JPS60120858A - Liquid crystal cyclohexylbenzene derivative, manufacture andliquid crystal composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal cyclohexyl derivative, a method for producing the same, and a liquid crystal composition containing the same.

Dinuclear liquid crystal compounds are well known and exhibit nematic properties, but
It has no central group. In this group of compounds, the applicant has provided derivatives of biphenyl, cyclohexylbenzene and bicyclohexyl having an alkyl or alkoxy group at one end and a cyano group at the other end (UK Patent No. 143313 (1), US Patent No. 3
947375 and West German Patent No. 2636684). These compounds have a melting temperature in the range of 20 to 40°C and a transition temperature from nematic to isobathic phase in the range of 30 to 80°C, and are used as components of liquid crystal compositions used in display devices. It has gained considerable importance.

Alkyl or alkoxy derivatives of biphenyl, cyclohexylbenzene or bicyclohexyl which have groups such as -NO2, halogen or alkoxy groups instead of the cyano group at the second end do not exhibit advantageous properties.

That is, they do not exhibit liquid crystalline properties or generally only have a high order smectic phase. For example, 4-pentyl-4'-7' lomobiphenyl is 94
．． It melts at 5℃ and is not a liquid crystal. 4-pentyl-4″-pentanoyl biphenyl has a phase transition temperature of C106SB110
．． 5 Smectic B with I, ability, 4.4
'-dibentilbiphenyl is smectic E and B phase 5
It has E475B52I. 4 of the above-mentioned compounds and ponds
The properties of the '-substituted bentylbiphenyl are as follows: Mo1. Cry
st, I-iq, Cryst, t 88, 55
/1982.

Although nematic liquid crystal compounds having an isothiocyanato group (-N=C=S) are known, only one compound, namely 4-pentyl-4'-isothiocyanatobiphenyl, has been described in the literature. , which shows only high order smectins Ill. In addition, other compounds belonging to this homologous series do not have nematic properties but exhibit the presence of a smectic phase with high ν1, or are not in an intermediate state).

It has been unexpectedly found that replacing 12 of the benzene rings of 4-alkyl-4'-thiocyanatobiphenyl with saturated cyclohexane rings results in novel liquid crystal compounds having a nematic phase.

The present invention relates to 4-) lance-4'-n-furkylcyclohexyl-1-thiocyanatobenzene, which is a new compound having a structure represented by the following general formula.

(1) [In the formula, summer 1 represents an integer from 1 to 12. ] In this compound, the phenyl group and the alkyl group are present in trans positions at the 1st and 4th positions of the cyclohexane ring. This compound is useful as a component of liquid crystal materials used in display elements; its presence causes an extension of the nematic phase range and a reduction in the viscosity of the liquid crystal material.

The compound of the present invention represented by general formula (1) has an alkyl group having 1 to 12 carbon atoms in the presence of a tertiary amine (preferably triethylamine) and carbon disulfide in an organic solvent solution (preferably benzene). Sur 4) Lance-4'l
It is obtained by treating +-alkylcyclosylaniline with an acid chloride (preferably thiophosdene) or an alkyl chloroformate. When using alkyl chloroformates (especially ethyl chloroformate), it is advantageous to carry out the reaction in two stages. First, in the first step, in the presence of a tertiary amine (preferably triethylamine) in an organic solvent solution (preferably benzene), 4-trans-4'-n-alkylcycloaniline having C1-CI2 alkyl is Treat with carbon disulfide. The sh′ obtained by the reaction
Separate the crystals of trialkylammonium thiocarbamate. In a subsequent second step, this product is converted into an alkyl chloroformate (e.g. ethyl chloroformate) in the presence of a tertiary amine.
Process with. In this reaction, the dithiocarbame F is converted to an inthiocyanato of formula (r).

The final product obtained by the above method is of higher purity than that obtained in one step. The products obtained in both the one-step and two-step processes are isolated by conventional methods.

The reaction formulas for both the one-step and two-step methods of the present invention are shown below. Note that R is an alkyl group.

The isothiocyanates of the present invention exhibit a stable nematic phase like the similar compounds having a cyano group mentioned at the beginning, but unlike the cyano derivatives, they often have a wide range of nematic phases. This is because the compounds of the invention have low melting points.

Particularly advantageous properties are found in compounds with hexyl groups (i.e.
The solid phase changes to a nematic phase in the temperature range of 11.5 to 12.5°C. This compound also has a low viscosity η2. ' = 21 mPa, s. Similar compounds with cyano groups dissolve in the nematic phase only at 42°C.

The compound obtained by the present invention has a positive dielectric anisotropy Δε
It is nematic showing =+7.5.

The table below shows 4-trans- obtained by the method of the present invention.
Phase transition temperature of representative examples of 4'-〇-furkylcyclohexyl-1-thiocyanatobenzenes (column A) and 4-
and that of a similar biphenylisothiocyanate derivative in the form of 4'-n-furkylphenyl-1-thiocyanatobenzene (column B). The alkyl groups shown in the table are for both columns A and B.

In the table, C: solid, N: nematic phase, isotropic phase, SE:
Shows smectic E phase. Also, the metastable solid form of compound *22 melts at 36°C.

The present invention also relates to a liquid crystal composition containing a compound of formula [11].

As mentioned, 4-trans-4'-n-furkylcyclohexyl-1-isothiocyanatobenzene successfully lowers the viscosity of liquid crystal mixtures and is also lower than e.g. mixtures containing the similarly structured furkylcyclohexylcyanobenzene. Makes it possible to obtain mixtures that melt at temperatures.

The composition of the present invention has the formula [1] as at least one component.
4-trans-4'-n-alkylcyclohexyl-
It is an at least two-component system containing 1-isothiocyanatobenzene.

The use of compounds of formula [+] as one or more components of the target composition results in liquid-crystalline mixtures that dissolve in the nematic phase at lower temperatures than in the case of mixtures in which alkylcyclohexylcyanobenzene is added. This great ability is
4-trans-4'-〇-furkylcyclohexyl-1
-thiocyanatobenzenes are 4-trans-4'-
This is because it dissolves in the nematic phase at a lower temperature than 〇-furkylcyclohexylcyanobenzene. for example,
4-trans-4'-n-hexylcyclohexyl-
1-isothiocyanatobenzene changes from solid to nematic phase at 12.5°C, while 4-) lance-'4
-n-hexylcyclohexyl-1-cyanobenzene changes to a nematic phase only at 42°C, and is the lowest melting point compound in the homologous series, 4-trans-4'-〇-pentylcyclohexyl-1-cyanobenzene. Benzene only changes to a nematic phase at 30°C.

The composition of the present invention may consist of the 4-trans-4'-〇-alkylcyclohexyl-1-isothiocyanatobenzene compound alone, or it may consist of a mixture of this compound and other conventional liquid crystal compounds. A group of isothiocyanate compounds which may be 4-trans-
4+-Rhopropylcyclohexyl-1-thiocyanatobenzene and/or 4-trans-4'-〇-
Particular preference is given to using hexylcyclohexyl-1-isothiocyanatobenzene in the compositions of the invention.

Regarding ordinary liquid crystal compounds, for example, 4-alkyl-4
'-cyanobiphenyls, 4-flufoxy-4'-cyanobiphenyls, 4-alkylbenzoic acid esters,
Esters of 4-flufoxybenzoic acid, esters of cycloalkane carboxylic acid, 4-furkylcyclohexylcyanobenzenes, Schiff bases, azo compounds, 2,5-
Disubstituted-1,37 dioxane derivatives, optically active compounds, etc. may be contained in the composition of the present invention.

The composition of the invention is suitable for use in display elements.

The following example illustrates a method for producing a novel compound represented by formula [I] and a method for preparing a liquid crystal composition, but the present invention is not limited thereto.

Example 1 4-trans-4'-〇-hexylcyclohexyl-1
-Synthesis of isothiocyanatobenzene In a conical flask containing 80c1 of benzene and 20cx3 of hexane, 4-
) Dissolve 25.8 g (0° 1 mole) of lance-4'-n-hexylcyclohexylaniline. Next, 7.5 cu' (0°1 mole) of carbon disulfide and 15 c of triethylamine
Add u3 and leave at 1'C for 45 hours. Collect the yellow precipitate of triethylammonium dithiocarbamate, wash with hexane, and dry. Transfer the resulting crystals to a three-neck flask. , chloroform 1
00cx' and 15.5CJl' of triethylamine, and to this 15.5CI! ' Add dropwise while stirring. The contents are then cooled to ambient temperature and poured into 3N hydrochloric acid.

After distilling off the chloroform, the remaining oil is recrystallized from ethanol.

Phase transition temperature CI 2.5N43. 15 g of 4-trans-4'-0-hexylcyclohexyl-1-thiocyanatobenzene with OI are obtained.

Example 2 4-trans-4'-〇-propylcyclohexyl 1
- Synthesis of isothiocyanatobenzene in a three-necked flask
-trans-4'-propylcyclohexylaniline 2
1.54g (0.1 mol) of chloroform 100c scraps 3
then add triethylamine 150I' and thiophosdene? , 55ci3 (0.1 mol) are introduced dropwise. The contents are stirred for 10 hours and the mixture is poured into 3N hydrochloric acid. The product is isolated analogously to Example 1.

4-trans-4'-n-7'rovylcyclohexyl-
The yield of 1-isothiocyanatobenzene is 11.5 g, and the phase transition temperature is C38,5N41°51.

Example 3 The liquid crystal composition is a binary eutectic mixture having the following composition.

4-trans-4'-n-7'ropylcyclohexyl-1-thiocyanatobenzene...42.9% by weight 4-) trans-4'-〇-hexylcyclohexyl-1
- Inthiocyanatobenzene...57.1% by weight Composition characteristics: Melting point...-3℃ Clearing point...41℃ Viscosity (20℃)...13.5IPa, s Alkyl of the same length A comparative eutectic mixture of alkylcyclohexylcyanobenzene with chains has the following composition:

4-trans-4'-n-propylcyclohexyl-1
-Cyanobenzene...64.7% by weight °4-trans-4'-n-hexylcyclohexyl-
1-cyanobenzene...35.3% by weight Melting point...11.5°C and the lowest melting point binary eutectic mixture in the composition of the alkylcyclohexylcyanobenzene homolog has the following composition: There is.

4-trans-4'-〇-pentylcyclohexyl-1
-Cyanobenzene...53.4% by weight 4-trans-4'-〇-hebutylcyclohexyl-1
-Cyanobenzene...46.6% by weight Melting point...7.5°C Example 4 The liquid crystal composition is a binary eutectic mixture having the following composition.

4-pentyl-4'-cyanobiphenyl...45.5
Weight% 4-trans-4'-〇-hexylcyclohexyl-1
-Inthiocyanatobenzene...54.4% by weight Melting point...-4°C For comparison consisting of 4-pentyl-4'-cyanobiphenyl and 4-furkylcyclohexyl-1-cyanobenzene selected as optimal The binary eutectic mixture of has the following composition:

4-pentyl-4'-cyanobiphenyl...55.0
Weight% 4-trans-4'=Lopentylcyclohexyl-1
-Cyanobenzene...45.0% by weight Melting point...-〇, S°C Example 5 A four-component liquid crystal composition has the following composition.

4-trans-4'-〇-propylcyclohexyl 1
-isothiocyanatobenzene...29.5% by weight 4-trans-4'-〇-pentylcyclohexyl-1
-isothiocyanatobenzene...32.8% by weight 4-trans-4'-n-hexylcyclohexyl-1
-Inthiocyanatobenzene...27.5% by weight 4-trans-4'-n-octylcyclohexyl-1
-isothiocyanatobenzene...10.2% by weight Composition characteristic values: Melting point...-18"C Clearing point...43°C Dielectric anisotropy △ε20"=+7.5 Example 6 Four-component liquid crystal The composition has the following composition.

4-trans-4″-n-propylcyclohexyl-1
-isothiocyanatobenzene...26.56% by weight 4-trans-4'-n-hexylcyclohexyl-
1-isothiocyanatobenzene...19.50% by weight 4-pentyl-4'-cyanobiphenyl...24.8
1% by weight 4-) Lance-4'-n7' lovylcyclohexyl-1
-Cyanobenzene...29.13% by weight Composition characteristic values: Melting point...-27°C Clearing point...42°C Example 7 First, a mixture A consisting of the following formulation is produced.

4'-Cyanophenyl 4-n '7'+ Rubenzoate ・ ・ 18.85 Weight i% 4'-Cyanophenyl 4-n-Pentylbenzoate ・ ・ 19
．． 82% by weight 4'-Cyanophenyl 4-Natsu 1-hexylbenzoate...20.75% by weight 4'-Cyanophenyl 4-n-hebutylbenzoate...21.72% by weight 4'-Butyl 4- Cyanobenzoate...18.8
6% by weight Next, manufacture a liquid crystal composition consisting of the following formulation.

Mixture A...59.40% by weight 4-trans-4'-rhohexylcyclohexyl-1
-isothiocyanatobenzene...24.75% by weight 4''-cyano7enyl 4-trans-4'-〇-pentylcyclohexylbenzoate...14.85% by weight 4'-nitrophenyl 4-2 -Methylbutyloxycarboxybenzoate (optical activity)...1.0% by weight Composition characteristics: Melting point -22°C Clearing point 72.5°C Dielectric anisotropy △ε20" = +14. S Example 8 Mixture A of liquid crystal composition Example 7 consisting of the following formulation: 49.00% by weight 4-trans-4'-1-propylcyclohexyl-1-isothiocyanatobenzene...17 .14% by weight 4-trans-4'-〇-pentylcyclohexyl-1
-isothiocyanatobenzene...9.50% by weight 4-trans-4'-n-hexylcyclohexyl-
1-inchocyanatobenzene...9.96% by weight 4-trans-4'-n-hebutylcyclohexyl-
1-isothiocyanatobenzene Φ...1('1,4(1% by weight) 4''-cyanophenyl 4-trans-4'-〇-propylcyclohexylbenzoate...6.00% by weight 4'-cya7 Phenyl 4-trans-4'-11-
Pentyl cyclohexyl benzoate...6.50% by weight 4-2-methylbutyloxy-4'-cya/biphenyl (optical activity)...(1,59% by weight) This liquid crystal composition can be frozen at -25°C. No, its clearing point is 62°C.

Example 9 First, a mixture B consisting of the following formulation is manufactured.

4-) Lance-4″-11-propylcyclohexyl-
1-inchocyanatobenzene...45.12% by weight 4-trans-4'-〇-hexylcyclohexyl-1
-inchocyanatobenzene 0.・26.22% by weight 4-trans-4'-〇-octylcyclohexyl-1
- Inthiocyanatobenzene...φ28.66% by weight Next, a liquid crystal composition containing mixture B having the following formulation is produced.

Mixture B...45.00% by weight 4-pentyl-4'-cyanobiphenyl...20.7
0% by weight 4-hebutyl-4'-cyanobiphenyl...11.6
6% by weight 4-hexyloxy-4'cyanobiphenyl...5.
80% by weight 4-octyloxy-4'-cya 7-biphenyl...6
．． 40% by weight 4''-cya/phenyl 4-trans-4'-ethylcyclohexylbenzoate...io, oo% by weight 4-2-methylbutyloxy-4'-cyanobiphenyl (optical activity)...0. This 50% by weight liquid crystal composition does not freeze up to -25°C and its clearing point is 54°C.

Example 10 Mixture B of Liquid Crystal Composition Example 9 consisting of the following formulation: 60.00% by weight 4''-nitrophenyl 4-trans-cyclohexyl benzoate... 9.00% by weight 4'-nitrophenyl 4-7'-pyrubenzoate 22.00% by weight 4''-nitrophenyl 4-trans-4'-〇-pentylcyclohexylbenzoate...8 .00% by weight 4'-nitrophenyl 4-2-methylphthyloxycarboxybenzoate (optical activity)...1.0% by weight This liquid crystal composition becomes transparent at +52°C and freezes at -5°C. do.

Example 11 Liquid crystal composition consisting of the following formulation 4-trans-4'-■-propylcyclohexyl 1
-Inthiocyanatobenzene...28.03% by weight 4-ethyl-4'-cyanobiphenyl...9.95% by weight 4-pentyl-4'-cyanobiphenyl...34.8
1% by weight 4'-cyanophenyl 4-n-butylbenzoate
...4.22% by weight 4'-cyanophenyl 4-n-hexylbenzoate ...5.68% by weight 4''-cyanophenyl 4-trans-4'-11-pentylcyclohexylbenzoate... 7.83% by weight 4″-methylphenyl 4-trans-4′-〇-pentylcyclohexylbenzoate...9.48% by weight This liquid crystal m-acid is nematic in the temperature range of -30 to 58°C. , positive dielectric anisotropy Δε20' = +10, limiting voltage UIO% = IV and saturation voltage use% = 1.6V
have.

Example 12 Liquid crystal composition 4-trans-4'-n-propylcyclohexyl-
1-isothiocyanatobenzene・φ・17.06% by weight 4-) Lance-4'-n-hexylcyclohexyl-
1-inchocyanatobenzene...27.76% by weight 4-trans-4'-ethylcyclohexyl-1-cyanobenzene...7.71% by weight 4-trans-4'
-n-pentylcyclohexyl-1-cyanobenzene...17.18% by weight 2-4'-cyanophenyl-5-11-hexyl-1,
3-dioxane...6.1) 7% by weight 4-propoxy-4'-cyanobiphenyl...5.34% by weight 4-pentyl-4'-cyanoterphenyl...4.5
7% by weight 2-[4'-)trans-4''-n-pentylcyclohexylphenyl]-5-n-butyl-1,3-dioxane...9.97% by weight 2-[4'-trans -4''-n-pentylcyclohexylphenyl]-5-〇-pe>f IH3-dioxane...8.44% by weight This composition contains -35-70
Nematic in the temperature range of °C, with positive induced anisotropy Δε
20" = + 6 and viscosity η2." = 3611+
Indicates Pa and s.

Patent Applicant Voyczba Academia Te7 Nichina im Jarosława Dombrovskiego

Claims (8)

[Claims] (1) General formula [In the formula, 11 represents an integer of 1 to 12. ] 4-trans-4'-n-alkylcyclohexyl-1
- Intiochyanatobenzene. (2) 4-trans-4 of the above first term, where n is 3 to 7
' -n-furkylcyclohexyl-1-isothiocyanatobenzene. (3) 4-trans-4'-rotsylschiff a hexylaniline having an alkyl substituent having 1 to 12 carbon atoms is dissolved in an organic solvent, and acid chloride is added in the presence of a tertiary amine and/or carbon disulfide. A method for producing a compound of formula [1] shown in item 1 above, which comprises treating the product with Jl and separating the product from Jl. (4) The production method according to the above item 3, wherein the acid chloride is thiophosdene. (5) The acid chloride is furkyl chloroformate (preferably ethyl chloroformate), and the alkyl group has 1 to 1 carbon atoms.
4-) lance-4'-n-alkylcyclohexyl 7niline, which is 2, is dissolved in an organic solvent and treated with carbon disulfide in the presence of a tertiary amine, and the isolated product is treated with carbon disulfide in the presence of a tertiary amine. The process according to paragraph 17.3 above, comprising treatment with purkyl chloroformate in the presence of purkyl chloroformate and isolation of the final product. (6) At least t11 of the compound of formula (T) in item 1 above.
A liquid crystal composition characterized by containing seeds. (7) 4-”) lance-4′-〇-propylcyclohexyl-1-thiocyanatobenzene and/or 4
-trans-4'-rhohexylcyclohexyl-1-
The liquid crystal composition according to item 6 above, containing isothiocyanatobenzene. (8) Known liquid crystal composition, preferably 4-alkyl-4'
-cyanobiphenyls, 4-flufoxy-4'-cyanobiphenyls, 4-alkylbenzoic acid esters, 4
- Esters of flufoxybenzoic acid, esters of 4-alkylcycloalkanecarboxylic acid, 4-alkylcyclohexylcyanobenzenes, 1,1'-disubstituted-4-
Phenyl-2,5-pyrimidines, Schiff bases, 2,5
The liquid crystal composition according to item 6 above, which contains a liquid crystal compound selected from -disubstituted-1,3-dioxane derivatives and optically active compounds.