45 N
108 ~ I.
Example 8 From 1-(4-trans-heptylcyclohexyL)-2-(3-fluoro-4-hydroxyphenyl)-ethane CM. 70 - 71; obtainable analo-gously to Example 1] and (trans-4-pro~ylcyclohexyl)-methyl bromide 1-C2-~trans-4-heptylcyclohexyl)-1-e~hyl~~
4-(trans-4-propylcyclohexyL)-methoxy-3-fluorobenzene is obtained analogously to Example 1;
C 50.5 ~ SA 90 ~ N 110 ~ I.
~5~ 8 Example From 1-(4-trans-heptylcyclohexyl)-2-(3-bromo-4-hydroxyphenyl)-ethane CM. 50 - 51; obtainable by brom;-nati~n of 1-(4-trans-heptylcyclohexyl)-2-(4-hydroxy-phenyl)-ethane in dichloromethane], 1-C2-trans-4-heptyl-cyclohexyl)-1-ethyl]-4-~trans-4-propylcyclohexyl)-methoxy-3-bromobenzene is obtained analogously to Example 8; C 44 N 85.S I.
Example 10 From 1-(4-trans-4-heptylcyclohexyl)-2-(3-chloro-4-hydroxyphenyl)-ethane CM. 56 - 57, obtainable analo-gously to Example 1] and (trans-4-propylcyclohexyl)-methyl bromide, 1-C2-(trans-4-heptylcyclohexyl)-1-ethyl]-4-(trans-4-propylcyclohexyl)-methoxy-3-chLorobenzene is obtained analogously to Example 1; C 46 N 96 I.
Example 11 From 1-(4-trans-4-heptylcyclohexyl)-~-~3-cyano-4-hydroxyphenyl)-ethane and (trans-4-propylcyclohexyl)-methyl bromide, 1-C2-(trans-4-heptylcyclohexyl)-1-ethyl]-4-(trans-4-propylcyclohexyl)-methoxy-3-cyanobenzene is obtained analogously to Example 1; C 57 SA 90 I.
Example 12 A mixture of 1.0 9 of 1-(4-trans-pentyLcyclo-hexyl)-2-(2-fluoro-4-hydroxyphenyl)-ethane (Example 1), 0.8 9 of 1-bromobutane, 1.9 9 of potassium carbonate and 30 ml of butanone is boiled overnight. The reaction mixture is added to 250 ml of water, and this is extrac-ted with three times 50 ml of chloroform. rhe combined organic phases are washed with twice 500 ml of water and ~L2~962~3 dried over MgS04. Conventional working-up gives 1-(4-trans-pentylcyc~ohex.yl)-2-t2-fluoro-4-butoxyphenyl~-ethane; C 24 - N 26 I.
Examp~.les 13 to 25:
S Follo~ing the procedure indicated in Example 12 the follo~ing compounds I according to the invention ~ere prepared, us;ng the corresponding 1-(4-trans-alkyl-cyclohexyl)-2-t2 fluoro-4-hydroxyphenyl)-ethanes or the corresponding 1-(4-trans-alkylcyclohexyl)-2-t3~fluoro-4-hydroxyphenyl)-e~hanes and the corresponding 1-bromo-alkanes:
tExample) (13) 1-(4-trans-propylcyclohexyl)-2-t2-fluoro-4-ethoxyphenyl)-ethane; M. 22; C. 14 tmonotropic);
(14) 1-t4-trans-propylcyclohexyl)-2-(2-fluoro-4-butoxyphenyl)-ethane; M. 21; C. 12 tmonotropic);
( 1 5 ) 1-(4-trans-propylcyclohexyl)-2-(2-fluoro-4-hexyloxy-phenyl)-ethane; M. 28; C. 22 (monotropic);
t16) - 1-t4-trans-pentylcyclohexyL)-2-(2-fluoro-4-ethoxyphenyL)-ethane; M. 32; C. 28 tmonotropic);
(17) 1-(4-trans-pentylcyclohexyl)-2-(2-fluoro-4-propoxy-phenyl)-ethane; M. 22.5; C. 10 (monotropic);
.(18) 1-(4-trans-pentylcyclohexyl)-2-(2-fluoro-4-pentyloxy-
5~628 . .
phenyl)-ethane; M. 26; C. 12 (monotropic);
~19) 1-(4-trans-pentylcyclohexyl)-2-~Z-fluoro-4-hexyloxy-phenyl^)-ethane; M. 23.5; C. 29.5;
(2~) 1-(4-trans-heptylcyclohexyl)-2-(2-fluoro-4-ethoxyphenyl)-ethane; M. 46; C 35 (monotropic);
(21) 1-(4-trans-heptylcyclohexyl)-2-(2-fluoro-4-butoxyphenyl)-ethane; M. 31; C. 34;(22~
1-~4-trans-heptylcyclohexyl)-2-(2-fluoro-4-hexyloxyphe-nyl)-ethane; M. 29.5; C. 35;
(23) tS 1-(4-trans-heptylcyclohexyl)~2-(3-fluoro-4-methoxyphe-nyl)-ethane; M. 32; C. 29 ~monotropic);
t24) 1-(4-trans-heptylcyclohexyl)-3-~3-fluoro-4-ethoxyphenyl)-ethane; M. 53; C. 34 (monotropic);
(25) 1-~4-trans-heptylcyclohexyl)-3-~3-fluoro-4-hexyloxy-phenyl)-ethane; Ma 45; C~ 35 (monotropic).
Example 26 A mixture of 0.65 9 of trans-4-pentylcyclohexane-car-boxylic acid chloride and 10 ml toluene is added to a mix-ture of 0., g of 1-(trans-4-pentylcyclohexyl) 2-(2-fluoro-4-hydroxyphenyl)-ethane (Example 1), 2 ml of pyrid;ne and 10 ml of toluene, and the whole is stirred overnight. rhe reaction mixture is poured into cold, dilute hydrochloric ~;~59~28 acid and ~orked up as usual. This gives 3-fluoro-4-CZ-(trans-4-pentylcyclohexyl)-ethyl]phenyltrans-4-pentyl-cyclohexane-carboxylate; M. 7Z.5, C. 147.
Examples 27 to 31 Following the procedure indicated in Example Z6, the follow;ng compounds I according to the in~ention - are prepared:
(Z7) 3-fluoro-4-C2-(trans-4~propylcyclohexyl)-ethyl~-phenyl trans-4-propylcyclohexane-carboxylate; M. 72; C. 140;
~28) 3-fluoro-4-C2-(trans-4-propylcyclohexyl)-ethyl]-phenyl trans-4-pentylcyclohexane-carboxylate; M. 68; C. 146.5;
(29) 3-fluoro-4-~2-~trans-4-propylcyclohexyl)-ethyl~-phenyl trans-4-heptylcyclohexane-carboxylate; C. 84 SA 91 N 140 ~ I;
(30) 3-fluoro-4-C2-(trans-4-pentylcyclohexyl)-ethyl]-phenyl trans-4-propylcyclohexane-carboxylate; M. 65; C~ 141;
(31) 3-fluoro-4-C2-(trans-4-pentylcyclohexyl~-ethyl]-phenyl trans-4-heptylcyclohexane-carboxylate;
C. 100 SA 111 ~ N 142 ~ I.
Z5 ~he following are further examples of compounds of the formula I: ~hey are prepared analogously to the foregoing.
2-(trans-4-pentyl-4'-bicyclohexyl~-1-(3-fluoro-4 pentyl-phenyl)-ethane;
2-(trans-4-pentyl-4'-bicyclohexyl)-1-(2-fluoro 4-pentyl-
phenyl)-ethane; M. 26; C. 12 (monotropic);
~19) 1-(4-trans-pentylcyclohexyl)-2-~Z-fluoro-4-hexyloxy-phenyl^)-ethane; M. 23.5; C. 29.5;
(2~) 1-(4-trans-heptylcyclohexyl)-2-(2-fluoro-4-ethoxyphenyl)-ethane; M. 46; C 35 (monotropic);
(21) 1-(4-trans-heptylcyclohexyl)-2-(2-fluoro-4-butoxyphenyl)-ethane; M. 31; C. 34;(22~
1-~4-trans-heptylcyclohexyl)-2-(2-fluoro-4-hexyloxyphe-nyl)-ethane; M. 29.5; C. 35;
(23) tS 1-(4-trans-heptylcyclohexyl)~2-(3-fluoro-4-methoxyphe-nyl)-ethane; M. 32; C. 29 ~monotropic);
t24) 1-(4-trans-heptylcyclohexyl)-3-~3-fluoro-4-ethoxyphenyl)-ethane; M. 53; C. 34 (monotropic);
(25) 1-~4-trans-heptylcyclohexyl)-3-~3-fluoro-4-hexyloxy-phenyl)-ethane; Ma 45; C~ 35 (monotropic).
Example 26 A mixture of 0.65 9 of trans-4-pentylcyclohexane-car-boxylic acid chloride and 10 ml toluene is added to a mix-ture of 0., g of 1-(trans-4-pentylcyclohexyl) 2-(2-fluoro-4-hydroxyphenyl)-ethane (Example 1), 2 ml of pyrid;ne and 10 ml of toluene, and the whole is stirred overnight. rhe reaction mixture is poured into cold, dilute hydrochloric ~;~59~28 acid and ~orked up as usual. This gives 3-fluoro-4-CZ-(trans-4-pentylcyclohexyl)-ethyl]phenyltrans-4-pentyl-cyclohexane-carboxylate; M. 7Z.5, C. 147.
Examples 27 to 31 Following the procedure indicated in Example Z6, the follow;ng compounds I according to the in~ention - are prepared:
(Z7) 3-fluoro-4-C2-(trans-4~propylcyclohexyl)-ethyl~-phenyl trans-4-propylcyclohexane-carboxylate; M. 72; C. 140;
~28) 3-fluoro-4-C2-(trans-4-propylcyclohexyl)-ethyl]-phenyl trans-4-pentylcyclohexane-carboxylate; M. 68; C. 146.5;
(29) 3-fluoro-4-~2-~trans-4-propylcyclohexyl)-ethyl~-phenyl trans-4-heptylcyclohexane-carboxylate; C. 84 SA 91 N 140 ~ I;
(30) 3-fluoro-4-C2-(trans-4-pentylcyclohexyl)-ethyl]-phenyl trans-4-propylcyclohexane-carboxylate; M. 65; C~ 141;
(31) 3-fluoro-4-C2-(trans-4-pentylcyclohexyl~-ethyl]-phenyl trans-4-heptylcyclohexane-carboxylate;
C. 100 SA 111 ~ N 142 ~ I.
Z5 ~he following are further examples of compounds of the formula I: ~hey are prepared analogously to the foregoing.
2-(trans-4-pentyl-4'-bicyclohexyl~-1-(3-fluoro-4 pentyl-phenyl)-ethane;
2-(trans-4-pentyl-4'-bicyclohexyl)-1-(2-fluoro 4-pentyl-
6~3 phenyl)-ethane;
2-ttrans-4-pentyl-4'-bicyclohexyl)-1-(3-fluoro-4-butoxy-phenyl)-ethane;
2-(trans-4-pentyl-4'-bicyclohexyl)-1-(2-fluoro-4-butoxy-phenyl)-ethane;
Z-(trans-4-pentyl-4'-bicyclohexyl)-1-(3-cyano-4-pentyl-phenyl)-ethane;
Z-(trans-4-pentyl-4'-bicyclohexyl)-1-(Z-cyano-4-pentyl-phenyl)-ethane;
Z-(trans-4-pentyl-4'-bicyclohexyl)-1-(3-cyano-4-ethoxy-phenyl)-ethane;
Z-(trans-4-pentyl-4'-bicyclohexyl)-1-(3-cyano-4-butoxy-phenyl)-ethane;
2-(trans-4-pentyl-4'-bicyclohexyl)-1-(3-cyano-4-hexyloxy-phenyl)-ethane;
2-(trans 4-pentyl-4'-bicyclohexyl)-1-(2-cyano-4-ethoxy-phenyl)-ethane;
2-~trans-4-pentyl-4'-bicyclohexyl)-1-(2-cyano-4-butoxy-phenyl)-ethane;
2-(trans-4-pentyl-4'-b;cyclohexyl)-1-(2-cyano-4-he%yloxy~
phenyl)-ethane;
2-fluoro-1-~2-(trans-4-propylcyclohexyl)-1-ethyl]-4~C2-<trans-4-pentylcyclohexyl)-1-ethyl]-benzene;
3-fluoro-1-CZ-(trans-4-propylcyclohexyl)-1-ethyl~-4-C2-ZS (trans-4-pentylcyclohexyl)-1-ethyl~-benzene;
Z-fluoro-1,4-d;-C2-(trans-4-pentylcyclohexyl)-1-ethyl~-; ben2ene;
2,3-difluoro-1,4-di-CZ-(trans-4-propylcyclohexyl)-1-ethyl]-benzene;
g~:8 .
2,3-difluoro-1,4-di-CZ-(trans-4-pentyLcyclohexyl)-1-ethyl]-benzene;
2,3-difluoro~1,4-di-~2-(trans-4-heptylcyclohexyl)-1-ethyl~-benzene;
2-cyano-1-C2-~trans-4-propylcyclohexyl)-1-ethyl]-4-C2-(trans-4-pentylcyclohexyl)-1-ethyl]-benzene;
3-cyano-1-C2-(trans-4-propylcyclohexyl)-1-ethyl~-4-C2-(trans-4-pentylcyclohexyl)-1-ethyl]-benzene;
Z-cyano-1,4-d;-C2-(trans-4-pentylcyclohexyl)-1-ethyl]-ben-zene;
2,3-dicyano-1,4-d;-C2-(trans-4-propylcyclohexyl)-1-ethyl]-benzene;
2,3-dicyano-1,4-di-C2-(trans-4-pentylcyclohexyl)-1-ethyl~-benzene;
2,3-dicyano~1,4-di-C2-(trans-4-heptylcyclohexyl)-1-ethyl~-benzene~
The following examples relate to mixtures of com-pounds of formula I with other liquid-crystall1ne substances whcih can be used as dielectrics according to the invention.
Example A
A liquid crystalline dielectric is prepared by mixing 0.25 g of 1-[2-trans-4-pentylcyclohexyl)-1~ethyl~-4-(trans-4-propylcyclohexyl)-methoxy-2-fluorobenzene (com-pound according to example 1) with 0.75 g of a known liquid crystalline phase consisting of 24.0% by weight of trans-5~?628 -22a-1-(4-etlloxyphenyl)-b-propylcyclohexane~ 21.2% by weight of trans-1-(4-butoxyphenyl)-4-propylcyclohexane, 19.3%
by weight of trans,trans-4-butylcyclohexanecarboxylic acid-4'-(4-propylcyclohexyl)phenylester and 35.5% by weight, of 4'-(trans-4-propyl-cyclohexyl)-benzoicacid-2'-cyano-4'-butyl phenylester.
This mixture shows a DCA of -2.3.
Example B
A liquid crystalline dielectric consisting of 15%
by weight of trans-1-p-ethoxyphenyl-4-propylcyclohexane, 10% by weight of trans-1-p-butoxyphenyl-4-propylcyclohexane 25% by weight of 4-ethyl-4'-(trans-4-pentylcyclohexyl)-biphenyl, 20% by weight of p-methoxybenzoic acid p-pentyl-phenylester and 30% by weight of 1-(4-trans-pentylcyclo-hexyl)-2-(2-fluoro-4-hexyloxyphenyl)-ethane shows a negative DCA.
Example C
A liquid crystalline dielectric consisting of 7%
by weight of trans-1-p-ethoxyphenyl-4-propylcyclohexane~
30% by weight of 4-ethyl-4'-(trans-4-pentylcyclohexyl)-2'-fluorbiphenyl, 9% by weight of 4-ethyl-4'-(trans-4-propylcyclohexyl)-biphenyl, 6% by weight of 4-ethyl-4'-(trans-4-pentylcyclohexyl)-biphenyl, 15% by weight of 4-(trans-4-pentylcyclohexyl)-4'-(trans-4-propylcyclo-hexyl)-biphenyl, 23% by weight of p-m-methoxybenzoic acid p-pentylphenylester, o% by weight of 3-fluoro~4-C2-(trans-4-pentylcyclohexyl)-ethyl]-phenyl-trans-4-pentylcyclohexane-carboxylate and 4% by weight of 2-~9~i~8 - 22b -(trans-4-pentyl-4'-bicyclohexyl)-1-(3-fluoro-4-pentyl-phenyl)-ethane shows a negative DCA.
Example D
A liquid crystalline dielectric consisting of 13% by weight of r-1-cyano-c;s-4-(trans-4-proPylcyclohexyl)-1-pentylcyclohexane, 6% by weight of Z-p-cyanophenyl-S-propyl-1,3-dioxane, 9% by weight of 2-p-octyloxyphenyl-5-pentyl-pyrimidine, 7% by weight of 2-p-nonyloxyphenyl-5-hexyl-pyrimidine, 10% by weight of trans-4-propyl-cyclohexane carboxylic acid-p-ethoxyphenylester, f5% by weight of 4-ttrans-4-pentylcyclohexyl)-4'-(trans-4-propylcyclohexyl)-biphenyl, 17% by weight of 1-(4-trans-pentylcyclohexyl)-2-(2-fluoro-4-hexyloxyphenyl)-ethane, 12% by weight of 1-(4-trans-pentylcyclohexyl)-2-(2-fluoro-4-ethoxyphenyl)-ethene and 11% by weight of 3-fluoro-4-C2-(trans-4-pentylcyclohexyl)-ethyl]-phenyl-trans-4-pentylcyclohexane-carboxylate shows a negative DCA~
Example E
A liquid crystalline dielectric consisting of 27%
by weight of 1-(4-trans-pentylcyclohexyl)-2-(2-fluoro-4-hexyloxyphenyl)-ethane, 11% by weight of 1-C2-(trans-4-propylcyclohexyl)-1-ethyl]-4-(trans-4-propylcyclohexyl)-methoxy-2-fluorobenzene, 39% by weight of 1-[2-ttrans-4-heptylcyclohexyl)-1-ethyl~-4-(trans-4-propylcyclohexyl)-methoxy-2-fluorobenzene and 23% by weight of 1-~4-trans-pentylcyclohexyl)-2-(2-fluoro-4-butoxyphenyl)-ethane shows a negative DCA.
~ 2~96~
, . , The preceding examples can be repeated with similar success by substituting the generically or sper,ifically described reactants and/or operating conditions of this invention for those used in the preceding examples.
2-ttrans-4-pentyl-4'-bicyclohexyl)-1-(3-fluoro-4-butoxy-phenyl)-ethane;
2-(trans-4-pentyl-4'-bicyclohexyl)-1-(2-fluoro-4-butoxy-phenyl)-ethane;
Z-(trans-4-pentyl-4'-bicyclohexyl)-1-(3-cyano-4-pentyl-phenyl)-ethane;
Z-(trans-4-pentyl-4'-bicyclohexyl)-1-(Z-cyano-4-pentyl-phenyl)-ethane;
Z-(trans-4-pentyl-4'-bicyclohexyl)-1-(3-cyano-4-ethoxy-phenyl)-ethane;
Z-(trans-4-pentyl-4'-bicyclohexyl)-1-(3-cyano-4-butoxy-phenyl)-ethane;
2-(trans-4-pentyl-4'-bicyclohexyl)-1-(3-cyano-4-hexyloxy-phenyl)-ethane;
2-(trans 4-pentyl-4'-bicyclohexyl)-1-(2-cyano-4-ethoxy-phenyl)-ethane;
2-~trans-4-pentyl-4'-bicyclohexyl)-1-(2-cyano-4-butoxy-phenyl)-ethane;
2-(trans-4-pentyl-4'-b;cyclohexyl)-1-(2-cyano-4-he%yloxy~
phenyl)-ethane;
2-fluoro-1-~2-(trans-4-propylcyclohexyl)-1-ethyl]-4~C2-<trans-4-pentylcyclohexyl)-1-ethyl]-benzene;
3-fluoro-1-CZ-(trans-4-propylcyclohexyl)-1-ethyl~-4-C2-ZS (trans-4-pentylcyclohexyl)-1-ethyl~-benzene;
Z-fluoro-1,4-d;-C2-(trans-4-pentylcyclohexyl)-1-ethyl~-; ben2ene;
2,3-difluoro-1,4-di-CZ-(trans-4-propylcyclohexyl)-1-ethyl]-benzene;
g~:8 .
2,3-difluoro-1,4-di-CZ-(trans-4-pentyLcyclohexyl)-1-ethyl]-benzene;
2,3-difluoro~1,4-di-~2-(trans-4-heptylcyclohexyl)-1-ethyl~-benzene;
2-cyano-1-C2-~trans-4-propylcyclohexyl)-1-ethyl]-4-C2-(trans-4-pentylcyclohexyl)-1-ethyl]-benzene;
3-cyano-1-C2-(trans-4-propylcyclohexyl)-1-ethyl~-4-C2-(trans-4-pentylcyclohexyl)-1-ethyl]-benzene;
Z-cyano-1,4-d;-C2-(trans-4-pentylcyclohexyl)-1-ethyl]-ben-zene;
2,3-dicyano-1,4-d;-C2-(trans-4-propylcyclohexyl)-1-ethyl]-benzene;
2,3-dicyano-1,4-di-C2-(trans-4-pentylcyclohexyl)-1-ethyl~-benzene;
2,3-dicyano~1,4-di-C2-(trans-4-heptylcyclohexyl)-1-ethyl~-benzene~
The following examples relate to mixtures of com-pounds of formula I with other liquid-crystall1ne substances whcih can be used as dielectrics according to the invention.
Example A
A liquid crystalline dielectric is prepared by mixing 0.25 g of 1-[2-trans-4-pentylcyclohexyl)-1~ethyl~-4-(trans-4-propylcyclohexyl)-methoxy-2-fluorobenzene (com-pound according to example 1) with 0.75 g of a known liquid crystalline phase consisting of 24.0% by weight of trans-5~?628 -22a-1-(4-etlloxyphenyl)-b-propylcyclohexane~ 21.2% by weight of trans-1-(4-butoxyphenyl)-4-propylcyclohexane, 19.3%
by weight of trans,trans-4-butylcyclohexanecarboxylic acid-4'-(4-propylcyclohexyl)phenylester and 35.5% by weight, of 4'-(trans-4-propyl-cyclohexyl)-benzoicacid-2'-cyano-4'-butyl phenylester.
This mixture shows a DCA of -2.3.
Example B
A liquid crystalline dielectric consisting of 15%
by weight of trans-1-p-ethoxyphenyl-4-propylcyclohexane, 10% by weight of trans-1-p-butoxyphenyl-4-propylcyclohexane 25% by weight of 4-ethyl-4'-(trans-4-pentylcyclohexyl)-biphenyl, 20% by weight of p-methoxybenzoic acid p-pentyl-phenylester and 30% by weight of 1-(4-trans-pentylcyclo-hexyl)-2-(2-fluoro-4-hexyloxyphenyl)-ethane shows a negative DCA.
Example C
A liquid crystalline dielectric consisting of 7%
by weight of trans-1-p-ethoxyphenyl-4-propylcyclohexane~
30% by weight of 4-ethyl-4'-(trans-4-pentylcyclohexyl)-2'-fluorbiphenyl, 9% by weight of 4-ethyl-4'-(trans-4-propylcyclohexyl)-biphenyl, 6% by weight of 4-ethyl-4'-(trans-4-pentylcyclohexyl)-biphenyl, 15% by weight of 4-(trans-4-pentylcyclohexyl)-4'-(trans-4-propylcyclo-hexyl)-biphenyl, 23% by weight of p-m-methoxybenzoic acid p-pentylphenylester, o% by weight of 3-fluoro~4-C2-(trans-4-pentylcyclohexyl)-ethyl]-phenyl-trans-4-pentylcyclohexane-carboxylate and 4% by weight of 2-~9~i~8 - 22b -(trans-4-pentyl-4'-bicyclohexyl)-1-(3-fluoro-4-pentyl-phenyl)-ethane shows a negative DCA.
Example D
A liquid crystalline dielectric consisting of 13% by weight of r-1-cyano-c;s-4-(trans-4-proPylcyclohexyl)-1-pentylcyclohexane, 6% by weight of Z-p-cyanophenyl-S-propyl-1,3-dioxane, 9% by weight of 2-p-octyloxyphenyl-5-pentyl-pyrimidine, 7% by weight of 2-p-nonyloxyphenyl-5-hexyl-pyrimidine, 10% by weight of trans-4-propyl-cyclohexane carboxylic acid-p-ethoxyphenylester, f5% by weight of 4-ttrans-4-pentylcyclohexyl)-4'-(trans-4-propylcyclohexyl)-biphenyl, 17% by weight of 1-(4-trans-pentylcyclohexyl)-2-(2-fluoro-4-hexyloxyphenyl)-ethane, 12% by weight of 1-(4-trans-pentylcyclohexyl)-2-(2-fluoro-4-ethoxyphenyl)-ethene and 11% by weight of 3-fluoro-4-C2-(trans-4-pentylcyclohexyl)-ethyl]-phenyl-trans-4-pentylcyclohexane-carboxylate shows a negative DCA~
Example E
A liquid crystalline dielectric consisting of 27%
by weight of 1-(4-trans-pentylcyclohexyl)-2-(2-fluoro-4-hexyloxyphenyl)-ethane, 11% by weight of 1-C2-(trans-4-propylcyclohexyl)-1-ethyl]-4-(trans-4-propylcyclohexyl)-methoxy-2-fluorobenzene, 39% by weight of 1-[2-ttrans-4-heptylcyclohexyl)-1-ethyl~-4-(trans-4-propylcyclohexyl)-methoxy-2-fluorobenzene and 23% by weight of 1-~4-trans-pentylcyclohexyl)-2-(2-fluoro-4-butoxyphenyl)-ethane shows a negative DCA.
~ 2~96~
, . , The preceding examples can be repeated with similar success by substituting the generically or sper,ifically described reactants and/or operating conditions of this invention for those used in the preceding examples.
Claims (23)
1. In a liquid crystalline dielectric comprising at least two liquid crystalline compounds, the improve-ment wherein at least one of these compounds is a nematic compound with a negative dielectric anisotropy of the formula wherein m = 1 or 2, r is zero or 1, m + r = 1 or 2, R1 and R2 are identical or different and each is alkyl or alkoxy each of 1 - 12 carbon atoms, Z is a bridging group which is a single bond, -CH2CH2-, -OCH2-, -O-CO- or -CO-O- and, one of X and Y is fluorine, chlorine, bromine or cyano and the other is hydrogen, fluorine, chlorine, bromine or cyano, with the proviso that m = r = 1 when X and Y are both cyano.
2. A dielectric of Claim 1, wherein R1 or R2 is straight chained.
3. A dielectric of Claim 1, wherein R1 or R2 is a chiral branched group.
4. A dielectric of Claim 1, wherein m + r = 2.
5. A dielectric of Claim 1, wherein said nematic compound is of the formula in which R1, R2, X and Y are as defined in Claim 1.
6. A dielectric of Claim 1, wherein said nematic compound is of the formula in which R1, R2, X and Y are as defined in Claim 1.
7. A dielectric of Claim 1, wherein said nematic compound is of the formula in which R1, R2, X and Y are as defined in Claim 1.
8. A dielectric of Claim 1, wherein said nematic compound is of the formula in which R1, R2, X and Y are as defined in Claim 1.
9. A dielectric of Claim 1, wherein said nematic compound is of the formula in which R1, R2, X and Y are as defined in Claim 1.
10. A dielectric of Claim 1, wherein said nematic compound is of the formula in which R1, R2, X and Y are as defined in Claim 1.
11. A dielectric of Claim 1, wherein X is fluoro and Y is H
12. A dielectric of Claim 1, wherein r = 1 and Z
is -CH2CH2-, -OCH2- or -O-CO-.
is -CH2CH2-, -OCH2- or -O-CO-.
13. A dielectric of Claim 1, wherein R1 is straight chain C2-8-alkyl.
14. A dielectric of Claim 1, wherein r = 0 and R2 is a straight chain alkoxy of 2-8 C-atoms or wherein r = 1 and R2 is straight chain alkyl of 2-8 C-atoms.
15. A compound of the formula wherein m = 1 or 2, r is zero or 1, m + r = 1 or 2, R1 and R2 are identical or different and each is alkyl or alkoxy each of 1 - 12 carbon atoms, Z is a bridging group which is a single bond, -CH2CH2-, -OCH2-, -O-CO- or -CO-O- and, one of X and Y is fluorine, chlorine, bromine or cyano and the other is hydrogen, fluorine, chlorine, bromine or cyano, with the proviso that m = r = 1 when X and Y are both cyano.
16, A compound of Claim 15 of the formula in which R1, R2, X and Y are as defined in Claim 15.
17. A compound of Claim 15 of the formula in which R1, R2, X and Y are as defined in Claim 15.
18. A compound of Claim 16 of the formula in which R1, R2, X and Y are as defined in Claim 15.
19. A compound of Claim 16 of the form in which R1, R2, X and Y are as defined in Claim 15.
20. A compound of Claim 16 of the formula in which R1, R2, X and Y are as defined in Claim 15.
21. A compound of Claim 16 of the formula in which R1, R2, X and Y are as defined in Claim 15.
22. In an electro-optical display element comprising a liquid crystalline dielectric and associated operational circuitry and hardware, the improvement wherein the dielectric is one of Claim 15.
23. A electrooptical display element of Claim 22 which is a guest/host display element or a homotropicnematic display element.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH323483 | 1983-08-04 | ||
| CH3234/83-5 | 1983-08-04 | ||
| DE19843410734 DE3410734A1 (en) | 1984-03-23 | 1984-03-23 | Nematic compounds |
| DEP3410734.7 | 1984-03-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1259628A true CA1259628A (en) | 1989-09-19 |
Family
ID=25692529
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000460292A Expired CA1259628A (en) | 1983-08-04 | 1984-08-02 | Nematic compounds containing cyclohexyl groups |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1259628A (en) |
-
1984
- 1984-08-02 CA CA000460292A patent/CA1259628A/en not_active Expired
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