JPH11140088A - Alpha, omega-disubstituted permethyloligosilane compound and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject new compound useful for a synthetic raw material of a liquid crystal compound exhibiting a liquid crystal state in the vicinity of a room temperature by a reaction of a dihalooligosilane compound or a dialkoxyoligosilane compound with dimethylphenyllithium. SOLUTION: This α,ω-disubstituted permethyloligosilane compound is a compound of formula I [R is a 2-6C alkyl or phenyl; (m) is 9-12 when R is an alkyl group, and 7-12 when R is phenyl group], (e.g.; 1,8-diphenylpermethyloctasilane), and useful as a synthetic intermediate for a liquid crystal compound exhibiting the liquid crystal state in the vicinity of a room temperature. The compound is obtained by reacting a dihalooligosilane compound or a dialkoxyoligosilane compound with dimethylphenylsilyllithium expressed by formula II, or reacting a reaction product of an α,ω-diphenylpermethyloligosilane compound with trifluoromethanesulfonic acid, with an alkylmetal or a halogenated alkylmagnesium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel liquid crystal compound, an .alpha.,. Omega.-disubstituted permethyl oligosilane compound as a synthetic intermediate thereof, and a method for producing the same.

[0002]

2. Description of the Related Art Polysilane compounds are known to exhibit unique optical and electronic properties due to the conjugation of silicon sigma electrons along the main chain, and are expected to be functional new materials such as photoconductive materials. ing. The oligosilane compound is a basic unit constituting the polysilane compound. The oligosilane compound having 8 or more silicon atoms has unique physical properties like polysilane, and has anisotropy in the direction of the oligosilane chain. Among the oligosilane compounds, silicon number 9 to
Twelve permethyl oligosilanes were recently reported to be liquid crystal compounds. The oligosilane compound having liquid crystallinity can control the molecular arrangement and can orient the oligosilane chain, so that the above-mentioned optical and electrical properties can be increased. Therefore, a liquid crystalline oligosilane compound has high physical properties as a functional material such as a photoconductive material and can be used as a liquid crystal material. However, in the case of permethyl oligosilane having 9 to 12 silicon atoms, The liquid crystal transition temperature is much higher than room temperature,
Heating was necessary to handle in a liquid crystal state. Therefore, development of a novel liquid crystal oligosilane compound exhibiting a liquid crystal state at room temperature has been expected.

[0003]

Accordingly, an object of the present invention is to provide a liquid crystal compound which exhibits a liquid crystal state at around room temperature, a novel oligosilane compound as a synthetic intermediate thereof, and a method for producing the same.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above problems, and as a result, have found that α, ω-
The present inventors have found that a dialkyl permethyl oligosilane compound has a lower transition temperature to liquid crystal than permethyl oligosilane and has a wider temperature range in a liquid crystal state, and based on this finding, the present invention has been accomplished. That is, the present invention provides (1) an α, ω-disubstituted permethyl oligosilane compound represented by the following formula (I):

Formula (I)

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(Wherein, R represents an alkyl group having 2 to 6 carbon atoms or a phenyl group, and m represents 9 to 1 when R is an alkyl group)
In the case of 2, a phenyl group, it represents an integer of 7 to 12. ) (2)
(1) The α, ω-dialkylpermethyl oligosilane liquid crystal compound in which R is an alkyl group in the above formula (I) described in the above item (1), (3) R is a phenyl group in the above formula (I), and m is 9 to 12 Wherein the α, ω-diphenylpermethyl oligosilane compound is reacted with trifluoromethanesulfonic acid to react with an alkyl metal or an alkyl magnesium halide. a method for producing a ω-dialkyl permethyl oligosilane liquid crystal compound, and (4) reacting a dihalo oligosilane compound or a dialkoxy oligosilane compound with dimethylphenylsilyllithium to obtain α, ω in which R is a phenyl group in the above formula (I). (3) A diphenyl permethyl oligosilane compound is obtained. It is intended to provide a method for producing the described α, ω-dialkylpermethyl oligosilane liquid crystal compound.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The α, ω-disubstituted permethyl oligosilane compound represented by the above formula (I) of the present invention can be represented by the following formulas (II) and (III).

Formula (II)

Embedded image (In the formula, n represents an integer of 2 to 6, and m ′ represents an integer of 9 to 12.)

Formula (III)

Embedded image (In the formula, m ″ represents an integer of 7 to 12.)

The compound represented by the above formula (II) of the present invention is a liquid crystal compound. 9 to 9 silicon atoms without alkyl group
Even though the permethyloligosilane of 12 has the lowest transition temperature, it does not crystallize unless the temperature is raised to about 60 ° C., but the compound represented by the above formula (II) of the present invention has an alkyl group having 2 to 6 carbon atoms at both ends. By having the compound, the crystal-liquid crystal transition temperature is low, and the liquid crystal is formed at or near room temperature.
Further, it has a feature that a temperature range in a liquid crystal state is wide and it is easy to use as a liquid crystal material. From the physical properties of these liquid crystal materials, particularly, n is 3 to 5 and m ′ is 10
~ 12 compounds are preferred.

The compound of the above formula (II) is a diphenylpermethyl oligosilane compound represented by the formula (III) (provided that the silicon number is 9 to 1) as shown in the following scheme 1.
2) can be produced by substituting a trifluoromethanesulfone group with a trifluoromethanesulfone group and reacting it with an alkyl metal having 2 to 6 carbon atoms.

[0012]

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(Wherein n and m ′ have the same meanings as in formula (II), and M represents a metal atom (preferably Li).) The solvent of the diphenyl oligosilane compound represented by formula (III) includes carbon A hydrogen-based solvent can be used, for example, hexane, pentane, cyclohexane, benzene, toluene, xylene, and the like. Preferably, toluene is used. The trifluoromethanesulfonic acid to be reacted therewith is used as it is without diluting with a solvent, and is usually not used in a large excess, and is preferably 2 to 3 mol, more preferably 2 to 3 mol per mol of the diphenyl oligosilane compound of the formula (III). Used in molar proportions. Usually, trifluoromethanesulfonic acid at room temperature is dropped into the above diphenyl oligosilane solution in 1 to 5 minutes, and the mixture is stirred and reacted for 1 to 24 hours. Usually, the diphenyl oligosilane solution is used after being cooled to −20 to 20 ° C., and stirring is performed at the temperature at the time of dropping to room temperature. When reacting the compound in this reaction solution with an alkyl metal, a hydrocarbon-based solvent can be used as a solvent for the alkyl metal, for example, hexane, pentane, cyclohexane, benzene, toluene, xylene and the like, and preferably hexane Is used. Usually, the alkyl metal reagent is added dropwise to the reaction solution at room temperature in 10 to 30 minutes.
Stir for ~ 24 hours. In the present invention, an alkyl magnesium halide [C
_n H _{2n + 1} MgX (n has the same meaning as an alkyl metal, and X represents a halogen atom (preferably chlorine, bromine or iodine)]. When an alkyl magnesium halide (Grignard reagent) is used, an ether solvent can be used as the solvent, for example, dimethyl ether, 1,2-dimethoxymethane (DME) and the like, and preferably diethyl ether is used. However, tetrahydrofuran (THF) is not preferred,
In the case of the above-described reaction using an alkyl metal, tetrahydrofuran can also be used since the reaction rate is higher than the reaction with a solvent. The above-mentioned alkyl magnesium halide solution is added to the above-mentioned reaction solution in the same manner as the alkyl metal reagent, and the mixture is usually heated to 60 to 80 ° C and stirred for 6 to 10 hours. The alkyl metal or alkyl magnesium halide is used in an amount of 2 per mole of the diphenyl oligosilane compound.
It is preferably used in a proportion of ３3 mol, and it is preferable to use it in a slightly excessive amount over trifluoromethanesulfonic acid.

Next, among the compounds represented by the formula (III) of the present invention used for the production of the compound of the above formula (II),
Those having m ″ of 7 or 8 can be obtained, for example, by reacting a dihalo-oligosilane compound or a dialkoxy-oligosilane compound (dichloro-oligosilane compound in Scheme 2) with dimethylphenylsilyllithium, as shown in Scheme 2 below. Examples of the dihalo oligosilane compound include dichloro oligo silane compounds and dibromo oligo silane compounds. Examples of the dialkoxy oligo silane compound include oligo silanes having a primary lower alkoxy group such as methoxy, ethoxy, and n-propoxy. Compounds can be mentioned.

[0015]

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(In the formula, p is 5 or 6, and q is an integer of 7 or 8.) As a solvent for the dichlorooligosilane compound, the same hydrocarbon solvent as described above can be used, and hexane is preferable. Use As the solvent for dimethylphenylsilyllithium, an ether solvent can be used, for example, diethyl ether, tetrahydrofuran (THF),
Examples thereof include 1,2-dimethoxyethane (DME), and THF is preferably used. Dimethylphenylsilyllithium is not usually used in a large excess, but is preferably used in a proportion of preferably 2 to 3 mol, more preferably 2 mol, per 1 mol of the dichlorooligosilane compound. A dimethylphenylsilyllithium reagent is added dropwise to the above dichlorooligosilane solution, and the mixture is reacted usually with stirring for 1 to 10 minutes. The dichlorooligosilane solution is usually used after cooling to -20 to 20 ° C,
The dropping and stirring may be performed at room temperature, but it is preferable that the reaction liquid does not become higher than room temperature due to heat of reaction. The dropping time depends on the amount of the dimethylphenylsilyllithium reagent dropped,
Usually, for 10 to 50 minutes.

Further, in the α, ω-diphenylpermethyl oligosilane compound represented by the formula (III), m ″ is 9-12.
Is obtained by substituting the phenyl group of the compound having m ″ of 7 or 8 obtained by the above-mentioned production method with a trifluoromethanesulfone group, and then reacting with dimethylphenylsilyllithium in the same manner as described above. The substitution with a group is performed once or twice by reacting with trifluoromethanesulfonic acid in the same manner as in the reaction of the diphenyloligosilane compound with trifluoromethanesulfonic acid described in the method for producing the compound of formula (II). Thereby, a diphenyl oligosilane compound having m ″ of 9 to 12 in the formula (III) can be obtained.

[0018]

The novel α, ω-dialkylpermethyl oligosilane liquid crystal compound of the present invention wherein R is an alkyl group in the above formula (I) is a liquid crystal compound showing a smectic B phase, and the oligosilane chain is formed by rubbing or the like. Since the orientation can be performed, unique optical and electronic properties in the oligosilane chain direction can be remarkably expressed, and the optical and electronic properties can be increased. Therefore, the α, ω-dialkylpermethyl oligosilane compound of the present invention has an effect of exhibiting excellent physical properties as a functional material such as a photoconductive material. It is also useful as a liquid crystal material such as a display or a recording material, and has an excellent property that it has a low crystal-liquid crystal transition temperature and is in a liquid crystal state in a wide temperature range. The novel α, ω-diphenylpermethyl oligosilane compound of the present invention wherein R in the formula (I) is a phenyl group is useful for producing the α, ω-dialkyl permethyl oligosilane liquid crystal compound.

[0019]

Next, the present invention will be described in more detail with reference to examples. Example 1 (Synthesis of 1,8-diphenylpermethyloctasilane) 1,8-diphenylpermethyloctasilane was synthesized according to the following scheme.

[0020]

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Under a nitrogen atmosphere, 69.8 g (166 mmol) of 1,6-dichloropermethylhexasilane (1) /
200 ml of hexane solution was cooled to 0 ° C.
45.1 g (166 mmol) of 2-diphenyl-1,1,2,2-tetramethyldisilane and 3.70 g of lithium
(533 mmol) Dimethylphenylsilyllithium (2) 331 mmol / 100 ml of THF
The solution was added dropwise over 19 minutes and further stirred at 0 ° C. for 1 minute. The reaction mixture was hydrolyzed, and the organic layer was washed with saturated saline and dried over anhydrous sodium sulfate. After concentrating the organic layer, the obtained white solid was washed with 400 ml of ethanol / methanol (1: 1), and 85.5 g of 1,8-diphenylpermethyloctasilane (3) (138 m
mol, yield 83%). Colorless crystal; melting point: 104.5 to 105 ° C .; ¹ H NMR (CDCl ₃ , δ) 0.05 (s, 12)
H), 0.10 (s, 12H), 0.11 (s, 12H)
H), 0.36 (s, 12H), 7.24-7.34.
(M, 6H), 7.37-7.47 (m, 4H); ¹³ C NMR (CDCl ₃ , δ) -5.31, -4.
42, -4.16, -2.94, 127.7, 128.
3,133.7,139.9

Example 2 (Synthesis of 1,10-diphenylpermethyldecasilane) 1,10-diphenylpermethyldecasilane was synthesized according to the following scheme.

[0023]

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Under a nitrogen atmosphere, 58.5 g (94.4 mmol) of 1,8-diphenylpermethyloctasilane (3)
l) / Toluene (200 ml) was cooled to 20 ° C., and trifluoromethanesulfonic acid (28.3 g, 189 mmol) was added.
After l) was added, the mixture was stirred at room temperature for 16 hours. The reaction mixture was cooled to 20 ° C. and 1,2-diphenyl-1,1,1
25.5 g of 2,2-tetramethyldisilane (94.1 m
mol) and 1.97 g (284 mmol) of lithium and dimethylphenylsilyllithium (2) 188.
A 100 ml mmol / THF solution was added dropwise over 20 minutes, and the mixture was further stirred at 20 ° C. for 5 minutes. The reaction mixture was hydrolyzed, and the organic layer was washed with saturated saline and dried over anhydrous sodium sulfate. After concentrating the organic layer, the obtained white solid was washed with 200 ml of ethanol to give 1,10
-Diphenylpermethyldecasilane (4) 60.7 g
(82.5 mmol, yield 88%) was obtained. Colorless crystals; melting point: 122 to 125 ° C .; ¹ H NMR (CDCl ₃ , δ) 0.08 (s, 12
H), 0.12 (s, 12H), 0.14 (s, 12H)
H), 0.16 (s, 12H), 0.38 (s, 12
H), 7.27-7.35 (m, 6H), 7.39-
7.47 (m, 4H); ¹³ C NMR (CDCl ₃ , δ) -5.31, -4.
41, -4.11, -4.05, -2.95, 127.
7, 128.3, 133.7, 139.9

Example 3 (Synthesis of 1,10-diethylpermethyldecasilane) 1,10-diethylpermethyldecasilane was synthesized according to the following scheme.

[0026]

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At room temperature under a nitrogen atmosphere, 3.68 g (5.00) of 1,10-diphenylpermethyldecasilane (4)
(mmol) / toluene (40 ml), 1.62 g (10.8 mmol) of trifluoromethanesulfonic acid was added, and the mixture was stirred for 1 hour. 5 ml of an ethyl magnesium bromide / ether solution (3 mol / l) was added to the reaction mixture.
Was added dropwise in 5 minutes, and the mixture was heated and stirred at 70 ° C. for 18 hours.
The reaction mixture was hydrolyzed, and the organic layer was washed with saturated saline and dried over anhydrous sodium sulfate. After concentrating the organic layer, the obtained white solid was distilled under reduced pressure (bp 180 to
190 ° C./0.1 mmHg), and 2.54 g of 1,10-diethylpermethyldecasilane (5) (3.97 mm
ol, yield 79%). Colorless waxy material; liquid crystal (S _B ^{phase) 30~102 ℃; 1 H NMR (} CDCl 3, δ) 0.05 (s, 12
H), 0.12 (s, 12H), 0.16 (s, 12H)
H), 0.18 (s, 12H), 0.19 (s, 12H)
H), 0.64 (t, J = 7.4 Hz, 4H), 0.8
9 (t, J = 7.4 Hz, 6H); ¹³ C NMR (CDCl ₃ , δ) −5.16, −4.
20, -3.96 (x2), -3.18, 14.5, 1
8.7

Example 4 (Synthesis of 1,10-dibutylpermethyloctasilane) 1,10-dibutylpermethyldecasilane was synthesized according to the following scheme.

[0029]

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At room temperature under a nitrogen atmosphere, 2.75 g (3.74) of 1,10-diphenylpermethyldecasilane (4)
(mmol) / toluene (40 ml), trifluoromethanesulfonic acid (1.15 g, 7.67 mmol) was added, and the mixture was stirred for 1 hour. To this reaction mixture, 5 ml of a butyllithium / hexane solution (1.69 mol / l) was added dropwise over 5 minutes, and the mixture was further stirred for 18 hours. The reaction mixture was hydrolyzed, and the organic layer was washed with saturated saline and dried over anhydrous sodium sulfate. After concentrating the organic layer, the obtained white solid was distilled under reduced pressure (bp 195 to 205 ° C /
0.1 mmHg) to obtain 1.81 g (2.60 mmol, 70% yield) of 1,10-dibutylpermethyldecasilane (6). Colorless waxy material; liquid crystal (S _B ^{phase) 23~69 ℃; 1 H NMR (} CDCl 3, δ) 0.05 (s, 12
H), 0.13 (s, 12H), 0.17 (s, 12
H), 0.190 (s, 12H), 0.194 (s, 1
2H), 0.60 (t, J = 8.0 Hz, 4H), 0.
87 (t, J = 6.8 Hz, 6H), 1,39-1,7
8 (m, 8H); ¹³ C NMR (CDCl ₃ , δ) -5.17, -4.
21, -3.97 (x2), -3.16, 13.6,1
5.5, 26.7, 26.8

Test Example The transition temperatures of the crystal-liquid crystal and the liquid crystal-liquid of the α, ω-dialkylpermethyl oligosilane compound and 1,12-dihexyl permethyl dodecasilane synthesized in Examples 3 and 4 were measured. For comparison, the same measurement was performed for permethyl oligosilane having 9 to 12 silicon atoms having no alkyl group at both ends. The transition was a phase transition when the temperature was raised, and all the liquid crystals were smectic B phases. The results are shown in Table 1.

[0032]

[Table 1]

As is clear from Table 1, α, ω of the present invention
The dialkyl permethyl oligosilane compound has a lower crystal-liquid crystal and liquid crystal-liquid transition temperature than the permethyl oligosilane of Comparative Example in which the number of silicon is the same, and particularly, the crystal-liquid crystal transition temperature is greatly reduced. This indicates that the liquid crystal is formed at or near room temperature.
Further, the difference between the two transition temperatures is as large as 14 to 40 ° C., and it can be seen that the liquid crystal state is exhibited in a wide temperature range.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshikazu Tanabe 1-1-1, Higashi, Tsukuba, Ibaraki Pref., National Institute of Advanced Industrial Science and Technology (72) Inventor Hideki Sakurai 2641 Yamazaki, Noda City, Chiba Prefecture, Tokyo University of Science Faculty of Science and Technology

Claims (4)

[Claims] 1. An α, ω-disubstituted permethyl oligosilane compound represented by the following formula (I). Formula (I) (In the formula, R represents an alkyl group having 2 to 6 carbon atoms or a phenyl group, and m represents an integer of 9 to 12 when R is an alkyl group and 7 to 12 when R is a phenyl group.) 2. The method of claim 1, wherein R is
Is an alkyl group, α, ω-dialkyl permethyl oligosilane liquid crystal compound. 3. In the above formula (I), R is a phenyl group,
And reacting an oligosilane compound obtained by reacting an α, ω-diphenylpermethyl oligosilane compound having m of 9 to 12 with trifluoromethanesulfonic acid with an alkyl metal or an alkyl magnesium halide. The method for producing a liquid crystal compound of α, ω-dialkyl permethyl oligosilane according to claim 2. 4. A dihalo-oligosilane compound or a dialkoxy-oligosilane compound and dimethylphenylsilyllithium are reacted to obtain an α, ω-diphenylpermethyloligosilane compound in which R in the above formula (I) is a phenyl group. The method for producing an α, ω-dialkylpermethyl oligosilane liquid crystal compound according to claim 3.