阅读说明：本技术 一种对苯醌二肟的制备方法 (Preparation method of p-benzoquinone dioxime ) 是由 马德龙 吕寻伟 于磊 韩涛 张广振 吴彩英 于 2021-08-20 设计创作，主要内容包括：本申请提供了一种对苯醌二肟的制备方法,将亚硝酸乙酯与苯酚在酸性反应促进剂的作用下发生亚硝化反应生成中间体对苯醌单肟和副产物乙醇,然后中间体对苯醌单肟直接与盐酸羟胺发生肟化反应生成对苯醌二肟,整个反应过程均在有机溶剂中完成；减少了生产废水的排出,符合绿色化生产的要求；亚硝化反应得到的副产物乙醇可与有机溶剂一起最终经蒸馏回收,提高了原材料的利用率；整个合成过程采用惰性气体隔绝空气的方式,避免了亚硝酸乙酯的歧化和分解以及中间体对苯醌单肟的氧化,减少了副反应的发生,提高反应的转化率,进而提高了对苯醌二肟的收率和纯度,收率为85.0％～95.0％,纯度≥99.0wt％,熔点为250℃～255℃。(The application provides a preparation method of p-benzoquinone dioxime, wherein ethyl nitrite and phenol are subjected to nitrosation reaction under the action of an acidic reaction promoter to generate intermediate p-benzoquinone monooxime and byproduct ethanol, then the intermediate p-benzoquinone monooxime is directly subjected to oximation reaction with hydroxylamine hydrochloride to generate p-benzoquinone dioxime, and the whole reaction process is completed in an organic solvent; the discharge of production wastewater is reduced, and the requirements of green production are met; the ethanol which is a byproduct obtained by the nitrosation reaction can be finally distilled and recovered together with the organic solvent, so that the utilization rate of raw materials is improved; the whole synthesis process adopts a mode of isolating inert gas from air, avoids disproportionation and decomposition of ethyl nitrite and oxidation of intermediate p-benzoquinone monooxime, reduces side reactions, improves the conversion rate of the reaction, and further improves the yield and purity of p-benzoquinone dioxime, wherein the yield is 85.0-95.0%, the purity is more than or equal to 99.0 wt%, and the melting point is 250-255 ℃.)

1. The preparation method of p-benzoquinone dioxime is characterized by comprising the following steps of:

1) dissolving ethyl nitrite in an organic solvent in a reaction kettle, and uniformly mixing to obtain an intermediate liquid A;

2) adding phenol into the intermediate liquid A prepared in the step 1), and uniformly mixing to obtain an intermediate liquid B;

3) vacuumizing the reaction kettle after the step 2) is finished, and then filling inert gas into the reaction kettle;

4) dissolving concentrated hydrochloric acid in an organic solvent, and uniformly mixing to obtain a mixed solution of hydrogen chloride and the organic solvent;

5) nitrosation reaction: dropwise adding the mixed solution of hydrogen chloride and an organic solvent prepared in the step 4) into the intermediate liquid B in the reaction kettle, and carrying out a chemical reaction on ethyl nitrite, phenol and hydrogen chloride in an inert gas atmosphere to generate p-benzoquinone monooxime, thus obtaining an intermediate liquid C;

6) oximation reaction: adding hydroxylamine hydrochloride solid into the intermediate liquid C prepared in the step 5), and carrying out chemical reaction on p-benzoquinone monooxime and hydroxylamine hydrochloride in an inert gas atmosphere to generate p-benzoquinone dioxime, thus obtaining an intermediate liquid D;

7) distilling the intermediate liquid D prepared in the step 6), condensing vapor generated by evaporation to obtain condensate, recovering the organic solvent from the condensate, and obtaining the residual liquid after evaporation;

8) filtering the residual evaporation solution prepared in the step 7), and obtaining filter residue and filtrate after filtering;

9) and (3) sequentially washing, centrifugally dewatering and drying the filter residue prepared in the step 8) to obtain powdery benzoquinone dioxime.

2. The method for preparing p-benzoquinone dioxime according to claim 1, wherein in step 1), the temperature of air in the reactor cavity in the reaction kettle is 0 ℃ to 5 ℃, the organic solvent is absolute ethanol, and the mass of ethyl nitrite is 1 (3 to 6).

3. The method for producing p-benzoquinone dioxime according to claim 1, wherein in step 2), the amount of ethyl nitrite to phenol is 1 to 1 (1 to 1.3).

4. The method as claimed in claim 1, wherein the inert gas is nitrogen in the step 3) for preventing air and inhibiting disproportionation and decomposition of ethyl nitrite and oxidation of intermediate p-benzoquinone monooxime.

5. The method for producing p-benzoquinone dioxime according to claim 1, wherein in step 4), the amount of hydrogen chloride is 1 to 1, the amount of phenol is 1 to 2, the organic solvent is absolute ethanol, and the amount of hydrogen chloride is 1 to 5.

6. The method for preparing p-benzoquinone dioxime according to claim 1, wherein in step 5), when the temperature of the intermediate liquid B in the reaction kettle is reduced to 0 ℃, the mixed solution of hydrogen chloride and the organic solvent prepared in step 4) is added dropwise into the intermediate liquid B in the reaction kettle, and the dropwise addition is completed within 1.5 to 3 hours;

the reaction temperature of the nitrosation reaction is 0-8 ℃, and the reaction time of the nitrosation reaction is 0.5-2 h.

7. The method for preparing p-benzoquinone dioxime according to claim 1, wherein in step 6), the mass of hydroxylamine hydrochloride is 1 to 1.3;

the reaction temperature of the oximation reaction is 60-75 ℃, and the reaction time of the oximation reaction is 2-4 h.

8. The method of claim 1, wherein the evaporation temperature of the distillation process in the step 7) is 70 to 85 ℃.

9. The method of claim 1, wherein the filtrate obtained in the step 8) is mixed with the waste water from the washing in the step 9), and then neutralized with an alkali solution, and then evaporated and condensed to remove hydrogen chloride from the filtrate and the waste water, wherein the evaporation temperature is 90 ℃ to 105 ℃.

Technical Field

The invention relates to the technical field of synthesis and preparation of p-benzoquinone dioxime, in particular to a preparation method of p-benzoquinone dioxime.

Background

The p-benzoquinone dioxime is a cross-linking agent with excellent performance, has the characteristics of easy dispersion in rubber materials, high vulcanization speed, high stretching strength of vulcanized rubber, heat resistance, weather resistance, ozone resistance, good electrical insulation performance and the like, and is widely applied to the rubber industry. The p-benzoquinone dioxime can be used as an acrylic acid polymerization inhibitor, can improve the thermal resistance of polyester fiber tire cords, and can also be used as an adhesive for hot melt connection of metal and glass, an olefin copolymer crosslinking regulator, an organic monomer stabilizer, a self-vulcanization type adhesive and an activating effect on an oxidant. The p-benzoquinone dioxime is particularly suitable for butyl rubber, natural rubber, ethylene propylene rubber, styrene butadiene rubber, polysulfide rubber and the like with high stretching strength and high vulcanization speed. However, the critical temperature of the p-benzoquinone dioxime is lower, the p-benzoquinone dioxime has a scorching tendency, and certain scorch retarders (such as phthalic anhydride and NA) and accelerators (such as thiurams, thiazoles and dithiocarbamates) can be added to effectively improve the operation safety. Meanwhile, the p-benzoquinone dioxime has pollution, and about five parts of titanium dioxide can be added to prevent or improve the pollution.

In recent years, methods for synthesizing p-benzoquinone dioxime mainly include:

the first method comprises the following steps: sodium nitrite and phenol dissolved in 30% NaOH solution are subjected to nitrosation reaction at 0 ℃ in the presence of concentrated sulfuric acid with a certain concentration to generate p-benzoquinone monooxime, and then the prepared p-benzoquinone monooxime is added with hydroxylamine for oximation to prepare a final product p-benzoquinone dioxime, wherein the purity and the yield of the product are both limited by the synthesis method, the purity is generally less than or equal to 90%, the product contains more impurities, and the yield is generally less than or equal to 60%. The concrete expression is as follows: 1) nitrous acid generated by sodium nitrite when meeting acid is extremely unstable, and is easily disproportionated and decomposed by heating, illumination or contacting with air to generate disproportionated products nitric acid and nitric oxide and decomposed products dinitrogen trioxide, and the dinitrogen trioxide is rapidly decomposed into nitric oxide and nitrogen dioxide, so that the yield and the quality of the p-benzoquinone dioxime are greatly reduced. 2) In the process of carrying out nitrosation reaction to generate benzoquinone monooxime, air in the reactor can oxidize part of benzoquinone monooxime to generate resin, which affects the quality of benzoquinone monooxime and further affects the quality of benzoquinone dioxime.

The second method comprises the following steps: p-benzoquinone and hydroxylamine hydrochloride are used as raw materials, calcium carbonate is used as a catalyst, and the p-benzoquinone dioxime is synthesized through one step at a certain temperature. Because the p-benzoquinone is a crystalline solid with adsorbability, the p-benzoquinone is very easy to be adsorbed to a human body to cause discomfort of the human body in the using process, and is not beneficial to industrial production. In addition, the appearance color and the purity of the p-benzoquinone dioxime synthesized by the method are darker.

Disclosure of Invention

The invention aims to provide a preparation method of p-benzoquinone dioxime, which adopts ethyl nitrite to replace sodium nitrite in the traditional process, adopts organic solvent to replace water as solvent, adopts inert gas to isolate air in the reaction process, and adopts hydrochloric acid as a reaction accelerator for providing hydrogen ions and promoting nitrosation reaction; nitrosation reaction is carried out on ethyl nitrite and phenol under the action of an acidic reaction promoter to generate an intermediate p-benzoquinone monooxime and a byproduct ethanol, then the intermediate p-benzoquinone monooxime directly carries out oximation reaction with hydroxylamine hydrochloride to generate p-benzoquinone dioxime, and the whole reaction process is completed in an organic solvent; the byproduct ethanol obtained by the nitrosation reaction can be used as an organic solvent and finally distilled, condensed and recycled, so that the utilization rate of raw materials is improved, the discharge of production wastewater is reduced, and the requirement of green production is met; in addition, the whole synthesis process adopts a mode of isolating inert gas from air, so that disproportionation and decomposition of ethyl nitrite and oxidation of intermediate p-benzoquinone monooxime are avoided, side reactions are reduced, the conversion rate of the reaction is improved, and the yield and purity of p-benzoquinone dioxime are improved.

In order to solve the technical problems, the technical scheme provided by the invention is as follows:

a preparation method of p-benzoquinone dioxime comprises the following steps of:

1) dissolving ethyl nitrite in an organic solvent in a reaction kettle, and uniformly mixing to obtain an intermediate liquid A;

2) adding phenol into the intermediate liquid A prepared in the step 1), and uniformly mixing to obtain an intermediate liquid B;

3) vacuumizing the reaction kettle after the step 2) is finished, and then filling inert gas into the reaction kettle;

4) dissolving concentrated hydrochloric acid in an organic solvent, and uniformly mixing to obtain a mixed solution of hydrogen chloride and the organic solvent;

5) nitrosation reaction: dropwise adding the mixed solution of hydrogen chloride and an organic solvent prepared in the step 4) into the intermediate liquid B in the reaction kettle, and carrying out a chemical reaction on ethyl nitrite, phenol and hydrogen chloride in an inert gas atmosphere to generate p-benzoquinone monooxime, thus obtaining an intermediate liquid C;

6) oximation reaction: adding hydroxylamine hydrochloride solid into the intermediate liquid C prepared in the step 5), and carrying out chemical reaction on p-benzoquinone monooxime and hydroxylamine hydrochloride in an inert gas atmosphere to generate p-benzoquinone dioxime, thus obtaining an intermediate liquid D;

7) distilling the intermediate liquid D prepared in the step 6), condensing vapor generated by evaporation to obtain condensate, recovering the organic solvent from the condensate, and obtaining the residual liquid after evaporation;

8) filtering the residual evaporation solution prepared in the step 7), and obtaining filter residue and filtrate after filtering;

9) and (3) sequentially washing, centrifugally dewatering and drying the filter residue prepared in the step 8) to obtain powdery benzoquinone dioxime.

Preferably, in the step 1), the temperature of air in a kettle cavity of the reaction kettle is 0-5 ℃, the organic solvent is absolute ethyl alcohol, and the mass of ethyl nitrite is 1 (3-6).

Preferably, in the step 2), the amount of the ethyl nitrite substance and the amount of the phenol substance are (1 to 1.3) and 1.

Preferably, in the step 3), the inert gas is nitrogen gas, so that the inert gas is used for isolating air and inhibiting disproportionation and decomposition of ethyl nitrite and oxidation of intermediate p-benzoquinone monooxime.

Preferably, in the step 4), the amount of the hydrogen chloride substance to the amount of the phenol substance is (1-2) to 1, the organic solvent is absolute ethyl alcohol, and the amount of the hydrogen chloride substance to the amount of the organic solvent is (1-5).

Preferably, in the step 5), when the temperature of the intermediate liquid B in the reaction kettle is reduced to 0 ℃, the mixed solution of the hydrogen chloride and the organic solvent prepared in the step 4) is dripped into the intermediate liquid B in the reaction kettle, and the dripping is completed within 1.5 h-3 h;

the reaction temperature of the nitrosation reaction is 0-8 ℃, and the reaction time of the nitrosation reaction is 0.5-2 h.

Preferably, in the step 6), the mass of hydroxylamine hydrochloride is (1-1.3) to 1;

the reaction temperature of the oximation reaction is 60-75 ℃, and the reaction time of the oximation reaction is 2-4 h.

Preferably, in step 7), the evaporation temperature during distillation is 70 ℃ to 85 ℃.

Preferably, the filtrate obtained in the step 8) and the waste water generated by the water washing in the step 9) are mixed, then neutralized by alkali liquor, and then evaporated and condensed to remove the hydrogen chloride in the filtrate and the waste water, wherein the evaporation temperature is 90-105 ℃.

The application obtains the following beneficial technical effects:

(1) adopt absolute ethyl alcohol to regard as the solvent of ethyl nitrite and concentrated hydrochloric acid respectively in this application, whole synthetic process only has the introduction of a small amount of water in the concentrated hydrochloric acid, and organic solvent absolute ethyl alcohol accessible distillation, the mode of condensation is retrieved, and this kind of synthetic method has reduced the production of waste water to a certain extent, has reduced waste water treatment's the degree of difficulty, is favorable to environmental protection. According to the method for synthesizing the p-benzoquinone dioxime, the introduction of a water solvent is avoided, so that the output of wastewater is reduced, and the treatment pressure of the wastewater is reduced.

(2) In the method, ethyl nitrite is used as a nitrosation agent, hydrochloric acid is used as a reaction promoter for providing hydrogen ions and promoting nitrosation reaction, nitrosation reaction is carried out between ethyl nitrite and phenol under the action of an acidic reaction promoter to generate intermediate p-benzoquinone monooxime, and ethanol is used as a byproduct; the byproduct ethanol can be distilled and recycled together with ethanol used as an organic solvent, so that the utilization rate of raw materials is improved, and the production cost is reduced; the hydrogen chloride in the filtrate and the waste water generated by washing can be neutralized by alkaline solution, and then the hydrogen chloride is removed by the way of filter residue through evaporation and condensation.

(3) In the application, because ethyl nitrite is heated or is easily decomposed by illumination, and the steam is unstable in contact with air, the mode of replacing the air in the reaction kettle by inert gas nitrogen is adopted, and the inert gas is adopted to isolate ethyl nitrite from the air, so that the disproportionation and decomposition of ethyl nitrite caused by air are inhibited, the generation of side reactions is reduced, the safety of the synthesis reaction is improved, and the yield and the quality of p-benzoquinone dioxime are improved.

(4) The method adopts the inert gas nitrogen to replace the air in the reaction system, because the p-benzoquinone monooxime is extremely unstable and generates quinone substances by side reactions under the conditions of temperature, air, illumination and the like, the p-benzoquinone monooxime is easily oxidized to generate resin when meeting the air, and the contact of the p-benzoquinone monooxime and the air is avoided by introducing the inert gas nitrogen, so that the oxidation of the p-benzoquinone monooxime is avoided, the quality of the p-benzoquinone monooxime is improved, and the quality and the yield of the p-benzoquinone dioxime are indirectly improved.

(5) The p-benzoquinone dioxime prepared by the preparation method provided by the application has high yield, purity and melting point, the yield is 85.0-95.0%, the purity is more than or equal to 99.0 wt%, the melting point is 250-255 ℃, and meanwhile, the discharge of productive wastewater is reduced.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The application provides a preparation method of p-benzoquinone dioxime, which comprises the following steps in sequence:

1) dissolving ethyl nitrite in an organic solvent in a reaction kettle, and uniformly mixing to obtain an intermediate liquid A;

2) adding phenol into the intermediate liquid A prepared in the step 1), and uniformly mixing to obtain an intermediate liquid B;

3) vacuumizing the reaction kettle after the step 2) is finished, and then filling inert gas into the reaction kettle;

4) dissolving concentrated hydrochloric acid in an organic solvent, and uniformly mixing to obtain a mixed solution of hydrogen chloride and the organic solvent;

5) nitrosation reaction: dropwise adding the mixed solution of hydrogen chloride and an organic solvent prepared in the step 4) into the intermediate liquid B in the reaction kettle, and carrying out a chemical reaction on ethyl nitrite, phenol and hydrogen chloride in an inert gas atmosphere to generate p-benzoquinone monooxime, thus obtaining an intermediate liquid C;

6) oximation reaction: adding hydroxylamine hydrochloride solid into the intermediate liquid C prepared in the step 5), and carrying out chemical reaction on p-benzoquinone monooxime and hydroxylamine hydrochloride in an inert gas atmosphere to generate p-benzoquinone dioxime, thus obtaining an intermediate liquid D;

7) distilling the intermediate liquid D prepared in the step 6), condensing vapor generated by evaporation to obtain condensate, recovering the organic solvent from the condensate, and obtaining the residual liquid after evaporation;

8) filtering the residual evaporation solution prepared in the step 7), and obtaining filter residue and filtrate after filtering;

9) and (3) sequentially washing, centrifugally dewatering and drying the filter residue prepared in the step 8) to obtain powdery benzoquinone dioxime.

In one embodiment of the application, in the step 1), the temperature of air in a kettle cavity of the reaction kettle is 0-5 ℃, the organic solvent is absolute ethyl alcohol, and the mass of ethyl nitrite to the mass of the organic solvent is 1 (3-6).

In one embodiment of the present application, in the step 2), the amount of the ethyl nitrite substance and the amount of the phenol substance are (1 to 1.3): 1.

In one embodiment of the present application, in step 3), the inert gas is nitrogen gas, so as to isolate air, inhibit disproportionation and decomposition of ethyl nitrite and oxidation of intermediate p-benzoquinone monooxime.

In one embodiment of the present application, in the step 4), the mass of hydrogen chloride to the mass of phenol is (1 to 2) to 1, the organic solvent is absolute ethanol, and the mass of hydrogen chloride to the mass of organic solvent is (1 to 5).

In one embodiment of the application, in the step 5), when the temperature of the intermediate liquid B in the reaction kettle is reduced to 0 ℃, the mixed solution of the hydrogen chloride and the organic solvent prepared in the step 4) is dripped into the intermediate liquid B in the reaction kettle, and the dripping is completed within 1.5-3 h in the dripping process;

the reaction temperature of the nitrosation reaction is 0-8 ℃, and the reaction time of the nitrosation reaction is 0.5-2 h.

In one embodiment of the application, in the step 6), the mass of hydroxylamine hydrochloride is (1-1.3) to 1;

the reaction temperature of the oximation reaction is 60-75 ℃, and the reaction time of the oximation reaction is 2-4 h.

In one embodiment of the present application, the evaporation temperature during the distillation in step 7) is 70 ℃ to 85 ℃.

In one embodiment of the application, the filtrate obtained in step 8) and the waste water generated by washing in step 9) are mixed, then neutralized with an alkaline solution, and then evaporated and condensed to remove hydrogen chloride in the filtrate and the waste water, wherein the evaporation temperature is 90 ℃ to 105 ℃.

The application solves the theory of operation of waste water technical problem: the water solvent in the traditional synthesis process is replaced by absolute ethyl alcohol as the solvent, so that the introduction of water is avoided, and the output of waste water is reduced. The water contained in the synthesis reaction is only a small amount of water contained in concentrated hydrochloric acid, and the finally existing form is the waste water containing hydrogen chloride, and the hydrogen chloride can be removed in a filter residue mode through liquid alkali neutralization, distillation and condensation after ethanol is distilled and recovered.

This application solves the theory of operation of the low technical problem of raw and other materials utilization ratio: ethyl nitrite and phenol are subjected to nitrosation reaction under the action of an acidic reaction promoter to generate p-benzoquinone monooxime and ethanol, the p-benzoquinone monooxime is an intermediate for synthesizing p-benzoquinone dioxime, and the byproduct ethanol and an organic solvent ethanol can be recovered after distillation and condensation.

The application solves the working principle that the ethyl nitrite is easy to disproportionate and decompose when meeting air: in the reaction process, air and ethyl nitrite are completely isolated by using inert gas, so that a side reaction caused by the unstable property of the ethyl nitrite is avoided, and the reaction safety and the conversion rate are improved.

The application solves the working principle of the technical problem that p-benzoquinone monooxime is oxidized in air: in the reaction process, the inert gas is used for completely isolating the air from the intermediate p-benzoquinone monooxime, so that the p-benzoquinone monooxime is prevented from being oxidized by contacting with the air to generate quinone substances, and the yield and the quality of the p-benzoquinone dioxime are improved.

Methods and devices not described in detail in the present invention are all the prior art and are not described in detail.

For further understanding of the present invention, the following examples are provided to illustrate the preparation method of benzoquinone dioxime, and the scope of the present invention is not limited by the following examples.

Example 1

A preparation method of p-benzoquinone dioxime comprises the following steps of:

1) cooling the reaction kettle to 0-5 ℃, dissolving 39.38g of ethyl nitrite in 157.52g of absolute ethyl alcohol, uniformly mixing to obtain an intermediate liquid A, and slowly adding the intermediate liquid A into the cooled reaction kettle;

2) adding 47g of phenol into the intermediate liquid A prepared in the step 1), and uniformly mixing to obtain an intermediate liquid B;

3) vacuumizing the reaction kettle after the step 2) is finished, and then filling inert gas into the reaction kettle;

in the step 3), the inert gas is nitrogen and is used for isolating air and inhibiting the decomposition of ethyl nitrite;

4) dissolving 48.02g of concentrated hydrochloric acid with the mass fraction of 36-38% in 72.03g of absolute ethanol, and uniformly mixing to obtain an ethanol solution of hydrogen chloride;

5) nitrosation reaction: when the temperature of the intermediate liquid B in the reaction kettle is reduced to 0 ℃, dropwise adding the ethanol solution of hydrogen chloride prepared in the step 4) into the intermediate liquid B in the reaction kettle, carrying out chemical reaction on ethyl nitrite, phenol and hydrogen chloride in an inert gas atmosphere to generate benzoquinone monooxime, and obtaining an intermediate liquid C after the reaction;

in the step 5), finishing the dripping within 1.5h in the dripping process;

the reaction temperature of the nitrosation reaction is 0-8 ℃, and the reaction time of the nitrosation reaction is 0.5 h;

6) oximation reaction: adding 41.7g of hydroxylamine hydrochloride solid into the intermediate liquid C prepared in the step 5), and carrying out a chemical reaction on p-benzoquinone monooxime and hydroxylamine hydrochloride in an inert gas atmosphere to generate p-benzoquinone dioxime, thus obtaining an intermediate liquid D;

the reaction temperature of the oximation reaction is 70 ℃, and the reaction time of the oximation reaction is 2 h;

7) distilling the intermediate liquid D prepared in the step 6), condensing vapor generated by evaporation to obtain condensate, recovering the organic solvent from the condensate, and obtaining the residual liquid after evaporation;

in the step 7), the evaporation temperature in the distillation process is 75 ℃;

8) filtering the residual evaporation solution prepared in the step 7), and obtaining filter residue and filtrate after filtering;

9) and (3) sequentially washing, centrifugally dewatering and drying the filter residue prepared in the step 8) to obtain powdery benzoquinone dioxime.

By detection and measurement, the p-benzoquinone dioxime prepared in example 1 had a mass of 60.06g, a yield of 86.97%, a light gray powder appearance, a purity of 99.562 wt%, and a DSC Peak point of 250.18 ℃.

Example 2

A preparation method of p-benzoquinone dioxime comprises the following steps of:

1) cooling the reaction kettle to 0-5 ℃, dissolving 39.38g of ethyl nitrite in 157.52g of absolute ethyl alcohol, uniformly mixing to obtain an intermediate liquid A, and slowly adding the intermediate liquid A into the cooled reaction kettle;

2) adding 47g of phenol into the intermediate liquid A prepared in the step 1), and uniformly mixing to obtain an intermediate liquid B;

3) vacuumizing the reaction kettle after the step 2) is finished, and then filling inert gas into the reaction kettle;

in the step 3), the inert gas is nitrogen and is used for isolating air and inhibiting the decomposition of ethyl nitrite;

4) dissolving 96.05g of concentrated hydrochloric acid with the mass fraction of 36-38% in 144.08g of absolute ethanol, and uniformly mixing to obtain an ethanol solution of hydrogen chloride;

5) nitrosation reaction: when the temperature of the intermediate liquid B in the reaction kettle is reduced to 0 ℃, dropwise adding the ethanol solution of hydrogen chloride prepared in the step 4) into the intermediate liquid B in the reaction kettle, carrying out chemical reaction on ethyl nitrite, phenol and hydrogen chloride in an inert gas atmosphere to generate benzoquinone monooxime, and obtaining an intermediate liquid C after the reaction;

in the step 5), finishing the dripping within 1.5h in the dripping process;

the reaction temperature of the nitrosation reaction is 0-8 ℃, and the reaction time of the nitrosation reaction is 0.5 h;

6) oximation reaction: adding 41.7g of hydroxylamine hydrochloride solid into the intermediate liquid C prepared in the step 5), and carrying out a chemical reaction on p-benzoquinone monooxime and hydroxylamine hydrochloride in an inert gas atmosphere to generate p-benzoquinone dioxime, thus obtaining an intermediate liquid D;

the reaction temperature of the oximation reaction is 70 ℃, and the reaction time of the oximation reaction is 2 h;

7) distilling the intermediate liquid D prepared in the step 6), condensing vapor generated by evaporation to obtain condensate, recovering the organic solvent from the condensate, and obtaining the residual liquid after evaporation;

in the step 7), the evaporation temperature in the distillation process is 75 ℃;

8) filtering the residual evaporation solution prepared in the step 7), and obtaining filter residue and filtrate after filtering;

9) and (3) sequentially washing, centrifugally dewatering and drying the filter residue prepared in the step 8) to obtain powdery benzoquinone dioxime.

By detection and measurement, the p-benzoquinone dioxime prepared in example 2 had a mass of 61.24g, a yield of 88.68%, a light gray powder appearance, a purity of 99.642 wt%, and a DSC Peak point of 251.66 ℃.

Example 3

A preparation method of p-benzoquinone dioxime comprises the following steps of:

1) cooling the reaction kettle to 0-5 ℃, dissolving 39.38g of ethyl nitrite in 157.52g of absolute ethyl alcohol, uniformly mixing to obtain an intermediate liquid A, and slowly adding the intermediate liquid A into the cooled reaction kettle;

2) adding 47g of phenol into the intermediate liquid A prepared in the step 1), and uniformly mixing to obtain an intermediate liquid B;

3) vacuumizing the reaction kettle after the step 2) is finished, and then filling inert gas into the reaction kettle;

in the step 3), the inert gas is nitrogen and is used for isolating air and inhibiting the decomposition of ethyl nitrite;

4) dissolving 96.05g of concentrated hydrochloric acid with the mass fraction of 36-38% in 288.15g of absolute ethanol, and uniformly mixing to obtain an ethanol solution of hydrogen chloride;

5) nitrosation reaction: when the temperature of the intermediate liquid B in the reaction kettle is reduced to 0 ℃, dropwise adding the ethanol solution of hydrogen chloride prepared in the step 4) into the intermediate liquid B in the reaction kettle, carrying out chemical reaction on ethyl nitrite, phenol and hydrogen chloride in an inert gas atmosphere to generate benzoquinone monooxime, and obtaining an intermediate liquid C after the reaction;

in the step 5), finishing the dripping within 2h in the dripping process;

the reaction temperature of the nitrosation reaction is 0-8 ℃, and the reaction time of the nitrosation reaction is 0.5 h;

6) oximation reaction: adding 41.7g of hydroxylamine hydrochloride solid into the intermediate liquid C prepared in the step 5), and carrying out a chemical reaction on p-benzoquinone monooxime and hydroxylamine hydrochloride in an inert gas atmosphere to generate p-benzoquinone dioxime, thus obtaining an intermediate liquid D;

the reaction temperature of the oximation reaction is 70 ℃, and the reaction time of the oximation reaction is 2 h;

7) distilling the intermediate liquid D prepared in the step 6), condensing vapor generated by evaporation to obtain condensate, recovering the organic solvent from the condensate, and obtaining the residual liquid after evaporation;

in the step 7), the evaporation temperature in the distillation process is 75 ℃;

8) filtering the residual evaporation solution prepared in the step 7), and obtaining filter residue and filtrate after filtering;

9) and (3) sequentially washing, centrifugally dewatering and drying the filter residue prepared in the step 8) to obtain powdery benzoquinone dioxime.

By detection and measurement, the p-benzoquinone dioxime prepared in example 3 had a mass of 62.74g, a yield of 90.85%, a pale gray powder appearance, a purity of 99.750 wt%, and a DSC Peak point of 254.39 ℃.

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.