阅读说明：本技术 一种多金属氧酸盐高效制备甲苯二异氰酸酯化合物的方法 (Method for efficiently preparing toluene diisocyanate compound by polyoxometallate ) 是由 韩志成 余焓 吴志康 但德敏 于 2019-04-23 设计创作，主要内容包括：本发明公开了一种多酸催化剂催化2,6-二氨基甲苯和甲醇偶联生成甲苯二异氰酸酯(TDI)的制备方法(其中多金属氧酸盐为Keggin型、Wells-Dawson型、Anderson型、Lindqvist型、Waugh型及Silverton型的六大基本构型中的一种,以Anderson型构型为主)本发明具体实施步骤为：将催化剂、济剂甲苯,原料2,6-二氨基甲苯和甲醇以及双氧水、缚酸剂和脱水剂一起放入洁净的反应管中,并在一定温度条件的空气氛围下磁力搅拌充分反应,分离纯化后即可得到目标产品；本发明避免了传统合成方法中使用高腐蚀性,易制毒试剂,高温高压的反应条件,而采用过氧化氢作为氧化剂,并采用非贵金属Fe,Cu,Ni,Cr等为中心金属的杂多酸作为催化剂催化生成甲苯二异氰酸酯(TDI),该催化剂具有极高的反应活性,反应结束后,样品经过简单处理后其使用的催化剂可回收再利用,对环境友好,提高了反应的清洁性,降低了生产制造成本。(The invention discloses a preparation method for generating Toluene Diisocyanate (TDI) by catalyzing 2, 6-diaminotoluene and methanol to be coupled by a polyacid catalyst (wherein polyoxometallate is one of six basic configurations of Keggin type, Wells-Dawson type, Anderson type, Lindqvist type, Waugh type and Silverton type, and the Anderson type configuration is taken as a main configuration), which comprises the following specific implementation steps: putting a catalyst, a solvent toluene, 2, 6-diaminotoluene, methanol, hydrogen peroxide, an acid-binding agent and a dehydrating agent into a clean reaction tube, magnetically stirring the materials under a certain temperature condition in an air atmosphere for full reaction, and separating and purifying the materials to obtain a target product; the invention avoids the reaction conditions of high corrosivity, easy-to-prepare toxic reagent, high temperature and high pressure in the traditional synthesis method, adopts hydrogen peroxide as an oxidant, and adopts heteropolyacid taking non-noble metal Fe, Cu, Ni, Cr and the like as central metal as a catalyst to catalyze and generate Toluene Diisocyanate (TDI), the catalyst has extremely high reaction activity, and after the reaction is finished, the used catalyst can be recycled after the sample is simply treated, so that the catalyst is environment-friendly, the reaction cleanness is improved, and the production and manufacturing cost is reduced.)

1. A preparation method of a catalyst for preparing Toluene Diisocyanate (TDI) by one-step coupling by using 2, 6-diaminotoluene and methanol as raw materials is characterized by comprising the following specific steps:

1) adding a polyoxometallate catalyst and an organic solvent toluene into a clean reaction vessel, then adding raw materials of 2, 6-diaminotoluene and methanol, finally adding hydrogen peroxide, an acid-binding agent and a dehydrating agent, uniformly mixing, carrying out magnetic stirring reaction at 0-50 ℃, reacting for about 6-24 h, and separating and purifying after the reaction to obtain the corresponding toluene diisocyanate compound.

2) And (2) recycling the heteropoly acid catalyst used in the step (1) and then inspecting the catalytic activity of the heteropoly acid catalyst.

3) The reaction conditions were optimized.

2. The method of claim 1, wherein: in the step 1), the polyoxometallate is mainly in an Anderson configuration.

3. The method of claim 1, wherein: in the step 1), the organic solvent is an aprotic polar solvent, the reaction temperature is 0-30 ℃, and the reaction time is 6-12 h.

4. The method of claim 1, wherein in step 1), the acid-binding agent is one of triethylamine or pyridine.

5. The method according to claim 1, wherein in step 1), the dehydrating agent is one of DMSO and phosphorus oxychloride.

6. The method according to claim 1, wherein in step 2), after the reaction is completed and the organic solvent is added to the phase system, the polyoxometallate (polyacid) catalyst is precipitated and treated for recycling, and the recycled catalyst can be reused in a new oxidative coupling reaction.

7. The method of claim 1, wherein in step 3), the temperature of the reaction, the solvent, the dehydrating agent, the acid-binding agent, the catalyst and the amount of the catalyst are selected by controlling variables to obtain optimal reaction conditions.

8. The process according to claim 3, wherein the catalyst is a polyoxometalate centered on a metal such as Fe, Cu, Ni or Cr, or a polyoxometalate centered on Fe, Cu, Ni or Cr modified with a Tris derivative (trialkoxy derivative), and the amount of the heteropolyacid catalyst is 0.1 to 3 mol%.

9. The method according to claim 4, wherein the dehydrating agent is phosphorus oxychloride, which can be added directly, and the amount of phosphorus oxychloride is 0.5 to 2.5 equivalents.

10. The preparation method of claim 5, wherein when the acid-binding agent is triethylamine, the acid-binding agent can absorb acid generated in the reaction process, so that the acid is prevented from influencing the reaction balance, and the amount of the triethylamine is 0.1-2 equivalents.

Technical Field

The invention relates to the technical field of catalysis, in particular to a method for preparing toluene diisocyanate by high-efficiency catalysis of polyoxometallate mainly of Anderson type.

Background

TDI is a basic raw material for producing polyurethane. Polyurethane is an important branch of synthetic resins, and soft foams, hard foams, elastomers and coatings made therefrom have a wide range of applications in the furniture making, automotive, construction and petrochemical industries. In addition, the dimer of 2, 4-toluene diisocyanate is also a vulcanizing agent for the slush type urethane rubber. In recent years, with the development of the polyurethane industry, the demand of toluene diisocyanate has also increased greatly. Therefore, the international and domestic TDI markets have great development space.

The polyacid is also called polyoxometallate, the structure of the polyacid is clear, the stability of the polyacid is good, the polyacid has good solubility in a polar solvent according to the current report, the polyacid is a bifunctional catalyst and has acidity and alkalinity, the research on the polyacid mostly focuses on Keggin type and Dawson type polyacid at present, the research on Anderson type polyacid which has a simple structure and is easy to prepare starts late, the current research mainly aims at modifying the polyacid by a plurality of different functional groups, most of the modifications are organic pairs called main, however, the desired heteropoly acid with one-side modification can be obtained by adjusting the proportion between organic and inorganic ligands, but the reaction has the disadvantage that the obtained product is difficult to purify, and the obtained yield is naturally low. Therefore, the research of an efficient and simple route for synthesizing the asymmetrically modified polyoxometallate is worthy of further research of scientific researchers.

The current production methods for preparing toluene diisocyanate mainly comprise 3 methods: amine phosgenation, nitro compound carbonylation and dimethyl carbonate. In 1849, Wurz successfully synthesized TDI. In 1884, Henthsel synthesized isocyanates by the primary amine phosgene process. The synthesis of TDI by a phosgene method becomes one of the main preparation methods of TDI. The amine phosgenation of TDI uses a liquid phase process, i.e. the raw materials are dissolved in a solvent and the reaction is carried out in solution. This is the predominant method of making TDI. The nitro compound carbonylation process uses dinitrotoluene, CO and fatty alcohol as raw materials, and uses chromium, rhodium, palladium and the like as carbonyl catalysts to directly react dinitrotoluene and CO in the fatty alcohol to generate toluene diisocyanate. The dimethyl carbonate method is to synthesize 2, 4-methyl diaminotoluene (TDC) under the catalysis of 2, 4-diaminotoluene (TDA) and DMC by using DMC instead of phosgene under mild reaction conditions. And (4) carrying out TDC (time delay converter) re-catalytic decomposition to obtain TDI.

Patent CN103936623B discloses a process for preparing toluene diisocyanate by using toluene diamine and dimethyl carbonate, which has the disadvantages of high temperature and high pressure. While causing heavy metal contamination, the production cost is also increased.

The method utilizes 2, 6-diaminotoluene and methanol to generate the toluene diisocyanate through one-step coupling, adopts a one-pot method, is simple and convenient to operate, high in yield, mild in condition, environment-friendly, easy to recycle and high in recycling rate, uses the hydrogen peroxide as an oxidant, and only has water as a product without other pollutants, so that the operation steps of separating and purifying intermediate products and the like can be avoided by directly synthesizing the toluene diisocyanate by taking amines and alcohol compounds as reaction substrates.

Disclosure of Invention

In order to solve the defects in the prior art, the method takes 2, 6-diaminotoluene and methanol as raw materials, adds a solvent, hydrogen peroxide, an acid-binding agent, a dehydrating agent and a polyoxometallate catalyst, and couples the raw materials under air magnetic stirring to generate corresponding toluene isocyanate.

Technical scheme

A preparation method of a catalyst for one-step preparation of toluene diisocyanate compounds by oxidative coupling of amine compounds is characterized by comprising the following specific steps:

1) adding 2, 6-diaminotoluene and methanol into a reactor filled with a catalyst and an organic solvent, finally adding hydrogen peroxide, an acid-binding agent and a dehydrating agent into a container, stirring and reacting at 0-30 ℃, separating and purifying to obtain the corresponding isocyanate compound-toluene diisocyanate, wherein the acid-binding agent and the dehydrating agent are used for reaction for 6-12 hours.

2) The catalyst used in step (1) was recovered and reused, and its catalytic activity was examined.

3) Reaction conditions are optimized, such as adding a dehydrating agent to improve the reaction yield, and the universality of reaction substrates is researched.

The oxidative coupling of amines of the present invention is represented by the general formula

In the invention, the organic solvent in the step 1) adopts an aprotic polar solvent such as anhydrous acetonitrile, DMSO, toluene and the like, preferably a solvent of toluene; the catalyst can be polyoxometallate taking non-noble metals such as Mn, Fe, Ni, Cr and the like as the center, and also can be Anderson type polyoxometallate taking Mn, Fe, Ni, Cr and the like as the center metal modified by a Tris derivative (trialkoxy derivative), the Fe-POM catalyst is adopted in the experiment, and the amount of the catalyst is more suitable when being 0.1 mol% -3 mol%, and is optimal when being 1 mol%; the reaction temperature can be 0-30 ℃, and the effect is optimal when the temperature is 0 ℃; the reaction time can be between 6h and 12h, and is optimal when 12h is needed; triethylamine is used as an acid-binding agent, and the amount of the triethylamine is optimal to 0.5 equivalent; the amount of phosphorus oxychloride is optimal at 1.0 equivalent, and the amount of hydrogen peroxide is optimal at 3 equivalents.

In the step 2) of the invention, the recovered catalyst is recycled, organic solvents such as ether, ethanol, methanol and the like can be added into a phase system after the reaction is finished, polyoxometallate (heteropoly acid) is separated out, the polyoxometallate (heteropoly acid) is recovered after treatment, and the recovered polyacid is reused for the oxidative coupling reaction.

And screening the solvent, the temperature, the additive amount, the catalyst amount and the dehydrating agent amount of the reaction by using a controlled variable method to obtain the optimal reaction condition.

Compared with the existing method for preparing toluene diisocyanate, the method has the following advantages: the catalyst is a novel catalyst, namely Anderson type polyoxometallate (heteropoly acid), the central metals are common non-noble metals of Mn, Fe, Ni and Cr, the price is low, the catalyst is easy to obtain, and the catalyst can be recycled for multiple times after simple treatment, thereby being very beneficial to industrialization.

Drawings

FIG. 1 is an Anderson type polyacid infrared modified with infrared polyoxometallate and Tris derivatives based on Anderson type (taking iron as the metal center as an example)

FIG. 2 is an Anderson type polyacid nuclear magnetic resonance modified with Tris derivative (taking iron as the metal center as an example)

FIG. 3 is an SEM image of an Anderson-type polyoxometallate (taking iron as a metal center as an example)

FIG. 4 is an SEM image of an Anderson-type polyacid modified with a Tris derivative (e.g., iron as the metal center)

FIG. 5 is a comparison of XRD of an Anderson-type polyoxometallate with that of a plurality of times recycled (taking iron as a metal center as an example)

Detailed Description

In order to further explain the present invention in detail, several specific embodiments are given below, but the present invention is not limited to these examples.

Example 1

A25 mL clean reaction tube was charged with 0.0240g (0.02mmol) of nickel-centered polyoxometallate [ NH ]₄]₄[NiMo₆O₁₈(OH)₆]·7H₂O(NiMo₆) 6mL of toluene solvent, 0.2484g (2mmol) of 2, 6-diaminotoluene, 0.0641g (2mmol) of methanol, 0.3067g (2mmol) of phosphorus oxychloride, 0.2041g (6mmol) of hydrogen peroxide and 0.1012g (1mmol) of triethylamine, and finally sleeving a balloon above a reaction tube to react for 12 hours at 0 ℃; after the reaction is finished, sampling and measuring GC-MS, obtaining that the conversion rate of a reaction substrate is more than 85 percent, the selectivity of a product is 89 percent, separating and purifying to obtain a light yellow liquid, and confirming the product toluene diisocyanate by nuclear magnetism.

Example 2

A25 mL clean reaction tube was charged with 0.0240g (0.02mmol) of iron-centered polyoxometallate [ NH ]₄]₃[FeMo₆O₁₈(OH)₆]·7H₂O(FeMo₆) 6mL of a toluene solvent, 0.2484g (2mmol) of 2, 6-diaminoToluene, 0.0641g (2mmol) of methanol, 0.3067g (2mmol) of phosphorus oxychloride, 0.2041g (6mmol) of hydrogen peroxide and 0.1012g (1mmol) of triethylamine are sleeved on a reaction tube, and the reaction is carried out for 12 hours at 0 ℃; after the reaction is finished, sampling and measuring GC-MS, obtaining that the conversion rate of a reaction substrate is more than 93 percent, the selectivity of a product is 91 percent, separating and purifying to obtain a light yellow liquid, and confirming the product toluene diisocyanate by nuclear magnetism.

Example 3

A25 mL clean reaction tube was charged with 0.0240g (0.02mmol) of copper-centered polyoxometallate [ NH ]₄]₄[CuMo₆O₁₈(OH)₆]·7H₂O(CuMo₆) 6mL of toluene solvent, 0.2484g (2mmol) of 2, 6-diaminotoluene, 0.0641g (2mmol) of methanol, 0.3067g (2mmol) of phosphorus oxychloride, 0.2041g (6mmol) of hydrogen peroxide and 0.1012g (1mmol) of triethylamine, and finally sleeving a balloon above a reaction tube to react for 12 hours at 0 ℃; after the reaction is finished, sampling and measuring GC-MS, obtaining that the conversion rate of a reaction substrate is more than 91 percent, the selectivity of a product is 89 percent, separating and purifying to obtain a light yellow liquid, and confirming the product toluene diisocyanate by nuclear magnetism.

Example 4

A25 mL clean reaction tube was charged with 0.0240g (0.02mmol) of chromium-centered polyoxometallate [ NH ]₄]₃[CrMo₆O₁₈(OH)₆]·7H₂O(CrMo₆) 6mL of toluene solvent, 0.2484g (2mmol) of 2, 6-diaminotoluene, 0.0641g (2mmol) of methanol, 0.3067g (2mmol) of phosphorus oxychloride, 0.2041g (6mmol) of hydrogen peroxide and 0.1012g (1mmol) of triethylamine, and finally sleeving a balloon above a reaction tube to react for 12 hours at 0 ℃; after the reaction is finished, sampling and measuring GC-MS, obtaining that the conversion rate of a reaction substrate is more than 88 percent, the selectivity of a product is 92 percent, separating and purifying to obtain a light yellow liquid, and determining the product toluene diisocyanate through nuclear magnetism.

Example 5

0.0407g (0.02mmol) of nickel-centered polyoxometallate modified on one side with a Tris derivative [ [ N (C) ] was added to a 25mL clean reaction tube₄H₉)₄]₄[NiMo₆O₁₈(OH)₃{(OCH₂)₃CCH₂OH}]·13H₂O (CH₂OH-NiMo₆) 6mL of solvent toluene, 0.4207g (2mmol) of 4, 4' -diaminodicyclohexylmethane, 0.0641g (2mmol) of methanol, 0.1012g (1mmol) of triethylamine, 0.2041g (6mmol) of hydrogen peroxide and 0.3067g (2mmol) of phosphorus oxychloride, and finally covering an oxygen balloon above a reaction tube to react for 12 hours at 0 ℃; after the reaction is finished, sampling and measuring GC-MS, and obtaining that the conversion rate of a reaction substrate is more than 92 percent and the selectivity of a product is 89 percent; adding diethyl ether (or ethyl acetate and other organic solvents) into the final reaction system, filtering to obtain a white solid, washing, drying, collecting and recycling. Separating and purifying to obtain light yellow liquid, and confirming the product toluene diisocyanate by nuclear magnetic test analysis.

Example 6

0.0407g (0.02mmol) of an iron-centered polyoxometalate modified on one side with a Tris derivative [ [ N (C) ] was added to a 25mL clean reaction tube₄H₉)₄]₃[FeMo₆O₁₈(OH)₃{(OCH₂)₃CCH₂OH}]·13H₂O (CH₂OH-FeMo₆) 6mL of solvent toluene, 0.4207g (2mmol) of 4, 4' -diaminodicyclohexylmethane, 0.0641g (2mmol) of methanol, 0.1012g (1mmol) of triethylamine, 0.2041g (6mmol) of hydrogen peroxide and 0.3067g (2mmol) of phosphorus oxychloride, and finally covering an oxygen balloon above a reaction tube to react for 12 hours at 0 ℃; after the reaction is finished, sampling and measuring GC-MS, and obtaining that the conversion rate of a reaction substrate is more than 92 percent and the selectivity of a product is 91 percent; adding diethyl ether (or ethyl acetate and other organic solvents) into the final reaction system, filtering to obtain a white solid, washing, drying, collecting and recycling. Separating and purifying to obtain light yellow liquid, and confirming the product toluene diisocyanate by nuclear magnetic test analysis.

Example 7

0.0407g (0.02mmol) of copper-centered polyoxometallate modified on one side with a Tris derivative [ N (C) ]was added to a 25mL clean reaction tube₄H₉)₄]₄[CuMo₆O₁₈(OH)₃{(OCH₂)₃CCH₂OH}]·13H₂O (CH₂OH-CuMo₆) 6mL of solvent toluene, 0.4207g (2mmol) of 4, 4' -diaminodicyclohexylmethane, 0.0641g (2mmol) of methanol, 0.1012g (1mmol) of triethylamine, 0.2041g (6mmol) of hydrogen peroxide and 0.3067g (2mmol) of phosphorus oxychloride, and finally covering an oxygen balloon above a reaction tube to react for 12 hours at 0 ℃; after the reaction is finished, sampling and measuring GC-MS, and obtaining that the conversion rate of a reaction substrate is more than 89 percent and the selectivity of a product is 90 percent; adding diethyl ether (or ethyl acetate and other organic solvents) into the final reaction system, filtering to obtain a white solid, washing, drying, collecting and recycling. Separating and purifying to obtain light yellow liquid, and confirming the product toluene diisocyanate by nuclear magnetic test analysis.

Example 8

0.0407g (0.02mmol) of chromium-centered polyoxometallate modified on one side with a Tris derivative [ [ N (C) ] was added to a 25mL clean reaction tube₄H₉)₄]₃[CrMo₆O₁₈(OH)₃{(OCH₂)₃CCH₂OH}]·13H₂O (CH₂OH-CrMo₆) 6mL of solvent toluene, 0.4207g (2mmol) of 4, 4' -diaminodicyclohexylmethane, 0.0641g (2mmol) of methanol, 0.1012g (1mmol) of triethylamine, 0.2041g (6mmol) of hydrogen peroxide and 0.3067g (2mmol) of phosphorus oxychloride, and finally covering an oxygen balloon above a reaction tube to react for 12 hours at 0 ℃; after the reaction is finished, sampling and measuring GC-MS, and obtaining that the conversion rate of a reaction substrate is more than 89 percent and the selectivity of a product is 90 percent; adding diethyl ether (or ethyl acetate and other organic solvents) into the final reaction system, filtering to obtain a white solid, washing, drying, collecting and recycling. Separating and purifying to obtain light yellow liquid, and confirming the product toluene diisocyanate by nuclear magnetic test analysis.

Example 9

The reaction steps are the same as example 6, and are different from example 2 in that the catalyst is recovered and used for the 1 st time, GC-MS analysis shows that the conversion rate of the reaction substrate is more than 90%, the selectivity is about 91%, the product is obtained by separation and purification, and the product is confirmed to be toluene diisocyanate by nuclear magnetism.

Example 10

The reaction steps are the same as example 6, and are different from example 2 in that the catalyst is used for the 2 nd time after being recovered, GC-MS analysis shows that the conversion rate of the reaction substrate is more than 89%, the selectivity is about 91%, the product is obtained by separation and purification, and nuclear magnetism confirms that the product is toluene diisocyanate.

Example 11

The reaction procedure is the same as that in example 6, and is different from example 2 in that the catalyst is recovered and used for the 3 rd time, the GC-MS analysis shows that the conversion rate of the reaction substrate is 88%, the selectivity is about 89%, the product is obtained by separation and purification, and the nuclear magnetism confirms that the product is toluene diisocyanate.

Example 12

The reaction procedure is the same as example 6, and is different from example 2 in that the catalyst is used 4 th time after recovery, GC-MS analysis shows that the conversion rate of the reaction substrate is 83%, the selectivity is about 85%, the product is obtained by separation and purification, and nuclear magnetism confirms that the product is toluene diisocyanate.

Example 13

The reaction procedure is the same as that of example 6, and is different from example 2 in that the catalyst is used for the 5 th time after being recovered, GC-MS analysis shows that the conversion rate of the reaction substrate is 81%, the selectivity is about 85%, the product is obtained by separation and purification, and nuclear magnetism confirms that the product is toluene diisocyanate.

All of the above-described first embodiments are not intended to suggest any alternative form of implementing the new and/or novel methods. Those skilled in the art will take advantage of this important information, and the foregoing will be modified to achieve similar performance. However, all modifications or adaptations based on the present invention belong to the rights reserved for the present invention.

The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.