JPH01258660A - 2-hydroxy-3-carbamoylbenzo(a)carbazole derivative - Google Patents

Abstract

NEW MATERIAL:2-Hydroxy-3-carbamoylbenzo>>a]carbazole derivative shown by the formula. EXAMPLE:2-Hydroxy-3-(2,3-dimethylphenyl)carbamoylbenzo>>a]carbazole. USE:A coupler for synthetic azo compounds useful as an organic photoconductive material. PREPARATION:Benzadilic acid(R) (2-hydroxy-3-carboxybenzo>>a]carbazole) is reacted with 2,3-dimethylaniline of 2,5-dimethylaniline in a solvent in the presence of a condensation agent such as phosphorus trichloride under heating to give a compound shown by formula. In the operation, since the solvent is suitable for condensation reaction through dehydration and required to dissolved benzadilic acid in a certain degree, a solvent having >=100 deg.C boiling point, immisicibility with water and >=1.20 Debye dipole moment is preferable as the solvent. Anisole, chlorobenzene, benzonitrile, etc. may be cited as the solvent.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to 2-hydroxy, 3-carbamoylbenzo[a]carbazole derivatives of couplers for azo dyes (2,
More specifically, the present invention relates to 2-hydroxy-3-carbamoylbenzo[alcarbazole derivatives which are couplers for synthesizing azo compounds useful as organic photoconductors.

[Conventional technology]

It has been known that certain azo compounds are useful as charge-generating pigments used in charge-generating layers of laminated photoreceptors, which are one form of electrophotographic photoreceptors.

The laminated photoreceptor referred to here is a charge-generating layer formed by applying a charge-generating pigment that has the ability to generate charges by light onto a conductive support in a thin layer by an appropriate method such as vapor deposition or coating with a pigment dispersion. (hereinafter referred to as CGL),
This is a photoreceptor on which a charge transport layer (hereinafter abbreviated as CTL) is formed to efficiently transfer charges generated by CGL.

One of the advantages of choosing azo pigments as charge-generating substances is that several types can be selected depending on the wavelength of the exposure light.

In recent years, the demand for photoreceptors for laser printers has increased, and in particular, it is desired to develop photoreceptors that are sensitive to the wavelength range of semiconductor lasers (780 nm). Examples of azo pigments used for this include JP-A Nos. 58-194035 and 6
Compounds described in No. 2-147463 and No. 62-298574 are known, but these are not satisfactory as photoreceptors for high sensitivity.

[Purpose of the invention]

An object of the present invention is to provide a coupler for obtaining an azo compound useful as a CGM in a highly sensitive electrophotographic photoreceptor, particularly a photoreceptor applied to a semiconductor laser.

[Structure of the invention]

As a result of research, the present inventors found that the above object of the present invention can be achieved by a compound represented by the following general formula (I) (hereinafter referred to as the compound of the present invention).

General Formula (I) In the formula, one of R and R2 represents a methyl group and the other represents a hydrogen atom.

When an azo pigment is prepared using this compound as a coupler and incorporated into an electrophotographic photoreceptor, a photoreceptor with high sensitivity and high charging potential can be obtained. The details will be described in the application examples.

The synthesis of the compounds of the present invention involves combining benzazilic acid (2-hydroxy-3-carboxybenzoCal carbazole) with
．． It is obtained by heating 3-dimethylaniline or 2,5-dimethylaniline in a solvent, adding a condensing agent such as phosphorus trichloride.

At this time, the solvent needs to be suitable for the dehydration condensation reaction and dissolve benzazilic acid to some extent, so the boiling point is 10.
Dipole moment immiscible in water above 0°C 1.20
Debye or higher is preferred.

For example, anisole (dipole moment 1.35D).

Chlorobenzene (1,78D), σ-dichlorobenzene (2,53D), benzonitrile (4,18D)
etc.

In a solvent with a dipole moment of 1.20D or less, such as toluene (0.37D), benzazilic acid does not dissolve, so even if the reaction is refluxed for 100 hours, a large amount of raw material remains, making it difficult to separate and purify the desired anilide. Ta.

In addition, when dimethylacetamide, which is a water-miscible solvent, is used, the reaction proceeds quickly, but stops after a certain amount of progress, and a small amount of raw material remains forever.

In this regard, if the reaction is carried out in the above-mentioned water-immiscible solvent with a certain degree of polarity, the reaction will proceed quickly and the purification will be easy since no raw materials will be used.

〔Example〕

Example 1 Synthesis of 2-hydroxy-3-(2,3 dimethylphenyl)carbamoylbenzo(a)carbazole 55.4 g (0.2 moff) of benzadilic acid (manufactured by Rohner) was dispersed in 250 fflα of orthodichlorobenzene, 2 for this
゜3-Dimethylaniline (Tokyo Kasei) 36y (0,3m
oQ), heat, and when the temperature reaches 80°C, add 13g of phosphorus trichloride and 2Qm of dichlorobenzene over about 5 minutes.
A solution of Q was added dropwise. Further increase the internal temperature to 150℃~)60℃
The temperature was raised to 100% and the reaction was allowed to proceed for 1 hour. Methanol 500m after cooling
(Add 2, filter the precipitated crystals, add methanol 500
Crude product 429 was obtained by washing with IIIQ. Yield 55%.

This product was heated and dissolved in 70 raQ of dimethylacetamide, 1.09% of activated carbon was added, and after thorough stirring, it was filtered when ripe. After cooling, the formed crystals were filtered and washed with methanol to obtain the desired product. 3591. Yield 46%, melting point 320
°C (decomposition).

The infrared absorption spectrum is shown in Figure 1.

y (C=O) 1645 cm-' Elemental analysis (%Xc 2.H□.N20.) Calculated value C78,93; H5,30; N 7.36 Actual value C
78,54i H5,50; N 7.25 Example 2 Synthesis of 2-hydroxy-3-(2,5-dimethylphenyl)carbamoylbenz[a]carbasol Benzazilic acid (manufactured by Rohner) 55.49 (0,2111012 )
was dispersed in 250 ml of orthodichlorobenzene, and 36 g of 2゜5-dimethylaniline (Tokyo Kasei) (0,
3moff) was added and heated, and when the mixture reached 80'OJ, a solution of 13g of phosphorus trichloride and 20IIIff of dichlorobenzene was added dropwise over about 5 minutes. Increase the internal temperature by 15
The temperature was raised to 0°C to 160°C and the reaction was carried out for 1 hour. After cooling, 300 ml of methanol was added to make a homogeneous solution, which was poured into a mixed solution of IQ toluene and 2Q water without stirring. After stirring for a while, the resulting granular solid was filtered.

60g, yield 80%.

2Q of this mixture of methanol: toluene = 3 = 1
After washing with stirring for 1 hour, 45 g of a crude product was obtained. Further, this was recrystallized twice with a mixture of dimethylacetamide and methanol using activated carbon to obtain 25 g of the desired product. Yield 33%, melting point 270°C-275°C.

The infrared absorption spectrum is shown in Figure 2.

ν (C-0) 1652 cm-' Elemental analysis (%) (as C26H2°N20.) Calculated value C78,93; H5,30; N 7.36 Actual value
C78,60; H5,55; N 7.30 Next, in order to show how useful the coupler of the present invention is, an example will be shown in which it is incorporated into an electrophotographic photoreceptor in the form of an azo dye. Of course, this does not limit the application of the present invention.

Application example 1 Synthesis of azo pigment According to JP-A-58-194035, 2,7-diami2-9-dicyanomethylidenefluorene is tetrazotized with sodium nitrite, and then tetrazolium hexafluorophosphate is obtained with ammonium phosphorus hexafluoride. This was coupled with the coupler of the present invention in an N,N dimethylformamide solution to obtain azo pigments 1 and 2, respectively.

Azo Pigment L Azo Pigment 2 Application Example 2 1 part by weight of Azo Pigment L using the coupler of the present invention,
0.5 parts by weight of polycarbonate resin "Panlite L-1250" (manufactured by Ondai Kasei Co., Ltd.) and 1 part by weight of 1,2-dichloroethane
A 0.2 μm CGL was formed by dispersing the solution in a solution containing 20 parts by weight for 10 hours using a sand mill and applying it onto a conductive support made of a polyester film coated with aluminum using a wire bar.

Next, 12 parts by weight of the following compound (A), polycarbonate resin "Panlite K-1300J (manufactured by Ondai Kasei Co., Ltd.)
A solution consisting of 15 parts by weight and 120 parts by weight of 1,2-dichloroethane was applied using a blade coater to form a CTL having a thickness of 23 μI to obtain a photoreceptor.

Compound (A) Application Example 3 A photoreceptor was obtained by using an azo pigment in place of the azo pigment 1 in Application Example 1.

Comparative Examples 1 to 8 The couplers used in the synthesis of azo pigment 1 were as shown in Comparative Examples 1 to 8 in Table 1.
A comparative azo pigment was synthesized in the same manner as in Application Example 1, except that the coupler shown in column 8 was replaced, and a comparative photosensitive compound was synthesized in the same manner as in Application Example 2, except that Azo Pigment 1 was replaced with the above comparative azo pigment. I got a body.

Evaluation The photoreceptors of Application Examples 2 and 3 and Comparative Examples 1 to 8 were evaluated as follows.

The photoreceptor was tested using an electrostatic tester (newly manufactured by Kawaguchi Electric, 5P-428).
(type). Next, the surface potential Va (V) immediately after being negatively corona charged for 5 seconds under a discharge condition of 40 pA, and the surface potential Vi after being left for 5 seconds.The surface potential was then exposed to white light to increase the surface potential from 1500V to 100V. The exposure amount E curvature 8 (Qux-sec) required to lower the voltage to 50V was measured.

The results are shown in Table 1.

Table 1 In the electrophotographic performance shown in Table 1, a large dark decay means that the photoreceptor has no surface charge retention ability.
A high-sensitivity photoreceptor requires not only a small E5:: but also a small D
D also needs to be small.

The azo pigment used in Comparative Example 1 was commercially available Su7toru^5SR.
This is an azo pigment using C. Hoechst Co., Ltd. as a coupler, and is disclosed as an exemplary compound in JP-A-58-194035. In comparison, it can be seen that the sensitivity of the azo pigment using the compound of the present invention as a coupler is greatly increased, and the dark decay is further improved in the case of the present invention.

Among the comparative examples, Comparative Example 3 (anilide moiety is 2-methyl) was the best, but the DD was large and Comparative Examples 6.7 and 8 (2,4
-dimethyl, 2,6-dimethyl, 2,4,6-trimethyl), on the contrary, the dark decay increased and the sensitivity deteriorated.

That is, from the above results, it can be seen that the azo dye using the compound of the present invention as a coupler is specifically excellent in electrophotographic performance.

Although the reason for this is not well understood, the inventor of the present invention thinks as follows.

Substituent at the ortho position of the anilide moiety in general formula (I) (
CH3) acts on N-H either sterically or by hyperconjugation to C=0, which affects the aggregation state of the dye through hydrogen bonds, and electrons Provides excellent photographic performance. In the present invention, it is believed that the effect is enhanced by further providing a methyl group at the ortho or rose position relative to the ortho-methyl group J.

〔Effect of the invention〕

By using the compound of the present invention as a coupler, it is possible to obtain a photoreceptor with higher sensitivity than an azo compound using a known coupler. , is useful as a coupler for obtaining an azo compound useful as a charge generating substance in a highly sensitive electrophotographic photoreceptor, particularly a photoreceptor applied to a semiconductor laser.

[Brief explanation of the drawing]

Figures 1 and 2 are infrared absorption spectra of the compounds of the present invention.

Claims (1)

[Claims] A 2-hydroxy-3-carbamoylbenzo[a]carbazole derivative represented by the following general formula (I). General Formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ [In the formula, either R_1 or R_2 represents a methyl group, and the rest represent a hydrogen atom. ]