JP2000128888A - Alfa,omega-diphenylpermethyloligosilane compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new compound useful as a synthetic intermediate for an α,ω-dialkyl-substituted permethyloligosilane liquid crystal compound having the low transition temperature to a liquid crystal, and a wide temperature range of the liquid crystal state. SOLUTION: This new compound is the one of formula I (m is 7-12), e.g. 1,8-diphenylpermethyloctasilane. The compound of formula I in which M is 7 or 8 is obtained by dropping a solution of dimethylphenylsilyllithium of formula III in a solvent (preferably tetrahydrofuran)into a solution of a dichlorooligosilane compound of formula II (p is 5 or 6) in a solvent (preferably hexane), normally stirring the obtained solution for 1-10 min to react the compounds. The compound of formula III in an amount of 2 mol is preferably used based on 1 mol compound of formula II. The solution of the compound of formula II is ordinary used by cooling the solution to 4-20 to 20 deg.C, and the temperature of the reaction liquid is preferably regulated so as not to over the room temperature. The dropping time is normally 10-50 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel .alpha.,. Omega.-diphenylpermethyl oligosilane compound used as an intermediate for synthesizing a novel liquid crystal compound.

[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 novel oligosilane compound used as a synthetic intermediate of a liquid crystal compound which exhibits a liquid crystal state at around room temperature.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above-mentioned problems, and as a result, among permethyl oligosilanes having 9 to 12 silicon atoms, the alkyl group at the α, ω terminal has 2 carbon atoms. The α, ω-dialkyl permethyl oligosilane compound having a range of from 6 to 6 has a lower transition temperature to a liquid crystal and a wider temperature range in a liquid crystal state than conventional permethyl oligosilane, and has a problem in producing the oligosilane compound. Was found to be obtained via a specific novel synthetic intermediate, and the present invention was accomplished based on this finding. That is, the present invention provides an α, ω-diphenylpermethyl oligosilane compound represented by the following formula (I):

Formula (I)

Embedded image (Wherein m represents an integer of 7 to 12).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The α, ω-diphenylpermethyl oligosilane compound represented by the above formula (I) of the present invention is an intermediate for the synthesis of an α, ω-dialkyl-substituted permethyl oligosilane compound represented by the following formula (II). Used as body.

Formula (II)

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

The compound represented by the above formula (II) obtained by using the synthetic intermediate of the present invention is a liquid crystal compound. In a conventional permethyl oligosilane having 9 to 12 silicon atoms,
Even if the transition temperature is the lowest, the liquid crystal will not be formed unless the temperature is raised to about 60 ° C., but the compound represented by the above formula (II) produced using the compound represented by the formula (I) of the present invention has both ends. By having an alkyl group having 2 to 6 carbon atoms, 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, in particular, n is 3 to
5, and a compound in which m ′ is 10 to 12 is preferable.

The compound of the above formula (II) is obtained by substituting the phenyl group of the diphenylpermethyloligosilane compound represented by the formula (I) of the present invention with a trifluoromethanesulfone group as shown in the following Scheme 1, It can be produced by reacting with 2 to 6 alkyl metals.

[0010]

Embedded image

(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 (I) includes 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 1 mol, per 1 mol of the diphenyl oligosilane compound of the formula (I). Used in a proportion of 2 mol. Usually, 1 to 5 trifluoromethanesulfonic acids at room temperature are added to the above diphenyl oligosilane solution.
The reaction is stirred for 1 to 24 hours. Normal,
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 solvent can be used as the solvent for the alkyl metal, for example, hexane, pentane, cyclohexane, benzene,
Examples thereof include toluene and xylene, and hexane is preferably used. Usually, an alkyl metal reagent is dropped into the reaction solution at room temperature in 10 to 30 minutes, and after dropping, the mixture is stirred at room temperature to about 80 ° C for 1 to 24 hours.

Further, halogen may be used instead of the above-mentioned alkyl metal.
Alkylmagnesium [C_n H _{2n + 1}MgX (n
Is synonymous with an alkyl metal, and X is a halogen atom (preferably
Or chlorine, bromine or iodine). )]
Can be. Alkyl magnesium halide (Grini
Solvent), use an ether-based solvent as the solvent.
For example, dimethyl ether, 1,2
-Dimethoxymethane (DME) and the like;
Uses diethyl ether. However, tetrahydrof
Run (THF) is not preferred, but the above alkyl metal
In the case of the reaction using
Because of its speed, tetrahydrofuran can also be used.
Reacting said alkylmagnesium halide solution with said reaction
The solution is added to the solution in the same manner as the alkyl metal reagent, and usually 60 to 8
Heat to 0 ° C. and stir for 6-10 hours. Alkyl metal or
Is the alkylmagnesium halide above diphenyl
2 to 3 moles per mole of oligosilane compound
Preferably, more than trifluoromethanesulfonic acid.
It is preferable to use a slight excess.

Next, among the compounds represented by the formula (I) of the present invention used for producing the compound of the formula (II), m
7 or 8 are 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-oligosilane compounds and dibromo-oligosilane compounds. Examples of the dialkoxy-oligosilane compound include oligosilanes having a primary lower alkoxy group such as methoxy, ethoxy, and n-propoxy. Compounds can be mentioned.

[0014]

Embedded image

(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 the heat of the 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 (I), m is 9 to 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 (I) can be obtained.

[0017]

The novel α, ω-diphenylpermethyl oligosilane compound of the present invention is useful for producing the α, ω-dialkyl permethyl oligosilane liquid crystal compound. Novel α, produced using the compound of the present invention.
The ω-dialkyl permethyl oligosilane liquid crystal compound is
A liquid crystal compound that exhibits a smectic B phase and can align oligosilane chains by rubbing or the like, so that unique optical and electronic properties in the oligosilane chain direction can be remarkably expressed, and optical and electronic properties can be increased. Can be. Therefore, the α, ω-dialkyl permethyl oligosilane compound 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.

[0018]

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.

[0019]

Embedded image

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, 1
2H), 0.10 (s, 12H), 0.11 (s, 12
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, 12
8.3, 133.7, 139.9

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

[0022]

Embedded image

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 crystal; melting point: 122 to 125 ° C .; ¹ H NMR (CDCl ₃ , δ) 0.08 (s, 1)
2H), 0.12 (s, 12H), 0.14 (s, 12
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, -2.95,12
7.7, 128.3, 133.7, 139.9

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

[0025]

Embedded image

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 over 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, 1
2H), 0.12 (s, 12H), 0.16 (s, 12
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.
5,18.7

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

[0028]

Embedded image

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, 1
2H), 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.
6,15.5,26.7,26.8

Test Examples With respect to the α, ω-dialkylpermethyl oligosilane compound synthesized in Reference Examples 1 and 2, and 1,12-dihexyl permethyl dodecasilane, the transition temperatures of crystal-liquid crystal and liquid crystal-liquid were measured, respectively. For comparison, the same measurement was performed for permethyl oligosilane having 9 to 12 silicon atoms having methyl groups 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.

[0031]

[Table 1]

As is clear from Table 1, the α, ω-dialkylpermethyl oligosilane compound obtained via the synthetic intermediate of the present invention has a crystal-liquid crystal, It can be seen that the transition temperature between the liquid crystal and the liquid is low, and the transition temperature between the crystal and the liquid crystal is greatly reduced. The difference between the two transition temperatures is 14 to 40.
° C has also increased, indicating that the liquid crystal state is exhibited over a wide temperature range.

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

Claims (1)

[Claims] 1. An α, ω-diphenylpermethyl oligosilane compound represented by the following formula (I). Formula (I) (In the formula, m represents an integer of 7 to 12.)