WO1998011173A1

WO1998011173A1 - Liquid crystal materials

Info

Publication number: WO1998011173A1
Application number: PCT/KR1997/000169
Authority: WO
Inventors: Vladimir St. Bezborodov; Valery Lapanik, Iv.
Original assignee: Samsung Display Devices Co Ltd
Current assignee: Samsung SDI Co Ltd
Priority date: 1996-09-12
Filing date: 1997-09-11
Publication date: 1998-03-19
Anticipated expiration: 1999-03-12
Also published as: KR20000036036A; AU4138097A; JP2001500502A; EP0946672A1

Abstract

Chiral liquid crystalline compounds of Formula (1): R1-(A')a-21-(A2)b-(22)c-(A3)d-R2 are particularly useful in a ferroelectric liquid crystal display device. These cyclic-containing compounds are chiral and contain lateral substituents. The compounds exhibit a low temperature smectic C phase and have a broad smectic C phase region.

Description

LIQUID CRYSTAL MATERIALS

Technical Field

The present invention relates to liquid crystal materials for use in ferroelectric liquid crystal display devices. More specifically, the invention relates to chiral, laterally substituted derivatives of cyclohexene, cyclohexane, benzene, biphenyl, terphenyl and quaterphenyl compounds, mixtures thereof, and liquid crystal displays utilizing the same.

Background Art

Liquid crystal displays have been commonly employed in electronic devices for many years. In general, commercial displays operate by the twisted nematic (TN) or super twisted nematic (STN) technique. However, liquid crystal displays based on a ferroelectric technique are also known. Such displays have superior properties such as higher switching efficiencies in comparison to TN and STN displays. But ferroelectric liquid crystal displays have not been widely used in commercial or consumer applications, in spite of their advantages, due to their limited operable temperature range. Specifically, in order to utilize the ferroelectric effect, the liquid crystal material must exhibit a smectic C phase. Liquid crystal compounds that exhibit a smectic C phase do so over a narrow temperature range. Moreover, the smectic C phase tends to be exhibited only at a relatively high temperature; i.e, above ambient temperature. Accordingly, designing a ferroelectric liquid crystal display for general consumer electronics becomes impractical. Liquid crystal compounds include derivatives of cyclohexane, cyclohexene, benzene, biphenyl, and terphenyl compounds. Such compounds are disclosed in Ferroelectrics 1991, vol. 114, p. 357; JP 04 216 525 (1992); EP 86/00529 (1987); DE 3608500 (1987); WO 87/05015 (1987); WO 87/01717; WO 87/05017; DE 3706766; JP 88 300 885.6 (1988); J. Am. Che. Soc. 1986, vol. 108, p. 5210; GB 2181429; JP 05 17409; JP 07 258642. Many of these compounds do not exhibit a smectic C phase and instead exhibit only a nematic phase. Accordingly, these compounds are useful only in TN or STN displays and are not operable as ferroelectric liquid crystal materials. The compounds that do exhibit a smectic C phase tend to suffer from the above-mentioned temperature drawbacks as well as having an unstable orientation.

U.S. P. 4,784,793 addresses some of the problems encountered with ferroelectric liquid crystal materials and proposes the use of terpenoid derivatives, such as an ester of a terpenoid alcohol, as either a smectic host or a chiral dopant. U.S. P. 5,382,380 and U.S. P. 5,494,605 both relate to p-terphenyl derivatives having lateral fluoro substitution. The compounds are described as exhibiting a smectic C phase over a wide temperature range. However, the compounds of the prior art are not yet fully satisfactory and do not satisfy all of the requirements for some of the new applications for liquid crystal displays. Specifically, compounds are needed that will allow the formation of ferroelectric liquid crystal mixtures exhibiting a low crystalline to smectic C phase transition temperature as well as a wide smectic C phase and that has a stable orientation.

Disclosure of the Invention

It is an object of the present invention to provide chiral liquid crystal compounds that exhibit a low transition temperature from the crystalline to smectic C phase, that exhibit the smectic C phase over a wide temperature range, and that provide stable orientation over time.

It is another object of the invention to provide a ferroelectric mixture that exhibits a smectic C phase over a broad temperature range and at low temperatures.

A further object of the invention is to provide a ferroelectric liquid crystal display device that is operable over a wide range of temperatures and at very low temperatures.

These and other objects of the present invention are achieved by a chiral liquid crystalline compound of formula (1):

R¹— (A¹ ) _a— Z¹— ( A² ) _b— ( Z² ) _c— (A³ ) _d— R² ( l ) wherein a, b, c, and d are each independently zero or 1;

R¹ and $ are each independently selected from the group consisting of formulas S¹, S² and S³ : I I

HC (CH₂) „— (O) _m C (CH₂) _k (O) _r (CH₂) (S¹

Y Y⁴

Y¹

C=CH (CH,)_n (0)_m C — (CH₂), (O), (CH₂)_n

Y^l

Y¹

HC — (CH, C O } _ — C CH=CH — ^• ( CH, ) (0) (CH, (S³

Y Y⁴

wherein Y¹, Y², Y³, and Y are each independently hydrogen, alkyl, F, CN, CF, or OCF₃, n, p, and k are each independently an integer from 0 to 7. and m and 1 are each independently zero or 1, with the proviso that at least one of R¹ and R² is a chiral radical;

Z¹ and Z² are each independently a ring selected from the group consisting of formulas 2-11

(2) (3) (4) (5)

(10) (11) wherein X represents O, F, Cl, OH, CN, or a group represented by formulas L¹- L⁶:

(L¹)

C=CH— (CH₂) _n— (O) _m— C— (CH₂) _k— (0} ,— (CH₂) ( ²

Y⁴

Y'

HC— ( CH₂ ) _n— ( O ) _m — C — CH=CH — ( CH₂ ) _k— ( O ) ,— ( CH₂ ) ( ³

γl _γ3 i I

HC— (CH₂)_n— (0)_m— C— (CH₂)_k— (O),— (CH₂)_p— COO— ( ⁴) γ2 γ

Y¹ γ³

I I

C=CH— (CH₂) — (O) _m— C— (CH₂) _k— (O) ,— { CH₂) _p— COO— ( )

Y² γ»

H

wherein Y¹, Y², Y³, Y⁴, n, p, k, m and 1 have the same meanings as above in formulas S'-S³;

A¹, A² and A³ are each independently a ring group selected from the group consisting of formulas 12-19:

ds)

( 14 )

wherein X¹, X², X³ and X ⁴ are each independently H, F, or Cl and B and B¹ are each independently a single bond, -CH₂CH₂-, -CH=CH-, -C ≡C-, -OCH,-, or -CH₂O-; with the proviso that when the ring structure formed by any three of A¹, Z¹ , A², Z² and A³ is teφhenyl, then none of X, X¹ , X² , X³ and X⁴ represent F.

Best mode for carrying out the Invention The present invention relates to a chiral liquid crystalline compound of

Formula (1): R¹— (A¹ ) _a— Z¹— (A²) _b— ( Z² ) _c— (A³ ) _d— R² _{( 1 )}

Because a, b, c and d are each independently 0 or 1 , the compounds of Formula (1) can have as few as one ring represented by Z¹ or a plurality of rings represented by Z¹ and any of A¹ -A³ and/or Z² . When a is 0, then the substituent group R¹ is directly bonded to the group Z¹. Similarly, if b, c and d were each 0, the group R² would be directly bonded to the moiety Z¹ .

R¹ and R² are each independently represented by one of the formulas S¹ - S³ with the proviso that at least one of R^! and R² is a chiral group. In this regard, it is specifically contemplated that R^l and R² can both be chiral groups, although such is not required. By requiring at least one of R¹ and R² to be a chiral group, the compounds of Formula (1) are optically active.

In the Formulas S'-S³, a chiral moiety can be obtained by appropriately selecting the groups for the pair Y¹ and Y² or the pair Y³ and Y ⁴ , as will be readily understood by workers skilled in the art. The groups Y¹ -Y ⁴ are independently selected for R¹ and R². That is, the Y¹ group of R¹ may be the same or different as the Y¹ group of R². The same is true of all other variables in the formulas S¹ - S³ such that the values selected for R ¹ are independent of the values selected for R². When Y ^] , Y² , Y³ or Y⁴ represents an alkyl, it may be straight or branched and typically has from 1 to 12 carbon atoms. More preferably, the alkyl group has from 1 to 8 carbon atoms. Examples of the alkyl group include methyl, ethyl, n-propyl, i-propyl, n-butyl, and t-butyl. The subscripts n, p and k are each independently an integer from 0 to 7 while the subscripts m and 1 are each independently 0 or 1. Preferably, p and k, as well as 1, are 0.

Examples of chiral R¹ and R² groups include 2-methylbutyl, 2-methylpentyl, 2-methylhexyl, 4-methylhexyl, citronellyl, citronellyloxy, 2-methylhexyloxy, 2- methyloctyloxy, 2-cyanobutyloxy, and 2-fluorobutyloxy. The non-chiral R¹ and R² groups include octyl, octyloxy, butyl, hexyl, hexyloxy, nonyl, nonyloxy, decyl, decyloxy, 2-octyloxyethyl, 2-octyloxyethyloxy, heptyloxymethyl, and heptyloxymethyloxy .

Z¹ and Z² each independently represent a six-membered ring selected from formulas 2-11 , each of which is substituted by a group X . Each X independently represents O, F, Cl, OH, CN or a group represented by formulas L¹ - L⁶. When X is O, as opposed to OH, it is connected to the ring by a double bond. Accordingly, X can not be O on ring formulas 4, 5, and 8-11. When Z² is present (c is 1), each X group is independently selected.

In formulas L¹ - L⁶, the variables Y¹ , Y² , Y³ , Y⁴ , n, p, k, m and 1 have the same definitions as in formulas S¹ - S ³. However, for emphasis and clarity, mention is again made of the fact that in this application, a group such as Y¹ can have different values with regard to each substituent and each formula. Examples of L ' - L⁶ include 2-methylbutyloxycarbonyl, 2-methylbutylcarbonyloxy, 2- methylhexyloxy, 2-methyloctyloxy, 2-methylbutyl, 2-methylbutyloxy, 2- chlorobutylcarbonyloxy, methyl, methyloxy, ethyl, and ethyloxy. As can be seen from the formulas and the above examples, L¹ - L⁶ can represent chiral or non- chiral groups. A¹ - A³ are each independently selected from the ring formulas 12 - 19. X

¹ - X⁴ are independently selected for each of A¹ - A³ and are H, F, or Cl. B and B ' are luiking groups selected from a single bond, -CH₂CH₂-, -CH=CH-, -C ≡C-, -OCH₂-, or -CH₂O-.

The chiral, laterally substituted compounds of formula (1) are liquid crystal compounds that exhibit a chiral smectic C phase. Preferably, the compounds exhibit a chiral smectic C phase over a broad temperature range, such as over a range of at least 20°C, more preferably at least 30°C, and most preferably over at least 40 °C range. Also it is preferred that the compounds exhibit a chiral smectic C phase at low temperatures, including ambient temperatures. Accordingly, it is preferred that the lower end of the chiral smectic C phase is 20 °C or less, more preferably 10°C or less, and most preferably, 5°C or less. The smectic C phase temperature values can be determined by conventional techniques known in the art; i.e., heating the compounds to the isotropic liquid phase, and then observing the phases and their transition temperatures during cooling and then heating again. In the present application the transition temperatures were determined using a Mettler FP5 hotstage and control unit in conjunction with a polarizing microscope and these values were confirmed using differential scanning calorimetry (Perkin-Elmer DSC- 7).

Preferably, the compound of formula (1) is represented by one of the formulas 1.1 - 1.39 set forth below. In these formulas, R³ and R⁴ represent a group of formulas L¹ - L⁶ , while R¹ , R ² , and X¹ - X ⁴ have the same definition as in formula (1).

Formula 1.1 Formula 1.2

Formula 1.3 Formula 1.4

Formula 1.5 Formula 1.6

Formula 1.7 Formula 1.8

Formula 1.9 Formula 1.10

Formula 1.11 Formula 1.12

Formula 1.13 Formula 1.14

Formula 1.15 Formula 1.16

Formula 1.23 Formula 1.24

Formula 1.26

Formula 1.27 Formula 1.28

Formula 1.29 Formula 1.30

Formula 1.31 Formula 1.32

Formula 1.33

Formula 1.34

Formula 1.35 R¹ and R² are each independently selected from the group consisting of formulas S¹, S² and S³:

Y¹ Y³ t I HC — (CH₂) „— (0) _m C (CH₂) _k— (O) , — (CH₂) _p- (S¹

C=CH— ( CH₂) _n (O) _m— C— ( CH₂) _k (O) ,— ( CH₂) , (S²

I I

Y² Y⁴

_k-(0) ,-(CH₂) - (s³)

wherein Y¹, Y², Y³, and Y⁴ are each independently hydrogen, alkyl, F, CN, CF₃ or OCF₃, n, p, and k are each independently an integer from 0 to 7, and m and 1 are each independently zero or 1 , with the proviso that at least one of R¹ and R² is a chiral radical;

Z¹ and Z ² are each independently a ring selected from the group consisting of formulas 2-11

The compounds of formula (1) can be prepared by workers skilled in this art without undue experimentation through conventional reactions that are per se known in the art and from conventional and/or commercially available starting materials. However, preferred reaction schemes are set forth hereinbelow. Liquid crystal compounds according to the present invention can be obtained by the transformation of 3,6-disubstituted cyclohex-2-enones. Synthesis of these starting compounds is shown in scheme 1. For convenience and clarity the compounds are shown without the subscripts a - d, but such should be assumed to be present.

COCH3

Ri-Ai -CH + (CH₃)₂NCH₂CH₂OC -A2-Z? -A3 -R2

COOC2H5

Formula 20 Formula 21

Formula 22

Formula 23

Formula 24

Scheme 1 The process consists of heating acetoacetic esters with hydrochloride 4- substituted β-N-dimethylaminoprophio-phenones in the presence of an alkaline hydroxide. The 3,6-disubstituted cyclohex-2-enones can then be transformed into

3,6-disubstituted cyclohexanones (Formula 24) by reduction with hydrogen in the presence of 10% palladium on carbon.

As shown in schemes 2 and 3, other compounds of formula (1) can be readily obtained from the compounds of Formulas 23 and 24. Again, for convenience, the subscripts a - d have been omitted from these schemes. However, the schemes embrace any one or more of a - d being zero. In detail, the 3,6-disubstituted cyclohex-2-enones can be transformed into the corresponding 4,4-disubstituted 3-hydroxybiphenyls, teφhenyls and quateφhenyls (Formula 27) by aromatization in the presence of 10% palladium on carbon at 200°C or by the boiling of them in alcohols in the presence of iodine. The 3,6-disubstituted cyclohexanones can be transformed into the corresponding cis and trans alcohols (Formula 34) by reduction with NaBH₄ or LIA1H₄ in an appropriate solvent.

Fluorosubstituted compounds (Formula 38-39) are prepared by heating ketones (Formula 24) with diethylaminosulfur trifluoride in benzene or methylene chloride and the resulting difluoroderivatives (Formula 36) are then treated with a base, advantageously KOH or with alcohalate.

Formula 26

Formula 25

Formula 23

— Z^Z—A³_R²

Formula 28 Formula 27

OR⁴

Ri-Ai— ' _A² — Z²-A³— R²

Formula 29

Scheme 2

Pαπnul- 44

Scheme 3

The cyanounsaturated compounds (Formula 42, 43) are obtained by treating the ketones (Formula 24) with acetone cyanohydrine in the presence of tertiary amines or alkaline metal carbonates in dioxane or tetrahydrofuran and then by treating of the corresponding cyanoalcohols with POCl₃ in the presence of a tertiary aliphatic amine or pyridine. The isomeric compounds (Formula 42, 43) are separated by crystallization. The chlorine substituted compounds (Formulae 26, 30, 31) are obtained by heating ketone (Formula 23, 24) with PC1₅, PCI, in hexane or benzene. The isomeric compounds (Formula 30, 31) are separated by crystallization or used in a form of the isomeric mixtures. Compounds of Formula 25 and 32 are obtained from ketone (Formula 23,

34) by treating them with Grignard reagent in anhydrous etheral solution. Then the corresponding alcohols are heated in the presence of catalytic amount of acids, advantageously p-toluenesulfonic acid, in toluene solution.

Compounds of Formula 36 are obtained by treating ketone 24 with triethyl orthoformate in the presence of p-toluenesulfonic acid in ethanol.

The chlorocyclohexane derivatives (Formula 33) are obtained by treating the corresponding alcohols (Formula 34) with PC1₅, SOCl₂, POCl₃.

The fluorocyclohexane derivatives (Formula 40) are synthesized by treating the alcohols 34 with diethylaminosulfur trifluoride (DAST) in methylene chloride at temperature below 20°C.

Using the above mentioned methods, one can easily obtain cyclohexene, cyclohexane, benzene, biphenyl, teφhenyl and quateφhenyl derivatives which until now were difficult to obtain and to investigate.

The compounds of formula (1) are useful in liquid crystal display devices including TN, STN, and ferroelectric LC displays. The compounds of Formula (1) are especially useful in creating compositions having various values of optical anisotropy and dielectric anisotropy as well as a wide temperature interval of the smectic C phase. Compositions according to the present invention require at least two compounds, with at least one of them being a compound of Formula (1). The compounds contained in the composition can be exclusively of formula (1) or a combination with other liquid crystal compounds.

Compositions containing compounds of Formula (1) that have 2 or 3 rings show low or intermediate clearing temperatures. Compositions containing compounds of Formula (1) that have 4 or 5 rings have a broadening of the smectic C phase, including broader than 100°C. The compositions are useful in ferroelectric liquid crystal displays, TN, STN, and active matrix displays. The high chemical stability and resistivity of these mixtures enable the stable performance of the display.

Preferably the composition is a ferroelectric composition and exhibits a chiral smectic C phase over a broad temperature range, preferably over at least a 40 °C interval. Moreover, preferably the composition simultaneously exhibits a lower end of the chiral smectic C phase at 10°C or less, more preferably at 10°C or less, and most preferably at -30°C or less.

In one embodiment, one or more compounds of Formula (1) is combined with at least one liquid crystal pyrimidine derivative. Preferably the pyrimidine derivative exhibits a smectic C phase and is capable of forming a ferroelectric liquid crystal composition. Such compounds include phenyl -substituted pyrimidines such as 2-alkoxyphenyl-5-alkylpyrimidines where the alkoxy and alkyl groups each contain from 1 to 12 carbon atoms.

The composition of the present invention can be used in any conventional liquid crystal display device. As understood by workers skilled in this art, such devices generally comprise two parallel electrodes, at least one of which is transparent, and having a layer of the liquid crystal composition disposed therebetween. In more detail, die liquid crystal layer is typically disposed between two parallel plates, one of which is transparent, that are in turn supported by (or surrounded by) the parallel electrodes. Between the parallel plates there may also be one or more of an aligning layer, isolating layer, and colored filter layer. In a preferred embodiment, the display device is operated by the ferroelectric effect.

The invention will now be described with reference to various examples.

However the invention should not be construed as being limited to the examples.

EXAMPLE 1.

3-(4-octyloxyphenyl-6-(2-methylbutyl)cyclohex-2-enone (Formula 23)

A mixture 0.1 mol of hydrochloride of /3-N-dimethylaminoethyl 4- octyloxypropiophenone, 0.12 mol of 2-(2-methylbutyl)acetoacetic ester, 0.25 mol sodium isopropylate in 200 ml anhydrous isopropanol was refluxed for 5 hours. The mixture was cooled and acidified with 20% solution of sulfuric acid. The oily substance from the mixture was extracted with diethyl ether. The extract was washed with water, dried over anhydrous Na₂SO₄ and filtrated. The residue obtained after the evaporation of the solvent was purified by crystallization from isopropanol. Yield 63% .

Using this method, the following compounds were prepared:

3-phenyl-6-(2-methylbutyl)cyclohex-2-enone,

3-(4-octyloxyphenyl)-6-(2-methylbutyl)cyclohex-2-enone,

3-(4-(2-methylbutyl)phenyl)-6-octylcyclohex-2-enone, 3-(4-citronellyloxyphenyl)-6-heptylcyclohex-2-enone,

3-(4-octyloxybiphenyl-4)-6-(2-methylbutyl)cyclohex-2-enone,

3-(4-citronelly loxybiphenyl-4)-6-(hexyl-21 )cyclohex-2-enone ,

3-(4-(2-methylbutyl)styryl-6-octylcyclohex-2-enone,

3-(4-citronellyloxystyryll)-6-heptylcyclohex-2-enone, 3-(4-octyloxystyryl)-6-citronellylcyclohex-2-enone,

3-(4-octyloxystyryl)-6-citronellylcyclohex-2-enone,

3-(4-pentylbiphenyl)-6-citronellycyclohex-2-enone (having m.p. 15 SmC 87 SmA 155 I), l ,4-bis-(3-citronellycyclox-2-enonoyl-6)benzene, 4,4-bis-(3-citronellycyclox-2-enonoyl-6)biphenyl,

3-(4-citronellyloxybiphenyl)-6-(2-cyanoethyl)cyclohex-2-enone,

3-(4-(2-methylbutyl)biphenyl)-6-(trans-4-butylcyclohexylethyl-2)cyclohex-2-enone, and

3-(trans-4-(2-methylbutyl)cyclohexylphenyl)-6-(trans-4-octylcyclohexyl)cyclohex-2- enone.

Example 2

3-(4-octyloxyphenyl-6-(2-methylbutyl)cyclohexanone (Formula 24) 0.1 mol of 3-(4-octyloxyphenyl-6-(2-methylbutyl)cyclohex-2-enone and 5 g of KOH were dissolved in 150 ml isopropanol and hydrogenated with gaseous hydrogen at 50 °C in the presence of 1 g of catalyzer (10% Pd/C) until hydrogen was not absorbed any longer. Then the catalyzer was filtrated off and the solvent was evaporated. The residue was poured into water and extracted with hexane. After hexane was evaporated, the residue was several times recrystallized from ethanol. Yield 47%.

Using this method the following compounds were prepared:

3-phenyl-6-(2-methylbutyI)cyclohexanone,

3-(4-octyloxyphenyl)-6-(2-methylbutyl)cyclohexanone,

3 -(4- (2-methy lbuty l)pheny l)-6-octy ley c lohexanone , 3-(4-octyloxybiphenyl-4)-6-(2-methylbutyl)cyclohexanone,

3-(2-(4-citronellyloxyphenyl)ethyl)-6-heptylcyclohexanone, l ,4-bis-(3-(2-methylhexyl)lcycloxanonoyl-6)benzene,

4,4-bis-(3-(2-methylbutyl)cycloxanonoyl-6)biphenyl,

3-(4-(2-methylbutyl)biphenyl)-6-(trans-4-butylcyclohexylethyl-2)cyclohexanone, and 3-(trans-4-(2-methylbutyl)cyclohexylphenyl)-6-(trans-4-octylcyclohexyl) cyclohexanone.

Example 3.

Synthesis of l-(2-methylbutyl)-2-cyano-4-(4-octyloxybiphenyl)cyclohex-l-ene (Formula 42)

A mixture of 0.5 mol of 3-cis-citronellyl-6-(4-octyloxybiphenyl)cyclohexanone, 0.2 mol acetone cyanohydrine, 0.2 mol triethylamine and 40 ml of tetrahydrofuran was left for 24 h at room temperature. After the addition of 100 ml of benzene, the mixture was diluted with water and diluted hydrochloric acid and dried over anhydrous sodium sulfate. Thereafter the mixture was filtrated and benzene was evaporated. To the residue 4 ml pyridine and 0.1 mol POCl₃ was added and the resulting mixture was heated while boiling 7 hours. Then the mixture was poured into water with ice and the product was extracted into benzene. The extract was washed with water and with diluted hydrochloric acid, dried over MgSO₄ and filtrated. After the evaporation of benzene, the residue was crystallized from methanol-isopropanol mixture. Yield 38% . Example 4.

Synthesis of l-cyano-3-trans-(4-octyloxybiphenyl)-6-(2-methylbutyl)cyclohex- 1 -ene

(Formula 43)

A mixture of 0.05 mol of 3-trans-citronellyl-6-(4-octyloxybiphenyl)cyclohexanone, 0.2 mol acetone cyanohydrine, 0.2 mol triethylamine and 40 ml of tetrahydrofurane was left for 24 h at room temperature. After the addition of 100 ml of benzene, the mixture was diluted with water and diluted hydrochloric acid and dried over anhydrous sodium sulfate. Thereafter the mixture was filtrated and benzene was evaporated. To the residue 4 ml pyridine and 0.1 mol POCl₃ was added and the resulting mixture was heated while boiling 7 hours. Then the mixture was poured into water with ice and the product was extracted into benzene. The extract was washed with water and with diluted hydrochloric acid, dried over MgSO₄ and filtrated. After the evaporation of benzene, the residue was crystallized from methanol-isopropanol mixture. Yield 45% .

Example 5

Synthesis of l-(2-methylbutyl)-2-cyano-4-(4-octyloxybiphenyl)cyclohexane (Formula

44)

A mixture of the corresponding cyanocompounds (0.03 mol) prepared as described in example 4 was dissolved in a tetrahydrofuran-isopropanol (10: 1) mixture. To the resulting mixture 0.2 g of Pd/C (10%) was added and connected to a source of hydrogen. The mixture was stirred until hydrogen was no longer absorbed. After that the catalyzer was filtrated off and the solvents distilled off and the product was crystallized from a methanol-isopropanol mixture. Yield 38% .

Example 6

Synthesis of l-(2-methylbutyl)-2-chloro-4-(4-octyloxybiphenyl)cyclohex-l-ene

(Formula 30)

A mixture 0.03 mol cis-3-(2-methylbutyl)-6-(4-octyloxybiphenyl)cyclohexanone, 0.07 mol PCI, NaSO and 50 ml benzene was heated while boiling and after cooling it was treated with 10% solution of KOH. Thereafter the organic layer separated, washed with water, dried over anhydrous MgS0₄ and filtrated through a layer of Al₂O₃. After the evaporation of the solvent, the oily liquid was crystallized from methanol-isopropanol mixture. Yield 48% .

Example 7.

Synthesis of l-(2-methylbutyl)-2-methyl-4-(4-octyloxybiphenyl)cyclohex-l-ene (Formula 32)

To 0.04 mol methylmagnesium iodide in 200 ml of diethyl ether. 0.03 mol cis-3-2- (2-methylbutyl)-6-4-octyloxybiphenyl)cyclohexanone was added and stirred for 4 hours. The resulting magnesium salt was decomposed with 20% solution of H₂SO₄ and the organic layer was separated and dried over Na₂SO₄. Then the solvent was evaporated and 50 ml of toluene and catalytic amount of p-toluenesulphonic acid were added to the residue and heated using azetropic head until water stopped to evolve. Then the mixture was cooled and diluted with water. The toluene layer was separated, dried over Na₂SO₄ and filtrated. The residue was dissolved in hexane and the crude product was purified by column chromatography and recrystallized from isopropyl alcohol. Yield 70%.

Example 8.

Synthesis of l-(2-methylbutyl)-2-ethoxy-4-(4-octyloxybiphenyl)cyclohex-l-ene (Formula 36)

A mixture containing 0.05 mol of cis-3-(2-methylbutyl)-6-4-octyloxybiphenyl) cyclohexanone, 0.15 mol ethyl ester of orthoformic acid, catalytic amounts of p- toluenesulphonic acid and 150 ml ethyl alcohol was stirred for 6 h. Thereafter it was diluted with water and extracted with benzene. After separating the benzene layer was washed with water and dried with Na₂SO₄. The oily residue left after distilling of benzene was dissolved in hexane and eluted on a column filled with silica gel collecting the fractions. On the basis of chromatographic analysis the fractions containing pure product were joined, solvent was evaporated. Yield 48% . Example 9.

Synthesis of trans-l-(2-methylbutyl)-2,2-difluoro-4-(4-octyloxybiphenylcyclohexane

(Formula 37)

A mixture containing 0.01 mol trans-3-(2-methylbutyl)-6-(4-octyloxybiphenyl) cyclohexanone, 0.01 mol diethylaminosulfur trifluoride (DAST) and 15 ml benzene was heated while boiling 24 hours. Thereafter the mixture was poured into water, benzene layer was separated, washed with water, dried with MgSO₄ and filtrated. The crude product remained after the evaporation of the solvent was recrystallized from isopropanol. Yield 60% .

Example 10.

Synthesis of l-(2-methylbutyl)-2-fluoro-4-(4-octyloxybiphenyl)cyclohex-l-ene

(Formula 39)

A mixture 0.01 mol of trans-l-(2-methylbutyl)-2,2-difluoro-4-(4-octyloxybiphenyl) cyclohexane, 0.05 mol KOH and 30 ml ethylene glycol was stirred at 130°C for 8 hours, thereafter it was diluted with water and extracted with benzene. The benzene layer was washed with water, dried with MgSO₄, filtrated. The residue left after the evaporation of the solvent was recrystallized from isopropanol. Yield 47%.

Example 11.

Synthesis of 2-(2-methylbutyl)-5-(4-octyloxybiphenyl)cyclohexan-l-ol (Formula 34).

The mixture 0.05 mol of trans-3-(2-methylbutyl)-6-4-octyloxybiphenyl) cyclohexanone, 0.05 mol sodium borohydride and 100 ml isopropyl alcohol was stirred at 50-60°C for 8 h. After the reaction mixture was acidified with hydrochloric acid and extracted into ether. The etheral extract was washed with water and dried MgSO₄. The solvent was removed in vacuo and the crude product was recrystallized from hexane. Yield 85%. Example 12.

Synthesis of l-(2-medιylbutyl)-2-fluoro-4-(4-octyloxybiphenyl)cyclohexane (Formula

40)

To 0.05 mol of 2-(2-memylbutyl)-(4-octyloxybiphenyl)cyclohexan-l-ol in 15 ml CH Cl was added 0.05 mol of diethylaminosulfur trifluoride (DAST) at - 70°C. Thereafter, the cooling was stopped and the mixmre was allowed to room temperature, poured into water and layers were separated. The organic layer was dried with Na₂SO₄, filtrated. After the evaporation of the solvent, the crude product was recrystallized from ethanol. Yield 50% .

Example 13.

Synthesis of 4-(2-methylbutyl)-3-hydroxy-4-octyloxyteφhenyl (Formula 27)

0.1 mol of 3-(4-octyloxyphenyl-6-(2-methylbutyl)cyclohex-2-enone were hydrogenated at 200 °C in the presence of 1 g of catalyzer (10% Pd/C). The reaction mixture was dissolved in ether and then the catalyzer was filtrated off and the solvent was evaporated. The residue was several times recrystallized from toluene. Yield 47%.

Example 14.

Synthesis of l-(2-methylbutyl)-2-chloro-4-(4-octyloxybiphenyl)cyclohexane

(Formula 33)

A mixture 0.05 mol of 2-(2-methylbutyl)-5-(4-octyloxybiphenyl)cyclohexan-l-ol, 0.05 mol SOCl₂ in 35 ml benzene was heated at 30°C O.05 h. Thereafter, the heating was stopped and the mixture poured into water. Thereafter, the organic layer was separated, washed with water, dried over anhydrous MgSO₄ and filtrated. After the evaporation of the solvent, the oily liquid was crystallized from methanol- isopropanol mixture. Yield 57% .

Example 14. Synthesis of 4-(2-methylbutyl)-3-chloro-4-octyloxyteφhenyl (Formula 26)

0.1 mol of 3-(4-octyloxyphenyl-6-(2-methylbutyl)cyclohex-2-enone, 0.01 mol PC1_S. In 30 ml benzene was boiled 4 h. Thereafter, the heating was stopped and the mixture poured into 10% solution of KOH. Thereafter, the organic layer was separated, washed with water, dried over anhydrous MgSO₄ and filtrated. After the evaporation of the solvent, the oil liquid was crystallized from isopropanol mixmre. Yield 65% .

Using this method the following compounds were prepared

4-citronellyl-3-chloro-4-octyloxyteφhenyl m.p. 5 SmC 67 SmA 105 I

Example 16.

Synthesis of 4-(2-methylbutyl)-3-citronyllyloxy-4-octyloxyteφhenyl (Formula 29).

A mixture of 0.01 mol of 4-(2-methylbutyl)-3-hydroxy-4-octyloxyteφhenyl, 0.012 mol citronellile bromide, 0.02 mol KOH and 50 ml isopropyl alcohol was boiled 5 h. Thereafter, it was diluted with water and extracted with benzene. The benzene layer was washed with water, dried with MgSO₄, filtrated. The residue left after the evaporation of the solvent was recrystallized from isopropanol. Yield 64% .

Example 17.

Synthesis of 2-(2-methylbutyl)-5-(4-octyloxybiphenyl)-l-(2-methylbutyl carbonyloxy)cyclohexane (Formula 35)

To 0.01 mol 2-(2-methylbutyl)-5-(4-octyloxybiphenyl)cyclohexan-l-ol and 0.12 mol 2-methyl-butyτol chloride in 50 ml anhydrous ether 0.02 mol pyridine was added.

After 12 h the reaction mixture was acidified with hydrochloric acid and separated.

The emeral layer was washed with water and dried MgSO₄. The solvent was removed in vacuo and the crude product was recrystallized from ethanol. Yield

45% .

Example 18. Mixmre A of the following composition:

2-(4-Heptyloxyphenyl)-5-heptylpyrimidine - 5% 2-(4-Octyloxyphenyl)-5-heptylpyrimidine - 10% 2-(4-Nonyloxyphenyl)-5-heptylpyrimidine - 15 % 2-(4-Octyloxyphenyl)-5-octylpyrimidine - 20% 2-(4-Decycloxyphenyl)-5-octylpyrimidine - 30% 2-(4-Hexyloxyphenyl)-5-nonylpyrimidine - 20%

m.p. 10 SmC 51 SmA 63 N 69 I

Example 19.

Mixmre B of the following composition:

Mixture A - 90% 4-citronellyl-3-chloro-4-octyloxy teφhenyl - 10% m.p. -5 SmC 59 SmA 61 N 65 I

The invention having been thus described it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Industrial Applicability The compounds of formula (1) are useful in liquid crystal display devices including TN, STN, and ferroelectric LC displays. The compounds of Formula (1) are especially useful in creating compositions having various values of optical anisotropy and dielectric anisotropy as well as a wide temperamre interval of the smectic C phase. The compound of the present invention can be used in any conventional liquid crystal display device.

Claims

What is claimed is:

1. A chiral liquid crystalline compound of formula (1):

R¹— (A¹),— Z¹— (A²)_b— (Z²)_c— <A³)_d— R² (1) wherein a, b, c, and d are each independently zero or 1; R¹ and R are each independently selected from the group consisting of formulas S¹, S² and S³:

yl γ3

H IC-(CH₂)_n-(0)_m-C I-(CH₂)_k-(0) -(CH₂)_p- (S¹)

I I γ² Y⁴

yl γ3

I I

C=CH- (CH₂) „- (O) _m-C-(CH₂) _k- (O) - (CH₂) .- (S²)

HC- ( CH₂ )^' _n- ( O ) _m-C-CH=CH- ( CH₂ ) _k- ( O ) ,- { CH₂ ) - (S³)

wherein Y¹, Y², Y³, and Y⁴ are each independently hydrogen, alkyl, F, CN, CF₃ or OCFj, n, p, and k are each independently an integer from 0 to 7, and m and 1 are each independently zero or 1 , with the proviso that at least one of R¹ and R² is a chiral radical;

(2) (3) (4) (5)

(6) (7) (8)

(9) (10) (11)

wherein X represents O, F, Cl, OH, CN, or a group represented by formulas L¹ L⁶:

Y¹

HC- (CH₂) _n- (0) _m-C- (CH₂) _k- (0) ,- (CH₂) - (L¹)

Y⁴

yl γ3

I I

C=CH- (CH₂) „- (O) _m-C- (CH₂) _k- (O) ,- (CH₂) . ( ²

Y'

HC- (CH₂) _n- (O) _m-C-CH=CH- (CH₂) _k- (O) ,- (CH₂) .- (L³)

Ϋ⁴ yl γ3

HC- ( CH₂ ) „- ( O ) _m-C- ( CH₂ ) _k- ( O ) - ( CH₂ ) ,-COO- γ ^!22 I γ4

Y¹ Y³

I I

C=CH- (CH₂) _n- (O) _m-C- (CH₂) _k- (O) - (CH₂) _p-CO - (L⁵ γ2 γ4

yl γ3

H { CH₂ ) _k- ( O ) - ( CH₂ ) _p-COO- ( L⁶

wherein Y¹, Y², Y , Y⁴ , n, p, k, m and 1 have the same definitions as above in formulas S'-S³;

(15)

(14)

(16) (17)

wherein X¹, X ², X ³ and X⁴ are each independently H, F, or Cl and B and B are each independently a single bond, -CH₂CH₂-, -CH =CII-, -C ≡C-, -OCH -, or - CH₂O-; with the proviso that when the ring structure formed by three of A¹. Z¹ , A² , Z² and A³ is teφhenyl, then none of X, X' , X² , X and X represent F.

2. The compound according to claim 1 , wherein R¹ and R² are both chiral radicals .

3. The compound according to claim 1 , wherein X is represented by one of formulas L'-L⁶.

4. The compound according to claim 3, wherein c and d are both zero.

5. The compound according to claim 1 , wherein at least one of a and b is 1.

6. The compound according to claim 1 , wherein R¹ and R² are each independently represented by formula S¹.

7. The compound according to claim 1 , wherein said compound exhibits a chiral smectic C phase.

8. The compound according to claim 7, wherein said compound exhibits a chiral smectic C phase over a temperamre interval having a range of at least about 40 °C.

9. The compound according to claim 7, wherein said compound exhibits a lower end of said chiral smectic C phase at a temperamre of 10°C or less.

10. A liquid crystal composition, comprising: at least one compound of formula 1 :

(A ( Z² ) _c ( A³ -R- ( 1 ) wherein a, b, c, and d are each independently zero or 1 ; R¹ and R² are each independently selected from the group consisting of formulas S\ S² and S ³ :

γl γ3

I I

HC — (CH₂) „ (0) _m C (CH₂) _k— (O) , — (CH₂) _p (S¹)

Y⁴

C=CH — (CH₂) _n (O) _m — C— (CH₂) _k — (O) ,— (CH₂) 2\ γ2 γ4

(CH₂) _k- (O) ,- (CH₂) - (s-

(2) (3) (4) (5)

wherein X represents O, F, Cl, OH, CN, or a group represented by formulas L¹ L⁶: γ^l Y³

HC— (CH₂) _n— (O) _ra— C— (CH₂) _k— (O) j— (CH₂) _p— (L¹)

C=CH ( CH₂) _n— (0) _m— C— ( CH₂) _k (O) ,— ( CH₂) ( ²)

Ϋ⁴

γl γ3

HC- ( CH₂ ) _π- ( O ) _m-C-CH=CH- ( CH₂ ) _k- ( 0 ) ,- ( CH₂ ) _p- ;L³) γ2 γ y. y3

I I

HC— (CH₂) _n (O) _m C (CH₂) (O) , — (CH₂) — COC ( ⁴

Y Y⁴

C=CH- (CH₂) _n- (O) _m-C- (CH₂) _k- (O) ,- (CH₂) _p-COO- 1 ⁵) γ2 γ4

HC- ( CH₂ ) _n- ( O ) _m-C-CH=CH- ( CH₂ ) _k- ( O ) , I- ( \ C ^Hn₂₂ ) 1 -COO- ( ⁶

Y⁴

wherein Y¹, Y², Y³ , Y⁴ , n, p, k, m and 1 have the same meanings as above in formulas S^J-S³;

(15)

(14)

αβ) (17)

wherein X¹, X², X³ and X are each independently H, F, or Cl and B and *B are each independently a single bond, -CH₂CH₂-, -CH = CH-, -C ≡ C-, -OCH ₂ -, or - CH₂O-; with the proviso that when e ring structure formed by three of A¹, Z\ A² , Z² and A³ is teφhenyl, then none of X, X¹ , X ² , X³ and X⁴ represent F; wherein said composition exhibits a chiral smectic C phase.

11. The composition according to claim 10, further comprising at least one pyrimidine compound.

12. The composition according to claim 11 , wherein said composition exhibits a chiral smectic C phase and has a lower limit at a temperamre of -30 °C or less.

13. The composition according to claim 12, wherein said composition exhibits a chiral smectic C phase over a temperamre interval having a range of at least 40°C.

14. A liquid crystal display, comprising: two parallel plate electrodes, at least one of which is transparent; and a liquid crystalline layer comprising the composition according to claim 10, disposed between said plates.

15. The liquid crystal display according to claim 14, which further comprises an aligning or isolating layer, or both, disposed between said plates.