JP2002220371A - Method for producing n-vinyl carbazoles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a convenient and inexpensive method for industrial use without any need of a special condition and equipment in the case of production of N-vinyl carbazoles from carbazoles. SOLUTION: A method for producing N-vinyl carbazoles of this invention consists of a process in which N-(2-hydroxyethyl)carbazoles are obtained by reacting carbazoles with ethylene carbonate in the presence of diazabicycloic base and/or a process in which hydroxy radical of hydroxyethyl radical of N-(2-hydroxyethyl)carbazoles is induced to sulfonate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing N-vinylcarbazole useful as a synthetic intermediate such as a dye, a synthetic intermediate of a liquid crystal material, or a synthetic intermediate of a thermoplastic resin.

[0002]

2. Description of the Related Art N-vinyl carbazoles have been produced by a great deal of research up to now. The main methods include (1) a direct liquid phase reaction between carbazole and acetylene (JP-A-48-68564), and (2) a direct atmospheric pressure gas phase reaction between carbazole and acetylene (Chem. I).
nd. (London), 1977, 12, 21, Hu.
a Hsueh Tung Pao. , 1977, 1,
21), (3) Reaction between carbazole and vinyl ether (JP-B-49-9466, Zh. Org. Khi)
m. , 1979, 15 (1), 174-177),
(4) A method of deriving N- (2-hydroxyethyl) carbazole from a potassium salt of carbazole and ethylene oxide, and then performing a dehydration reaction in the presence of a base (Japanese Patent Publication No. Sho 49)
-9468), and the like.

However, in the above cases (1) and (2),
Since acetylene is used, sufficient protection equipment must be provided, the operation is complicated, and a pressure-resistant device may be required in some cases. In the case of (3), an expensive catalyst is used for the reaction, which is not industrially suitable, and it is difficult to treat the catalyst after the reaction. In the method (4), metal potassium or potassium hydride must be used when synthesizing a potassium salt of carbazole, or special equipment must be used to perform a melting reaction with potassium hydroxide, which is highly toxic. On top of this is the disadvantage of using explosive ethylene oxide. Also,
After the reaction, purification by vacuum distillation must be performed, and the operation is complicated.

On the other hand, as a method similar to the above (4),
There is a method of reacting carbazole and ethylene carbonate in the presence of potassium carbonate to obtain N- (2-hydroxyethyl) carbazole (US Pat. No. 466227). However, since this method is performed under high temperature conditions, usable equipment is limited.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for separating and purifying high-temperature and high-pressure conditions, explosive substances, and a target substance, which uses a method such as distillation under reduced pressure, and does not require special equipment and equipment. A simple and inexpensive industrial production method for N-vinylcarbazoles.

[0006]

Means for Solving the Problems The present inventor has studied to achieve the above object, and as a result, the following object of the present invention is achieved by the following manufacturing method. (1) A method for producing N-vinylcarbazoles, comprising a step of reacting carbazoles with ethylene carbonate in the presence of a diazabicyclo base to obtain N- (2-hydroxyethyl) carbazoles. (2) a step of deriving a hydroxyl group of a hydroxyethyl group of N- (2-hydroxyethyl) carbazole into a sulfonate form;
A method for producing N-vinylcarbazoles, comprising a step of obtaining vinylcarbazoles. (3) a step of reacting carbazoles with ethylene carbonate in the presence of a diazabicyclo base to obtain N- (2-hydroxyethyl) carbazoles, and a step of reacting the N- (2-hydroxyethyl) carbazoles obtained in the step. A step of deriving a hydroxyl group of a hydroxyethyl group into a sulfonate form, and a step of obtaining N-vinylcarbazoles from the sulfonate form obtained in the above step.
-A method for producing vinyl carbazoles.

According to the present invention, N- (2-hydroxyethyl) carbazoles can be efficiently obtained by reacting carbazoles with ethylene carbonate in the presence of a diazabicyclo base, without requiring any industrially specialized equipment. And N-vinyl carbazoles can be efficiently obtained via this. Further, an N-vinylcarbazole can be efficiently obtained by inducing a hydroxyl group of a hydroxyethyl group into a sulfonate by a sulfonylation reaction of the N- (2-hydroxyethyl) carbazole, and then removing the sulfonic acid derivative. Can be. According to these methods, N-vinylcarbazoles can be obtained in a high yield without using any special conditions or equipment, which is extremely industrially advantageous.

[0008]

Next, the present invention will be described in detail. The carbazole used as a raw material in the present invention is represented by the following general formula (I).

[0009]

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In the formula, Y and Z may be the same or different and represent a group of non-metallic atoms necessary for forming a 4- to 8-membered ring.

Preferred non-metallic atomic groups of Y and Z in the general formula (I) include carbon, nitrogen, oxygen and sulfur. The ring formed by Y and Z may be a saturated ring or an unsaturated ring. And aprotic heterocycles such as pyridine, pyrazine, pyrimidine, thiazole, thiophene, furan, and isoxazole. Particularly, Y and Z are preferably carbon atoms, and particularly preferably a benzene ring. Further, these rings may have a substituent which is inert to the reaction, and examples thereof include a hydrogen atom, a halogen, an alkyl group, an alkoxy group, and a nitro group. Halogen here means fluorine, chlorine, bromine and iodine. Alkyl is lower alkyl having 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl,
Examples include cyclopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl and isohexyl. Alkoxy includes methoxy, ethoxy, propoxy and the like. Preferred substituents are hydrogen, bromine, chlorine, methyl, ethyl, isopropyl, methoxy, ethoxy and nitro groups, and more preferred substituents include hydrogen, methyl and ethyl.

The following are specific examples of the compound represented by the formula (I), but the present invention is not limited thereto.

[0013]

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Next, the production method will be described in detail. The carbazoles represented by the general formula (I) are commercially available and easily available. In the case of a compound that is not commercially available, it can be synthesized by a known method using carbazole as a raw material, and the synthesis method is described in detail in Dai-Organic Chemistry, Vol. 14, Asakura Shoten, and the like.

One embodiment of the method for producing N-vinylcarbazoles of the present invention is to react N- (2-) with carbazoles and ethylene carbonate in the presence of a diazabicyclo base.
Step of obtaining (hydroxyethyl) carbazoles (hereinafter, referred to as
(Also referred to as a first step). Examples of the diazabicyclo base used include 1,8-diazabicyclo [5.
4.0] -7-undecene, 1,5-diazabicyclo
[4.3.0] -5-Nonene, 1,4-diazabicyclo
[2.2.2] octane and the like, preferably 1,8
-Diazabicyclo [5.4.0] -7-undecene. The amount of the base used is suitably 0.2 to 3.0 equivalents,
It is preferably 0.8 to 1.5 equivalents, and more preferably 1.0 to 1.3 equivalents.

The amount of ethylene carbonate used in the first step is suitably 1.0 to 10.0 equivalents, preferably 2.0 to 7.0 equivalents, and more preferably 3.0 equivalents to carbazoles. ~ 5.0 equivalents.

In the first step, a reaction solvent may not be used, but a solvent may be used if necessary. The solvent may be any solvent as long as it does not react with the reaction raw materials or reagents, but is preferably a polar solvent, more preferably N, N-dimethylformamide, N, N-dimethylacetamide, N, N-
Dimethylimidazolidinone. The amount of the solvent to be used is usually 50 to 1000 ml, preferably 100 to 200 ml, per 1 mol of the carbazole.

In the present invention, the temperature during the reaction in the first step is usually 30 to 180 ° C., preferably 50 to 180 ° C.
To 120 ° C, more preferably 80 to 100 ° C. The reaction time is generally 10 minutes to 5 hours, preferably 30 minutes to 2 hours. The completion of the reaction can be confirmed by the disappearance of the raw material carbazoles, which can be confirmed by thin-layer chromatography (TLC) or high-performance liquid chromatography (HPLC).

In another embodiment of the process for producing N-vinylcarbazoles of the present invention, N- (2-hydroxyethyl) carbazoles are prepared by converting a hydroxyl group of a hydroxyethyl group to a sulfonate using a generally known sulfonylating agent. (Hereinafter also referred to as a second step) and a step of obtaining a target N-vinylcarbazole by removing a sulfonic acid derivative from the sulfonate form (hereinafter also referred to as a third step). Including. Here, the N- (2-hydroxyethyl) carbazoles may be those obtained in the first step or commercially available ones. In the case of a compound that is not commercially available, it can be synthesized by a known method (for example, the method described in US Pat. No. 466227). Preferably, N- (2-hydroxyethyl) carbazoles are obtained by the above-mentioned first step. It was obtained in In the second step, N- (2-hydroxyethyl) carbazoles are converted into a sulfonate form from a hydroxyl group of a hydroxyethyl group using a generally known sulfonylating agent. When the first step is used, the intermediate N-
(2-Hydroxyethyl) carbazoles can be directly derived into a sulfonate form by a single bath method without isolation, and are industrially useful.

The sulfonylating agent used in the second step may be a general one, but is preferably industrially useful methanesulfonyl chloride and p-toluenesulfonyl chloride. The amount of the sulfonylating agent to be used is suitably 1.0 to 2.0 equivalents, preferably 1.05 to 1.2 equivalents, based on N- (2-hydroxyethyl) carbazoles.

In the second step, the reaction solvent may not be used, but may be used if necessary. The solvent may be any as long as it does not react with the reaction raw materials or reagents, but is preferably acetonitrile, acetone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-dimethylimidazolidinone, N, N-dimethylsulfoxide. And more preferably acetonitrile and acetone. The amount of the solvent used is N- (2-hydroxyethyl)
Usually 50 to 2000 ml per 1 mol of carbazoles
Is suitable, and preferably 300 to 1500 ml.

In the second step, a base is usually added. The base to be used includes those usually used, for example, pyridine, triethylamine, aniline, inorganic bases such as sodium hydroxide, etc., and preferably pyridine.
The amount of the base to be used is generally 0.5 to 5.0 mol, preferably 1.0 to 2.0 mol, per 1 mol of N- (2-hydroxyethyl) carbazoles. The temperature during the reaction in the second step is usually from 0 to 80 ° C, preferably from 10 to 40 ° C. Reaction time is usually 1
It is from 0 minutes to 5 hours, preferably from 30 minutes to 2 hours.

Next, in the third step, a sulfonic acid derivative is eliminated from the above-mentioned sulfonate compound,
This is the step of obtaining the desired N-vinylcarbazoles. The third step is preferably a step of obtaining a target N-vinylcarbazole by removing a sulfonic acid derivative from the above-mentioned sulfonate compound using a base. As the base used, those usually used,
For example, metal alkoxide, triethylamine, pyridine, sodium hydroxide and the like can be mentioned, and a metal alkoxide is preferable. Specific examples of the metal alkoxide include metal alkoxides such as sodium methoxide, sodium ethoxide, potassium t-butoxide and sodium t-butoxide, and preferably sodium ethoxide and potassium t-butoxide. The amount of the base to be used is appropriately 0.2 to 1.5 equivalents, preferably 1.1 to 1.2 equivalents, relative to the sulfonate compound.

In the reaction in the third step, it is preferable to use a solvent. The solvent used is preferably a polar solvent,
More preferably, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide,
N-dimethylimidazolidinone. The amount of the solvent used is usually 50 to 5000 m per 1 mol of the sulfonate compound.
l is suitable, preferably 500-2000 ml.

The reaction temperature in the third step is usually -5 to 1
The temperature is 20 ° C, preferably 0 to 30 ° C, and more preferably 10 to 15 ° C. It is preferable to add a known polymerization inhibitor such as hydroquinone or metadinitrobenzene to the reaction system. The amount of the polymerization inhibitor to be used is 0.1 to 5 g, preferably 1 to 3 g, more preferably 1.5 to 2 g, per 1 mol of the sulfonate compound.

The N-vinylcarbazoles, which are the desired compounds, can be easily removed as crystals by adding water after the reaction, and high-purity products can be obtained. However, if necessary, purification such as recrystallization is performed. .

[0027]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The purity was evaluated by high performance liquid chromatography (hereinafter abbreviated as “HPLC”). Example 1 Synthesis of 9-vinylcarbazole (IV-1)

[0028]

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100.3 g of carbazole (I-1)
(0.6 mol) and 264.2 g of ethylene carbonate (A)
(3.0 mol) in N, N-dimethylformamide 12
It was suspended in 0 ml and stirred. To this, 1,8-diazabicyclo [5.4.0] -7-undecene (B) 109.6
g (0.72 mol), and the internal temperature of the solution was adjusted to 100
The mixture was stirred for 2 hours while maintaining the temperature. After cooling, ethyl acetate and water were added and extracted into an organic layer. After the liquid separation operation, the ethyl acetate in the organic layer was concentrated and acetonitrile 750 ml
Was added and stirred. To this was added 94.9 g of pyridine (1.2
mol), and keeping the internal temperature of the solution at 20 ° C to 25 ° C, 116.8 g of methanesulfonyl chloride (1.
02 mol) was added dropwise over 20 minutes, followed by stirring at this temperature range for 2 hours. After the reaction, 750 ml of water was added, and the resulting precipitate was filtered by suction, and 151.1 g of 2- (9-carbazolyl) ethyl methanesulfonate (III-1) was used.
(Yield 87%, HPLC content 98.5%). Next, 92.6 g (0.32 mol) of 2- (9-carbazolyl) ethyl methanesulfonate and 0.64 g of hydroquinone were added to N, N-dimethylformamide (320 m).
and stirred. Sodium ethoxide 2
6.1 g (0.384 mol) was added, and the solution was stirred for 30 minutes while maintaining the internal temperature of the solution at 10 ° C. Then water 320
of the desired product.
7 g (95% yield, 99.5% HPLC content) were obtained.

Example 2 Synthesis of 3,6-dibromo-9-vinylcarbazole (IV-2)

[0031]

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3,6-dibromocarbazole (I-2)
65.0 g (0.2 mol) and ethylene carbonate (A) 8
8.1 g (1.0 mol) was suspended in 40 ml of N, N-dimethylformamide and stirred. To this, 1,8-diazabicyclo [5.4.0] -7-undecene (B) 3
3.1 g (0.25 mol) was added, and the solution was stirred for 3 hours while maintaining the internal temperature of the solution at 100 ° C. Then cool down,
Ethyl acetate and water were added and extracted into the organic layer. After the liquid separation operation, the ethyl acetate in the organic layer was concentrated, and methanol
and stirred for 1 hour in a temperature range of 10 ° C to 20 ° C.
The resulting precipitate was filtered off with suction, and 2- (3,6-dibromo-
9-carbazolyl) -1-ethanol (II-2) 5
9.6 g (80.7% yield, 98.9% HPLC content)
I got Next, 36.9 g of this 2- (3,6-dibromo-9-carbazolyl) -1-ethanol (0.1 mol
l) was suspended in 50 ml of acetonitrile and stirred. To this, 9.5 g (0.12 mol) of pyridine was added, and 12.6 g (0.11 mol) of methanesulfonyl chloride was added dropwise over 15 minutes while keeping the internal temperature of the solution at 10 ° C to 20 ° C. The mixture was stirred at this temperature range for 2 hours.
After the reaction, 50 ml of water was added, and the resulting precipitate was filtered by suction and filtered to give 2- (3,6-dibromo-9-carbazolyl) ethyl.
42.0 g of methanesulfonate (III-2) (yield 94
%, HPLC content 98.2%). 2- (3,6-
Dibromo-9-carbazolyl) ethyl methanesulfonate (44.7 g, 0.1 mol) and hydroquinone (0.2 g) were suspended in dimethyl sulfoxide (100 ml), and the solution was stirred while maintaining the internal temperature at 5 to 10 ° C. To this, 13.5 g of potassium t-butoxide (0.12 g) was added.
mol), and the mixture was stirred at this temperature range for 30 minutes. Thereafter, 150 ml of water was added, and the resulting precipitate was filtered by suction, and 33.7 g of the desired product was obtained (96% yield, 99.3% HPLC content).
I got

Example 3 Synthesis of 5,6,7,8-tetrahydro-9-vinylcarbazole (IV-3)

[0034]

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85.6 g (0.5 mol) of 5,6,7,8-tetrahydrocarbazole (I-3) and 132.1 g (1.5 mol) of ethylene carbonate (A) were suspended in 40 ml of N, N-dimethylformamide. It became cloudy and was stirred. To this, 68.3 g (0.55 mol) of 1,5-diazabicyclo [4.3.0] -5-nonene (C) was added, and the solution was stirred for 30 minutes while keeping the internal temperature at 80 ° C. After cooling, ethyl acetate and water were added and extracted into an organic layer. After the liquid separation operation, the ethyl acetate in the organic layer was concentrated and concentrated in methanol 2
00 ml was added and stirred. To this, 150 ml of water was added dropwise, followed by stirring for 1 hour in a temperature range of 10 ° C to 20 ° C. The resulting precipitate was filtered off with suction and 2- (5,6,7,8).
Thus, 65.7 g (yield 61.0%, HPLC content 97.7%) of -tetrahydro-9-carbazolyl) -1-ethanol (II-3) was obtained. Next, the 2- (5, 6, 7, 8)
-Tetrahydro-9-carbazolyl) -1-ethanol 21.7 g (0.1 mol) in acetonitrile 50 ml
And stirred. 9.5 g of pyridine (0.1 g
2 mol), and keeping the internal temperature of the solution at 20 ° C to 30 ° C, p-toluenesulfonyl chloride (21.0) was added.
g (0.11 mol) was added dropwise over 15 minutes, followed by stirring at this temperature range for 1 hour. After the reaction, 50 ml of water was added, and the resulting precipitate was filtered by suction, and 2- (5,6,7,8-
33.8 g of tetrahydro-9-carbazolyl) ethyl 4-methylbenzenesulfonate (III-3) (yield 9
1%, HPLC content 99.0%). The obtained 2-
(5,6,7,8-tetrahydro-9-carbazolyl)
Ethyl 4-methylbenzenesulfonate (III-3) 3
7.2 g (0.1 mol) and hydroquinone (0.2
g) was suspended in 100 ml of dimethyl sulfoxide, and the solution was stirred while maintaining the internal temperature of the solution at 10 ° C. To this, 8.2 g (0.12 mol) of sodium ethoxide was added, and the mixture was stirred at this temperature range for 30 minutes. Then 150m of water
and the resulting precipitate was filtered off with suction to obtain 18.1 g of the desired product
(91% yield, 99.6% HPLC content).

Comparative Example Using carbazole (I-1) as a starting material,
N-vinylcarbazole (IV-1) was synthesized by the method described in No. -9468. This is a method in which carbazole is converted to a carbazole potassium salt, and then reacted with ethylene oxide to further induce N- (2-hydroxyethyl) carbazole, followed by a dehydration reaction in the presence of a base. Table 1 shows the results of this comparative example and the method of the present invention (Example 1).

[0037]

[Table 1]

The following is evident from the results shown in Table 1. In the method of the present invention, the desired product can be obtained at a low temperature in a short time in both steps, and the purification method is simple.
On the other hand, in Comparative Example 1, carbazole as a starting material must be once derived into a potassium salt in the N- (2-hydroxyethyl) carbazole step, and the reaction must be performed at a high temperature. In addition, it is necessary to use highly toxic ethylene oxide. The N-vinyl carbazole step is also a high temperature reaction, and must be further purified by distillation under reduced pressure.

[0039]

According to the present invention, carbazoles are converted to N
-A simple and inexpensive industrial method can be provided without requiring special conditions or special equipment when producing vinyl carbazoles.

Claims (3)

[Claims] 1. A process for producing N-vinyl carbazoles, comprising the step of reacting carbazoles with ethylene carbonate in the presence of a diazabicyclo base to obtain N- (2-hydroxyethyl) carbazoles. 2. A method comprising the steps of: deriving a hydroxyl group of a hydroxyethyl group of N- (2-hydroxyethyl) carbazole into a sulfonate; and obtaining N-vinylcarbazole from the sulfonate obtained in the above step. A method for producing N-vinyl carbazoles, characterized in that: 3. A step of reacting carbazoles with ethylene carbonate in the presence of a diazabicyclo base to obtain N- (2-hydroxyethyl) carbazoles, and N- (2-hydroxyethyl) carbazole obtained in said step. A method for producing N-vinyl carbazoles, comprising a step of deriving a hydroxy group of a hydroxyethyl group into a sulfonate form, and a step of obtaining N-vinyl carbazoles from the sulfonate form obtained in the above step.