CN108794305A - A method of preparing benzenediol - Google Patents

Abstract

The invention discloses a method for preparing hydroquinone, which comprises reacting dichlorobenzene with alkali metal hydroxide in a deep eutectic solvent, and separating the reaction product to obtain hydroquinone after acidification; the low eutectic The molten solvent is a mixture of hydrogen bond donors and hydrogen bond acceptors after drying, and heats and melts to form a uniform colorless transparent liquid as an alkaline hydrolysis carrier. Compared with the traditional method, the present invention has the advantages of simple reaction conditions, short reaction time, high yield and low cost, reduces the use of volatile organic solvents, is easy to industrialize, and is a green, simple and efficient synthesis method.

Description

A kind of method for preparing hydroquinone

technical field

The invention belongs to the field of organic chemical synthesis, and in particular relates to a method for preparing hydroquinone.

Background technique

Hydroquinone (catechol, resorcinol, hydroquinone) is an important raw material for fine organic chemical synthesis, and each isomer plays an important role in different fields. Among them, catechol is mainly used in the preparation of pharmaceutical intermediates, dyes, pesticides, photosensitive materials, electroplating materials, oxygen disruptors, light stabilizers, preservatives and accelerators. Resorcinol is mainly used in the preparation of rubber adhesives, synthetic resins, preservatives, pharmaceutical and analytical reagents, azo dyes, fur dye intermediates, cosmetics and dermatological drug pastes and ointments, etc. Hydroquinone can be used as a photographic developer, an antioxidant for rubber and gasoline, a corrosion inhibitor, a stabilizer and an antioxidant for detergents, and a hair dye for cosmetics.

The traditional industrial production methods of catechol and hydroquinone mainly contain: (1) o-chlorophenol or o-dichlorobenzene hydrolysis method; (2) o-methoxyphenol hydrolysis method; (3) aniline oxidation method; ( 4) Dicumyl oxidation method; the above four processes have complex reaction processes, many by-products, serious environmental pollution, and high production costs, which have been phased out abroad. (5) Hydroxylation of phenol hydrogen peroxide; the process route is simple, raw materials are cheap, and environmental pollution is low. The phenol hydrogen peroxide hydroxylation method uses phenol and hydrogen peroxide as raw materials, under the action of a catalyst, to generate catechol, co-produce hydroquinone, and a small amount of tar as a by-product. Although this method has a short process flow, less equipment, low investment, and no other by-products, it is technically difficult and difficult to realize in China in the short term. (6) Rhone-Planck method: hydroxylation reaction; carried out in three steel reactors in series, each reactor should be vigorously stirred to facilitate diffusion and heat conduction, but due to the use of HClO ₄ , H ₃ PO ₄ etc. are used as catalysts, which makes the post-treatment process complicated and the environment polluted greatly. (7) Ube method: Ube company uses the ketone peroxide generated by sulfuric acid and 60% hydrogen peroxide and methyl isobutyl ketone as a catalyst. The reaction product is distilled, and the added ketone can be recovered and recycled in the distillation. But its phenol conversion rate is too low. (8) Brichima method; the advantage of this method is that the conversion rate of phenol is high, the amount of recovery and circulation is small, and the post-treatment of the product is relatively simple. The disadvantage is that high-concentration H ₂ O ₂ is used, thereby increasing the cost of the product.

At present, looking at home and abroad, the technical means of producing diphenol mainly have the following disadvantages: (1) Most of the solvents used in the reaction process are volatile and toxic organic solvents, which cause certain pollution to the environment and certain harm to human health. , and the solvent recycling rate is low, and the post-processing cost is high. (2) The catalyst used is a noble metal oxide, and the cost is relatively high. (3) The technological process is loaded down with trivial details, and technical requirement is high, and the processing step of follow-up product is many, and productive rate is low. Therefore, the optimization of the preparation process of hydroquinone is a problem to be solved urgently, and has broad application prospects.

In the production and processing of chemical products, organic solvents are commonly used, and organic solvents are one of the important sources of environmental pollution. In recent years, the use of non-toxic and harmless green solvents to replace organic solvents has become the general trend of green chemical industry. Deep eutectic solvent is a substance formed by mixing two or more solid substances in a certain proportion. It is a new type of green and environmentally friendly solvent with the advantages of ionic liquids. It is characterized by readily available and cheap raw materials, recyclable use, easy preparation, low toxicity, biodegradability, high stability and renewable raw materials.

At present, deep eutectic solvents have attracted extensive attention from researchers all over the world. In 2003, Abbott's research group discovered a new class of urea-containing deep eutectic solvents, which can be easily obtained by mixing stoichiometric urea and choline chloride in a solid state. The melting point of this deep eutectic solvent is relatively high. Low, especially two molecules of urea and one molecule of choline chloride can form a mixture with a minimum melting point of 12°C through hydrogen bonding, and there will be no three-waste problem in the process; this kind of eutectic mixture is more acceptable to the environment, and now it has It is used in synthetic chemical reactions and other fields.

Contents of the invention

The technical problem solved: the present invention overcomes the deficiencies in the above-mentioned prior art and provides a method for preparing quinone, which uses a deep eutectic solvent (DES) as a reaction solvent and a catalyst for alkaline hydrolysis to prepare quinone , which has the advantages of low raw material cost, simple synthesis steps, recyclable solvent, low production cost, high yield, and environmental protection.

Technical solution: a method for preparing hydroquinone, the method comprising: in a deep eutectic solvent, reacting dichlorobenzene with an alkali metal hydroxide; cooling and filtering after the reaction to obtain a filtrate and a phenate solid; The solid is dispersed in water, acidified to a pH value of 4-5, and hydroquinone is separated from the system.

The synthesis reaction equation is:

Preferably, the deep eutectic solvent is a hydrogen bond donor and a hydrogen bond acceptor mixed after drying, heated and melted into a uniform colorless transparent liquid; the molar ratio of the hydrogen bond donor and hydrogen bond acceptor is 1:3 ~3:1.

Preferably, the hydrogen bond donor is at least one of urea, ethylene glycol, malonic acid, trans-cinnamic acid, suberic acid or adipic acid; the hydrogen bond acceptor is choline chloride, At least one of acetylcholine chloride or tetramethylammonium chloride.

Preferably, the molar ratio of the hydrogen bond donor and the hydrogen bond acceptor is 1:1.

Preferably, the mass ratio of the deep eutectic solvent to dichlorobenzene is 5-8:1; the molar ratio of dichlorobenzene to alkali metal hydroxide is 1:2-4.

Preferably, the dichlorobenzene is o-dichlorobenzene, m-dichlorobenzene or p-dichlorobenzene; the alkali metal hydroxide is at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide or barium hydroxide A sort of.

Preferably, the reaction temperature is 200-260°C, and the reaction time is 5-10 hours; after the reaction, the liquid-solid mixture is cooled to 150-180°C and filtered, and the product and liquid are mixed and separated by filtration to obtain the filtrate And phenate solid, wherein the filtrate is a mixture of unreacted dichlorobenzene and deep eutectic solvent, and the solid is alkali metal salt of quinone.

Preferably, the acid is at least one of hydrochloric acid, sulfuric acid or phosphoric acid; the mass fraction of the acid is 5% to 35%. After acidification, the system is divided into an oil layer and a water layer, and the oil layer obtained by liquid separation is The reaction product, the aqueous layer is an aqueous solution of an alkali metal salt.

Preferably, the mass fraction of the acid is 10% to 20%. If the acidity of the selected acid is too weak, it is not enough to acidify the sodium hydrochloride into hydroquinone. If the mass fraction of the selected acid is too large, the hydroquinone will Oxidized.

Beneficial effects: ① The present invention uses dichlorobenzene as raw material to produce hydroquinone, which is cheap and easy to obtain. Make the production cost lower.

②The present invention uses a deep eutectic solvent as a reaction solvent and a catalyst to prepare quinone, wherein the deep eutectic solvent has the advantages of not being volatile, low-toxic and degradable, low in price, easy to obtain and easy to prepare, and has the advantages of being used as a solvent to participate in the synthesis reaction. High, no solvent residue, recyclable and other advantages, is a new type of green solvent.

3. the present invention compares with traditional method, and the reaction condition of this method is simple, reaction time is short, productive rate is high, scope of application is wide, and has avoided the use of poisonous volatile solvent and expensive catalyst; In addition, deep eutectic solvent separation is simple, And can be recycled.

Detailed ways

The following examples can enable those skilled in the art to understand the present invention more fully, but do not limit the present invention in any way.

Example 1

The preparation process of deep eutectic solvent is as follows:

The hydrogen bond donor and the hydrogen bond acceptor were dried in a vacuum environment at 60°C, and mixed in a certain ratio (Table 1), and stirred at 300r/min at 120°C for 3h to become a uniform colorless transparent liquid. Cool to room temperature and set aside.

Table 1 deep eutectic solvent preparation molar ratio

Example 2

With 220.5g (1.5mol) o-dichlorobenzene, 120g (3.0mol) sodium hydroxide and 1.1kg deep eutectic solvent 3 (mass ratio of deep eutectic solvent and dichlorobenzene is 5: 1) prepared in embodiment 1 ) into a high-pressure reactor with a volume of 3L, react at 240°C for 5h; after stopping the reaction, cool to about 150°C, filter while it is hot, and collect the solid. The filtrate contains deep eutectic solvent and unreacted o-dichlorobenzene , which can be directly used in the next batch reaction.

The solid product obtained by filtration was dissolved in a certain amount of aqueous solution, acidified with 20% hydrochloric acid to pH = 4, and the oil phase was separated and refined to obtain catechol 73.2g with a yield of 44.4%.

Example 3

With 220.5g (1.5mol) p-dichlorobenzene, 160g (4mol) sodium hydroxide and 1.6kg deep eutectic solvent 20 prepared in embodiment 1 (mass ratio of deep eutectic solvent and dichlorobenzene is 7: 1) Add it into a high-pressure reactor with a volume of 3L, stir and react at 260°C for 6.5h; after stopping the reaction, cool to 150°C, heat filter, separate the solid and filtrate, the filtrate contains deep eutectic solvent and unreacted p-dichlorobenzene , which can be directly used in the next batch reaction.

The solid salt obtained by filtration was dissolved in water, acidified with 20% hydrochloric acid to pH=4, the oil phase was separated and then distilled to obtain 95.8 g of hydroquinone with a yield of 58.0%.

Example 4

With 22.0g (0.15mol) m-dichlorobenzene, 16.0g (0.4mol) sodium hydroxide and 160g deep eutectic solvent 7 prepared in embodiment 1 (the mass ratio of deep eutectic solvent and dichlorobenzene is 7: 1 ) was added to a high-pressure reactor with a volume of 0.5L, and reacted at 250°C for 7.5h; after the reaction was stopped, it was cooled to 150°C, filtered by heat, and the solid and the filtrate were separated. The filtrate contained deep eutectic solvent and unreacted metadiox Chlorobenzene can be directly used in the next batch of reactions.

The solid salt obtained by filtration was dissolved in water, acidified with 20% hydrochloric acid to pH = 4, and the oil phase was separated and distilled to obtain 7.4 g of resorcinol with a yield of 44.9%.

Example 5

With 220.5g (1.5mol) p-dichlorobenzene, 336g (6.0mol) potassium hydroxide and 1.2kg deep eutectic solvent 18 prepared in embodiment 1 (the mass ratio of deep eutectic solvent and dichlorobenzene is 5.5: 1 ) into a reaction kettle with a volume of 3L, stirred and reacted at 250°C for 5h; after the reaction, cooled to 150°C, filtered hot, separated solid and filtrate, the filtrate contained deep eutectic solvent and unreacted p-dichlorobenzene , which can be directly used in the next batch reaction.

The solid salt obtained by filtration was dissolved in water, acidified with 20% hydrochloric acid to pH=4, and the oil phase was separated and distilled to obtain 74.7 g of hydroquinone with a yield of 45.3%.

Example 6

With 220.5g (1.5mol) p-dichlorobenzene, 144g (6.0mol) lithium hydroxide and 1.2kg deep eutectic solvent 31 prepared in embodiment 1 (the mass ratio of deep eutectic solvent and dichlorobenzene is 5.5: 1 ) into a reaction kettle with a volume of 3L, stirred and reacted at 250°C for 5h; after the reaction, cooled to 130°C, filtered hot, and separated solid and filtrate, the filtrate contained deep eutectic solvent and unreacted p-dichlorobenzene , which can be directly used in the next batch reaction.

The solid salt obtained by filtration was dissolved in water, acidified with 20% sulfuric acid to pH = 4, and the oil phase was separated and distilled to obtain 103.9 g of hydroquinone with a yield of 63.0%.

Example 7

With 220.5g (1.5mol) m-dichlorobenzene, 144g (6.0mol) lithium hydroxide and 1.2kg deep eutectic solvent 36 prepared in embodiment 1 (the mass ratio of deep eutectic solvent and dichlorobenzene is 5.5: 1 ) was added to a reaction kettle with a solvent of 3L, and the reaction was stirred at 240°C for 5h; after the reaction, cooled to 100°C, hot filtered, and the solid and filtrate were separated, the filtrate contained deep eutectic solvent and unreacted m-dichlorobenzene , which can be directly used in the next batch reaction.

The solid salt obtained by filtration was dissolved in water, acidified with 20% sulfuric acid to pH=4, the oil phase was separated and distilled to obtain 90.0 g of resorcinol with a yield of 55.0%.

Example 8

With 220.5g (1.5mol) p-dichlorobenzene, 513g (3.0mol) barium hydroxide and 1.2kg deep eutectic solvent 4 prepared in embodiment 1 (the mass ratio of deep eutectic solvent and dichlorobenzene is 5.5: 1 ) into a reaction kettle with a volume of 3L, stirred and reacted at 250°C for 5h; after the reaction, cooled to 130°C, filtered hot, and separated solid and filtrate, the filtrate contained deep eutectic solvent and unreacted p-dichlorobenzene , which can be directly used in the next batch reaction.

The solid salt obtained by filtration was dissolved in water, acidified with 20% sulfuric acid to pH = 4, and the oil phase was separated and distilled to obtain 113.8 g of hydroquinone with a yield of 69.0%.

Example 9

The deep eutectic solvent 3 (mass ratio of deep eutectic solvent and dichlorobenzene is 6: 1) prepared in 22kg p-dichlorobenzene, 22.4kg potassium hydroxide and 130kg embodiment 1 is joined in the 300L reactor , Stir the reaction at 250°C for 5h; after the reaction, cool to 130°C, heat filter, separate the solid and the filtrate, the filtrate contains deep eutectic solvent and unreacted p-dichlorobenzene, and can be directly used for the next batch reaction.

The solid salt obtained by filtration was dissolved in water, acidified with 20% hydrochloric acid to pH=4, the oil phase was separated and distilled to obtain 9.8 kg of hydroquinone with a yield of 59.0%.

Example 10

The deep eutectic solvent 20 (mass ratio of deep eutectic solvent and dichlorobenzene is 6: 1) prepared in 22.0kg o-dichlorobenzene, 20.0kg sodium hydroxide and 120kg embodiment 1 is added to the reaction volume that is 300L In the kettle, stir and react at 200°C for 7h; after the reaction, cool to 110°C, heat filter, separate the solid and filtrate, the filtrate contains deep eutectic solvent and unreacted o-dichlorobenzene, which can be directly used in the next batch reaction .

The solid salt obtained by filtration was dissolved in water, acidified with 20% hydrochloric acid to pH=4, and the oil phase was separated and distilled to obtain catechol 7.0 kg with a yield of 42.4%.

Example 11

On the basis of Example 8, the temperature and time of the stirring reaction were changed, and the results are shown in Table 2.

The impact of table 2 reaction temperature and time on yield

Numbering Reaction temperature (°C) Reaction time (h) Yield (%) Experimental group 1-1 200 5 65.1 Experimental group 1-2 210 5 66.4 Experimental group 1-3 220 5 66.7 Experimental group 1-4 230 5 68.5 Experimental group 1-5 240 5 68.6 Experimental group 1-6 260 5 69.1 Control group 1-1 180 5 57.3 Control group 1-2 280 5 67.1 Experimental group 2-1 250 7 70.5 Experimental group 2-2 250 9 71.7 Experimental group 2-3 250 10 71.5 Control group 2-1 250 12 71.3 Control group 2-2 250 3 55.4

Example 12

On the basis of Example 8, the type of deep eutectic solvent used was changed, and the results are shown in Table 3.

The influence of table 3 different deep eutectic solvents on yield

Claims (9)

1. a kind of method preparing benzenediol, which is characterized in that the method includes：In eutectic solvent, dichloro-benzenes and alkali Metal hydroxides reacts；Cooling after reaction, filtering, obtains filtrate and phenates solid；The solid is dispersed in water, It is 4~5 to be acidified with acid to pH value, the isolated benzenediol from system.

2. a kind of method preparing benzenediol according to claim 1, it is characterised in that：The eutectic solvent is hydrogen bond It is mixed after donor and hydrogen bond receptor drying, heating and melting is at uniform colourless transparent liquid；The hydrogen bond donor and hydrogen bond receptor Molar ratio is 1: 3~3: 1.

3. a kind of method preparing benzenediol according to claim 2, it is characterised in that：The hydrogen bond donor be urea, At least one of ethylene glycol, malonic acid, trans-cinnamic acid, suberic acid or adipic acid；The hydrogen bond receptor is choline chloride, chlorine At least one of acetylcholine or tetramethyl ammonium chloride.

4. a kind of method preparing benzenediol according to claim 2, it is characterised in that：The hydrogen bond donor and hydrogen bond by The molar ratio of body is 1: 1.

5. a kind of method preparing benzenediol according to claim 1, it is characterised in that：The eutectic solvent and dichloro The mass ratio of benzene is 5~8: 1；The molar ratio of the dichloro-benzenes and alkali metal hydroxide is 1: 2~4.

6. a kind of method preparing benzenediol according to claim 1, it is characterised in that：The dichloro-benzenes is adjacent dichloro Benzene, m-dichlorobenzene or paracide；The alkali metal hydroxide is sodium hydroxide, potassium hydroxide, lithium hydroxide or hydroxide At least one of barium.

7. a kind of method preparing benzenediol according to claim 1, it is characterised in that：The reaction temperature be 200~ 260 DEG C, the reaction time is 5~10h；After reaction, the liquid-solid mixture is filtered after being cooled to 150~180 DEG C.

8. a kind of method preparing benzenediol according to claim 1, it is characterised in that：It is described acid be hydrochloric acid, sulfuric acid or At least one of phosphoric acid；The mass fraction of the acid is 5%~35%.

9. a kind of method preparing benzenediol according to claim 1, it is characterised in that：The mass fraction of the acid is 10%~20%.