KR20210057520A - zinc-imidazolate frameworks catalyst, manufacturing method thereof and preparation method for methyl N-aryl carbamate using the same - Google Patents

Abstract

The present invention relates to a catalyst, a manufacturing method thereof and a method for manufacturing methyl N-aryl carbamate using the same, and can provide the catalyst for manufacturing methyl N-aryl carbamate having very high catalytic activity even at a low temperature. In addition, when the catalyst for manufacturing the methyl N-aryl carbamate is used, the methyl N-aryl carbamate can be manufactured with high production yield and selectivity with only a small amount of catalyst.

Description

A catalyst, a method for preparing the same, and a method for preparing methyl N-aryl carbamate using the catalyst {zinc-imidazolate frameworks catalyst, manufacturing method thereof and preparation method for methyl N-aryl carbamate using the same}

The present invention relates to a catalyst, a method for preparing the same, and a method for preparing methyl N-aryl carbamate using the same, and more particularly, a zeolitic imidazole framework (ZIF) functionalized with dimethyl carbonate as a catalyst. By manufacturing, it relates to a method for producing methyl N-aryl carbamate with improved production rate and selectivity.

Aromatic carbamates are used in various fields such as carbonylating agents, methylating agents, gasoline additives, octane number enhancing agents, raw materials for producing isocyanates, which are monomers of polycarbonate resins and polyurethanes, and synthetic reactants of intermediates in pharmaceuticals. Isocyanates are usually produced by reacting amines with phosgene. The phosgene process has caused a significant problem in terms of environmental pollution due to its harmfulness.

Accordingly, in order to overcome the shortcomings of the phosgene process, a method capable of producing isocyanate without using phosgene has been studied in various ways, and representatively, the reductive carbonylation method of nitrobenzene [J. Mol. Catal. A: Chem. (2001) 9; J. Mol. catal. A: Chem. (2006) 64] and the oxidative carbonylation method of aniline [Green Chem. (2011) 3406; J. Catal. (1999) 526] and a method of methoxycarbonylation through the reaction of dimethyl carbonate and amine (US Pat. No. 4,268,683). The above methods obtain an aromatic carbamate as a final product, and the aromatic carbamate can be pyrolyzed as follows to synthesize an isocyanate.

As such, the reductive carbonylation of nitrobenzene and the oxidative carbonylation of aniline are advantageous in that they produce aromatic carbamates without using phosgene, but they use CO, which is known as a toxic gas, and use high temperatures (130- 250 ℃) and pressure (40-80 bar) conditions must be preceded, and there is a problem that noble metal catalysts (Ru, Pd, Rh, Se) must be used.

On the other hand, in the case of the methoxycarbonylation method of amine using dimethyl carbonate, the following reaction can be carried out under milder conditions than the above two methods, and has advantages such as using dimethyl carbonate, an environmentally friendly chemical substance. In addition, methanol produced as a by-product can be reused as a material to produce dimethyl carbonate through oxidative carbonylation, and relatively inexpensive metals such as Zn and Pb can be used as catalysts.

Patent Document 2 (U.S. Patent No. 3,763,217) describes a method of reacting an amine and an alkyl carbonate by using it as a Lewis acid catalyst such as uranyl nitrate under reflux condition, and in this case, the reaction time is 18 It is long at 24 hr, and the conversion and selectivity is low at about 20%.

In addition, Patent Document 1 (U.S. Patent No. 4,268,683) relates to a method of synthesizing carbamate using a halogen compound (halide) or an organic acid salt of Sn(II) or Zn(II), which is Lewis acid. As a result, when methyl N-phenyl carbamate was synthesized using zinc acetate among various catalysts, the selectivity was 99.8% at a temperature of 140° C. and a pressure of 0.88 MPa. However, according to the study of Non-Patent Literature 1 (Feng Li et al.), production of methyl N-phenyl carbamate using zinc acetate has difficulty in separation and recovery, and it is converted to zinc oxide by reacting with methanol after the reaction, thereby reducing the activity of the catalyst. It is known to lose.

In order to solve the above-described problem, a method of synthesizing an aromatic carbamate using _{Zn(OAc) 2} supported on a carrier is known in Non-Patent Document 2 (Zhangg L, etc.), but due to the change in the shape of _{Zn(OAc) 2} There is a disadvantage in that the catalytic activity gradually decreases as the reaction is repeated.

Patent Document 1. US Patent No. 3,763,217 Patent Document 2. US Patent No. 4,268,683

Non-Patent Document 1. Fang Li et. al. Appl., Catal. A: Gen., 475, 355-362 (2014) Non-Patent Document 2. Zhangg L et. al., Catalysis Today., 158, 279-285 (2010)

The present invention was conceived in consideration of the above problems, and an object of the present invention is to provide a catalyst that has high catalytic activity for the production reaction of methyl N-aryl carbamate and is capable of regeneration by reaction with dimethyl carbonate. It is to do.

Another object of the present invention is to provide a method for producing a catalyst for producing methyl N-aryl carbamate that can be mass-produced in a single process.

Another object of the present invention is to provide a method for preparing methyl N-aryl carbamate having excellent selectivity of methyl N-aryl carbamate by adding dimethyl carbonate to an aromatic amine compound using the catalyst.

One aspect of the present invention relates to a catalyst for preparing methyl N-aryl carbamate, characterized in that a methoxycarbonyloxy group is bonded to the edge of a zeolite imidazolate skeleton.

The methoxycarbonyloxy group may be contained in an amount of 0.01 to 0.07 mol per 1 mol of Zn in the zeolite imidazolate skeleton.

Another aspect of the present invention is (a) preparing a suspension by mixing a zeolite imidazolate skeleton with dimethyl carbonate; And

(b) It relates to a method for preparing a catalyst for preparing methyl N-aryl carbamate comprising the step of heating the suspension.

The step (a) comprises the steps of (a-1) dissolving a zinc salt and an imidazole or imidazole derivative in a solvent to prepare a precursor solution; And (a-2) heating the precursor solution to prepare a zeolite imidazolate skeleton.

The zinc salt is in the group consisting of zinc nitrate, zinc acetate, zinc chloride, zinc sulfate, zinc bromide, and zinc iodide. It may be one or more selected.

The imidazole or the imidazole derivative is benzimidazole, 2-methylimidazole, 4-methylimidazole, 2-methylbenzimidazole ), 2-nitroimidazole, 5-nitrobenzimidazole, and 5-chlorobenzimidazole.

The solvent is methanol, ethanol, propanol, iso-propanol, tert-butanol, n-butanol, methoxyethanol, ethoxyethanol, dimethylacetamide, dimethylformamide, n-methyl-2-pyrrolidone (NMP), It may be at least one selected from the group consisting of formic acid, nitromethane, acetic acid, and distilled water.

The zinc salt and the imidazole or the imidazole derivative may be mixed in a molar ratio of 1: 2 to 4, respectively.

In the step (a), the molar ratio of the zeolite imidazolate skeleton and dimethyl carbonate may be 1:15 to 25.

Another aspect of the present invention is a method for preparing methyl N-aryl carbamate comprising mixing a catalyst, an aromatic amine and dimethyl carbonate, and reacting at 150 to 250° C., wherein the catalyst is a zeolite imidazolate skeleton. It relates to a method for producing methyl N-aryl carbamate, characterized in that a methoxycarbonyloxy group is bonded to the edge.

The molar ratio of the aromatic amine compound and the dimethyl carbonate may be 1:5 to 40.

The catalyst may be added in an amount of 1 to 20 parts by weight based on 100 parts by weight of the aromatic amine compound.

The aromatic amine compound may be any one or more selected from the group consisting of aniline, phenylenediamine, methylenediphenyldiamine, and toluenediamine.

The present invention can provide a catalyst for preparing methyl N-aryl carbamate having very high catalytic activity and long-term stability.

In addition, it is more economical by providing a method for easily manufacturing the catalyst according to the present invention in a single process.

In addition, when the catalyst for preparing methyl N-aryl carbamate is used, it is possible to prepare methyl N-aryl carbamate with high production yield and selectivity with only a small amount of catalyst.

The left side of FIG. 1 is _{an SEM image of the zeolite imidazolate skeleton represented by Zn (Benzimidaole) 2} , and the right side of FIG. 1 is an SEM image of the catalyst for preparing methyl N-aryl carbamate prepared in Example 1.
The left side of FIG. 2 is _{an XPS result graph of the zeolite imidazolate skeleton represented by Zn (Benzimidaole) 2} , and the right side of FIG. 2 is an XPS result graph of the catalyst for preparing methyl N-aryl carbamate prepared in Example 1.
3 is a 1H NMR graph for ZIF-7 as a catalyst and a standard sample prepared from Example 1. FIG.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a catalyst for preparing methyl N-aryl carbamate, characterized in that a methoxycarbonyloxy group is bonded to the edge of a zeolite imidazole framework (ZIF).

The catalyst is a zeolite imidazole framework (ZIF) functionalized with dimethyl carbonate, and specifically, a methoxycarbonyloxy group is bonded to the edge of the zeolite imidazole framework, and the methoxycarbo The niloxy group may include 0.01 to 1 mole, preferably 0.01 to 0.5 mole, and most preferably 0.01 to 0.07 mole per 1 mole of Zn in the zeolite imidazolate skeleton.

When the methoxycarbonyloxy group at the edge of the zeolite imidazolate skeleton is contained in an amount of 0.01 mol to 0.5 mol based on 1 mol of Zn of the zeolite imidazolate skeleton, the zeolite imidazolate It is possible to achieve a much better efficiency than using the skeleton without any treatment.

Nevertheless, it is most preferable that the methoxycarbonyloxy group at the edge of the zeolite imidazolate skeleton is contained in an amount of 0.01 mol to 0.07 mol based on 1 mol of Zn of the zeolite imidazolate skeleton. In this case, the activation site of the catalyst There is an advantage of being able to obtain the highest catalytic efficiency and the highest lifetime (1.5 to 2 times or more) at the same time by not being insufficient or excessively generated.

It was confirmed that the catalyst for preparing methyl N-aryl carbamate had the following characteristics. First, the catalyst for preparing methyl N-aryl carbamate according to the present invention is an X-ray photoelectron spectroscopy (XPS) analysis of the OC(=O)-O peak area relative to the CC/C=C peak area. The ratio {(OC(=O)-O peak area)/(CC/C=C peak area)} can be calculated, through which the methoxycarbonyloxy group at the edge of the imidazolate skeleton falls within the above condition range. It can also be confirmed experimentally that it is bound.

The present invention is a method that can easily and conveniently prepare a catalyst having excellent yield (%) and selectivity (%) and excellent catalytic activity in preparing methyl N-aryl carbamate, which is carried out through the following steps. I can.

(a) preparing a suspension by mixing a zeolite imidazolate skeleton with dimethyl carbonate; And

(b) heating the suspension.

First, the zeolite imidazolate skeleton is a complete structure formed by conjugation of zinc and imidazole or imidazole derivatives, and this is a form in which the Lewis acid site of zinc is completely covered by imidazole or imidazole derivatives. If the zeolite imidazolate skeleton is directly used as a catalyst without any special process, there is a problem that no matter how much the amount or temperature of the aromatic amine and dimethyl carbonate is adjusted, it cannot function as a catalyst at all.

Therefore, in the present invention, in order to solve this problem, in order to use the zeolite imidazolate skeleton as a catalyst, it must undergo a process of reacting and activating it with dimethyl carbonate. More specifically, (a) a zeolite imidazolate skeleton is mixed with dimethyl carbonate to prepare a suspension.

In this case, the step (a) comprises (a-1) preparing a precursor solution by dissolving a zinc salt and an imidazole or imidazole derivative in a solvent; And (a-2) heating the precursor solution to prepare a zeolite imidazolate skeleton.

That is, the zeolite imidazolate skeleton in step (a) is not particularly limited as long as it is a conventional zeolite imidazolate skeleton, but is preferably prepared through the above (a-1) and (a-2) steps. I can.

The zinc salt is in the group consisting of zinc nitrate, zinc acetate, zinc chloride, zinc sulfate, zinc bromide, and zinc iodide. It may be one or more selected, more preferably zinc acetate.

The imidazole or the imidazole derivative is not particularly limited as described in Experimental Examples, but preferably, benzimidazole, 2-methylimidazole, and 4-methylimidazole (4-methylimidazole), 2-methylbenzimidazole, 2-nitroimidazole, 5-nitrobenzimidazole, and 5-chlorobenzimidazole (5 -chlorobenzimidazole) may be one or more selected from the group consisting of, more preferably benzimidazole (benzimidazole), 2-methylimidazole (2-methylimidazole), most preferably 2-methylimidazole (2-methylimidazole).

The solvent is methanol, ethanol, propanol, iso-propanol, tert-butanol, n-butanol, methoxyethanol, ethoxyethanol, dimethylacetamide, dimethylformamide, n-methyl-2-pyrrolidone (NMP), Vinylpyrrolidone, 1, 3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, hexamethylphosphoride, formic acid, nitromethane, acetic acid, and may be one or more selected from the group consisting of distilled water, preferably May be dimethylformamide.

The molar ratio of the zinc salt and the imidazole or the imidazole derivative may be appropriately selected and mixed according to the desired zeolite imidazolate skeleton. Preferably, the zinc salt and the imidazole or the imidazole derivative are each It is preferable in terms of long-term stability as well as catalytic activity of the catalyst to be prepared by mixing in a molar ratio of 1:2 to 4.

The (a-2) is preferably carried out at 50 to 200 ℃, preferably 100 to 150 ℃ with a high pressure reactor. Outside the above temperature range, a zeolite imidazolate skeleton having a desired structure cannot be obtained. Specifically, since the methoxycarbonyloxy group is not sufficiently bonded to the edge of the zeolite imidazolate skeleton (the activation site is not formed), the function as a catalyst may not be displayed.

The zeolite imidazolate skeleton prepared from step (a) is not particularly limited as long as it is a zeolite imidazolate skeleton, but in the embodiment of the present invention, ZIF-7 containing zinc is used as the zeolite imidazolate skeleton. I did.

The zeolite imidazolate skeleton prepared in step (a-2) may further include a process of recovering the precipitate by precipitating in a solvent, and drying the precipitate at high temperature (a-3).

In the step (a), the mixing weight ratio of the zeolite imidazolate skeleton and dimethyl carbonate may be 1: 1 to 50, preferably 1: 10 to 30, more preferably 1: 15 to 25. . If it is less than or exceeds the above range, sufficient active sites may not be formed in the zeolite imidazolate skeleton, or unreacted substances remain as impurities, which may adversely affect yield or selectivity.

Next, (b) the suspension is heated. This process is a single heat treatment process. In the zeolite imidazolate skeleton, the Lewis acid site of zinc is covered, and through the above process, a part of the imidazole or imidazole derivative of ZIF is substituted with dimethyl carbonate to activate the reaction. The seat is formed. As described in the actual experimental example, it can be seen that when the zeolite imidazolate skeleton is activated with dimethyl carbonate, the shape of the catalyst is deformed compared to before activation (FIG. 1). In addition, by mixing the zeolite imidazolate skeleton (ZIF) with dimethyl carbonate and heat treatment, it can be seen that the surface (edge) of the zeolite imidazolate skeleton (ZIF) is functionalized with a methoxycarbonyloxy group. Specifically, a methoxycarbonyloxy group is bonded to zinc (Zn) located on the surface of the zeolite imidazolate skeleton (ZIF). In other words, it may be said that zinc (Zn) located on the surface of the zeolite imidazolate skeleton (ZIF) _{is substituted with Zn-OC(=O)R 1} , but it may be preferably bound.

The methoxycarbonyloxy group is derived from dimethyl carbonate and may be _{*-OC(=O)R 1.} The R ₁ may be an alkyl group having 1 to 6 carbon atoms, and preferably R ₁ may be a methyl group (CH ₃ ).

The step (b) may be performed at 50 to 250° C. for 1 to 24 hours, and preferably at 180 to 200° C., for 1 to 10 hours. If performed under the above heat treatment conditions, the surface (edge) of the zeolite imidazolate skeleton (ZIF) is not sufficiently functionalized with a methoxycarbonyloxy group derived from dimethyl carbonate, and thus sufficient catalytic activity when preparing methyl N-aryl carbamate. Can't get In addition, if the heat treatment conditions are exceeded, defects may occur in the zeolite imidazolate skeleton (ZIF), resulting in deterioration in properties such as long-term stability and reusability.

In addition, the present invention is a method for producing methyl N-aryl carbamate comprising mixing a catalyst, an aromatic amine and dimethyl carbonate, and reacting at 150 to 250° C., wherein the catalyst is a zeolite imidazolate skeleton (ZIF; zeolitic imidazole framework), a method for producing methyl N-aryl carbamate, characterized in that a methoxycarbonyloxy group is bonded to the edge.

First, the methyl N-aryl carbamate reaction may be carried out at 150° C. or higher, preferably 150 to 250° C., and more preferably 150 to 170° C.. If the reaction conditions are less than 150° C., the production yield of methyl N-aryl carbamate significantly decreases to less than 70%, and the lower the reaction temperature, the longer the reaction time, which is not preferable in terms of economy.

In addition, the methyl N-aryl carbamate reaction may be performed for 2 hours or more, and preferably may be performed for 2 to 4 hours. If the reaction time is less than 2 hours, there is a problem that the production yield of methyl N-aryl carbamate is significantly reduced to less than 30%, and it is uneconomical because the reaction temperature must be increased as the reaction time is shortened.

Therefore, when any one of the above reaction temperature and reaction time range is out of the range, the production yield of methyl N-aryl carbamate rapidly decreases, and when it exceeds the above range, the methylation product (MMPC+MA+DMA) (by-product ), there is a problem that the production yield exceeds 1%.

In order to maintain the yield of the methylated product, which is a by-product, to less than 1%, but maintain the production yield of methyl N-aryl carbamate more than 90%, it is most preferable to satisfy both the reaction temperature and reaction time conditions.

The aromatic amine compound is not particularly limited, but may be preferably any one or more selected from the group consisting of aniline, phenylenediamine, methylenediphenyldiamine, and toluenediamine, and most preferably aniline.

It is preferable that the molar ratio of the aromatic amine compound and the dimethyl carbonate is 1:5 to 40. If it is out of the molar ratio range, it is not preferable because the production yield of methyl N-aryl carbamate may be reduced by 1.5 to 2 times, and it was confirmed that the yield is rapidly improved by 1.5 to 2 times or more within the molar ratio range.

In the reaction between the aromatic amine compound and dimethyl carbonate, dimethyl carbonate may also function as a methylating agent. That is, dimethyl carbonate synthesizes various methylated products as by-products through the route of Scheme 1 below. When the methylation by-product is mixed in excess, it is uneconomical because an additional purification process must be included inevitably. As described above, the present invention significantly reduces the synthesis of these methylated products to less than 1%, thereby producing high-purity methyl N-aryl carbamate with only a single process, so it is very economical because no separate purification process is required. It has a great advantage.

[Scheme 1]

In addition, the catalyst according to the present invention may be added in an amount of 1 to 20 parts by weight based on 100 parts by weight of the aromatic amine compound. If it is less than 1 part by weight, the production yield of methyl N-aryl carbamate is insignificant, and 20 parts by weight Even if it exceeds the part, since the production yield of methyl N-aryl carbamate no longer increases, cost or waste of catalyst may occur, thereby increasing the process unit cost.

Hereinafter, the present invention will be described in more detail through examples and the like, but the scope and contents of the present invention are reduced or limited by the following examples, and thus cannot be interpreted. In addition, if based on the disclosure of the present invention including the following examples, it is obvious that the present invention for which no specific experimental results are presented can be easily carried out by a person skilled in the art. It is natural to fall within the scope of the claims.

In addition, the experimental results presented below are only representative of the experimental results of the above examples and comparative examples, and the effects of each of the various embodiments of the present invention that are not explicitly presented below will be described in detail in the corresponding section.

Example 1: Preparation of a catalyst for preparing methyl N-aryl carbonate (activated ZIF-7).

A precursor solution was prepared by dissolving zinc acetate (Zn(OAc) ₂ ) and benzimidazole (Chemical Formula 1) in 60 g of an N,N-dimethylformamide solvent. At this time, zinc acetate (Zn(OAc) ₂ ) and benzimidazole were added so that the mixing molar ratio was 1:2.

The precursor solution was put into a high-pressure reactor, and reacted at 130° C. for 48 hours. Only the solid generated from the reaction solution was collected by filtering, and the recovered solid was vacuum-dried at 180° C. for 3 hours _{to form a zeolite imidazolate skeleton represented by Zn (benzimidazole) 2} (hereinafter also referred to as'ZIF-7'. ) Was synthesized.

1 g of ZIF-7 and 20 g of dimethyl carbonate were placed in a high-pressure reactor and reacted at 190° C. for 12 hours to prepare an activated ZIF-7 (catalyst). Since activated ZIF-7 (catalyst) and impurities were mixed in the reaction product, only activated ZIF-7 (catalyst) in a solid state was collected by a filter and dried at room temperature for 3 hours.

The activated ZIF-7 (catalyst) prepared through the above-described process was analyzed by SEM and XPS, and the results are shown on the right side of FIGS. 1 and 2.

[Formula 1]

Example 2: Preparation of a catalyst for preparing methyl N-aryl carbonate (activated catalyst).

A catalyst (activated catalyst) for preparing methyl N-aryl carbonate was prepared in the same manner as in Example 1, except that imidazole (Formula 2) was used instead of benzimidazole.

[Formula 2]

Example 3: Preparation of a catalyst for preparing methyl N-aryl carbonate (activated catalyst).

In the same manner as in Example 1, except that 2-methylimidazole (Chemical Formula 3) was used instead of benzimidazole, a catalyst for preparing methyl N-aryl carbonate (activated catalyst) was prepared. Was prepared.

[Formula 3]

Experimental Example 1: Analysis of the yield of methyl N-phenylcarbamate according to the catalyst

[Scheme 2]

Using the catalysts prepared in Examples 1 to 3, respectively, as in Scheme 2, methyl N-phenyl carbamate was prepared in methyl N-aryl carbamate. First, one of the catalysts (0.11 g) (10 wt% based on aniline) of Examples 1 to 3 was added to a batch reactor, and then 13.5 g (150 mmol) of dimethyl carbonate was added, and then in the aromatic amine compound. Aniline was selected, and 1.16 g (12.5 mmol) were added respectively. After raising the temperature of the reactor to 150° C., it was reacted for 2 hours at a stirring speed of 500 rpm to prepare methyl N-phenylcarbamate. The aniline conversion rate and the yield (%) of each product were calculated and shown in Table 1.

division catalyst Aniline conversion rate (%) Product yield (%) MPC MMPC MA DMA Experimental Example 1-1 Example 1 99.5 99.3 - 0.1 0.1 Experimental Example 1-2 Example 2 98.4 97.9 0.1 0.2 0.2 Experimental Example 1-3 Example 3 98.5 98.0 0.1 0.2 0.2

*MPC is methyl N-phenyl carbamate, MMPC is methylated N-methyl phenyl carbamate, MA is methyl aniline, DMA is dimethyl aniline stands for (dimethyl aniline).

As shown in Table 1, as a result of comparing the aniline conversion (%) and the methyl N-phenylcarbamate yield (%) for each of the catalysts prepared from Examples 1 to 3, in the zeolite imidazolate skeleton It was confirmed that the difference according to the type of imidazole or imidazole derivative was not large.

Experimental Example 2: Analysis of the yield of methyl N-aryl carbamate according to the aromatic amine compound

The reaction temperature was set at 180 ^° C., except that 2,4-diaminotoluene or methylenediphenyl 4,4′-diamine was used as the aromatic amine compound. Methyl N-aryl carbamate was prepared. The specific reaction process is shown in Scheme 2 and Scheme 3 below. Scheme 2 uses 2,4-diaminotoluene, and Scheme 3 uses methylenediphenyl 4,4'-diamine.

[Scheme 2]

[Scheme 3]

In the above reaction scheme, DMC is dimethyl carbonate, and the catalyst of Example 1 was used together with DMC. Table 2 shows the aniline conversion (%) and the yield (%) of each product.

division catalyst Aromatic amine compounds Aniline Conversion Rate (%) Product yield (%) MAC MMAC MA DMA Experimental Example 2-1 Example 1 aniline 99.5 99.4 - 0.2 0.1 Experimental Example 2-2 2,4-diaminotoluene 98.3 98.1 1.2 0.3 0.3 Experimental Example 2-3 Methylenediphenyl 4,4'-diamine 97.9 97.8 2.4 0.5 0.4

In this experimental example, MAC is methyl N-aryl carbamate, MMAC is methylated N-methyl phenyl carbamate, MA is a methylated aromatic amine compound, DMA is dimethyl It means an aromatic amine compound.

Looking at the bars shown in Table 2, it can be seen that the yield (%) of methyl N-phenylcarbamate is similar to the results of Experimental Examples 2-2 and 2-3. That is, it can be seen that even if other aromatic amine compounds other than aniline are used, the catalyst according to the present invention exhibits excellent catalytic activity. However, considering the yield (%) of the methylated product (by-product), it can be seen that aniline is preferably used as the aromatic amine compound.

Experimental Example 3: Analysis of the yield of methyl N-phenylcarbamate according to the amount of catalyst used.

As shown in Table 3 below, the amount of the catalyst prepared from Example 1 was tested in the same manner as in Experimental Example 1-1, except for various additions. It was measured.

division Amount of catalyst used (based on aniline, wt%) Aniline Conversion Rate (%) Product yield (%) MPC MMPC MA DMA Experimental Example 3-1 One 23.7 23.4 - 0.2 0.1 Experimental Example 3-2 5 63.3 63.0 0.1 0.2 - Experimental Example 3-2 7 85.2 84.2 0.1 0.3 0.1 Experimental Example 3-3 15 100 99.5 0.1 0.3 0.1 Experimental Example 3-4 20 100 99.2 0.3 0.3 0.2

*MPC is methyl N-phenyl carbamate, MMPC is methylated N-methyl phenyl carbamate, MA is methyl aniline, DMA is dimethyl aniline stands for (dimethyl aniline).

As shown in Table 3, methyl N-phenylcarbamate was prepared by varying the amount of the catalyst prepared from Example 1, and the result of comparing their aniline conversion and methyl N-phenylcarbamate yield (%), It can be seen that as the amount of catalyst used increases, the ani conversion rate and the yield (%) of methyl N-phenylcarbamate increase.

Therefore, it can be seen that the amount of the catalyst prepared in Example 1 is preferably 7% by weight or more, more preferably 10 to 20% by weight, and most preferably 10 to 15% by weight based on the aromatic amine compound.

Experimental Example 4: Analysis of the yield of methyl N-phenylcarbamate according to the reaction conditions.

As shown in Table 4 below, methyl N-phenyl carbamate was prepared in the same manner as in Experimental Example 1-1, except that the reaction time was changed to 0.5 to 5 hours or the reaction temperature was changed to 100 to 220°C.

The reactants of each experiment were recovered and analyzed using gas chromatography, and the conversion rate (%) and production yield (%) according to the reaction conditions were measured and compared.

division
(Experimental example) Reaction conditions Aniline Conversion Rate (%) Product yield (%) MPC MMPC MA DMA 4-1 0.5 hr 32.8 32.4 - 0.2 0.2 4-2 1 hr 70.6 70.1 0.1 0.2 0.2 4-3 3 hr 99.6 99.2 0.3 0.3 0.2 4-4 4 hr 99.7 99.1 0.4 0.3 0.2 4-5 5 hr 99.6 99.0 0.6 0.2 0.1 4-6 100℃ 10.2 10.0 - 0.1 0.1 4-7 130℃ 26.1 25.9 - 0.1 0.1 4-8 170℃ 100 99.5 0.2 0.2 0.1 4-9 190℃ 100 99.1 0.6 0.2 0.1 4-10 220℃ 100 98.9 0.8 0.2 0.1

*MPC is methyl N-phenyl carbamate, MMPC is methylated N-methyl phenyl carbamate, MA is methyl aniline, DMA is dimethyl aniline stands for (dimethyl aniline).

As shown in Table 4, considering the yield (%) of methyl N-phenyl carbamate, the reaction time is preferably performed for 2 hours or more, and the reaction temperature is preferably performed at 150° C. or more. Considering the yield (%) of the methylated product generated during the reaction, it was confirmed that the reaction time is more preferably performed for 2 to 4 hours, and the reaction temperature is more preferably performed at 150 to 170°C. If any one is out of the above conditions, the yield (%) of methyl N-phenylcarbamate may drop to less than 70% or the yield of by-products may increase to close to 1%.

Experimental Example 5: Analysis of long-term stability of catalyst

In order to check the life of the catalyst prepared in Example 1, the preparation process of methyl N-phenylcarbamate of Experimental Example 1-1 was carried out four times in a row (batch reactor). After the last methyl N-phenylcarbamate production process was completed, and 2 hours passed, the reaction was stopped, and only the catalyst was recovered, then immediately put it into a new batch reactor, and then dimethyl carbonate and aniline were added again as in the beginning. Four consecutive experiments were performed (reuse once). This was repeated up to 5 times, and the aniline conversion rate (%) and the yield (%) of each product were measured for each run, and are shown in Table 5 below.

Number of reuse Aniline Conversion Rate (%) Product yield (%) MPC MMPC MA DMA One 99.5 99.1 0.2 0.1 0.1 2 99.4 99.1 0.1 0.1 0.1 3 98.7 98.5 - 0.1 0.1 4 98.3 98.0 0.1 0.1 0.1 5 97.9 97.7 - 0.1 0.1

*MPC is methyl N-phenyl carbamate, MMPC is methylated N-methyl phenyl carbamate, MA is methyl aniline, DMA is dimethyl aniline stands for (dimethyl aniline).

According to Table 5, in the case of preparing methyl N-phenyl carbamate through the catalyst prepared in Example 1, it is possible to prepare methyl N-phenyl carbamate in excellent yield (90% or more) even if it is repeatedly used several times. Can be seen. If zinc acetate salt (Zn(OAc) ₂ ) is used as a catalyst, the activity of the catalyst is greatly reduced during the reaction process to produce methyl N-phenylcarbamate, and there is a problem that the use of the catalyst is impossible for a long time, Has a great advantage in that it can produce a high yield of methyl N-phenylcarbamate without a long-term catalyst exchange.

Test Example 6: Activity of non-activated zinc-amine structure catalyst

The activity of the catalyst prepared from Example 1 was compared with the zeolitic imidazole framework (ZIF) that did not undergo the activation process.

In the same manner as in Example 1, a zeolitic imidazole framework (ZIF-7) was prepared, but the activation process was not performed, and ZIF-7 was prepared.

Methyl N-aryl carbamate was prepared in the same manner as in Experimental Example 1-1, except that ZIF-7 was used instead of the catalyst of Example 1, and the reaction temperature was changed as shown in Table 6 below.

division Reaction temperature(℃) Aniline Conversion Rate (%) Product yield (%) MPC MMPC MA DMA Test Example 1 150 21.2 17.0 - 3.1 1.0 Test Example 2 190 97.2 67.3 11.7 9.3 8.9

*MPC is methyl N-phenyl carbamate, MMPC is methylated N-methyl phenyl carbamate, MA is methyl aniline, DMA is dimethyl aniline stands for (dimethyl aniline).

According to Table 6, when the zeolite imidazole framework (ZIF-7) is used directly without the activation process, the yield (%) of methyl N-aryl carbomate at 150 °C, which is the most appropriate reaction temperature, is It is insignificant, and the aniline conversion rate was 90% or more at 190°C, but the actual methyl N-phenylcarbamate yield (%) was less than 70%, and it can be seen that an excess methylation product was produced as a by-product.

Accordingly, according to various embodiments of the present invention, a zinc-imidazole complex catalyst that can be reused due to high reaction stability can be prepared.

In addition, the production yield and selectivity can be remarkably improved when methyl N-phenyl carbamate is prepared using the thus prepared zinc-imidazole complex catalyst.

Experimental Example 7. Characteristics of the catalyst prepared from Example 1

In order to analyze the concentration of each component of the catalyst prepared from Example 1, it was measured by ICP-AES (Thermo science iCAP 7000). Proton NMR was performed with Bruker Avance 400 MHz (Bruker Corp.: Billerica, MS, USA).

For the preparation of 1 H NMR samples, 0.05 g of ZIF-7 was diluted in _{0.5 g of D 2} SO ₄ and 0.5 g of H ₂ SO _{4 with 10% by weight of methane sulfonic acid as an internal standard.}

The concentration of benzimidazole leached from the catalyst prepared in Example 1 and the type of species attached to zinc were confirmed using 1H NMR and ICP analysis, and are shown in FIGS. 3 and 7.

3 is a 1H NMR graph for ZIF-7 as a catalyst and a standard sample prepared from Example 1. FIG. 1H NMR was measured _{in D 2} SO _4. Figure 3a is a standard sample ZIF-7, Figure 3b is that the catalyst of Example 1 was used to prepare MPC twice, Figure 3c is that the catalyst of Example 1 was used to prepare MPC four times, and Figure 3d is to Example 1 The catalyst of 6 times was used to prepare MPC, FIG. 3E is methanol (MeOH), and FIG. 3F is methyl N-phenylcarbamate (MPC).

Catalyst Run Zn: BeIm: Methoxy: MPC(Molar ratio) ^a Fresh 1: 2.08: 0: 0 2 1: 1.86: 0.07: 0.02 4 1: 1.69: 0.15: 0.29 6 1: 1.44: 0.29: 0.50

^a Zinc concentration and organic compound were analyzed by ICP and 1H-NMR, respectively.

When ZIF-7 is _{dissolved in D 2} SO ₄ , it is destroyed by zinc ions and benzimidazole, allowing the quantification of zinc and benzimidazole in ZIF-7. As shown in Fig. 3 and Table 7, in 1H NMR, ZIF-7, which is a standard sample, has only benzimidazole, and it can be seen that the amount of benzimidazole per 1 mole of Zn is 2.06 moles. This means that it _{has a Zn(BeIm) 2} structure close to the empirical formula of ZIF-7. However, the catalyst of Example 1 according to the present invention had a benzimidazole molar ratio per 1 mole of Zn of 1.86 according to the MPC manufacturing process, and it can be seen that the benzimidazole molar ratio further decreased to 1.44 as the amount of the catalyst increased gradually. .

In addition, it can be seen that the methoxycarbonyloxy group (methoxy) derived from dimethyl carbonate per mole of Zn increases from 0.07 to 0.29 moles depending on the amount of catalyst used. Thereafter, when the MPC was prepared 10 or more times, the increase was reduced, so it can be seen that the catalyst of Example 1 according to the present invention can be stably used 10 or more times in the production of MPC.

In addition, it can be seen that the catalyst for preparing methyl N-aryl carbamate can be used in MPC production without difficulty if the methoxycarbonyloxy group is 0.01 to 0.07 mol per 1 mol of Zn of the zeolite imidazolate skeleton.

Claims (14)

A catalyst for preparing methyl N-aryl carbamate, characterized in that a methoxycarbonyloxy group is bonded to the edge of a zeolite imidazole framework (ZIF). The method of claim 1,
The methoxycarbonyloxy group is a catalyst for producing methyl N-aryl carbamate, characterized in that it contains 0.01 to 0.07 mol per 1 mol of Zn of the zeolite imidazolate skeleton. (a) preparing a suspension by mixing a zeolite imidazolate skeleton with dimethyl carbonate; And
(b) a method for producing a catalyst for preparing methyl N-aryl carbamate comprising heating the suspension. The method of claim 3,
The step (a) is
(a-1) dissolving a zinc salt and an imidazole or imidazole derivative in a solvent to prepare a precursor solution; And
(a-2) heating the precursor solution to prepare a zeolite imidazolate skeleton. The method of claim 4,
The zinc salt is in the group consisting of zinc nitrate, zinc acetate, zinc chloride, zinc sulfate, zinc bromide, and zinc iodide. Method for producing a catalyst for producing methyl N-aryl carbamate, characterized in that at least one selected. The method of claim 4,
The imidazole or the imidazole derivative is benzimidazole, 2-methylimidazole, 4-methylimidazole, 2-methylbenzimidazole ), 2-nitroimidazole, 5-nitrobenzimidazole, and 5-chlorobenzimidazole, characterized in that at least one selected from the group consisting of methyl Method for producing a catalyst for producing N-aryl carbamate. The method of claim 4,
The solvent is methanol, ethanol, propanol, iso-propanol, tert-butanol, n-butanol, methoxyethanol, ethoxyethanol, dimethylacetamide, dimethylformamide, n-methyl-2-pyrrolidone (NMP), Vinylpyrrolidone, 1, 3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, hexamethylphosphoride, formic acid, nitromethane, acetic acid, and methyl, characterized in that at least one selected from the group consisting of distilled water Method for producing a catalyst for producing N-aryl carbamate. The method of claim 4,
The zinc salt and the imidazole or the imidazole derivative are each mixed in a molar ratio of 1: 2 to 4, wherein the method for producing a catalyst for preparing methyl N-aryl carbamate. The method of claim 3,
The step (b) is a method for producing a catalyst for preparing methyl N-aryl carbamate, characterized in that it is carried out at 180 to 200° C. for 1 to 24 hours. The method of claim 3,
In the step (a), the molar ratio of the zeolite imidazole framework (ZIF) and dimethyl carbonate is 1: 15 to 25. Method for producing a catalyst for preparing methyl N-aryl carbamate. As a method for producing methyl N-aryl carbamate comprising mixing a catalyst, an aromatic amine and dimethyl carbonate, and reacting at 150 to 250° C.,
The catalyst is a method for producing methyl N-aryl carbamate, characterized in that a methoxycarbonyloxy group is bonded to the edge of a zeolite imidazole framework (ZIF). The method of claim 11,
The method for producing methyl N-aryl carbamate, characterized in that the molar ratio of the aromatic amine and the dimethyl carbonate is 1:5-40. The method of claim 11,
The catalyst is a method for producing methyl N-aryl carbamate, characterized in that the addition of 1 to 20 parts by weight based on 100 parts by weight of the aromatic amine compound. The method of claim 11,
The aromatic amine compound is any one or more selected from the group consisting of aniline, phenylenediamine, methylenediphenyldiamine, and toluenediamine. Method for producing methyl N-aryl carbamate.

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