JP3013143B2 - Silacyclohexane compound, method for producing the same, and liquid crystal composition containing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel silacyclohexane compound, a method for producing the same, a liquid crystal composition containing the compound, and a liquid crystal display device containing the liquid crystal composition.

[0002]

2. Description of the Related Art A liquid crystal display device utilizes an optical anisotropy and a dielectric anisotropy of a liquid crystal material. Depending on the display mode, a TN type (twisted nematic type), an STN type (super twisted nematic type), SBE type (super birefringent type), DS
There are various types such as a type (dynamic scattering type), a guest-host type, a DAP type (an alignment phase deformation type), and an OMI type (optically mode interference type). The most common display devices are based on the Schadt-Helfrich effect and have a twisted nematic structure.

The properties required of the liquid crystal material used in these liquid crystal displays slightly vary depending on the display system, but the liquid crystal temperature range is wide, and the liquid crystal material is stable against moisture, air, light, heat, an electric field, and the like. This is commonly required in any of the display methods. Further, it is desired that the liquid crystal material has a low viscosity and provides a short address 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. In practice, a liquid crystal mixture obtained by mixing several to several tens of liquid crystal compounds and latent liquid crystal compounds is used. . Therefore, it is an important characteristic that the components of the liquid crystal composition can be easily mixed with each other.

[0005] Among the liquid crystal compounds that can be these components, one of the basic components that governs electro-optical performance has been a conventional one.

Embedded image (Japanese Patent Publication No. 63-13411)

Embedded image (Japanese Patent Publication No. 63-32051),

Embedded image (JP-B 63-44132),

Embedded image (JP-B-63-46738),

Embedded image (Japanese Patent Publication No. 2-29055),

Embedded image (JP-A-4-54138),

Embedded image (Tokuhyo Hei 4-506376),

Embedded image (Tokuhyo Hei 2-5011311),

Embedded image So-called cyclohexyl ring-cyclohexyl ring-phenyl ring structure (CCP structure) such as JP-A-2-233626.
Are known.

[0006]

In recent years, as the applications of liquid crystal displays have expanded, the characteristics required for liquid crystal materials have become increasingly severe and strict. In particular, it has been desired to further improve the characteristics of the conventional liquid crystal material, such as lowering the driving voltage, widening the temperature range corresponding to the needs for vehicles, and improving the low-temperature performance.

In view of the above, the present invention is a liquid crystal material newly developed for the purpose of improving the properties of the liquid crystal material, and has the above-mentioned cyclohexyl ring-cyclohexyl ring-phenyl ring structure (CCP). It is an object of the present invention to provide a liquid crystal compound having a silacyclohexane ring completely different from a liquid crystal compound having the structure

[0008]

That is, the present invention provides a compound represented by the following general formula (I):

Embedded image Is a silacyclohexane compound represented by In the formula, R is hydrogen, a linear alkyl group having 1 to 10 carbon atoms,
It represents a branched alkyl group having 3 to 8 carbon atoms, an alkoxyalkyl group having 2 to 7 carbon atoms, or an alkenyl group having 2 to 8 carbon atoms.

Embedded image as well as

Embedded image Transformer, with the at least one is 1 or 4 position of the silicon H, F, substituents Cl or CH _3-1-
A silacyclohexylene or trans-4-silacyclohexylene group, and the other represents a trans-1,4-cyclohexylene group. X is CN, F, Cl, CF ₃ , CF _{2
Cl, CHFCl, OCF 3, OCHF} 2, OCF 2 C
l, OCHFCl, R or OR group (R is hydrogen, carbon number 1
A linear alkyl group having 10 to 10, a branched alkyl group having 3 to 8 carbon atoms, an alkoxyalkyl group having 2 to 7 carbon atoms or an alkenyl group having 2 to 8 carbon atoms). Y represents H or F. Z represents H or F.

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

Embedded image (W represents H, F, Cl or CH ₃ group, Q represents a halogen or an alkoxy group) and a general formula (2)

Embedded image (2) This is a method for producing a (trans-4-) silacyclohexane compound.

[0010] The present invention also relates to an organometallic reagent.

Embedded image (However,

Embedded image Represents 1 or 4-position of the silicon H, F, trans-1-sila-cyclohexylene or trans-4-sila-cyclohexylene group or a cyclohexylene group having a substituent of Cl or CH _3. M is MgP (P represents halogen),
Represents ZnP or Li. ) And a silacyclohexane compound

Embedded image (W is H, F, Cl or CH ₃ group, Q is halogen
And an alkoxy group. General formula by reaction with
(3)

(3) This is a method for producing a (trans-4-) silacyclohexane compound.

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

The novel compounds represented by the general formula (I) are specifically exemplified by the following [Chemical Formulas 24 to 30]
A silacyclohexane compound having a ring structure containing at least one trans-1 or 4-silacyclohexane ring.

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

In the formula, R is hydrogen, a linear alkyl group having 1 to 10 carbon atoms, ie, methyl, ethyl, n-propyl, n
-Butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl group, or
A branched alkyl group having 3 to 8 carbon atoms, 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, i.e., methoxymethyl, ethoxymethyl, propoxymethyl, butoxymethyl, pentoxymethyl, hexyloxymethyl, Methoxyethyl, ethoxyethyl, propoxyethyl, butoxyethyl, pentoxyethyl, methoxypropyl, ethoxypropyl, propoxypropyl, butoxypropyl, methoxybutyl,
Ethoxybutyl, propoxybutyl, methoxypentyl, ethoxypentyl group, or alkenyl group 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, 6-heptenyl, 7-octenyl group.

W, W ¹ and W ² are each independently of the other
It represents H, F, Cl, or CH _3.

X is CN, F, Cl, CF ₃ , CF ₂ Cl,
_{CHFCl, OCF 3, OCHF 2,} OCF 2 Cl, OC
Represents an HFCl, R or OR group. Y represents H or F. Z represents H or F.

[0016]

Embedded image Specifically,

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image Represents a group.

Of these, the ring structure is represented by
4], [Chemical Formula 26] and [Chemical Formula 28] are practically desirable.

R is a straight-chain alkyl group having 2 to 7 carbon atoms, that is, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl group, or 3 carbon atoms.
Isopropyl, 1-methylpropyl, 2-methylpropyl, 1-methylbutyl,
2-methylbutyl, 3-methylbutyl, 1-methylpentyl, 2-methylpentyl, 2-ethylhexyl group, or an alkoxyalkyl group having 2 to 6 carbon atoms, that is, methoxymethyl, methoxyethyl, methoxypropyl, methoxypentyl, ethoxymethyl , Ethoxyethyl, propoxymethyl, pentoxymethyl, or alkenyl, vinyl, 1-propenyl, 3-butenyl, 1-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 5-hexenyl, 6- Heptenyl, 7-octenyl groups are practically desirable.

For W, W ¹ and W ² , H, F, CH ₃
Groups are practically desirable.

Regarding [Chemical 31], [Chemical 32] to [Chemical 35], [Chemical 38], [Chemical 41] to [Chemical 47], [Chemical 5]
0], [Formula 53] to [Formula 58], [Formula 61] to [Formula 6]
4] is practically preferable.

Next, methods for producing these compounds will be described. Although the reaction substrates differ slightly depending on the ring structure, they are commonly produced by the following organic metal coupling reaction.

Embedded image

Embedded image

Embedded image P: halogen, Q: halogen or alkoxy group, M: M
g, Zn or Li (W = F or Cl, W ² = F or Cl
In the case of W = Q, W ² = Q, W ¹ ≠ F or Cl)

In the above production method, a corresponding organometallic reagent is prepared from cyclohexyl halide, R-halide or silacyclohexyl halide in a solvent such as THF (tetrahydrofuran) by a conventional method. At this time, an appropriate metal species is selected depending on the type of the substituent X. The resulting metal halide is then reacted with a silacyclohexane compound in which silicon has been replaced by W or W ² , and Q. Since the compound formed here is a mixture of a trans form and a 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. A silacyclohexane compound represented by the general formula (I) is obtained.

The liquid crystal composition can be obtained by mixing the silacyclohexane compound of the present invention with a known compound.
Compounds that are specifically mixed to produce a liquid crystal composition can be selected from the following known compounds.

Embedded image

Embedded image

In Chemical Formulas 68 and 69, (M) and (N) are unsubstituted or substituted with one or more F or C
l, Br, CN, trans-1, 4 having an alkyl group
A cyclohexylene group, a ring in which one or two non-adjacent CH ₂ groups in a cyclohexane ring are replaced by O or S, a 1,4-cyclohexenylene group, unsubstituted or one as a substituent Or two F, Cl, C
1,4-phenylene group having H ₃ or CN group, and one or two CH groups in the ring of 1,4-phenylene group represent any of rings replaced by N atoms.

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

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

R is hydrogen, a linear alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 8 carbon atoms, and 2 carbon atoms.
To 7 alkoxyalkyl groups or alkenyl groups having 2 to 8 carbon atoms.

X, Y and Z are the same as defined in the general formula (I).

In the above, 1 (ell), n = 2
In the case of (M), a heterocyclic ring may be contained in (M), and when m = 2, in (N).

The ratio of the silacyclohexane compound of the present invention in the liquid crystal composition may be one or two or more.
The content is 50% by weight, preferably 5 to 30% by weight. Further, the liquid crystal composition may contain a polychromatic dye for generating a colored guest-host system or an additive for changing the dielectric anisotropy, viscosity, and alignment 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 sealed between transparent substrates having electrodes of a desired shape and used as a liquid crystal display device. This element may have various undercoats, an overcoat for orientation control, a polarizing plate, a filter, a reflective layer, and the like, if necessary. Various types using a light source or the like can be used.

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

[0033]

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

Example 1 4- (trans-4- (trans-4-n-propylcyclohexyl) -4-silacyclohexyl) -1,
Preparation of 2-difluorobenzene 0.5 g (21 mmol) of magnesium and THF50
To the mixture of ml, 4.1 g (20 mmol) of 4-n-propylcyclohexyl bromide was added dropwise to obtain a Grignard reagent. Subsequently, the solution was treated with 4- (4-chloro-4-
4- (4- (trans-4-n-propylcyclohexyl) -4-silacyclohexyl) -1,2-difluoro was added dropwise to a solution of 4.9 g (20 mmol) of silacyclohexyl) -1,2-difluorobenzene in 50 ml of THF. Benzene was obtained. This is a mixture of a trans-isomer and a cis-isomer with respect to the silacyclohexane ring.
(91% yield). CN transition temperature: 28 ° C, NI transition temperature: 79 ° C IR (liquid film) νmax: 2914, 2845, 209
8, 1608, 1518, 1286, 1213, 81
2,808,769cm ^-1

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

Example 2 4- (trans-4- (trans-4-n-propylcyclohexyl) -4-silacyclohexyl) -1-
Fluorobenzene CN transition temperature: 56 ° C, NI transition temperature: 111 ° C IR (KBr disc) νmax: 2914,28
43,2102,1605,1508,1225,98
5,887,879,812,710cm ^-1

Example 3 4- (trans-4- (trans-4-n-butylcyclohexyl) -4-silacyclohexyl) -1-fluorobenzene CN transition temperature: 40 ° C., NI transition temperature : 107 ° C IR (KBr disc) νmax: 2920, 28
46,2102,1605,1508,1225,98
5,812,719 cm ^-1

Example 4 4- (trans-4- (trans-4-n-pentylcyclohexyl) -4-silacyclohexyl) -1-
Fluorobenzene This compound has the following properties, and appeared in a hydrocarbon compound having a similar structure, 4- (4- (trans-4-n-pentylcyclohexyl) -trans-4-cyclohexyl) -1-fluorobenzene. The smectic phase (66-76 ° C) disappeared. CN transition temperature: 55 ° C, NI transition temperature: 113 ° C IR (KBr disc) νmax: 2920, 28
43, 2094, 1605, 1510, 1223, 98
7,887,877,814,715cm ^-1

Example 5 4- (trans-4- (trans-4-n-propylcyclohexyl) -4-silacyclohexyl) -1-
Chlorobenzene This compound has the following properties, and a smectic phase which appears in a hydrocarbon compound having a similar structure, 4- (4- (trans-4-n-propylcyclohexyl) -trans-4-cyclohexyl) -1-chlorobenzene. (70-78 ° C) disappeared. CN transition temperature 48 ° C, NI transition temperature 136 ° C IR (KBr disc) νmax: 2912,28
43, 2102, 1491, 987, 877, 810,
725,683 cm ^-1

Example 6 4- (trans-4- (trans-4-n-pentylcyclohexyl) -4-silacyclohexyl) -1,
2-difluorobenzene CN transition temperature: 45 ° C, NI transition temperature: 87 ° C IR (KBr disc) νmax: 2924,28
45, 2092, 1608, 1520, 1113, 98
9,891,808,771,715cm ^-1

Example 7 4- (trans-4- (trans-4-n-propylcyclohexyl) -4-silacyclohexyl) -1-
Trifluoromethoxybenzene

Example 8 4- (trans-4- (trans-4-n-propylcyclohexyl) -4-silacyclohexyl) -1,
2,6-trifluorobenzene

Example 9 4- (trans-4-methyl-4- (trans-4)
-N-pentylcyclohexyl) -4-silacyclohexyl) -1-methoxybenzene

Example 10 4- (trans-4-methyl-4- (trans-4)
-Isobutylcyclohexyl) -4-silacyclohexyl) -1-chloro-2,6-difluorobenzene

Example 11 0.5 g (21 mmol) of magnesium 4- (trans-4- (trans-4-n-propylcyclohexyl) -4-silacyclohexyl) benzonitrile and THF 50
To the mixture of ml, 4.1 g (20 mmol) of 4-n-propylcyclohexyl bromide was added dropwise to obtain a Grignard reagent. Next, 3.0 g of zinc chloride (22 mm
ol) and 10 ml of THF to give an organozinc reagent. Subsequently, this reagent was combined with 4.7 g of 4- (4-chloro-4-silacyclohexyl) benzonitrile (20 mm).
ol) in 50 ml of THF dropwise.
ran-4-n-propylcyclohexyl) -4-silacyclohexyl) benzonitrile was obtained. This was a mixture of a trans form and a cis form for the silacyclohexane ring, and was separated by chromatography to obtain 5.4 g of the trans form (83% yield).

Example 12 4- (trans-4- (trans-4-n-pentyl-4-silacyclohexyl) -4-cyclohexyl)
0.5 g (21 mmol) of magnesium-1-difluoromethoxy-2,6-difluorobenzene and THF50
2.5 g of n-pentyl bromide (20 ml)
mmol) was added dropwise to obtain a Grignard reagent. Subsequently, 7.9 g of 4- (4- (4-chloro-4-silacyclohexyl) -trans-4cyclohexyl) -1-difluoromethoxy-2,6-difluorobenzene was added to this solution.
(20 mmol) was added dropwise to a 50 ml solution of THF to give 4-
(4- (trans-4-n-pentyl-4-silacyclohexyl) -4-cyclohexyl) -1-difluoromethoxy-2,6-difluorobenzene was obtained. This was a mixture of a trans-isomer and a cis-isomer with respect to the silacyclohexane ring. CN transition temperature: 52 ° C, NI transition temperature: 75 ° C IR (KBr disc) νmax: 2924,28
54, 2102, 1603, 1518, 1444, 13
42,1217,1115,1034,984,95
8,887,849,816cm ^-1

The following compounds were obtained in the same manner as in Example 12.

Example 13 4- (trans-4- (trans-4-n-propyl-4-silacyclohexyl) -4-cyclohexyl)
-1-fluorobenzene CN transition temperature: 65 ° C, NI transition temperature: 109 ° C IR (KBr disc) νmax: 2918, 28
48, 2104, 1605, 1510, 1448, 12
27,985,887,879,835cm ^-1

Example 14 4- (trans-4- (trans-4-n-pentyl-4-silacyclohexyl) -4-cyclohexyl)
-1-Fluorobenzene This compound has the following properties, and is a hydrocarbon compound having a similar structure: 4- (4- (trans-4-n-pentylcyclohexyl) -trans-4-cyclohexyl) -1-fluoro With benzene, the smectic phase (66-76 ° C.) that had appeared disappeared. CN transition temperature: 38 ° C, NI transition temperature: 92 ° C IR (KBr disc) νmax: 2918, 28
48, 2100, 1603, 1510, 1227, 98
7,885,825cm ^-1

Example 15 4- (trans-4- (trans-4-n-propyl-4-silacyclohexyl) -4-cyclohexyl)
-1,2-difluorobenzene CN transition temperature: 20 ° C., NI transition temperature: 79 ° C. IR (liquid film) νmax: 2924, 2854, 210
0, 1606, 1518, 1279, 987, 887,
843,818cm ^-1

Example 16 4- (trans-4- (trans-4-n-pentyl-4-silacyclohexyl) -4-cyclohexyl)
-1,2-difluorobenzene CN transition temperature: 14 ° C., NI transition temperature: 72 ° C. IR (liquid film) νmax: 2922, 2852, 210
0,1606,1518,1279,1207,98
7,816,768 cm ^-1

Example 17 4- (trans-4- (trans-4-n-propyl-4-silacyclohexyl) -4-cyclohexyl)
-1-trifluoromethoxybenzene This compound has the following properties and is a hydrocarbon compound having a similar structure, that is, 4- (4- (trans-4-n-propylcyclohexyl) -trans-4-cyclohexyl) -1-. With trifluoromethoxybenzene, the smectic phase (38-69 ° C.) that had appeared disappeared. CN transition temperature: 42 ° C, NI transition temperature: 106 ° C IR (KBr disc) νmax: 2924,28
54, 2108, 1510, 1263, 1225, 11
90,1161,985,845cm ^-1

Example 18 4- (trans-4- (trans-4-n-pentyl-4-silacyclohexyl) -4-cyclohexyl)
-1-trifluoromethoxybenzene This compound has the following properties, and is a hydrocarbon compound having a similar structure, that is, 4- (4- (trans-4-n-pentylcyclohexyl) -trans-4-cyclohexyl) -1-. With trifluoromethoxybenzene, the smectic phase (52-73 ° C) that had appeared disappeared. CN transition temperature: 38 ° C, NI transition temperature: 80 ° C IR (KBr disc) νmax: 2924,28
54, 2102, 1510, 1267, 1223, 11
94, 1159, 987, 818 cm ^-1

Example 19 4- (trans-4- (trans-4-n-pentyl-4-silacyclohexyl) -4-cyclohexyl)
-1-Chloro-2-fluorobenzene CN transition temperature: 22.8 ° C., NI transition temperature: 10
6.3 ° C IR (liquid film) νmax: 2922, 2852, 210
0, 1485, 987, 887, 833, 816, cm
^-1

Example 20 4- (trans-4- (trans-4- (3-pentenyl) -4-silacyclohexyl) -4-cyclohexyl) -1-fluorobenzene

Example 21 4- (trans-4- (trans-4-methoxypropyl-4-silacyclohexyl) -4-cyclohexyl) -1-chloro-2-fluorobenzene

Example 22 4- (trans-4- (trans-4-n-propyl-4-silacyclohexyl) -4-cyclohexyl)
-2,3-Difluoro-1-ethoxybenzene CN transition temperature: 59.3 ° C., SN transition temperature: 56.
7 ° C., NI transition temperature: 142.5 ° C. IR (KBr disc) νmax: 2926, 28
54, 2092, 1514, 1475, 1115, 10
78,885,843,816cm ^-1

Example 23 4- (trans-4- (trans-4-n- (3-
Methoxypropyl) -4-silacyclohexyl) cyclohexyl) -1,2-difluorobenzene CN transition temperature: 37 ° C., NI transition temperature: 69 ° C. IR (KBr disc) νmax: 2926, 28
54, 2121, 2096, 1606, 1518, 12
77,1207,1113,985,887,814c
m ^-1 IR (KBr disc) νmax: cm ^-1

Example 24 4- (trans-4- (trans-4- (4-pentenyl) -4-silacyclohexyl) -4-cyclohexyl) -1,2-difluorobenzene CN transition temperature: 5 ° C, NI transition temperature: 42 ° C IR (KBr disc) νmax: 2922,28
52, 2100, 1606, 1518, 1279, 11
17,887,818cm ^-1

Example 25 4- (trans-4- (trans-4- (3-methylbutyl) -4-silacyclohexyl) -4-cyclohexyl) -1,2-difluorobenzene CN transition temperature: 38 ° C, NI transition temperature: 36 ° C IR (KBr disc) νmax: 2922,28
52, 2100, 1608, 1518, 1279, 12
07, 987, 889, 816 cm ^-1

Example 26 0.5 g (21 mmol) of magnesium 4- (trans-4- (trans-4-n-propyl-4-silacyclohexyl) -4-silacyclohexyl) -1-trifluoromethylbenzene and THF50
4.4 g (20 mmol) of 4-n-propylsilacyclohexyl bromide was added dropwise to the mixture of ml to obtain a Grignard reagent. Subsequently, the solution was treated with 4- (4-chloro-4).
-Silacyclohexyl) -1-trifluoromethylbenzene 5.6 g (20 mmol) was added dropwise to a 50 ml THF solution to give 4- (4- (4-n-propylsilacyclohexyl) -4-silacyclohexyl) -1-trifluoromethyl. Benzene was obtained. This is a mixture of a trans-isomer and a cis-isomer with respect to the silacyclohexane ring.
g (85% yield).

The following compounds were obtained in the same manner as in Example 26.

Example 27 4- (trans-4- (trans-4- (3-pentenyl) -4-silacyclohexyl) -4-silacyclohexyl) -1-n-propylbenzene

Example 28 4- (trans-4- (trans-4-methoxypropyl-4-methyl-4-silacyclohexyl) -4-
(Silacyclohexyl) -1-trifluoromethoxy-2
-Fluorobenzene

Next, the compound of the present invention obtained in the above example was added to an existing liquid crystal composition to produce a liquid crystal composition of the present invention. Then, the operation threshold voltage and the transition temperature of the obtained liquid crystal composition were measured.

"Example of liquid crystal composition" 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 exhibits the following properties. CN transition temperature: 7 ° C NI transition temperature: 106 ° C Threshold voltage: 2.50V

This mixture A (85%) and Example 16 4-
(Trans-4- (trans-4-n-pentyl-
4-silacyclohexyl) -4-cyclohexyl)-
The mixture consisting of 15 mol% of 1,2-difluorobenzene exhibited the following properties: CN transition temperature: 2 ° C NI transition temperature: 101 ° C Threshold voltage: 2.23V

[0068]

The liquid crystal compound of the present invention in which Si is introduced as a ring constituent element has the following advantages as compared with a conventional liquid crystal compound having a CCP structure of a similar hydrocarbon ring. (1) The following low-temperature performance is improved due to having a nematic liquid crystal phase expanded to a low temperature. (2) The viscosity at low temperatures can be reduced, and the response speed at low temperatures can be improved. (3) Compatibility at low temperature is improved.

A liquid crystal compound in which X in formula (I) is not R or OR has the effect of further lowering the threshold voltage in addition to the above advantages.

On the other hand, when the present invention is used as a liquid crystal display element, in the twisted nematic display mode,
A smectic phase is not preferred as a liquid crystal form, and it is desired that each single compound constituting the liquid crystal phase does not have a smectic phase. Certain conventional CCP-structured liquid crystal compounds having a similar hydrocarbon ring have a smectic phase, but the liquid crystal compound of the present invention has an advantage that it disappears and shows only a nematic phase.

The liquid crystal compound of the present invention can be widely used as a base material constituting a main part of a liquid crystal phase, similarly to a conventional CCP structure liquid crystal compound having a similar hydrocarbon ring, depending on the selection of the substituent. Substituent X in the general formula [Formula 17]
However, since the liquid crystal compounds of R and OR have a dielectric anisotropy close to zero, dynamic scattering (DS) or deformation of the aligned phase (DAP)
Effect) is preferably used for a liquid crystal phase for display. Further, it is preferable that the compound other than X be used for producing a liquid crystal phase having a large positive dielectric anisotropy for use in a twisted nematic cell or a display element based on a cholesteric-nematic phase transition.

Continued on the front page (72) Inventor Takeshi Kaneo 28-1, Nishifukushima, Nishifukushima-mura, Nakakubijo-gun, Niigata Prefecture Inside the Synthetic Technology Research Laboratory, Shin-Etsu Chemical Co., Ltd. (72) Inventor Tatsushi Kaneko, Nishigata-ku, Niigata Prefecture (28) Inventor Ryuichi Saito (28) Nishifukushima, Nakakushiro-gun, Niigata Pref. Shin-Etsu Chemical Industry Co., Ltd. (72) ) Inventor Eiji Kurihara 3-2-1, Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Shin-Etsu Chemical Co., Ltd. Corporate Research Center (56) References JP-A-2-91080 (JP, A) JP-A-6-9653 (JP, A) JP-A-3-181490 (JP, A) JP-A-6-504784 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07F 7 / 08 C07F 7/12 C09K 19/40 CAPLUS (STN) REGISTRY (STN) WPIDS (STN)

Claims (5)

(57) [Claims] 1. A silacyclohexane compound represented by the following general formula (I). Embedded image In the formula, R is hydrogen, a linear alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 8 carbon atoms, and 2 carbon atoms.
Represents an alkoxyalkyl group having 7 to 7 carbon atoms or an alkenyl group having 2 to 8 carbon atoms. Embedded image And Transformer, with the at least one is 1 or 4 position of the silicon H, F, substituents Cl or CH _3-1-
A silacyclohexylene or trans-4-silacyclohexylene group, and the other represents a trans-1,4-cyclohexylene group. X is CN, F, Cl, CF ₃ , CF _{2
Cl, CHFCl, OCF 3, OCHF} 2, OCF 2 C
1, represents OCHFCl, R or OR group. Y is H or F
Represents Z represents H or F. 2. An organometallic reagent RM (M represents MgP (P represents halogen), ZnP or Li) and a silacyclohexane compound (W is H, F, Cl or CH ₃ group, Q is a halogen, an alkoxy group) formula by reaction with (2) embedded image (2) The method for producing a (trans-4-) silacyclohexane compound of the above. 3. An organometallic reagent (However, Represents 1 or 4-position of the silicon H, F, trans-1-sila-cyclohexylene or trans-4-sila-cyclohexylene group or a cyclohexylene group having a substituent of Cl or CH _3. M is MgP (P represents halogen),
Represents ZnP or Li. ) And a silacyclohexane compound (W is H, F, Cl or CH ₃ group, Q is halogen
And an alkoxy group. General formula by reaction with
(3) embedded image (3) The method for producing a (trans-4-) silacyclohexane compound of the above. 4. A liquid crystal composition comprising the silacyclohexane compound according to claim 1. 5. A liquid crystal display device comprising the liquid crystal composition according to claim 4.