KR20120041881A - Silver nanoparticle catalyzed for selective hydration of nitriles - Google Patents

Abstract

PURPOSE: A selective hydration method of nitriles is provided to promote reaction in natural water effectively, and to recycle the silver nanoparticle catalyst used in hydration under natural conditions. CONSTITUTION: A selective hydration method of nitriles comprises a step of generating a mixture by mixing silver nano particles, nitriles, and water, and a step of stirring the mixture. The molar ratio of the nitrile compound is 3mmol:389mmol - 3mmol:445mmol. The amount of the silver nanoparticles is 0.3-0.5 mol% on the basis of the mixture. The selective hydration method is conducted at 373-423 K, for 30-60 minutes. The nitrile compound is benzonitrile.

Description

[Silver Nanoparticle Catalyzed for Selective Hydration of nitriles}

FIELD OF THE INVENTION The present invention relates to the production of amides by the hydration of nitriles, and more particularly to the hydration of nitrile compounds with amides using silver nanoparticle catalysts under neutral conditions.

Metal nanoparticles have been studied a lot because of the physical and chemical properties that distinguish them from most metals. Over the years, almost all metals on the periodic table have been used in a variety of applications, from photography and DNA analysis to quantum dots (QDT). In this field, transition element nanoparticles are very important for catalysts and have been particularly applied to hydrogenation, oxidation, coupling reactions and selective photocatalytic reactions. In addition, many publications have recently been published on successful applications of silver nanoparticles in catalytic reactions such as oxidation of styrene, oxidation of alcohols, oxidation of phenylsilanes, CC cross-coupling, and epoxidation of alkenes. have.

Hydration of nitriles to the corresponding amides plays a very important role in organic synthesis as an important synthetic mediator in the production of pharmaceutical products and drug stabilizers, and in the production of engineering plastics, detergents, polymers and lubricants.

Traditional catalyst systems require organic solvents in the presence of homogeneous strong acids and strong base catalysis. Thus, there is still a need for a method of hydration of nitriles that is capable of recovering amides in high yields and which is both environmentally friendly and economically advantageous.

One object of the present invention is to provide a hydration reaction of a nitrile compound which can promote the reaction efficiently in neutral water.

Another object of the present invention is to provide a hydration reaction of a nitrile compound which can recycle the silver nanoparticle catalyst used to hydrate the nitrile to amide under neutral conditions.

Another object of the present invention is to provide an amide compound prepared by the hydration of nitrile using silver nanoparticle catalyst under neutral conditions.

One aspect of the invention provides a method of mixing a silver nanoparticle, nitrile and water to produce a mixture; And it relates to a hydration method of a nitrile compound comprising the step of stirring the mixture.

Another aspect of the invention relates to an amide compound obtained by the above method.

The method of hydrating nitrile according to the embodiments of the present invention uses water as a solvent and can recycle the silver catalyst under neutral conditions, thereby reducing the environmental impact in the process and increasing industrial applicability. Can be. In addition, high conversion and selectivity can convert both activated and inactivated nitriles to the corresponding amides.

Figure 1a shows a TEM photograph of the silver nanoparticles synthesized in Preparation Example 1.
Figure 1b shows a SEM photograph of the silver nanoparticles synthesized in Preparation Example 1.
Figure 1c shows the XRD data of the silver nanoparticles synthesized in Preparation Example 1.
1D is a graph showing the size distribution of silver nanoparticles synthesized in Preparation Example 1. FIG.

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

The present invention is a method for hydrating a nitrile compound with an amide compound, wherein the hydration reaction is characterized by using silver nanoparticles as a catalyst.

The reaction mechanism of the nitrile hydration reaction according to the embodiments of the present invention can be represented by the following scheme (1).

Scheme 1

In embodiments of the present invention, silver nanoparticles are used as heterogeneous catalysts in hydration of nitrile with water as solvent, which is modified solvent-based polyol reduction using Poly vinyl pyrrolidone (PVP). Can be synthesized by

Hereinafter, the specific synthesis method will be described. First, an ethylene glycol solution of silver nitrate and an ethylene glycol solution of polyvinyl pyrrolidone are injected into ethylene glycol at a rate of 0.3 to 0.5 ml / min using a syringe pump. After injection, the reaction mixture is refluxed for 60-90 minutes at a temperature of 423-433 K.

The obtained colloidal dispersion was cooled to room temperature, precipitated with acetone, centrifuged at 6000 to 8000 rpm for 10 to 20 minutes, and the precipitated silver nanoparticles were washed several times with ethanol to obtain silver nanoparticles.

The silver nanoparticles, nitrile and water thus synthesized are placed in a reactor and the mixture is stirred for 30 to 60 minutes at a temperature of 373 to 423 K to convert the nitrile to an amide.

Nitrile compounds usable in embodiments of the invention include, but are not limited to, benzonitrile, toluonitrile, nitrobenzonitrile, chlorobenzonitrile, bromobenzonitrile, acetonitrile, acrylonitrile, and annitrile, and the like. no.

The molar ratio of the nitrile compound to water is 3 mmol: 389 mmol to 3 mmol: 445 mmol.

In addition, silver nanoparticles may be used in an amount of 0.3 to 0.5 mol% based on the total mixture. If the molar ratio is out of the above range, the yield of the resulting amide compound is lowered.

According to embodiments of the present invention, the silver nanoparticle catalyst may be recovered by separating the silver nanoparticle catalyst and the reaction mixture after the hydration reaction with the silver nanoparticle catalyst. Recovery of this silver nanoparticle catalyst is accomplished by precipitation, filtration or centrifugation.

According to this method both activated nitrile and inactivated nitrile can be converted to the corresponding amides with high conversion and selectivity. In addition, the silver nanoparticles used in the reaction may be immediately recovered by centrifugation or the like and used five times or more under the same reaction conditions without loss of catalytic activity. Therefore, the hydration reaction according to the present invention can be applied to synthesizing amide in high yield under neutral conditions using water which is harmless to the environment.

The present invention will be described in more detail with reference to the following examples. These examples are intended to illustrate preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to these examples.

Analysis and measuring method

Reagents used in the examples of the present invention were purchased from Aldrich Chemical Co., Ltd. and Strem Chemical Co., Ltd. Reactants were analyzed by ¹ H-NMR using Varian Mercury Plus (300 MHz). Chemical shift values were reported in parts per million (ppm) for tetramethylsilane, unless otherwise indicated, and the coupling constants were reported in Hertz. The reaction product was assigned in comparison with the literature values of known compounds. Samples were discriminated by TEM (Philips F20 Tecnai operated at 200 kV, KAIST) by placing a few drops of the corresponding colloidal form of solution onto carbon-coated copper grids (Ted Pellar, Inc). X-ray powder diffraction was recorded on a Rigaku D / MAX-RB (12 kW) diffractometer. The amount of copper loaded was measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES).

Manufacturing example  1: Silver Nanoparticle Catalyst Synthesis

Silver nanoparticles were synthesized by modified solvent based polyol reduction using poly vinyl pyrrolidone (PVP). First, a syringe pump (KDS-100, Kd Scientific Co., Wood Dale, IL, USA) was used to inject 15 mL of ethylene glycol (anhydrous, 99.8%, Aldrich) at a rate of ˜0.3 ml / min. After injection, the reaction mixture was refluxed at 433K for 60 minutes. The ocher colloidal dispersion was cooled to room temperature, precipitated with acetone and centrifuged at 8,000 rpm for 10 minutes. The precipitated silver nanoparticles were washed several times with ethanol.

Figure 1a is a TEM picture of the silver nanoparticles synthesized as described above, Figure 1b is a SEM picture thereof. The TEM image shown in FIG. 1A and the SEM image shown in FIG. 1B show the general spherical shape of the silver nanoparticles. Referring to these figures, it can be seen that silver nanoparticles are well dispersed and have an average diameter of approximately 100 nm.

Figure 1c shows the XRD data of the silver nanoparticles synthesized in Preparation Example 1, the crystal features of the hollow sphere is shown in the XRD data. Main peaks at 37.9 ^o , 44.1 ^o , 64.2 ^o , and 77.2 ^o are projected onto the (111), (200), (220), and (311) planes in the Ag phase (JCPDS No. 65-2871) Assigned. The X-ray powder diffraction pattern of these precipitates indicates that metal silver is present.

1D is a graph showing the size distribution of silver nanoparticles synthesized in Preparation Example 1. FIG. Scale bars represent (a) 250 nm and (b) 300 nm, respectively.

Example  Hydration of Nitrile by 1: Silver Nanoparticle Catalyst

Silver nanoparticles (16.0 mg, 0.3 mol%), nitrile (0.3 mL, 3.0 mmol) and water (7.0 mL) synthesized in Preparation Example 1 were placed in a 25 mL stainless steel reactor, and the mixture was stirred at 423 K for 1 hour. .

Benzonitrile was used as a reference substrate in tests to test the effectiveness of the catalyst. The reaction mechanism for the hydration of benzonitrile can be represented by Scheme 2 below.

Scheme 2

Hydration reaction results of benzonitrile using silver nanoparticles are shown in Table 1 below.

[Table 1] Hydration of benzonitrile using silver nanoparticles

^a Measured by ¹ H-NMR. Yield is calculated based on the amount of benzonitrile used.

As shown in Table 1, no reaction occurred without a catalyst. When silver nanoparticles (0.5 mol%) were used and refluxed within 3 hours, benzamide was obtained by 100% conversion.

In general, increasing the reaction temperature and time was an efficient way to increase conversion (Table 1, number 3, 4). In addition, when 0.3 mol% of the catalyst was used, 25% yield was obtained under the same reaction time (No. 6). In No. 5, only 0.3 mol% of silver nanoparticles were used to obtain 100% conversion. Optimum reaction conditions were to put nitrile (0.3 mL, 3.0 mmol) with silver nanoparticles (16.0 mg, 0.3 mol%) in water (7.0 mL) in a 25 mL stainless steel reactor, and then stir the mixture at 423 K for 1 hour. It is to let. After the reaction, the silver nanoparticles were separated by centrifugation and reused five times under the same reaction conditions without any deterioration of the catalytic activity. Inductively coupled plasma-mass spectrometry (ICP-AES) studies have shown that silver from the catalyst is negligible. These results confirm that the catalyst system of the present invention satisfies homogeneous catalyst conditions of easy separation, recyclability and persistence. In addition, as shown in the TEM photograph, the structure of the silver nanoparticles does not change even after the reaction is to prove the catalyst recycling.

Additionally Catalytic hydration reactions for various nitriles were performed and the results are shown in Table 2. As shown in Table 2, silver nanoparticles showed excellent activity against a wide range of nitriles.

Table 2 Hydration of Various Nitriles Using Silver Nanoparticles

^a Reaction conditions: Ag NPs (16.0 mg, 0.3 mol%), nitrile (3.0 mmol) and water (7.0 mL) were mixed in 25 mL of stainless steel reactor.

The reaction was carried out on various nitriles at 423-453 K. Silver nanoparticles have high catalytic activity against hydration of activated or inactivated nitriles with water as solvent. In general, increasing the reaction temperature was an efficient way to increase the reaction yield. The reaction rate was not significantly affected by the electrical effects of the substituents substituted on the aromatic ring of benzonitrile. σ-, m- , and p -toluonitriles were catalyzed by silver nanoparticles and steric hindrance of ortho-substituted nitriles was observed at the reaction rate (Table 2, numbers 2, 5, 7). Silver nanoparticles were less reactive to hydration of aliphatic nitriles such as, for example, acetonitrile and acrylonitrile (Table 2, numbers 15, 16, 17). Substituted aromatic nitriles with electron-withdrawing groups were less reactive than aromatic nitriles with electron donating groups (Table 2, numbers 9-14).

Although the present invention has been described in detail with reference to preferred embodiments of the present invention, the present invention is not limited to the above-described embodiments, and many modifications are made by those skilled in the art to which the present invention pertains within the scope of the technical idea of the present invention. This possibility will be self-evident.

Claims (10)

Mixing the silver nanoparticles, nitrile and water to produce a mixture; And stirring the mixture.
The method of claim 1, wherein the molar ratio of the nitrile compound to water is 3 mmol: 389 mmol to 3 mmol: 445 mmol.
The method of claim 1, wherein the silver nanoparticles are used in an amount of 0.3 to 0.5 mol% based on the mixture.
The method for hydrating a nitrile compound according to claim 1, wherein the method is performed at a reaction temperature of 373 to 423K.
The method of claim 1, wherein the method is carried out by stirring for 30 to 60 minutes.
The method of hydrating a nitrile compound according to claim 1, wherein the silver nanoparticle catalyst is recovered by performing a hydration reaction using the silver nanoparticle as a catalyst and separating the catalyst and the reaction mixture after the reaction.
The method of claim 6, wherein the recovery of the silver nanoparticle catalyst is carried out by precipitation, filtration or centrifugation.
The nitrile compound according to any one of claims 1 to 7, wherein the nitrile compound is selected from the group consisting of benzonitrile, toluonitrile, nitrobenzonitrile, chlorobenzonitrile, bromobenzonitrile, acetonitrile, acrylonitrile and annitrile. Hydrating method of a nitrile compound, characterized in that at least one selected.
9. The method of hydrating a nitrile compound according to claim 8, wherein the nitrile compound is benzonitrile.
An amide compound obtained by the hydration method according to claim 1.

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