JPH09110993A - Cyanophenylpolysilane and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cyanophenylpolysilane represented by a specified formula having a high efficiency of forming photocarriers by reacting a halogenated polysilane or an alkoxylated polysilane with cyanolithiobenzene. SOLUTION: Cyanolithiobenzene is dissolved in a solvent such as an ether/ tetrahydrofuran mixed solution, the solution is cooled to and kept at about -60 to -100 deg.C, a THF solution containing dissolved halogenated polysilane such as chlorinated polysilane or an alkoxylated polysilane is added dropwise to the above mixture and reacted and agitated for about 0.5-12hr. After the reaction, excess cyanolithiobenzene is deactivated by the addition of distilled water, and the organic layer is withdrawn and concentrated, and the formed polymer is fractionally precipitated to obtain a cyanophenylpolysilane having cyanophenyl groups as side chains, represented by the formula (wherein R<1> to R<3> are each H or a 1-18C hydrocarbon group; 0<(l)<=1; 0<=(m)<1; (l)+(m)=1; and (n)>=2) and having a weight-average molecular weight of about 500-500,000.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel polysilane, cyanophenylpolysilane, which is excellent in photoconductivity, conductivity, and non-linear optical characteristics, and a method for producing the same.

[0002]

2. Description of the Related Art Polysilane has been widely studied in the fields of, for example, precursors for ceramics, conductive materials, photoconductive materials (photoconductors), and nonlinear optical materials, and has become an interesting polymer material. . In the prior art, as a polysilane having only silicon in the polymer main chain, a polymer represented by the following general formula (A) is
For example, Organomet. Chem., 300 (1986), 3
27, R.I. West, and Chem. Rev., 89 (198
9), 1359, R.I. D. Miller and J.M. Reported in Michl's review.

[0003]

Embedded image [In the formula, R ⁴ and R ⁵ are each a hydrocarbon group. ]

However, they are generally
It has a normal hydrocarbon group such as an alkyl group and a phenyl group, and there are few reports of polysilanes having a polar group as a side chain. Among the polar groups, polysilanes having electron-donating side chains include p-N, N-dimethylaminophenylpolysilane and other polysilanes having dialkylaminophenyl groups, dialkylamino groups, and alkoxy groups as side chains. Has been done. On the other hand, synthesis examples of polysilane having an electron-withdrawing side chain have hardly been reported until now, and a weak electron-withdrawing group of p-trifluoromethylphenyl side-chain polysilane copolymer is described in J. M. S. Pure App
l. Chem., A29 (1992) 787, H .; K. There are only examples such as those reported by Kim et al., And polysilanes having a strong electron-withdrawing group in the side chain, such as p-
No cyanophenyl side chain polysilanes have been reported.

Further, a p-nitrophenylsilane compound, which is a silicon compound having a p-nitrophenyl group as a strong electron-withdrawing group, is reported in JP-A-63-159387, which is a monosilane or disilane compound. However, it is not a polysilane compound having a high degree of polymerization. As described above, the reason why polysilane having a strong electron-withdrawing group as a functional group has not been reported so far is that in the conventional technique, a polymerization method using molten sodium called a Wurtz reaction is generally used, and the reaction condition is It is considered that this is because a monomer having a strong electron-withdrawing group cannot withstand. Moreover, polysilanes having a strong electron-withdrawing group in the side chain have not been reported by other synthetic methods such as ring-opening polymerization, dehydrogenative condensation, anionic polymerization, and electrolytic polymerization.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its object is to provide a photoconductive material (photoconductor), a conductive material, a nonlinear optical material, and the like. It is an object of the present invention to provide a very useful new cyanophenyl polysilane in which a cyanophenyl group which is a strong electron-withdrawing group is bonded to a silicon atom in the main chain, and a method for producing the same.

[0007]

In order to solve the above-mentioned problems, the present invention has the general formula (1):

Embedded image [In the formula, R ¹ , R ² and R ³ are each a hydrogen atom or a hydrocarbon group. Also, l, m and n are 0 <l
≦ 1,0 ≦ m <1,1 + m = 1, n ≧ 2. ] The cyanophenyl polysilane which has the cyanophenyl group shown by these in a side chain is provided.

In the formula (1), when R ¹ , R ² and R ³ are hydrocarbon groups, those having 1 to 18 carbon atoms are preferably used as the hydrocarbon group, for example, alkyl group and aryl group. Base,
Aralkyl groups and the like. The hydrocarbon group may be substituted with an alkoxy group or the like. The number of carbon atoms of the alkyl group is usually 1 to 18, preferably 1 to 10, more preferably 1 to 6 (eg, methyl group, ethyl group, propyl group, butyl group, pentyl group, and hexyl group). The aryl group preferably has 6 to 18 carbon atoms, more preferably 6 to 10 carbon atoms (for example, a phenyl group and a naphthyl group). The carbon number of the aralkyl group is preferably 7 to 18, more preferably 7 to 10 (eg, anisyl group, β-phenethyl group, etc.).

Cyanophenyl polysilane of the present invention (1)
Has a cyanophenyl group in its side chain, and the number of silicon atoms in the polymer main chain is at least 2 or more. The cyanophenyl polysilane (1) may have a cyanophenyl group at the molecular end. Cyanophenyl polysilane (1)
In, the terminal groups connected to both ends of the formula (1) are hydrogen,
Examples thereof include an alkyl group, an aryl group, an alkoxy group, a trialkylsilyl group and a cyanophenyl group. The weight average molecular weight of cyanophenyl polysilane (1) is 500 to 50.
It is ten thousand.

Cyanophenyl polysilane of the present invention (1)
Has a feature that a cyanophenyl group is directly bonded to a silicon main chain, and is thus useful as a photoconductive material (photoconductor), a conductive material and the like.

The present invention has the general formula (2):

Embedded image [In the formula, R ¹ , R ² and R ³ are each a hydrogen atom or a hydrocarbon group, and X is a halogen atom or an alkoxy group. Further, l, m and n are 0 <l ≦
1,0 ≦ m <1,1 + m = 1, n ≧ 2. ] The halogenated polysilane or alkoxypolysilane represented by the formula (4):

Embedded image Also provided is a method for producing cyanophenylpolysilane, which comprises reacting cyanolithiobenzene represented by

In the formula (2), when R ¹ , R ² and R ³ are hydrocarbon groups, those having 1 to 18 carbon atoms are preferably used as the hydrocarbon group, for example, alkyl groups and aryl groups. Base,
Aralkyl groups and the like. The hydrocarbon group may be substituted with an alkoxy group or the like. The number of carbon atoms of the alkyl group is usually 1 to 18, preferably 1 to 10, more preferably 1 to 6 (eg, methyl group, ethyl group, propyl group, butyl group, pentyl group, and hexyl group). The aryl group preferably has 6 to 18 carbon atoms, more preferably 6 to 10 carbon atoms (for example, a phenyl group and a naphthyl group). The carbon number of the aralkyl group is preferably 7 to 18, more preferably 7 to 10 (eg, anisyl group, β-phenethyl group, etc.).

In the formula (2), when X is a halogen atom, examples thereof include chlorine, fluorine and bromine,
Chlorine and bromine are preferably used. When X is an alkoxy group, the number of carbon atoms in the alkoxy group is, for example, 1 to 10, more preferably a methoxy group or an ethoxy group.

As an example of the halogenated polysilane or alkoxypolysilane represented by the formula (2), a chlorinated polysilane (for example, polysilane having a phenyl group as a side chain is used as a benzene solution and hydrochloric acid gas is blown in the presence of an aluminum chloride catalyst). A chlorinated polysilane obtained by (1), and an alkoxypolysilane obtained by treating polymethylphenylsilane with methyl triflate and then reacting it with alcohol. The cyanolithiobenzene represented by the formula (3) is obtained by, for example, dissolving cyanobromobenzene in diethyl ether, and applying an organolithium reagent (preferably n-butyllithium or t
-Butyllithium solution).

The reaction between the halogenated polysilane or the alkoxypolysilane and the cyanolithiobenzene is carried out by keeping the solution of the cyanolithiobenzene synthesized at a low temperature at a low temperature (eg, -60 to -100 ° C). The solution of the alkoxylated polysilane is slowly dropped to react. The reaction time is, for example, 0.5 to 12 hours. After completion of the reaction, excess cyanolithiobenzene is deactivated with distilled water or the like, the organic layer is taken out and concentrated, and the produced polymer is fractionally precipitated to obtain cyanophenyl polysilane having a weight average molecular weight of 500 to several hundreds of thousands. can get.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Comparative Example 1 A 300 mL three-necked flask equipped with a cooling tube and a dropping funnel was replaced with nitrogen, and then 5.52 g (0.240 g) of metallic sodium was obtained.
Mol) and 75 mL of toluene were charged, and the sodium dispersion was formed by heating and stirring at 110 ° C. Commercially available methylphenyldichlorosilane (LS-1490 manufactured by Shin-Etsu Chemical) 7.64 g (0.040 mol) and methyl-n-propyldichlorosilane (LS-4 manufactured by Shin-Etsu Chemical)
A solution of 12.57 g (0.080 mol) of 50) dissolved in 50 mL of toluene was added dropwise from the dropping funnel, and the mixture was heated and stirred at 110 ° C. (toluene reflux condition) for 3 hours to complete the reaction. After cooling the reaction solution to room temperature, ethanol 50
After adding mL, washing with water several times, the insoluble matter was removed by filtration, the organic layer was concentrated, and fractional precipitation was carried out from a THF / ethanol system to obtain a white powdery polymer. further,
The polymer was reprecipitated and purified twice with THF / ethanol. As a result, the yield was 30% and the weight average molecular weight (Mw) was 5
A methylphenylsilane / methyl-n-propylsilane copolymer having a molecular weight of 3,900 and a dispersion (Mw / Mn) of 4.5 was obtained (the molecular weight was determined by gel permeation chromatography (G
It was calculated in terms of polystyrene using (PC)).

The copolymerization ratio (molar ratio) obtained from the integral ratio of the ¹ H-NMR spectrum of this polymer was n: m = 1: 3.
Met.

[Chemical 6]

Example 1 Methylphenylsilane / methyl-n synthesized in Comparative Example 1
-Propylsilane copolymer (Mw = 53,900, Mw / M
2.00 g of n = 4.5) was dissolved in 150 mL of dry benzene in a 300 mL three-necked flask, and about 0.10 g of sublimed and purified aluminum chloride (AlCl ₃ ) was added as a catalyst. This was dephenylchlorinated by reacting concentrated sulfuric acid with ammonium chloride under magnetic stirring. 15 hours (overnight)
After stirring, 10 mL of dry acetone was added to deactivate the catalyst,
After the reaction was completed, the reaction solution was quickly suction-filtered to remove the catalyst, the filtrate was transferred to an eggplant-shaped flask, and the solvent and hydrochloric acid were distilled off with an evaporator to obtain a chlorinated polysilane.

200 mL in another 500 mL three neck flask
A dropping funnel and a cooling tube were attached, the system was dried under reduced pressure, and then a nitrogen atmosphere was created. 18.20 g (0.10 mol) of 4-bromocyanobenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) was placed in a 500 mL three-necked flask, 100 mL of dry ether and dry THF.
It was dissolved in 50 mL of mixed solvent. N-Butyllithium hexane solution (1.6M) was added to a 200 mL dropping funnel at 63.0 m.
L (0.10 mol) was added and the reaction vessel (3
The one-necked flask) was cooled to about -80 ° C. When this temperature was maintained and magnetic stirring was performed, an n-butyllithium hexane solution was dropped from the dropping funnel, and the solution turned reddish brown, and formation of 4-lithiocyanobenzene was confirmed. After dropping the whole amount of n-butyllithium hexane solution, -80
The mixture was magnetically stirred for about 2 hours while being kept at ℃.

To this reddish brown solution (4-lithiocyanobenzene solution), a solution prepared by dissolving the chlorinated polysilane synthesized above in 100 mL of dry THF was placed in a dropping funnel and slowly dropped to react. After the entire amount was dropped, the temperature was kept at -80 ° C for about 2 hours, and then the temperature was slowly returned to room temperature. About 150 mL of distilled water was added to the solution to crush the excess lithiated product and the produced lithium salt, and then the oil layer and the water layer were separated, and the water layer was extracted with ether and combined with the oil layer. After evaporation and evaporation of the solvent, the red solid obtained was dissolved in THF and added dropwise into ethanol, giving an orange powder, and the ethanol solution turned red.

When the orange solid was reprecipitated and purified twice with a THF / ethanol system, 0.40 g of orange powder (high molecular weight polymer) was obtained. On the other hand, when the red ethanol solution was evaporated, 0.82 g of a red sticky solid (low molecular weight polymer) was obtained from here. When the molecular weights of both components were measured by GPC, the results shown in Table 1 below were obtained, and it was found that all the components were polymers containing almost no low-molecular components such as unreacted compounds.

[0023]

[Table 1] Table 1. Molecular weight of the obtained p-cyanophenylpolysilane Polymer Mw Mw / Mn Color Base Poymer (Comparative Example 1) 53,900 4.5 White High molecular weight polymer (alcohol insoluble matter) 14,900 2.5 Orange low molecular weight polymer (alcohol soluble matter) 5,000 2. 3 red

Further, the infrared absorption spectrum was measured. As a result, it was found that the cyano group was found at 2228 cm ^-1 for all the polymers.
Since the peak derived from (C≡N) was observed, it is considered that the p-cyanophenyl group could be introduced into the polymer. Fig. 1 shows the ¹³ C-NM of the obtained cyanophenylpolysilane.
2 shows an R spectrum. A peak derived from a cyano group (C≡N) carbon attached to a phenyl group was confirmed near δ = 118 ppm, which shows that the desired cyanophenyl polysilane was obtained.

Measurement of Absorption Spectrum The cyanophenylpolysilane (low molecular weight component and high molecular weight component) obtained in Example 1 was formed into a film of about 0.2 μm on a quartz substrate, and the absorption spectrum was measured. Further, for comparison, the absorption spectrum of the polymer of Comparative Example 1, which is the base polymer, was measured in the same manner. The absorption spectrum chart is shown in FIG. According to this, in the high molecular weight component, strong absorption due to Si-Siσ conjugation similar to that of the base polymer is observed, and weak absorption reaching a wavelength of about 500 nm from cyanophenyl group peaks near 500 nm. all right. For low molecular weight components, Si-Siσ
Conjugation-based absorption is seen as a shoulder near 300 nm, 4
It was found that the absorption derived from the cyanophenyl group near 20 nm was stronger than that of the polymer component.

From these results, it is shown that the p-cyanophenyl group was introduced into the polymer in both the high molecular weight component and the low molecular weight component, and the introduced amount was small in the high molecular weight component, and the low molecular weight component was introduced. It can be considered that there are many ingredients. Furthermore, since the molecular weight is reduced compared to the base polymer, the introduction of the cyanophenyl group into the chlorinated part causes the polysilane main chain to be cleaved by the lithiated product, and p-cyanophenyl groups are also present at the terminals. It is expected that the group has been introduced.

Measurement of Photoconductivity (Photocarrier Generation Quantum Efficiency) The cyanophenylpolysilane (low molecular weight component and high molecular weight component) obtained in Example 1 was replaced with ITO (Indium Tin Oxide).
A quartz substrate on which was vapor-deposited was spin-coated with a thickness of 2 to 4 μm, and gold was vapor-deposited thereon to a thickness of 20 nm to prepare a sample for evaluation. The base polymer of Comparative Example 1 was also prepared in the same manner. While applying a voltage with the ITO electrode of these samples as a positive bias, monochromatic light obtained by dispersing light from a 300 W xenon (Xe) lamp was irradiated from the ITO electrode side, and the change in current value at this time was measured.

The quantum efficiency was determined from the photoelectric flow rate that flowed with respect to the number of incident photons during light irradiation, and this was taken as the photocarrier generation quantum efficiency. FIG. 3 shows the wavelength dependence of the photocarrier generation quantum efficiency of the high molecular weight component and the low molecular weight component of cyanophenyl polysilane and the polysilane of Comparative Example 1. (The applied electric field strength is 2 × 10 ⁵ V / cm in each case). All polysilanes have a peak of photocarrier generation near 350 nm which is the absorption edge of strong light absorption shown in FIG. 2, which is considered to be based on Si-Siσ conjugation. The photocarrier generation quantum efficiency is
It was found that the cyanophenylpolysilane of Example 1 was about 100 to 1000 times larger in both the high molecular weight component and the low molecular weight component than the base polymer of Comparative Example 1. From these results, it can be seen that the cyanophenylpolysilane of the present invention is a material having high photoconductivity.

[0029]

The cyanophenyl polysilane of the present invention is
It is a novel polymer not described in the literature. INDUSTRIAL APPLICABILITY The cyanophenylpolysilane of the present invention can be expected to improve the efficiency of photocarrier generation due to the strong electron-withdrawing property of the cyanophenyl group, and can be easily molded into a thin film, and is a photoconductive material.
It can be used as (photoconductor), conductive material, and non-linear optical material.

Further, according to the method for producing cyanophenylpolysilane of the present invention, it is possible for the first time to introduce a cyanophenyl group without destroying a functional group during a polymerization reaction using molten sodium called the Wurtz reaction which is a conventional technique. Became. That is, according to the present invention, it is also possible to synthesize cyanophenylpolysilane without destroying the functional group. The cyanophenylpolysilane of the present invention can be applied to a charge generation / charge transport layer, a non-linear optical material, a conductive material, etc. in an electrophotographic photoreceptor, and its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a diagram showing a ¹³ C-NMR spectrum of p-cyanophenylpolysilane obtained in Example 1 in a deuterated chloroform solution.

FIG. 2 p-cyanophenylpolysilane obtained in Example 1 (high molecular weight component and low molecular weight component), and Comparative Example 1
FIG. 3 is a diagram showing a light absorption spectrum of the base polymer (methylphenylsilane / methylpropylsilane copolymer) of FIG.

3 is a diagram showing wavelength dependence of photocarrier generation quantum efficiency of p-cyanophenylpolysilane (high molecular weight component and low molecular weight component) obtained in Example 1 and the base polymer of Comparative Example 1. FIG.

Claims (3)

[Claims] 1. General formula (1): [In the formula, R ¹ , R ² and R ³ are each a hydrogen atom or a hydrocarbon group. Also, l, m and n are 0 <l
≦ 1,0 ≦ m <1,1 + m = 1, n ≧ 2. ] The cyanophenyl polysilane which has the cyanophenyl group shown by these in a side chain. 2. The method for producing cyanophenylpolysilane according to claim 1, wherein the halogenated polysilane or the alkoxylated polysilane is reacted with cyanolithiobenzene. 3. A photoconductive material using the cyanophenylpolysilane according to claim 1.