JPH0853469A - Silacyclohexane compound, its production and liquid crystal composition containing the same - Google Patents

Abstract

PURPOSE:To obtain the subject compound contributing to the viscosity reduction and melting point depression of liquid crystal compositions, by reaction between a specific organometallic reagent and a silacyclohexane compound. CONSTITUTION:This compound is expressed by formula I (R is a 1-10C straight chain alkyl, 3-8C branched chain alkyl, 2-7C alkoxyalkyl or 2-8C alkenyl; ring A is trans-1-silacyclohexylene or trans-4-silacyclohexylene with the Si atom on 1- or 4-site bearing H, F, Cl or Cl3 substituent, respectively; X is CN, F, Cl, CF<3>, CF2Cl, CHFCl, OCF3, OCHF2, OCH2Cl, OCHFCl, R or OR; Y and Z are each H or F), e.g. 4-(trans-4-n-heptyl-4-silacyclohexyl)benzonitrile. This compound of formula I is obtained by reaction between an organometallic reagent R-M [M is MgP (P is a halogen), Zn, P or Li] and a silacyclohexane compound of formula II (W is H, F, Cl or CH3; Q is a halogen or alkoxyl).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel silacyclohexane compound, a method for producing the same, a liquid crystal composition containing the same, and a liquid crystal display device containing the liquid crystal composition.

[0002]

2. Description of the Related Art A liquid crystal display device utilizes optical anisotropy and dielectric anisotropy of a liquid crystal substance, and depending on its display mode, TN type (twisted nematic type), STN type (super twisted nematic type), SBE type (super birefringence type), DS
There are various types such as a type (dynamic scattering type), a guest-host type, a DAP type (deformation of aligned phase), and an OMI type (optically mode interference type). The most common display device is based on the Schut-Helfrich effect and has a twisted nematic structure.

The properties required for the liquid crystal substances used for these liquid crystal displays are slightly different depending on the display system, but they are stable against a wide range of liquid crystal temperature, moisture, air, light, heat, electric field and the like. Things are commonly requested in any display method. Furthermore, it is desired that the liquid crystal material has a low viscosity and provides a short addressing time, a low threshold voltage and a high contrast in the cell.

At present, there is no substance that satisfies all of these requirements with a single compound, and actually, a liquid crystal mixture obtained by mixing several to several dozen liquid crystal compounds / latent liquid crystal compounds is used. . Therefore, it is an important property that the constituent components of the liquid crystal composition can be easily mixed with each other.

The liquid crystal compounds that can be these constituents can be classified as follows according to their functions. Compounds that contribute to viscosity reduction and melting point drop of mixed liquid crystal composition Compounds that mainly control electro-optical function of mixed liquid crystal composition Compounds that contribute to increase clearing point of mixed liquid crystal composition Refractive anisotropy of mixed liquid crystal composition Compounds that contribute to control Compounds that control the color display and orientation of mixed liquid crystal compositions

Among these classifications, compounds belonging to

[Chemical 9] (Japanese Patent Publication No. 56-38146),

[Chemical 10] (Japanese Patent Publication No. 64-373),

[Chemical 11] A compound having a so-called PCH structure such as (Japanese Patent Publication No. 1-38772) has been known.

[0007]

With the recent widespread use of liquid crystal displays, the properties required of liquid crystal materials are becoming more and more severe. Especially, improvement of low temperature performance, wide temperature range corresponding to vehicle needs,
In terms of lowering the driving voltage and the like, it has been desired to further improve the characteristics of conventional liquid crystal substances.

From this point of view, the present invention is particularly
It is a liquid crystal material newly developed for the purpose of reducing the viscosity of a mixed liquid crystal composition and improving the characteristics of the compound that contributes to the melting point effect, and has a silacyclohexane ring which is completely different from the conventional liquid crystal compound having a PCH structure. It is intended to provide a novel liquid crystal compound.

[0009]

Means for Solving the Problems That is, the present invention is a silacyclohexane compound represented by the following general formula (I).

[Chemical 12] In the formula, R is a linear alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 8 carbon atoms, and 2 to 7 carbon atoms.
Represents an alkoxyalkyl group or an alkenyl group having 2 to 8 carbon atoms.

[Chemical 13] Represents a trans-1-silacyclohexylene group or a trans-4-silacyclohexylene group in which silicon at the 1- or 4-position has a substituent of H, F, Cl or CH ₃ . X is C
N, F, Cl, CF ₃ , CF ₂ Cl, CHFCl, OCF
₃ , OCHF ₂ , OCF ₂ Cl, OCHFCl, R or O
Represents an R group. Y represents H or F. Z represents H or F.

The present invention also relates to an organometallic reagent RM (M is MgP (P represents halogen), ZnP or Li), and a silacyclohexane compound.

Embedded image (W represents H, F, Cl or CH ₃ group, and Q represents halogen or alkoxy group.) The method for producing a silacyclohexane compound represented by the above general formula (I), characterized in that .

The present invention also relates to an organometallic reagent.

[Chemical 15] And silacyclohexane compound

Embedded image The method for producing a silacyclohexane compound represented by the above general formula (I) is characterized by reacting with.

The present invention also relates to an organometallic reagent.

[Chemical 17] (M represents MgP ′ (P ′ represents Br or I), Zn or Li, and X ′ represents halogen), and a silacyclohexane compound.

Embedded image Phenyl silacyclohexane compound obtained by reaction with

[Chemical 19] 2. The method for producing a silacyclohexane compound according to claim 1, wherein X is CN, which comprises reacting the Grignard reagent of 1) with a cyanating agent.

Further, the present invention is a liquid crystal composition containing the silacyclohexane compound represented by the general formula (I) and a liquid crystal display device containing the liquid crystal composition.

The novel compound represented by the general formula (I) is
Specifically, it is a novel silacyclohexane compound having a ring structure represented by the following [Chemical Formula 20] or [Chemical Formula 21] and containing a trans-1 or 4-silacyclohexane ring.

Embedded image

[Chemical 21]

In the formula, R is a linear alkyl group having 1 to 10 carbon atoms, that is, methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-.
Octyl, n-nonyl, n-decyl group; or C3
~ 8 branched alkyl groups, i.e. isopropyl, sec
-Butyl, isobutyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-methylpentyl, 2-
Methylpentyl, 3-methylpentyl, 1-ethylpentyl, 1-methylhexyl, 2-methylhexyl, 3-
Methylhexyl, 2-ethylhexyl, 3-ethylhexyl, 1-methylheptyl, 2-methylheptyl, 3-
Methylheptyl; or an alkoxyalkyl group having 2 to 7 carbon atoms, that is, methoxymethyl, ethoxymethyl, propoxymethyl, butoxymethyl, pentoxymethyl, mehexyloxymethyl, toxyethyl, ethoxyethyl, proxyethyl, butoxyethyl, pentoxy. Ethyl, methoxypropyl, ethoxypropyl, propoxypropyl, butoxypropyl, methoxybutyl, ethoxybutyl, propoxybutyl, methoxypentyl, ethoxypentyl groups; or alkenyl groups having 2 to 8 carbon atoms, that is, vinyl, 1-propenyl, allyl, 1-butenyl, 3-butenyl, isoprenyl, 1-pentenyl, 3-pentenyl, 4-pentenyl, dimethylallyl, 1-hexenyl, 3-hexenyl, 5-hexenyl, 1-heptenyl, 3-heptenyl, - represents heptenyl, 7-octenyl group.

W represents H, F, Cl or CH ₃ .

X is CN, F, Cl, CF ₃ , CF ₂ C
1, CHFCl, OCF ₃ , OCHF ₂ , OCF ₂ Cl,
It represents an OCHFCl, R or OR group.

Y represents H or F. Z is H or F
Represents

[0019]

[Chemical formula 22] Specifically, the following groups can be mentioned.

[Chemical formula 23]

[Chemical formula 24]

[Chemical 25]

[Chemical formula 26]

[Chemical 27]

[Chemical 28]

[Chemical 29]

Embedded image

[Chemical 31]

[Chemical 32]

[Chemical 33]

Embedded image

Embedded image

Embedded image

Embedded image

[Chemical 38]

[Chemical Formula 39]

[Chemical 40]

Embedded image

Embedded image

[Chemical 43]

[Chemical 44]

Embedded image

Embedded image

[Chemical 47]

Embedded image

[Chemical 49]

Embedded image

[Chemical 51]

Embedded image

Embedded image

[Chemical 54]

[Chemical 55]

As for R, a linear alkyl group having 3 to 7 carbon atoms, that is, n-propyl, n-butyl, n-pentyl,
n-hexyl, n-heptyl group, or a branched alkyl group having 3 to 7 carbon atoms, isopropyl, 1-methylpropyl, 2-methylpropyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1- Methyl pentyl, 2
-Methylpentyl, 2-ethylhexyl group, or alkoxyalkyl group having 2 to 6 carbon atoms, that is, methoxymethyl, methoxyethyl, methoxypropyl, methoxypentyl, ethoxymethyl, ethoxyethyl, propoxymethyl, pentoxymethyl group, or Of the alkenyl groups, vinyl, 1-propenyl, 3-butenyl, 1-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 5-hexenyl, 6-heptenyl and 7-octenyl groups are practically desirable.

As for W, H, F and CH ₃ groups are practically desirable. However, when the ring structure of the silacyclohexane ring is [Chemical Formula 21] and X is CN, W is limited to H or CH ₃ group.

Regarding [Chemical formula 22], [Chemical formula 23] to [Chemical formula 26], [Chemical formula 29], [Chemical formula 32] to [Chemical formula 37], [Chemical formula 4]
1], [Chemical 44] to [Chemical 49], [Chemical 52] to [Chemical 5
5] is practically preferable.

Next, a method for producing these compounds will be described.

(1) A method for producing a compound of the present invention wherein the ring structure of the silacyclohexane ring is [Chemical Formula 21] and X is CN. In this production method, p-halobromobenzene or p-haloiodobenzene having a Y or Z substituent is reacted with magnesium in a solvent such as THF (tetrahydrofuran) to give a corresponding Grignard reagent. Then, the silacyclohexane compound in which silicon is substituted with W and Q is reacted. Then, metal magnesium is further reacted in a solvent such as THF (tetrahydrofuran) to prepare a Grignard reagent, and then reacted with a cyanating agent such as cyanogen. Since the compound produced here is a mixture of the trans form and the cis form in the conformation of the silacyclohexane ring, the trans form is separated and purified by a conventional purification means such as chromatography or recrystallization to obtain the compound of the present invention. A silacyclohexane compound represented by the general formula (I) is obtained. The reaction formula is shown below.

[0025]

[Chemical 56] (P: Br or I, X ′: halogen, Q: halogen or alkoxy group)

(2) A method for producing the compound of the present invention other than the above (1). Although the reaction substrates differ slightly depending on the ring structure, they are commonly produced by the coupling reaction of the following organometallic reagents.

In this production method, the corresponding organometallic reagent is prepared from R-halide or substituted aryl halide in a solvent such as THF (tetrahydrofuran) by a conventional method. The resulting organometallic reagent is then reacted with a silacyclohexane compound in which silicon is replaced by W and Q. Since the compound produced here is a mixture of the trans form and the cis form in the conformation of the silacyclohexane ring, the trans form is separated and purified by a conventional purification means such as chromatography or recrystallization to obtain the compound of the present invention. A silacyclohexane compound represented by the general formula (I) is obtained. The reaction formula is shown below.

[0028]

[Chemical 57]

Embedded image {M is MgP ₁ (P ₁ represents halogen), ZnP ₁ or Li, M ′ is Mg (P ₂ is Br, I (when X is Cl)) or Cl, Br, I (when X is not Cl) ), ZnP ₂ or Li. Q represents a halogen or an alkoxy group, and W represents H, F, Cl or CH ₃ . X is CN, F, Cl, CF ₃ , CF ₂ Cl, CHF
Cl, OCF ₃ , OCHF ₂ , OCF ₂ Cl, OCHFC
represents an R, R or OR group. Y represents H or F. Z is
Represents H or F. However, when W = F or Cl, W =
Q. ｝

The silacyclohexane compound of the present invention can be mixed with a known compound to obtain a liquid crystal composition.
Specifically, a liquid crystal composition can be obtained by mixing with the compounds shown below.

Embedded image

Embedded image

In addition, in [Chemical formula 59] and [Chemical formula 60], (M) and (N) are unsubstituted or one or more F, C as a substituent.
1, Br, CN, trans-1,4 having an alkyl group
-Cyclohexylene group, a ring in which one or two non-adjacent CH ₂ groups in a cyclohexane ring are replaced by O and S, 1,4-cyclohexenylene group, unsubstituted or one as a substituent Or two F, Cl, C
H ₃ or 1,4-phenylene group having a CN group, one or two CH groups in the ring of the 1,4-phenylene group represents any ring is replaced by N atoms.

Z ¹ and Z ² are --CH ₂ CH _2- , --CH =
CH -, - C≡C -, - CO 2 -, - OCO -, - CH 2
O -, - represents a single bond or - OCH _2.

L (ell), m = 0, 1, 2 (provided that l +
m = 1, 2, 3, n = 0, 1, 2).

R is hydrogen, a straight chain alkyl group having 1 to 10 carbon atoms, a branched chain alkyl group having 3 to 8 carbon atoms, or 2 carbon atoms.
Is an alkoxyalkyl group having 7 to 7 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.

X, Y and Z have the same definitions as in formula (I).

In the above, l (n), n = 2
In the case of, a heterocyclic ring may be contained in (M), and in the case of m = 2, a heterocyclic ring may be contained in (N).

The proportion of the silacyclohexane compound of the present invention in the liquid crystal composition is 1 to 2 inclusive,
50% by weight, preferably 5 to 30% by weight. In addition, the liquid crystal composition may include a pleochroic dye for forming a colored guest-host system or an additive for changing the dielectric anisotropy, the viscosity and the orientation of the nematic phase.

Various liquid crystal display devices can be manufactured by a usual method using the liquid crystal composition thus formed. That is, the liquid crystal composition containing the silacyclohexane compound of the present invention is used as a liquid crystal display device by enclosing it between transparent substrates having electrodes of a desired shape. If necessary, this element may have various undercoats, alignment control overcoats, polarizing plates, filters, reflective layers, etc., and can be used as a multilayer cell, in combination with other display elements, using a semiconductor substrate, or Various things such as using a light source can be used.

The driving method of the liquid crystal display device is a dynamic scattering (DSM) method, a twisted nematic (TN) method, a guest host (GH) method, a super twisted nematic (STN) method, a polymer dispersed liquid crystal (PDLC) method. For example, a method known in the liquid crystal display element industry can be adopted.

[0039]

EXAMPLES The present invention will be described in more detail with reference to specific examples.

Example 1 Preparation of 4- (trans-4-n-heptyl-4-silacyclohexyl) benzonitrile 0.5 g (21 mmol) magnesium and THF 50
To a mixture of ml, 3.6 g of 1-bromo-n-heptane
(20 mmol) was added dropwise to obtain a Grignard reagent. This was added to a mixture of 2.8 g of zinc chloride and 20 ml of THF to obtain an organozinc reagent. Subsequently, this solution was added to 4- (4
4-Chloro-4-silacyclohexyl) benzonitrile (4.7 g, 20 mmol) was added dropwise to a solution of 50 ml of THF to obtain 4- (4-n-heptyl-4-silacyclohexyl) benzonitrile. This is a mixture of trans and cis isomers with respect to the silacyclohexane ring,
Chromatographic separation gives trans-form 5.5
g (yield 92%) was obtained. C-N transition temperature: 16 ° C, NI transition temperature: 19 ° C IR (liquid film) νmax: 2920, 2227, 210
0,1608,1502,1458,1408,118
4,987,893,889,820 cm ^-1

The following compounds were obtained in the same manner as in Example 1.

[Example 2] 4- (trans-4-n-pentyl-4-silacyclohexyl) benzonitrile C-I transition temperature: 38 ° C, NI transition temperature: 13 ° C IR (liquid film) νmax: 2920, 2227, 210
4,1608,1502,1458,1408,98
7,881,825 cm ^-1

[Example 3] 4- (trans-4-n-hexyl-4-silacyclohexyl) benzonitrile C-I transition temperature: 18 ° C, NI transition temperature: 10 ° C IR (liquid film) νmax: 2920, 2227, 210
0,1608,1502,1458,1407,118
4,987,889,879,817cm ^-1

[Example 4] 4- (trans-4-n-nonyl-4-silacyclohexyl) benzonitrile C-I transition temperature: 32 ° C, NI transition temperature: 25 ° C IR (liquid film) νmax: 2916, 2225, 209
0,1606,1502,1470,1406,98
9,933,889,812 cm ^-1

Example 5 Preparation of 4- (trans-4-n-heptyl-4-silacyclohexyl) -1,2-difluorobenzene 0.5 g (21 mmol) magnesium and THF 50
3.0 g of 1-bromo-n-heptane (2
0 mmol) was added dropwise to obtain a Grignard reagent. Subsequently, this reagent was added to 4- (4-chloro-4-silacyclohexyl) -1,2-difluorobenzene (4.9 g, 20 mm).
ol) in a solution of 50 ml of THF, and then 4- (4-n-
Heptyl-4-silacyclohexyl) -1,2-difluorobenzene was obtained. This product was a mixture of trans isomer and cis isomer with respect to the silacyclohexane ring and was separated by chromatography to obtain 5.3 g of trans isomer (yield 93%). C-I transition temperature: -17 ° C IR (liquid film) νmax: 2920, 2102, 151
7,1431,1407,1284,1213,111
4,987,960,889,811 cm ^-1

The following compounds were obtained in the same manner as in Example 5.

[Example 6] 4- (trans-4-n-heptyl-4-silacyclohexyl) -1-fluorobenzene C-I transition temperature: 11 ° C IR (liquid film) νmax: 2920, 2100, 151
0,1458,1408,1228,985,887,
820 cm ^-1

"Example 7" 4- (trans-4-n-pentyl-4-silacyclohexyl) -1-fluorobenzene C-I transition temperature: 2 ° C IR (liquid film) νmax: 2920, 2100, 151
0,1458,1408,1228,987,887,
825 cm ^-1

"Example 8" 4- (trans-4-n-hexyl-4-silacyclohexyl) -1-fluorobenzene C-I transition temperature: 8 ° C IR (liquid film) νmax: 2920, 2100, 151
0,1458,1408,1228,1159,98
7,887,816 cm ^-1

[Example 9] 4- (trans-4-n-pentyl-4-silacyclohexyl) -1-chlorobenzene C-I transition temperature: 9 ° C IR (liquid film) νmax: 2920, 2110, 149
5,1465,1415,1095,990,880,
815 cm ^-1

[Example 10] 4- (trans-4-n-hexyl-4-silacyclohexyl) -1-chlorobenzene C-I transition temperature: 35 ° C IR (liquid film) νmax: 2920, 2100, 149
5,1460,1410,1180,1095,98
5,880,805 cm ^-1

"Example 11" 4- (trans-4-n-heptyl-4-silacyclohexyl) -1-chlorobenzene C-I transition temperature: 23 ° C GC-MS (70 eV) (m / z) ⁺ : 127 , 15
4,209,252,280,308

Example 12 4- (trans-4-n-octyl-4-silacyclohexyl) -1-chlorobenzene C-I transition temperature: 43 ° C IR (KBr) νmax: 2920, 2100, 14
95, 1460, 1410, 1090, 985, 88
0,805 cm ^-1

"Example 13" 4- (trans-4-n-nonyl-4-silacyclohexyl) -1-chlorobenzene CI transition temperature: 41 ° C IR (liquid film) νmax: 2925, 2100, 149
5,1460,1410,1095,990,880,
815 cm ^-1

Example 14 4- (trans-4-n-heptyl-4-silacyclohexyl) -1-trifluoromethoxybenzene

Example 15 4- (trans-4-isopentyl-4-silacyclohexyl) -1-methoxybenzene

Example 16 4- (trans-4-methoxypentyl-4-fluoro-4-silacyclohexyl) -1-chloro-2-fluorobenzene

Example 17 4- (trans-4-methoxypentyltyl-4-methyl-4-silacyclohexyl) -1,2,6-trifluorobenzene

Example 18 4- {trans-4- (3-pentenyl) -4-methyl-4-silacyclohexyl})-1-trifluoromethoxy-2-fluorobenzene

"Example 19" 4- (trans-4- (3-methoxypropyl) -4
-Silacyclohexyl) -1-fluorobenzene CI transition temperature: 5.9 ° C IR (liquid film) νmax: 2922, 2852, 210
0, 1604, 1508, 1225, 1117, 88
7,818 cm ^-1

"Example 20" 4- (trans-4- (E-3-hexenyl) -4-
Silacyclohexyl) -1-fluorobenzene CI transition temperature: -9.0 ° C IR (liquid film) νmax: 2962, 2916, 210
2,1604,1510,1228,1159,96
6,887,818cm ^-1

"Example 21" 4- (trans-4- (3-methylbutyl) -4-silacyclohexyl) -1-fluorobenzene CI transition temperature: 5.7 ° C IR (liquid film) νmax: 2954, 2916, 210
0, 1606, 1510, 1228, 1159, 98
7,889,812 cm ^-1

Example 22 4- (trans-4-n-pentyl-4-silacyclohexyl) -2,3-difluoro-1-ethoxybenzene

Example 23 Preparation of 4- (trans-4-n-pentyl-1-silacyclohexyl) benzonitrile 0.5 g (21 mmol) magnesium and 50 THF
3.8 g of 4-bromochlorobenzene in a mixture of ml
A solution of (20 mmol) in 5 ml of THF was added to obtain a Grignard reagent. Then, this is added to 4-n-pentyl-1-
Chloro-1-silacyclohexane 4.1 g (20 mmo
l) was dropped into a solution of 50 ml of THF, and 4- (4-n-
5.5 g (yield 97%) of pentyl-1-silacyclohexyl) chlorobenzene was obtained. Next, the obtained 4- (4-n-pentyl-1-silacyclohexyl) chlorobenzene was added to a mixture of 0.5 g (21 mmol) of magnesium and 50 ml of THF to obtain a Grignard reagent. This was added to an ether solution of 1.6 g of cyanodiene (CN) ₂ to give 4- (4-n-pentyl-1-silacyclohexyl) benzonitrile. This was a mixture of trans isomer and cis isomer with respect to the silacyclohexane ring, and was separated by chromatography to obtain 4.5 g of trans isomer (yield 90%). ¹ H-NMR (100 MHz, CDCl ₃ ) δ: 0.30 (s, 3H), 0.75 to 1.00 (m, 7H), 1.10 to 1.40 (m, 10H), 1.60. ˜2.10 (m, 3H), 7.60 (s, 4H) IR (liquid film) νmax: 2924, 2229, 138
5,1252,1101,985,810,775cm
^-1

"Example 24" 4- (trans-4-n-propyl-1-methyl-1)
-Silacyclohexyl) benzonitrile CI transition temperature: 36 ° C IR (liquid film) νmax: 2910,2229,138
5,1252,1101,972,812,775cm
^-1

Example 25 4- (trans-4-n-butyl-1-methyl-1-)
Silacyclohexyl) benzonitrile C-I transition temperature: 25 ° C IR (liquid film) νmax: 2922, 2229, 138
5,1252,1101,980,810,768cm
^-1

Example 26 Preparation of 4- (trans-4-isopentyl-1-silacyclohexyl) -1-trifluoromethylbenzene. Magnesium 0.5 g (21 mmol) and THF 50
4.5 g (20 mmol) of 4-bromo-1-trifluoromethylbenzene was added dropwise to the mixture of ml to obtain a Grignard reagent. Subsequently, this solution was added to 4-isopentyl-1-
Chloro-1-silacyclohexane 4.1 g (20 mmo
l) was added dropwise to a solution of 50 ml of THF to give 4- (4-isopentyl-1-silacyclohexyl) -1-trifluoromethylbenzene. This is a mixture of trans-form and cis-form with respect to the silacyclohexane ring, which was separated by chromatography to give 5.8 g of trans-form (yield 9
2%) was obtained.

The following compound was obtained in the same manner as in Example 26.

Example 27 4- (trans-4-methoxypentyl-1-silacyclohexyl) -1-difluoromethoxybenzene

Next, the liquid crystal composition of the present invention was manufactured by adding the compound of the present invention obtained in the above Examples to the existing liquid crystal composition. Then, the operation threshold voltage and the viscosity at 20 ° C. of the obtained liquid crystal composition were measured.

"Liquid Crystal Composition Example" 4- (4- (tra
ns-4-ethylcyclohexyl) -trans-4-
Cyclohexyl) -1,2-difluorobenzene 40 mol%, 4- (4- (trans-4-n-propylcyclohexyl) -trans-4-cyclohexyl)-
35 mol% of 1,2-difluorobenzene and 4- (4-
(Trans-4-n-pentylcyclohexyl) -t
Mixture A consisting of 25 mol% of trans-4-cyclohexyl) -1,2-difluorobenzene has the following properties: C-N transition temperature: 7 ° C N-I transition temperature: 106 ° C Threshold voltage: 2.50V Viscosity (20 ° C): 26 cp

A mixture consisting of 85% of this mixture A and 15% of 4- (trans-4-n-hexyl-4-silacyclohexyl) -1-fluorobenzene obtained in Example 8 exhibits the following properties: C-N transition temperature: 2 ° C N-I transition temperature: 81 ° C Threshold voltage: 2.30V Viscosity (20 ° C): 19.7 cp

[0073]

The silacyclohexane compound of the present invention in which the substituent X is CN has a strong tendency to exhibit a tautomeric phase transition.
Further, when the substituent X is other than CN, most of them show a single phase transition or a crystal-isotropic liquid type transition, and they do not show electro-optical characteristics as a liquid crystal by themselves. When used as a liquid crystal composition together with a liquid crystal compound, it exhibits a function of reducing viscosity and a function of lowering melting point.

When the liquid crystal compound of the present invention having Si introduced as a ring-constituting element is used as a constituent component of a liquid crystal composition, the viscosity can be lowered, the response speed can be improved, and the compatibility at low temperature can be improved. improves.

The liquid crystal compound in which X in the general formula (I) is not R or OR has the effect of lowering the threshold voltage because of its large dielectric anisotropy, in addition to the above advantages.

Since the liquid crystal compound in which the substituent X in the general formula (I) is R or OR, the dielectric anisotropy is close to zero,
It is preferably used for the liquid crystal phase of the display solution based on dynamic scattering (DS) or deformation of the aligned phase (DAP effect). Also,
Compounds other than X are preferably used for preparing a liquid crystal phase having a large positive dielectric anisotropy for use in a display element based on a twisted nematic cell or a cholesteric-nematic phase transition.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Kinsei 28, Nishi-Fukushima, Kikuki-mura, Nakakubiki-gun, Niigata Prefecture-1 Synthetic Technology Laboratory, Shin-Etsu Chemical Co., Ltd. (72) Tatsushi Kaneko, Nakakubiki, Niigata Prefecture 28, Nishi-Fukushima, Gunju, Kugunagi-mura-1 Synthetic Technology Laboratory, Shin-Etsu Chemical Co., Ltd. (72) Inventor Ryuichi Saito 28, Nishi-Fukushima, Kubiki-mura, Nakakubiki-gun, Niigata Prefecture-1 Synthetic Technology Laboratory, Shin-Etsu Chemical Co., Ltd. (72) Inventor Hideshi Kurihara 28, Nishi-Fukushima, Kubiki-mura, Nakakubiki-gun, Niigata Prefecture-1 Shin-Etsu Chemical Co., Ltd.

Claims (6)

[Claims] 1. A silacyclohexane compound represented by the following general formula (I): Embedded image In the formula, R is a linear alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 8 carbon atoms, and 2 to 7 carbon atoms.
Represents an alkoxyalkyl group or an alkenyl group having 2 to 8 carbon atoms. Embedded image Represents a trans-1-silacyclohexylene group or a trans-4-silacyclohexylene group in which the silicon at the 1- or 4-position has a substituent of H, F, Cl or CH ₃ . X is
CN, F, Cl, CF ₃ , CF ₂ Cl, CHFCl, OC
It represents an F ₃ , OCHF ₂ , OCF ₂ Cl, OCHFCl, R or OR group. Y represents H or F. Z represents H or F. 2. An organometallic reagent RM (M is MgP (P represents halogen), ZnP or Li) and a silacyclohexane compound. (W represents H, F, Cl or CH ₃ group, Q represents halogen or alkoxy group.) The method for producing a silacyclohexane compound according to claim 1, wherein 3. An organometallic reagent And a silacyclohexane compound The method for producing a silacyclohexane compound according to claim 1, which is characterized by reacting with. 4. An organometallic reagent (M is MgP '(P' represents Br or I), Zn
P'or Li and X'represent halogen. ) And a silacyclohexane compound Phenyl silacyclohexane compound obtained by reaction with 2. The method for producing a silacyclohexane compound according to claim 1, wherein X is CN, which comprises reacting the Grignard reagent of 1) with a cyanating agent. 5. A liquid crystal composition comprising the silacyclohexane compound according to claim 1. 6. A liquid crystal display device comprising the liquid crystal composition according to claim 5.