JPH0770148A - Silacyclohexane compound, its production and liquid crystal composition containing the same - Google Patents

Abstract

PURPOSE:To obtain the subject new compound consisting of a silacyclohexane ring-bearing aromatic compound, having nematic liquid crystal phase extended to low temperature range, reduced in viscosity even at low temperatures, quick in response at low temperatures, thus useful for liquid crystal display elements etc. CONSTITUTION:A silacyclohexane compound of the formula (R is H, a 1-10C straight chain alkyl, a 3-8C branched alkyl, a 2-7C alkoxyalkyl or a 2-8C alkenyl; A-ring and B-ring are trans-1-silacyclohexylene, trans-4-silacycloxylene whose 1- or 4-site silicon bears a substituent, i.e., H, F, Cl, or CH3, one party thereof being trans-1,4-cyclohexylene; X is CN, F, Cl, CF3, CF2Cl, CHFCl, OCF3, OCHF2, OCF2Cl, OCHFCl, R or OR; Y and Z are each H, F) [e.g. 4-(trans-4-(trans-4-n-propylcyclohexyl)-4-silacyclohexyl)-1,2-difluoro benzene].

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.

Among the liquid crystal compounds that can be these constituent components, as one of the basic components that govern the electro-optical performance, conventionally,

[Chemical 8] (Japanese Patent Publication No. 63-13411),

[Chemical 9] (Japanese Patent Publication No. 63-32051),

[Chemical 10] (Japanese Patent Publication No. 63-44132),

[Chemical 11] (Japanese Patent Publication No. 63-46738),

[Chemical 12] (Japanese Patent Publication No. 2-29055),

[Chemical 13] (JP-A-4-54138),

[Chemical 14] (Tokutei Hira 4-506376),

[Chemical 15] (Tokuheihei 2-501131),

[Chemical 16] So-called cyclohexyl ring-cyclohexyl ring-phenyl ring structure (CCP structure) such as JP-A-2-233626.
Compounds with are known.

[0006]

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

From this point of view, the present invention is a liquid crystal material newly developed for the purpose of improving the characteristics of the liquid crystal material, and the above-mentioned conventional cyclohexyl ring-cyclohexyl ring-phenyl ring structure (CCP). An object of the present invention is to provide a liquid crystal compound having a silacyclohexane ring which is completely different from the liquid crystal compound having a structure).

[0008]

That is, the present invention provides the following general formula (I):

[Chemical 17] It 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 chain 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.

[Chemical 18] as well as

[Chemical 19] Is at least one of trans-1- whose silicon at the 1- or 4-position has a substituent of H, F, Cl or CH _3.
It is a silacyclohexylene or trans-4-silacyclohexylene group, and the other is 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 is MgP (P represents halogen), ZnP or Li), and a silacyclohexane compound.

[Chemical 20] (W represents an H, F, Cl or CH ₃ group, and Q represents a halogen or an alkoxy group.) The method for producing a silacyclohexane compound represented by the above general formula (I) is characterized in that .

The present invention also relates to an organometallic reagent.

[Chemical 21] (However,

[Chemical formula 22] Represents a trans-1-silacyclohexylene group, a trans-4-silacyclohexylene group or a cyclohexylene group in which silicon at the 1- or 4-position has a substituent of H, F, Cl or CH ₃ . ) And a silacyclohexane compound

[Chemical formula 23] (However, W and Q are the same as in [Chemical Formula 20].) The method for producing a silacyclohexane compound represented by the above general formula (I) is characterized in that

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

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

[Chemical formula 24]

[Chemical 25]

[Chemical formula 26]

[Chemical 27]

[Chemical 28]

[Chemical 29]

[Chemical 30]

In the formula, R is hydrogen, 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
A branched chain alkyl group having 3 to 8 carbon atoms, that is, isopropyl, sec-butyl, isobutyl, 1-methylbutyl,
2-methylbutyl, 3-methylbutyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1-
Ethyl pentyl, 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, 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 and 7-octenyl groups.

W, W ¹ and W ² are independent of each other,
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
It represents an HFCl, R or OR group. Y represents H or F. Z represents H or F.

[0016]

[Chemical 31] Specifically,

[Chemical 32]

[Chemical 33]

[Chemical 34]

[Chemical 35]

[Chemical 36]

[Chemical 37]

[Chemical 38]

[Chemical Formula 39]

[Chemical 40]

[Chemical 41]

[Chemical 42]

[Chemical 43]

[Chemical 44]

[Chemical formula 45]

[Chemical formula 46]

[Chemical 47]

[Chemical 48]

[Chemical 49]

[Chemical 50]

[Chemical 51]

[Chemical 52]

[Chemical 53]

[Chemical 54]

[Chemical 55]

[Chemical 56]

[Chemical 57]

[Chemical 58]

[Chemical 59]

[Chemical 60]

[Chemical formula 61]

[Chemical formula 62]

[Chemical formula 63]

[Chemical 64] Represents a group.

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

As for R, a linear 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.
Of the branched alkyl groups of ~ 7, 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 group, or vinyl among alkenyl groups, 1-propenyl, 3-butenyl, 1-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 5-hexenyl, 6- Heptenyl and 7-octenyl groups are practically desirable.

Regarding W, W ¹ and W ² , H, F and CH ₃
The group is practically desirable.

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

Next, a method 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 organometallic coupling reactions.

[Chemical 65]

[Chemical formula 66]

[Chemical formula 67] 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 kind of the substituent X. The metal halide formed is then reacted with a silacyclohexane compound in which silicon is replaced by W or W ² , 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 silacyclohexane compound of the present invention can be mixed with a known compound to obtain a liquid crystal composition.
The compound specifically mixed for producing the liquid crystal composition can be selected from the known compounds shown below.

[Chemical 68]

[Chemical 69]

In the formulas [68] and [69], (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 = C
H -, - 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 linear alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 8 carbon atoms, or 2 carbon atoms.
A C7 to C7 alkoxyalkyl group or a C2 to C8 alkenyl group.

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

In the above, l (ell) and 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 ratio of the silacyclohexane compound of the present invention in the liquid crystal composition may be 1 to 2 or more.
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.

As a driving method of the liquid crystal display device, 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.

[0033]

EXAMPLES The present invention will be described 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) magnesium and THF 50
4.1 g (20 mmol) of 4-n-propylcyclohexyl bromide was added dropwise to the mixture of ml to obtain a Grignard reagent. Subsequently, this solution was added to 4- (4-chloro-4-
Silacyclohexyl) -1,2-difluorobenzene was added dropwise to a solution of 4.9 g (20 mmol) of THF in 50 ml of 4- (4- (trans-4-n-propylcyclohexyl) -4-silacyclohexyl) -1,2-difluoro. I got benzene. This is a mixture of trans isomer and cis isomer with respect to the silacyclohexane ring, which was separated by chromatography to give 6.1 g of trans isomer.
(Yield 91%) was obtained. C-N transition temperature: 28 ° C, NI transition temperature: 79 ° C IR (liquid film) νmax: 2914, 2845, 209
8, 1608, 1518, 1286, 1213, 81
2,808,769 cm ^-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 C—N transition temperature: 56 ° C., N—I 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 C—N transition temperature: 40 ° C., N—I 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 appears in a hydrocarbon compound of similar structure, 4- (4- (trans-4-n-pentylcyclohexyl) -trans-4-cyclohexyl) -1-fluorobenzene. The smectic phase (66-76 ° C) disappeared. C-N 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 is a smectic phase that appears in a hydrocarbon compound of similar structure, 4- (4- (trans-4-n-propylcyclohexyl) -trans-4-cyclohexyl) -1-chlorobenzene. (70-78 ° C) disappeared. C-N 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 C—N transition temperature: 45 ° C., N—I 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 4- (trans-4- (trans-4-n-propylcyclohexyl) -4-silacyclohexyl) benzonitrile 0.5 g (21 mmol) magnesium and 50 THF.
4.1 g (20 mmol) of 4-n-propylcyclohexyl bromide was added dropwise to the mixture of ml to obtain a Grignard reagent. Next, 3.0 g of zinc chloride (22 mm
ol) and 10 ml of THF to obtain a organozinc reagent. Subsequently, this reagent was added to 4- (4-chloro-4-silacyclohexyl) benzonitrile (4.7 g, 20 mm).
ol) in a THF 50 ml solution and 4- (4- (t
rans-4-n-propylcyclohexyl) -4-silacyclohexyl) benzonitrile 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 5.4 g of trans isomer (yield 83%).

Example 12 4- (trans-4- (trans-4-n-pentyl-4-silacyclohexyl) -4-cyclohexyl)
-1-Difluoromethoxy-2,6-difluorobenzene magnesium 0.5 g (21 mmol) and THF 50
2.5 g of n-pentyl bromide (20 ml) in a mixture of ml.
(mmol) was added dropwise to obtain a Grignard reagent. Subsequently, this solution was treated with 4- (4- (4-chloro-4-silacyclohexyl) -trans-4cyclohexyl) -1-difluoromethoxy-2,6-difluorobenzene (7.9 g).
(20 mmol) was added dropwise to a solution of 50 ml of THF and 4-
(4- (trans-4-n-pentyl-4-silacyclohexyl) -4-cyclohexyl) -1-difluoromethoxy-2,6-difluorobenzene was obtained. This was a mixture of trans isomer and cis isomer with respect to the silacyclohexane ring, and 7.2 g (yield 90%) of trans isomer was obtained by chromatography. C-N 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 C—N transition temperature: 65 ° C., N—I transition temperature: 109 ° C. IR (KBr disc) νmax: 2918, 28
48, 2104, 1605, 1510, 1448, 12
27,985,887,879,835 cm ^-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 of similar structure, 4- (4- (trans-4-n-pentylcyclohexyl) -trans-4-cyclohexyl) -1-fluoro. The smectic phase (66 to 76 ° C.) that appeared in benzene disappeared. C-N transition temperature: 38 ° C, N-I transition temperature: 92 ° C IR (KBr disc) νmax: 2918, 28
48, 2100, 1603, 1510, 1227, 98
7,885,825 cm ^-1

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

Example 16 4- (trans-4- (trans-4-n-pentyl-4-silacyclohexyl) -4-cyclohexyl)
-1,2-Difluorobenzene C-N transition temperature: 14 ° C, N-I transition temperature: 72 ° C IR (liquid film) νmax: 2922, 2852, 210
0, 1606, 1518, 1279, 1207, 98
7,816,768cm ^-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 of similar structure: 4- (4- (trans-4-n-propylcyclohexyl) -trans-4-cyclohexyl) -1- The smectic phase (38 to 69 ° C.) that appeared in trifluoromethoxybenzene disappeared. C-N 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 of similar structure: 4- (4- (trans-4-n-pentylcyclohexyl) -trans-4-cyclohexyl) -1- The smectic phase (52 to 73 ° C.) that appeared in trifluoromethoxybenzene disappeared. C-N transition temperature: 38 ° C, NI transition temperature: 80 ° C IR (KBr disc) νmax: 2924, 28
54, 2102, 1510, 1267, 1223, 11
94,1159,987,818cm ^-1

Example 19 4- (trans-4- (trans-4-n-pentyl-4-silacyclohexyl) -4-cyclohexyl)
-1-Chloro-2-fluorobenzene C-N transition temperature: 22.8 ° C, N-I 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 C-N transition temperature: 59.3 ° C, S-N 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 C-N transition temperature: 37 ° C, N-I 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 C-N transition temperature: 5 ℃, NI transition temperature: 42 ℃ IR (KBr disc) νmax: 2922, 28
52, 2100, 1606, 1518, 1279, 11
17,887,818 cm ^-1

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

Example 26 4- (trans-4- (trans-4-n-propyl-4-silacyclohexyl) -4-silacyclohexyl) -1-trifluoromethylbenzene magnesium 0.5 g (21 mmol) 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, this solution was added to 4- (4-chloro-4).
4- (4- (4-n-propylsilacyclohexyl) -4-silacyclohexyl) -1-trifluoromethyl by adding dropwise to a solution of 5.6 g (20 mmol) of -silacyclohexyl) -1-trifluoromethylbenzene in 50 ml of THF. I got benzene. This is a mixture of a trans isomer and a cis isomer with respect to the silacyclohexane ring, which is separated by chromatography to give a trans-trans isomer 6.5.
g (yield 85%) was obtained.

The following compounds were obtained 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 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 transition temperature 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 NI transition temperature: 106 ° C Threshold voltage: 2.50V

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

[0068]

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

The liquid crystal compound in which X in the general 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 type display mode,
A smectic phase is not preferable as a liquid crystal form, and it is desired that each simple substance compound that constitutes the liquid crystal phase does not have a smectic phase. Some of the conventional liquid crystal compounds having a CCP structure having a similar hydrocarbon ring have a smectic phase, but the liquid crystal compound of the present invention has the advantage that it disappears and exhibits only a nematic phase.

The liquid crystal compound of the present invention can be widely used as a base material constituting the main part of the liquid crystal phase, as in the conventional CCP structure liquid crystal compound having a similar hydrocarbon ring, depending on the selection of the substituent. Substituent X in the general formula
However, since the liquid crystal compound of R and OR has a dielectric anisotropy close to zero, dynamic scattering (DS) or deformation of the aligned phase (DAP)
It is preferably used for a liquid crystal phase for display based on (effect). Further, compounds in which X is other than that are preferably used for producing 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 Niigata Prefecture Nakakubiki-gun Kubiki-mura Large number 28 Nishifukushima 1 Shinsei Chemical Industry Co., Ltd. Synthetic Technology Research Institute (72) Inventor Tatsushi Kaneko Nikgata Pref. 1 of 28, Nishi-Fukushima, Kunagi-gun, Shinetsu Chemical Industry Co., Ltd. (72) Inventor, Ryuichi Saito 1 of 28, Nishi-Fukushima, Kubiki-mura, Nakakubiki-gun, Niigata 1 Shin-Etsu Chemical Co., Ltd. (72) Inventor Hideshi Kurihara 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Shin-Etsu Chemical Co., Ltd. Inside the corporate tracer center

Claims (5)

[Claims] 1. A silacyclohexane compound represented by the following general formula (I): [Chemical 1] 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 from 7 to 7 or an alkenyl group having from 2 to 8 carbon atoms. [Chemical 2] And Is at least one of trans-1- whose silicon at the 1- or 4-position has a substituent of H, F, Cl or CH _3.
It is 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 C
1, CHFCl, OCF ₃ , OCHF ₂ , OCF ₂ Cl,
It represents an 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. The method for producing a silacyclohexane compound according to claim 1, wherein the reaction is carried out with (W represents an H, F, Cl or CH ₃ group, and Q represents a halogen or an alkoxy group). 3. An organometallic reagent (However, Represents a trans-1-silacyclohexylene group, a trans-4-silacyclohexylene group or a cyclohexylene group in which silicon at the 1- or 4-position has a substituent of H, F, Cl or CH ₃ . ) And a silacyclohexane compound (However, W and Q are the same as in [Chemical Formula 4].) The method for producing a silacyclohexane compound according to claim 1, wherein 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.