CN1322710A - Prepn of triphenylamine derivative - Google Patents

Abstract

The prepn of triphenylamine derivative includes the first step of synthesizing arene iodide with diazo salt or other compound as material and the second step of condensating different aromatic amine compound and arene iodide. Potassium iodide solution produced during the reaction may be recovered for reuse and reduction of potassium iodide. In addition, mixed crown ether as phase transfer catalyst is adopted during the condensation of the second step, and this raises the activity of catalyst while reducing consumption and exhaust of the toxic catalyst.

Description

The preparation method of triphenylamine derivative

The invention relates to a preparation method of triphenylamine derivatives, which can efficiently and low-consumption prepare triphenylamine derivatives, an important intermediate of novel photoelectric functional materials.

Compounds containing triphenylamine structure are important raw materials for the preparation of new optoelectronic materials such as electrostatic copying, charge transport materials for laser printers, and electroluminescent materials. Generally adopt Ullmann (Ullmann) reaction to prepare, with the difference of synthetic starting material adopted, the yield of the synthetic triphenylamine has bigger difference. If one of the halogenated aromatic hydrocarbons of synthetic raw materials adopts iodo aromatic hydrocarbons, the yield of the obtained triphenylamine derivatives is the best. At the same time, because the Ullmann reaction requires high temperature conditions, general quaternary ammonium salt phase transfer catalysts cannot meet the requirements, and the reaction yield of polyethylene glycol phase transfer catalysts is relatively low. Therefore, only crown ether catalysts can use.

The method for preparing triphenylamine derivatives using different arylamine compounds and different halogenated aromatics and different phase transfer catalysts is in the literature (Gauthier S. et al., Synthesis 4:383-385 (1987) and Sutaka K. et al. J. Org.Chem.54:1476-79 (1989)) has been involved. Based on the preparation methods mentioned in the literature, the effect of using iodoarene as one of the reaction raw materials and 18-crown-6 ether as a phase transfer catalyst is the best. But the disadvantages are: 1. Iodoarenes are relatively difficult to prepare, and the raw materials are not easy to obtain, and often need to be prepared in advance before the preparation of triphenylamine derivatives. Moreover, the potassium iodide produced in the reaction to prepare triphenylamine derivatives is discarded as waste. The comprehensive consumption of the whole process is relatively high. 2. Although 18-crown-6 ether is used as a phase transfer catalyst, although the stability and catalytic effect are good, the price is relatively high, so that the overall consumption is large, and more importantly, its toxicity is relatively large, and the discharge of waste water after the reaction will cause environmental pollution . Other preparation methods, such as the method of adopting cyclohexanone derivatives as reactants described in Chinese patent (publication number 1130174) by Chiyuki Kikuchi et al., have the disadvantages that the raw materials are not easy to obtain.

The purpose of this invention is to develop a new process for the synthesis of triphenylamine derivatives. Starting from diazonium salt compounds, a general method is adopted. The first step uses potassium iodide solution and diazonium salt to react to prepare iodo aromatics, and the second step selects Different arylamine compounds and iodoaromatics undergo condensation reactions to prepare triphenylamine derivatives, and the potassium iodide solution produced by the condensation reaction can be recovered and recycled, so that the consumption of potassium iodide in the whole process is less. Using a mixed crown ether phase transfer catalyst in the second-step condensation reaction not only makes the reaction yield of the synthesis of triphenylamine derivatives higher, but also reduces the emission of the more toxic 18-crown-6 ether. The purpose of preparing triphenylamine derivatives with high efficiency and low consumption is realized.

The preparation method of the present invention comprises: the first step adopts the general method for preparing diazonium salts to prepare diazonium salt compounds of different structures, reacts potassium iodide and diazonium salts to prepare iodoaromatic hydrocarbons, and the second step uses a compound crown ether catalyst Preparation of triphenylamine derivatives and recycling of potassium iodide and other steps.

The preparation of diazonium salt adopts general method, and according to the difference of the triphenylamine derivative structure of preparation, selects different aromatic amines as starting raw material, and synthetic reaction equation is as follows:

Here R1 can be substituted in the para-position of the benzene ring, meta-methyl, methoxy and other groups; the acid H ⁺ can be hydrochloric acid or sulfuric acid. Concrete reaction conditions adopt general method to control the proportioning of raw materials and reaction temperature.

The preparation of iodoarenes is to adopt general method, reacts with the diazonium salt prepared in the above-mentioned steps with the saturated solution of potassium iodide, adopts different methods to purify reaction product according to the difference of the structure of the iodoarenes of preparation, can adopt steam distillation, Vacuum distillation, crystallization and other methods. The potassium iodide solution used here should be prepared with commercially available solids when preparing for the first time. In the subsequent preparation process, the solution containing crown ether and copper ions recovered after the condensation reaction can be used. The potassium iodide solution of recovery does not affect the iodine The yield of the reaction.

After preparing iodoarenes, different arylamines and iodoarenes can be used to react to prepare triphenylamine derivatives of different structures. The reaction formula for preparing triphenylamine derivatives is as follows:

Here R1 is the same as above, R2 can be hydrogen, para- or meta-substituted methyl, methoxy, etc. of the benzene ring, and R3 can be hydrogen, phenyl, p-tolyl, etc.

Because the reaction requires a higher temperature (about 200°C), the selectivity of the solvent required for the reaction is limited, and only high-temperature inert solvents, such as nitrobenzene and o-dichlorobenzene, can be used. Heating to the boiling point of the solvent and maintaining reflux can meet the high temperature conditions required for the reaction, and these two solvents can be removed by steam distillation after the reaction. The solvent can be recycled after being purified and dried. For the same reason, the phase transfer catalyst of this reaction is a high temperature stable crown ether catalyst. In addition, the reaction system also needs to add activated copper powder catalyst and anhydrous potassium carbonate as alkaline reagents.

The phase transfer catalyst used in the reaction is a composite crown ether catalyst. Because 18-crown-6 ether has high solubility in water, high price and high toxicity, the consumption of reaction is large, and the pollution of water body is relatively serious when discharged. The present invention selects dibenzo-18-crown-6 and 18-crown-6 to be compounded into composite catalyst, reduces the consumption of 18-crown-6, simultaneously, because dibenzo-18-crown-6 in benzene solvent The solubility is better than that of 18-crown-6, but the solubility in water is poor, which not only effectively improves the catalytic activity of the composite catalyst, but also reduces the content of 18-crown-6 in consumption and emissions. The specific compounded components are prepared by dibenzo-18-crown-6 and 18-crown-6 in a molar ratio of 3:1. The usage amount of the catalyst in the catalytic reaction is 1-5% (wt). The structures of dibenzo 18-crown-6 and 18-crown-6 are respectively:

After the reaction of preparing triphenylamine is finished, the recovered aqueous solution is analyzed by atomic absorption spectrum to prove that the recovery rate of iodide ion is generally about 80%. The recovered solution was left to settle for 4 days and then filtered. The content of copper ions in the solution was analyzed to be 30-60 ppm. The presence of copper ions and other impurities was not enough to affect the iodination reaction. The recovered KI solution can be used to prepare iodoarenes.

By adopting the above-mentioned technical route, not only the yield of preparing triphenylamine derivatives is higher (substantially more than 75%), but also the consumption of potassium iodide in the whole process is less, and the emission of toxic crown ether catalysts is less.

The following examples are to further illustrate the present invention, but not to limit the scope of the present invention.

Example 1:

Put 54 grams of p-toluidine in a 1000ml round bottom flask, add 100ml of 20% dilute hydrochloric acid under stirring, heat and stir until all the solids are dissolved, then cool the solution to below 5°C. Keep the temperature below 5°C and add the pre-prepared sodium nitrite solution, stir until the solution turns blue with KI starch test paper, stop adding the sodium nitrite solution, continue stirring for 10 minutes, the obtained transparent solution is an aqueous solution of diazonium salt.

Dissolve 75 grams of KI in as little water as possible to make a KI solution, keep the temperature of 0-5°C, add the KI solution to the diazonium salt solution prepared above, and keep stirring. Slowly raise the temperature to 60-70°C, keep the temperature for 3-4 hours, then cool the solution to room temperature, and separate the water to obtain a brown-black crude product. The resulting solid was washed with NaOH solution until yellow, further purification required transferring the solid to a distillation flask for steam distillation. The finally obtained pure product is light yellow waxy solid with a yield of 86%.

In a 500ml three-neck flask equipped with a mechanical stirring device, a water separator and a gas introduction device, add 85 grams of diphenylamine, 120 grams of p-iodotoluene, 70 grams of potassium carbonate, 0.5 grams of activated copper powder, and 0.6 grams of composite phase transfer Catalyst and 240ml of nitrobenzene. Pass nitrogen gas from the gas inlet to the liquid surface, and keep the nitrogen flow rate at 0.01-0.03 cubic meters per hour. Start the mechanical stirring, slowly raise the temperature to the reflux temperature (about 200° C.), and stop feeding nitrogen gas after reflux for 10-16 hours. Cool the reaction liquid to room temperature under stirring, change the reaction flask into a steam distillation flask for steam distillation, and recycle the evaporated solvent nitrobenzene. After the distillation, the water phase and the oil phase in the distillation flask were separated, and the water phase containing a large amount of KI was transferred to a beaker for sedimentation. The oil phase is dissolved with toluene, and solid impurities such as insoluble copper powder are removed by filtration. Distill the toluene solution after drying. After the toluene distillation is complete, change to a vacuum distillation device, distill at a pressure of 5-10 mm Hg, and collect fractions at 180-200 ° C. The obtained product 4-methyltriphenylamine is a pale yellow solid with a yield of 76%.

After the above-mentioned aqueous solution containing KI was left to settle for 4 days, the precipitate at the bottom of the container was removed by filtration, and the atomic absorption spectrum test was performed after constant volume. After testing the content of iodine in the solution, the calculated KI recovered was 65 grams; the content of copper ions was 43 ppm. The KI solution can be used for the reaction of preparing iodoarene after supplementing and dissolving a small amount of KI solid.

Example 2

Prepare each raw material ratio of diazonium salt with p-toluidine and concrete technological process are identical with above-mentioned embodiment 1, the KI solution used in the iodination reaction is to prepare the KI solution 150ml that triphenylamine reaction reclaims in above-mentioned embodiment (containing KI65g) made by adding 10g of KI solid. The technique of iodination reaction and the purification method of product are the same as in Example 1, and the p-iodotoluene yield after drying is 84%.

In a 1000ml three-necked flask equipped with a mechanical stirring device, a water separator and a gas introduction device, add 47 grams of aniline, 220 grams of p-iodotoluene, 140 grams of potassium carbonate, 0.5 grams of activated copper powder, and 0.6 grams of composite phase transfer catalyst and 400ml of o-dichlorobenzene. Pass nitrogen gas from the gas inlet to the liquid surface, and keep the nitrogen flow rate at 0.01-0.03 cubic meters per hour. Start the mechanical stirring, and make the stirring speed as high as possible while ensuring that the reaction solution does not overflow. Slowly raise the temperature to reflux temperature (about 180° C.), and stop feeding nitrogen gas after reflux for 10-16 hours. Cool the reaction liquid to room temperature under stirring, change the reaction flask into a steam distillation flask for steam distillation, and recycle the o-dichlorobenzene solvent evaporated. After the distillation, the water phase and the oil phase in the distillation flask were separated, and the water phase containing a large amount of KI was transferred to a beaker for sedimentation. The oil phase is dissolved with toluene, and solid impurities such as insoluble copper powder are removed by filtration. Distill the toluene solution after drying. After the toluene distillation is complete, change to a vacuum distillation device, distill at a pressure of 5-10 mm Hg, and collect fractions at 200-220°C. The obtained product 4,4'-dimethyltriphenylamine is a yellow solid with a yield of 70%.

After the aqueous solution containing KI was left to settle for 4 days, the precipitate at the bottom of the container was removed by filtration, and atomic absorption spectrometry was performed after constant volume. After testing the content of iodine in the solution, the calculated KI recovered was 128 grams; the content of copper ions was 51 ppm. The KI solution can also be used for the reaction of preparing iodoarenes after supplementing and dissolving a small amount of KI solid.

Example 3

Put 61 grams of p-aminoanisole in a 1000ml round bottom flask, add 130ml of 20% dilute hydrochloric acid under stirring, heat and stir until all the solids are dissolved, then cool the solution to about 0°C. Keep the temperature around 0°C and add the pre-prepared sodium nitrite solution, stir until the solution turns blue with KI starch test paper, stop adding the sodium nitrite solution, and continue stirring for 10 minutes, the obtained transparent solution is an aqueous solution of diazonium salt.

Prepare p-iodoanisole and can adopt the process condition of embodiment 1 to use the newly prepared KI solution, also can adopt the KI solution that the method for preparing p-iodotoluene in embodiment 2 adopts reclaiming, the raw material proportioning of preparation and reaction condition control are the same Example 1. There is no difference in the physical properties and reaction yields of p-iodoanisole prepared by the two methods.

In a 500ml three-neck flask equipped with a mechanical stirring device, a water separator and a gas introduction device, add 85 grams of diphenylamine, 70 grams of p-iodotoluene, 80 grams of potassium carbonate, 0.5 grams of activated copper powder, and 0.6 grams of composite phase transfer Catalyst and 250ml of nitrobenzene. Pass nitrogen gas from the gas inlet to the liquid surface, and keep the nitrogen flow rate at 0.01-0.03 cubic meters per hour. Start the mechanical stirring, slowly raise the temperature to the reflux temperature (about 200° C.), and stop feeding nitrogen after reflux for 10 hours. Cool the reaction liquid to room temperature under stirring, change the reaction flask into a steam distillation flask for steam distillation, and recycle the evaporated solvent nitrobenzene. After the distillation, the water phase and the oil phase in the distillation flask were separated, and the water phase containing a large amount of KI was transferred to a beaker for sedimentation. The oil phase is dissolved with toluene, and solid impurities such as insoluble copper powder are removed by filtration. The toluene solution was dried and then distilled. After the toluene was distilled, the product was recrystallized twice with 95% ethanol to obtain pure 4-methoxytriphenylamine as a light yellow solid with a yield of 68%.

The treatment method of the aqueous solution containing KI is the same as in Example 1, and the content of KI detected by atomic absorption spectroscopy is 63 grams, and the content of copper ions is 48 ppm. This KI solution can also be used for the preparation of iodoarenes.

Claims (3)

1. A method for preparing triphenylamine derivatives is characterized in that in the first step, diazonium salt compounds are used as raw materials to synthesize iodoaromatics, and in the second step, condensation reactions are carried out with different aromatic amine compounds and iodoaromatics. 2. The preparation method of triphenylamine derivative according to claim 1 is characterized in that the potassium iodide solution produced in the second step condensation reaction can reclaim and recycle. 3. The preparation method of triphenylamine derivative according to claim 1 is characterized in that in the second step reaction, the composite phase transfer catalyst of dibenzo-18-crown-6 and 18-crown-6 is used, wherein dibenzo-18- The molar ratio of crown-6 and 18-crown-6 is 3:1, and the usage amount of the composite catalyst is 1-5% (wt).