CN107814723A - A kind of recovery method of triethylamine in the preparation process of permanent violet - Google Patents

Abstract

The invention provides a method for recovering triethylamine in a permanent violet preparation process, which comprises the following steps: providing a closed-loop product in the process of preparing permanent violet by using triethylamine as an acid-binding agent; adjusting the pH value of the obtained closed-loop product to obtain an alkaline system, wherein the pH value of the alkaline system is not lower than 12; distilling the alkaline system, recovering triethylamine, filtering, washing and drying to obtain permanent violet; the termination temperature of the distillation is 105-120 ℃, and the distillation pressure is normal pressure. Compared with the method of 'terminal treatment' in the prior art, the method belongs to source treatment, the pH value of a closed-loop product containing triethylamine hydrochloride is adjusted to be more than 12, triethylamine is dissociated, and the triethylamine is separated from a system through distillation, so that the difficulty and the cost of filtering and washing wastewater treatment are greatly reduced, the recovered triethylamine can be repeatedly used, and the production cost is further reduced.

Description

A kind of recovery method of triethylamine in the preparation process of permanent violet

technical field

The invention relates to the technical field of triethylamine recovery, in particular to a method for recovering triethylamine during the preparation of permanent violet.

Background technique

Permanent Violet belongs to high-grade dioxazine organic pigments. It has outstanding coloring strength, brightness, excellent heat resistance, permeation resistance and good light fastness. It is widely used in coatings, plastics, plexiglass, rubber, textile printing, It is a popular pigment variety in water-based ink, packaging printing and other fields.

The current process of permanent violet mainly uses 3-amino-N-ethylcarbazole and chloranil as raw materials, and is prepared through a series of reaction steps such as condensation and ring closure. Among them, the condensation step is mainly the condensation reaction of 3-amino-N-ethylcarbazole and chloranil, and the acid-binding agent triethylamine needs to be added in the condensation reaction to neutralize the hydrogen chloride generated by the reaction and promote the reaction. However, the added triethylamine will cause a large amount of triethylamine hydrochloride to be contained in the wastewater produced by permanent violet, and the wastewater treatment will be difficult and costly, and will lead to a waste of triethylamine resources. Therefore, it is of great significance to recover triethylamine during the preparation of permanent violet.

Contents of the invention

In order to solve the problem of high difficulty and high cost in the treatment of permanent violet production wastewater, the present invention provides a method for recovering triethylamine in the production process of permanent violet, which can fully recover triethylamine added to the reaction system as an acid-binding agent .

The invention provides a method for recovering triethylamine in the preparation process of permanent violet, comprising the steps of:

(1) Provide a ring-closed product in the process of preparing permanent violet with triethylamine as an acid-binding agent;

(2) adjusting the pH value of the ring-closed product obtained in the step (1) to obtain an alkaline system, the pH value of which is not lower than 12;

(3) Distill the alkaline system obtained in the step (2), recover triethylamine, and obtain permanent violet; the termination temperature of the distillation is 105-120° C., and the pressure of the distillation is normal pressure.

Preferably, the adjustment temperature of the pH value in the step (2) is below 90°C.

Preferably, in the step (2), a strong alkali solution is used to adjust the pH value of the ring-closed product.

Preferably, the mass concentration of the strong alkali solution is 5%-40%.

Preferably, the preparation method of the ring-closed product comprises the following steps:

Using triethylamine as an acid-binding agent, condensing 3-amino-N-ethylcarbazole and chlorobenzoquinone to obtain a condensate, the condensation reaction is carried out in the presence of an organic solvent;

The obtained condensate is mixed with benzenesulfonyl chloride for a ring-closing reaction to obtain a ring-closed product.

Preferably, the temperature of the condensation reaction is 30-50° C., and the time of the condensation reaction is 2-6 hours.

Preferably, the mass ratio of 3-amino-N-ethylcarbazole, chloranil and triethylamine in the condensation reaction is 1:0.6-0.8:0.4-0.6.

Preferably, the temperature of the ring-closing reaction is 160-180° C., and the time of the ring-closing reaction is 2-6 hours.

Preferably, the mass ratio of benzenesulfonyl chloride to 3-amino-N-ethylcarbazole in the ring-closing reaction is 0.4˜0.6:1.

The invention provides a method for recovering triethylamine in the preparation process of permanent violet, comprising the steps of: providing a closed-loop product in the process of preparing permanent violet with triethylamine as an acid-binding agent; adjusting the ring-closed product obtained by The pH value is obtained to obtain an alkaline system, wherein the pH value of the alkaline system is not lower than 12; the alkaline system is then distilled to recover triethylamine, and then filtered, washed, and dried to obtain permanent violet. The present invention recovers triethylamine in the process of preparing permanent violet, which is a source treatment method. The present invention adjusts the pH value of the closed-loop product containing triethylamine hydrochloride to above 12, so that triethylamine is freed, Then triethylamine is separated from the body system by distillation, which greatly reduces the difficulty and cost of filtration and washing wastewater treatment, and the recovered triethylamine can be used repeatedly, further reducing production costs. Compared with the method of "terminal treatment" in the prior art, the method provided by the invention can effectively avoid the problem that the recovery of triethylamine dissolved in the waste liquid is relatively difficult and cannot be fully recovered, and it can also avoid the problem of triethylamine being recycled permanently. Solid purple residue in the filter cake, and then completely recover triethylamine.

Detailed ways

The invention provides a method for recovering triethylamine in the preparation process of permanent violet, comprising the steps of:

(1) Provide a ring-closed product in the process of preparing permanent violet with triethylamine as an acid-binding agent;

(2) adjusting the pH value of the ring-closed product obtained in the step (1) to obtain an alkaline system, the pH value of which is not lower than 12;

(3) Distill the alkaline system obtained in the step (2), recover triethylamine, and obtain permanent violet; the termination temperature of the distillation is 105-120° C., and the pressure of the distillation is normal pressure.

In the present invention, the preparation method of the ring-closed product preferably comprises the following steps: using triethylamine as an acid-binding agent, condensing 3-amino-N-ethylcarbazole and chlorobenzoquinone to obtain a condensate, The condensation reaction is carried out in the presence of an organic solvent; the obtained condensate is mixed with benzenesulfonyl chloride for a ring-closing reaction to obtain a ring-closed product.

In the present invention, triethylamine is preferably used as an acid-binding agent, and 3-amino-N-ethylcarbazole and chloranil are condensed to obtain a condensate. The present invention further preferably first mixes 3-amino-N-ethylcarbazole with an organic solvent to obtain a 3-amino-N-ethylcarbazole solution, and then adds chloranil to the 3-amino-N- In the ethyl carbazole solution, a reaction system is obtained for condensation reaction; triethylamine is added into the reaction system to neutralize the acidic substance produced by the condensation reaction. In the present invention, the organic solvent is preferably o-dichlorobenzene. In the present invention, the mass ratio of the organic solvent to 3-amino-N-ethylcarbazole is preferably 10-20:1, more preferably 12-18:1, and more preferably 15:1. In the organic solvent, 3-amino-N-ethylcarbazole and chloranil can fully react to form a condensation product.

In the present invention, the mass ratio of the 3-amino-N-ethylcarbazole, chloranil and triethylamine is preferably 1:0.6-0.8:0.4-0.6, more preferably 1:0.7:0.5. In the present invention, chloranil is added into the reaction system in stages, which avoids the problem that the reaction system is viscous and unable to be stirred due to one-time addition of a large amount of chloranil, which affects the progress of the reaction.

In the present invention, the adding temperature of the chloranil is preferably 25-45°C, more preferably 30-40°C, more preferably 35°C. The present invention adds chloranil at the temperature, so that chloranil and 3-amino-N-ethylcarbazole can fully react, and the temperature is controlled within the above-mentioned range, which avoids the higher activity of chloranil. The reaction system is viscous and cannot be stirred.

In the present invention, triethylamine is preferably added dropwise to the reaction system, so as to avoid the excessively violent reaction caused by adding a large amount of triethylamine at the same time, and the viscosity of the reaction system is too large. In the present invention, it is preferable to add triethylamine dropwise Time control in 1 ~ 2h.

In the present invention, the temperature of the condensation reaction is preferably 30-50°C, more preferably 35-45°C, even more preferably 40-45°C; the condensation reaction time is preferably 2-6h, more preferably 3-5h, more preferably 4-5h. In the present invention, the 3-amino-N-ethylcarbazole and chlorobenzoquinone are condensed to generate an acid, and triethylamine acts as an acid-binding agent in the condensation reaction to neutralize the acid generated by the condensation , so that the reaction can proceed smoothly.

After the condensate is obtained, the present invention mixes the obtained condensate with benzenesulfonyl chloride for a ring-closing reaction to obtain a ring-closed product.

In the present invention, the mass ratio of benzenesulfonyl chloride to 3-amino-N-ethylcarbazole is preferably 0.4˜0.6:1, more preferably 0.5:1. In the present invention, the mixing method is preferably adding the benzenesulfonamide to the condensate; the adding temperature of the benzenesulfonyl chloride is preferably 120-140°C, more preferably 125-135°C, more preferably 130-135°C.

In the present invention, the temperature of the ring-closing reaction is preferably 160-180°C, more preferably 170-180°C, more preferably 175-180°C. When the mixing of the raw materials is achieved by adding the benzenesulfonamide to the condensate, after the mixture of benzenesulfonamide and the condensate is obtained, the present invention preferably adopts a method of raising the temperature of the mixture to reach the ring-closing temperature. In the present invention, the time for the ring-closing reaction is preferably 2-6 hours, more preferably 3-5 hours, even more preferably 4-5 hours.

After the ring-closing reaction, the present invention adjusts the pH value of the obtained ring-closing product to obtain an alkaline system, and the pH value of the alkaline system is not lower than 12.

In the present invention, the temperature for adjusting the pH value is preferably below 90°C, more preferably 40-90°C, more preferably 70-90°C.

The present invention adjusts the pH value of the closed-loop product at the temperature, which can effectively avoid the problem of rapid vaporization of the free triethylamine due to the low boiling point of triethylamine, and also avoids the problem of excessively low temperature and excessive cooling. The follow-up needs additional heating and causes the waste of energy and time.

In the present invention, a strong alkali solution is preferably used to adjust the pH value of the ring-closed product. The strong alkali solution is preferably sodium hydroxide solution and/or potassium hydroxide solution; the mass concentration of the strong alkali solution is preferably 5% to 40%, more preferably 10% to 35%, and even more preferably 20% ~30%. The present invention utilizes the principle of "strong base replacing weak base" to adjust the pH value of the closed-loop product to not less than 12, so that the triethylamine in the closed-loop product is completely replaced.

In the present invention, a strong alkali solution is used to adjust the pH value of the closed-loop product to not be lower than 12, preferably 12-14, more preferably 13-14.

In the present invention, the triethylamine in the ring-closed product is completely replaced by adjusting the pH value of the ring-closed product to the target range.

After the basic system is obtained, the present invention distills the obtained basic system to realize the recovery of triethylamine and obtain permanent violet.

In the present invention, the termination temperature of the distillation is 105-120°C, preferably 110-120°C, more preferably 115-120°C. In the present invention, the distillation time is controlled by the temperature of the distillate, that is The temperature of the distillate during the distillation is monitored in real time, and when the temperature reaches the termination temperature of the distillation, the distillation is stopped. In the present invention, the pressure of the distillation is normal pressure.

In the present invention, under the distillation temperature, the triethylamine in the alkaline system can be fully distilled out, and then the triethylamine obtained by distillation is recovered to realize the reuse of the triethylamine.

After the distillation, the present invention preferably filters the obtained permanent violet material liquid to obtain permanent violet. In the present invention, there is no special limitation on the filtering, and the filtering operation well known to those skilled in the art can be adopted; in the embodiment of the present invention, the filtering is specifically centrifuge rejection filtering.

After the filtration, the present invention preferably washes the obtained filter cake to obtain pure permanent violet; the washing preferably uses o-dichlorobenzene and/or hot water to wash the filter cake, more preferably o-dichlorobenzene Benzene performs primary washing and drying on the filter cake in turn to obtain the primary washing filter cake; adopts hot water to carry out deep washing on the primary washing filter cake; the number of times of the o-dichlorobenzene washing is preferably 2 to 3 times, and the The number of times of hot water washing is preferably based on the clarity of the washed filtrate.

The method for recovering triethylamine in a kind of permanent violet preparation process provided by the present invention is described in detail below in conjunction with the examples, but they cannot be interpreted as limiting the protection scope of the present invention.

Example 1

Mix 300kg of o-dichlorobenzene and 30kg of 3-amino-N-ethylcarbazole, add 18kg of chlorobenzoquinone in batches at 35°C, control the temperature at 35°C, cover and seal the mixture, and continue stirring for 30 minutes;

Within 1.5 hours, 12kg of triethylamine was added dropwise, the temperature was controlled at 35°C, and the reaction was continued under stirring for 4 hours at this temperature to obtain a condensate;

Transfer the condensate to a closed-loop kettle, raise the temperature to 135°C, add 18kg of benzenesulfonyl chloride, continue to heat up to 175°C, and then keep warm and reflux at 175°C for 4 hours to obtain a closed-loop product;

After the ring closure is completed, the reaction system is cooled to 70°C, the pH is adjusted to 12 by adding liquid alkali, and triethylamine is recovered by distillation, and the termination temperature of the distillation is 105°C. 9.8kg of triethylamine was collected, and the collected triethylamine was recycled. Put the material into the centrifuge and filter it, wash the filter cake twice with o-dichlorobenzene, dry it, and then wash it with hot water until the filtrate is clear, and you can get the permanent purple filter cake. After testing, the filtrate does not contain triethylamine; the filter cake is dried to obtain 35.2kg of permanent violet, with a content of 97.5%. Tinting power 101.2%.

Example 2

Mix 300kg of o-dichlorobenzene and 30kg of 3-amino-N-ethylcarbazole, add 24kg of chlorobenzoquinone in batches at 30°C, control the temperature at 30°C, cover and seal the mixture, and continue stirring for 30 minutes;

Within 1 hour, 12kg of triethylamine was added dropwise, the temperature was controlled at 40°C, and the stirring reaction was continued at this temperature for 3 hours to obtain the condensate;

Transfer the condensate to a closed-loop kettle, raise the temperature to 130°C, add 18kg of benzenesulfonyl chloride, continue to heat up to 170°C, and then keep warm and reflux at 170°C for 3 hours to obtain a closed-loop product;

After the ring closure is completed, the reaction system is cooled to 90°C, the pH is adjusted to 13 by adding liquid alkali, and triethylamine is recovered by distillation, and the termination temperature of the distillation is 110°C. 10.2kg of triethylamine was collected, and the collected triethylamine was recycled.

Put the material into the centrifuge and filter it. The filter cake is washed twice with o-dichlorobenzene, dried and then washed with hot water until the filtrate is clear, and the permanent purple filter cake can be obtained. After testing, the filtrate does not contain triethylamine; the filter cake is dried to obtain 35.8kg of permanent violet, with a content of 97.3%. Tinting power 100.5%.

Example 3

Mix 600kg of o-dichlorobenzene and 30kg of 3-amino-N-ethylcarbazole, add 18kg of chlorobenzoquinone in batches at 25°C, control the temperature at 25°C, cover and seal the mixture, and continue stirring for 30 minutes;

Within 2 hours, gradually add 18kg of triethylamine dropwise, control the temperature at 30°C, and continue to stir and react at this temperature for 2 hours to obtain the condensate;

Transfer the condensate to a closed-loop kettle, raise the temperature to 120°C, add 18kg of benzenesulfonyl chloride, continue to heat up to 160°C, and then keep warm and reflux at 160°C for 2 hours to obtain a closed-loop product;

After the ring closure is completed, the reaction system is cooled to 60°C, the pH is adjusted to 13 by adding liquid alkali, and triethylamine is recovered by distillation, and the termination temperature of the distillation is 115°C. Collect 15.6kg triethylamine, and the collected triethylamine is recycled.

Put the material into the centrifuge and filter it. The filter cake is washed twice with o-dichlorobenzene, dried and then washed with hot water until the filtrate is clear, and the permanent purple filter cake can be obtained. After testing, the filtrate does not contain triethylamine; the filter cake is dried to obtain 34.6kg of permanent violet, with a content of 97.8%. Tinting power 99.8%.

Example 4

Mix 600kg of o-dichlorobenzene and 30kg of 3-amino-N-ethylcarbazole, add 18kg of chlorobenzoquinone in batches at 45°C, control the temperature at 45°C, cover and seal the mixture, and continue stirring for 30 minutes;

Within 1.5 hours, 12kg of triethylamine was added dropwise, the temperature was controlled at 50°C, and the reaction was continued under stirring for 5 hours at this temperature to obtain a condensate;

Transfer the condensate to a closed-loop kettle, raise the temperature to 140°C, add 12kg of benzenesulfonyl chloride, continue to heat up to 180°C, and then keep warm and reflux at 180°C for 6 hours to obtain a closed-loop product;

After the ring closure is completed, the reaction system is cooled to 50°C, the pH is adjusted to 14 by adding liquid alkali, and triethylamine is recovered by distillation, and the termination temperature of the distillation is 120°C. 10.3kg of triethylamine was collected, and the collected triethylamine was recycled.

Put the material into the centrifuge and filter it. The filter cake is washed twice with o-dichlorobenzene, dried and then washed with hot water until the filtrate is clear, and the permanent purple filter cake can be obtained. After testing, the filtrate does not contain triethylamine; the filter cake is dried to obtain 36.1kg of permanent violet, with a content of 98.2%. Tinting power 102.7%.

As can be seen from the results of the above examples, the recovery rate of triethylamine in the synthetic process of the permanent violet provided by the present invention is high, and the permanent violet waste water obtained by the recovery method of the present invention does not contain triethylamine, and is obtained by the present invention. Also do not contain triethylamine in the permanent violet filter cake that described method obtains, have realized the thorough recovery of triethylamine.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (9)

1. a recovery method of triethylamine in the permanent violet preparation process, comprises the steps: (1) Provide a ring-closed product in the process of preparing permanent violet with triethylamine as an acid-binding agent; (2) adjusting the pH value of the ring-closed product obtained in the step (1) to obtain an alkaline system, the pH value of which is not lower than 12; (3) Distill the alkaline system obtained in the step (2), recover triethylamine, and obtain permanent violet; the termination temperature of the distillation is 105-120° C., and the pressure of the distillation is normal pressure. 2. The recovery method according to claim 1, characterized in that, the adjustment temperature of the pH value in the step (2) is below 90°C. 3. The recovery method according to claim 1 or 2, characterized in that, in the step (2), a strong alkali solution is used to adjust the pH value of the closed-loop product. 4. The recovery method according to claim 3, characterized in that, the mass concentration of the strong alkali solution is 5% to 40%. 5. recovery method according to claim 1, is characterized in that, the preparation method of described closed-loop product comprises the following steps: Using triethylamine as an acid-binding agent, condensing 3-amino-N-ethylcarbazole and chlorobenzoquinone to obtain a condensate, the condensation reaction is carried out in the presence of an organic solvent; The obtained condensate is mixed with benzenesulfonyl chloride for a ring-closing reaction to obtain a ring-closed product. 6. The recovery method according to claim 5, characterized in that, the temperature of the condensation reaction is 30-50° C., and the time of the condensation reaction is 2-6 hours. 7. The recovery method according to claim 5 or 6, characterized in that, in the condensation reaction, the mass ratio of 3-amino-N-ethylcarbazole, chloranil and triethylamine is 1:0.6～ 0.8:0.4～0.6. 8 . The recovery method according to claim 5 , wherein the temperature of the ring-closing reaction is 160-180° C., and the time of the ring-closing reaction is 2-6 hours. 9. The recovery method according to claim 5 or 8, characterized in that, the mass ratio of benzenesulfonyl chloride to 3-amino-N-ethylcarbazole in the ring-closing reaction is 0.4 to 0.6:1.