JP5050182B2 - Catalyst for amide dehydration reaction and method for producing nitrile using the same - Google Patents

Description

  The present invention relates to a catalyst for amide dehydration reaction and a method for producing nitrile using the same.

  Nitriles are used in many applications such as solvents, synthetic resins, dyes, and pharmaceutical intermediates. As a method for synthesizing nitriles, a method using a halide and a halide such as NaCN or KCN is known, but a point using a dangerous cyanate, a point that a large amount of inorganic salt is by-produced as waste, There is a problem. On the other hand, there is nitrile synthesis by dehydration of amides, but it is very difficult to actually synthesize nitriles by this method, and only a few stoichiometric reactions using titanium tetrachloride, thionyl chloride, trifluoroacetic anhydride, etc. have been reported. It ’s just that.

On the other hand, a reaction system using a rhenium oxo complex ((HO) ReO ₃ ) as a catalyst in the dehydration reaction of amide is also known, and a maximum catalyst rotation speed of 194 has been achieved (Non-patent Document 1).

However, since rhenium becomes the rarest metal among rare metals, it is necessary to realize a dehydration reaction of amides in a reaction system using a more easily available material. Further, since the method using the rhenium oxo complex is a homogeneous system, subsequent steps such as purification after nitrile synthesis and separation of the catalyst become complicated.
K. Ishihara et al., Angew. Chem. Int. Ed. 2002, 41, 2983

  Accordingly, a main object of the present invention is to provide a catalyst capable of realizing nitrile production by dehydration reaction of amide on an industrial scale.

  As a result of intensive studies in view of the problems of the prior art, the present inventor has found that the above object can be achieved by a combination of a specific component and a specific carrier, and has completed the present invention.

  That is, the present invention relates to the following amide dehydration reaction catalyst and a nitrile production method using the same.

1. A catalyst used for producing a nitrile by dehydrating a primary amide, wherein at least one vanadium component of metal vanadium and a vanadium compound is supported on a hydrotalcite-like compound.
2. The hydrotalcite-like compound has the following general formula (1)
M ²⁺ _1-x M ³⁺ _x (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1)
^{(Wherein, M 2+} represents a divalent metal ^{ion, M 3+} represents a trivalent metal ^{ion, A n-is} .x showing a n-valent anion of 0.1 ≦ x ≦ 0.5 The positive number in the range, y is a positive number in the range of 0.1 ≦ y ≦ 0.5, and n is an integer of 1 or 2.) .
3. Item 3. The catalyst for amide dehydration reaction according to Item 1 or 2, wherein M ²⁺ is Mg ²⁺ and M ³⁺ is Al ³⁺ .
4). The amide dehydration according to any one of Items 1 to 3, wherein a molar ratio of the divalent metal ion to the trivalent metal ion (M ²⁺ : M ³⁺ ) is M ²⁺ : M ³⁺ = 2 to 7: 1. Catalyst for reaction.
5. Item 5. The catalyst for amide dehydration reaction according to any one of Items 1 to 4, which contains at least pentavalent vanadium as a vanadium component.
6). Item 6. The catalyst for amide dehydration reaction according to any one of Items 1 to 5, obtained by impregnating a hydrotalcite-like compound with a solution containing vanadium ions and then drying.
7). A method for producing a nitrile, wherein a nitrile is produced by heating and dehydrating a primary amide in the presence of the catalyst according to any one of Items 1 to 6.
8). Item 8. The production method according to Item 7, wherein the dehydration reaction is performed in the presence of an organic solvent or in an organic solvent.
9. Item 9. The method according to Item 7 or 8, wherein the heating temperature is 160 to 200 ° C.

  According to the catalyst for amide dehydration reaction of the present invention, the dehydration of amide, which has been considered difficult so far, can be efficiently advanced. Can be realized.

  The catalyst for amide dehydration reaction according to the present invention employs vanadium which is relatively easily available as a vanadium component, so that stable supply is possible as compared with the case where a rare rhenium-based catalyst is used, and the rhenium-based catalyst. It is also advantageous in that it is less expensive than the catalyst.

Further, since the catalyst for amide dehydration reaction of the present invention is a solid catalyst, the reaction system can be made heterogeneous by dehydrating in the liquid phase. This facilitates recovery of the catalyst after completion of the reaction, and is excellent in production efficiency as compared with a homogeneous system.

1. Catalyst for amide dehydration reaction

  The catalyst for amide dehydration reaction of the present invention (the catalyst of the present invention) is a catalyst used for producing a nitrile by dehydrating a primary amide. It is supported by a talcite-like compound.

  The catalyst of the present invention is used for producing a nitrile by dehydrating a primary amide. That is, it is used when nitrile is produced by the following reaction.

R—CONH ₂ → R—CN + H ₂ O (where R represents a hydrocarbon group)

As the vanadium component, at least one of metal vanadium and a vanadium compound is used. The vanadium compound is not limited as long as it is a supply source of vanadium, and examples thereof include at least one of vanadium oxide, vanadium chloride, vanadic acid, vanadate, vanadyl-containing compound, and the like. More specifically, vanadium pentoxide, vanadium trioxide, divanadium tetroxide, vanadium chloride, sodium metavanadate, potassium metavanadate, ammonium metavanadate, vanadium oxide sulfate (vanadyl sulfate), vanadium chloride oxide, vanadium bromide oxide 1 type, or 2 or more types, such as vanadyl acetylacetonate, can be used. In the catalyst of the present invention, it is desirable to contain pentavalent vanadium as the vanadium component. For example, sodium metavanadate can be used. The valence of the supported vanadium component can be confirmed by the V K-edge XAFS method.

  The supported amount of the vanadium component can be appropriately set according to the type of the component, the type of amide used, etc., but is generally about 0.1 to 20% by weight, particularly 1 to 10% by weight in the catalyst of the present invention. be able to. Elemental analysis of the catalyst of the present invention can be performed by ICP measurement.

  In the catalyst of the present invention, components other than the vanadium component (other than vanadium and vanadium compounds) may be present within a range not impeding the catalytic activity.

A known or commercially available hydrotalcite-like compound can be used. Moreover, what is obtained by a well-known manufacturing method can also be used. Although it may be either a natural hydrotalcite-like compound or a synthetic hydrotalcite-like compound, it is preferable to use a synthetic hydrotalcite-like compound.

In the present invention, in particular, the following general formula (1)
M ²⁺ _1-x M ³⁺ _x (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1)
^{(Wherein, M 2+} represents a divalent metal ^{ion, M 3+} represents a trivalent metal ^{ion, A n-is} .x showing a n-valent anion of 0.1 ≦ x ≦ 0.5 (The positive number in the range, y is a positive number in the range of 0.1 ≦ y ≦ 0.5, and n is an integer of 1 or 2.)
The hydrotalcite-like compound shown by can be used suitably.

As said bivalent metal ion, at least 1 sort (s), such as Mg ^<2+> , Ca ^<2+> , Fe ^<2+> , Zn ^{<2+ >} , Cu ^{< 2+ >} , can be employ ^| adopted, for example. In the present invention, at least one of Mg ²⁺ and Ca ²⁺ is particularly preferable, and Mg ²⁺ is more preferable among them. In addition, M ^<2+ > may be comprised from 1 type of metal ions, and may be comprised from 2 or more types of metal ions. Moreover, as said trivalent metal ion, at least 1 sort (s) of ^{Al3 +} and Fe3 ⁺ is ^employable , for example. Among these, Al ³⁺ is preferable. Similarly to M ²⁺ , M ³⁺ may be composed of one type of metal ion, or may be composed of two or more types of metal ions.

In the catalyst of the present invention, the molar ratio of divalent metal ions to trivalent metal ions (M ²⁺ : M ³⁺ ) is preferably M ²⁺ : M ³⁺ = 2 to 7: 1, and particularly M ²⁺ : M More preferably, ^{3 +} = 2-4: 1. By setting within this range, more excellent catalytic activity can be obtained.

Examples of the anion include CO ₃ ²⁻ , Cl ⁻ , OH ⁻ , NO ₂ ⁻ , NO ₃ ⁻ and SO ₄ ²⁻ . Among these, at least one of CO ₃ ²⁻ and OH ⁻ can be mentioned. An anion may also be comprised from 1 type, and may be comprised by arbitrary combinations of 2 or more types.

  The hydrotalcite-like compound used in the catalyst of the present invention may be a hydrate or an anhydride.

Specific examples of the hydrotalcite-like compound include, for example, Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, Mg ₄ Al ₂ (OH) ₁₂ CO ₃ , and Mg ₁₀ Al ₂ (OH) ₂₄ CO in the composition formula. What is shown by ₃ grade | etc., Can be used suitably. In particular, in the present invention, as the hydrotalcite-like compound, a compound represented by the composition formula Mg ₆ Al ₂ (OH) ₁₆ CO ₃ can be suitably used. As such a hydrotalcite-like compound, Mg ²⁺ is contained in an amount of 34 to 38% by weight in terms of magnesium oxide, Al ³⁺ is contained in an amount of 13 to 19% by weight in terms of aluminum oxide, and the liquid pH is about 8 to 10%. A hydrotalcite-like compound having physical properties of 10% or less on loss on drying is preferred. As such a hydrotalcite-like compound, for example, there is a commercially available product “Tomita-AD 500NS” (manufactured by Tomita Pharmaceutical Co., Ltd.). This product contains 37% by weight of Mg ^{2+ in} terms of magnesium oxide, 16% by weight of Al ^{3+ in} terms of aluminum oxide, has a physical pH of about 8.9, and a loss on drying of 5.7%. In addition, the dehydration reaction of the primary amide can proceed more effectively.

The shape of the hydrotalcite-like compound used in the present invention is not limited, but usually a powdery or particulate material may be used. In this case, the powder may have an average particle size of 10 μm or less, and the particles may have an average particle size of about 10 to 200 μm. In the present invention, an average particle size of about 5 to 10 μm may be used. preferable. The average particle diameter can be appropriately adjusted by classification, pulverization, or the like. The average particle diameter is a value determined by a laser diffraction measurement method.
The method for producing the hydrotalcite-like compound is not particularly limited. For example, first, a solution containing a divalent metal ion and a trivalent metal ion (first solution) and a solution containing an anion and an alkali (second solution) are prepared, and the precipitates are prepared by mixing the two. After precipitation, the hydrotalcite-like compound can be obtained by drying the obtained precipitate. More specifically, when the divalent metal ion is Mg ²⁺ , the trivalent metal ion is Al ³⁺ , and the anion is CO ₃ ²⁻ , a water-soluble magnesium salt and a water-soluble aluminum salt are dissolved in water. A first solution was prepared, carbonate and sodium hydroxide were dissolved in water to prepare a second solution, and both solutions were stirred and mixed at 60 to 70 ° C. for 12 to 24 hours, and then precipitated. A predetermined hydrotalcite-like compound can be obtained by collecting the precipitate, washing with water as necessary, and then drying at about 100 to 120 ° C.

  The method for producing the catalyst of the present invention is not particularly limited as long as the metal vanadium and / or vanadium compound can be supported (immobilized) on the hydrotalcite-like compound. For example, the catalyst of the present invention can be obtained by impregnating a hydrotalcite-like compound with a solution containing vanadium ions and then drying.

  The solution containing vanadium ions can be prepared by dissolving a vanadium supply source in a solvent. As the supply source of vanadium, those exemplified above as the vanadium compound can be employed. That is, at least one of vanadium oxide, vanadium chloride, vanadic acid, vanadate, vanadyl-containing compound and the like is exemplified. More specifically, vanadium pentoxide, vanadium trioxide, divanadium tetroxide, vanadium chloride, sodium metavanadate, potassium metavanadate, ammonium metavanadate, vanadium oxide sulfate (vanadyl sulfate), vanadium chloride oxide, vanadium bromide oxide 1 type, or 2 or more types, such as vanadyl acetylacetonate, can be used. The solvent used in the solution is preferably water, but is not limited thereto. Although the density | concentration of a solution can be suitably set according to the kind etc. of vanadium supply source to be used, what is necessary is just to be in the range of about 1-4 weight% normally.

  The method of impregnating the hydrotalcite-like compound with the solution containing vanadium ions is not limited. It may be.

  After the hydrotalcite-like compound is impregnated with the solution, the vanadium-supported hydrotalcite-like compound may be recovered by a known solid-liquid separation method such as filtration or centrifugation. Then, you may use for a drying process as needed.

2. Nitrile production method

  The production method of the present invention is characterized in that a nitrile is produced by heating and dehydrating a primary amide in the presence of the catalyst of the present invention.

The primary amide is not particularly limited as long as it is an organic compound having an amide group (—CONH ₂ group). The primary amide may have one or more amide groups. For example, in the present invention, a primary amide having one amide group can be suitably used. Examples of the primary amide include 1) an amide (aromatic amide) in which the carbon atom of the amide group is bonded to an optionally substituted aromatic ring, and 2) the carbon atom of the amide group is a substituent. An amide bonded to a heterocyclic ring which may have a ring; 3) an amide bonded to a condensed ring which may have a substituent (polycyclic amide); 4) an amide group The carbon atom is active in any aliphatic amide bonded to an aliphatic hydrocarbon which may have a substituent and can effectively perform a dehydration reaction, and nitriles corresponding to these are synthesized. can do.

  More specifically, benzamide, aminobenzamide, chlorobenzamide, bromobenzamide, nitrobenzamide, methoxybenzamide, toluamide, 1-naphtholamide, 2-naphtholamide, nicotinamide, isonicotinamide, 2-fluamide, 3-fluamide, acetamide, Examples include primary amides such as propionamide, butyramide, methacrylamide, acrylamide, stearamide, cinnamamide, lactamide, glyceramide, 2-thiophenecarboxamide, phenylacetamide, cyclohexacarboxamide, caproic acid amide.

  The reaction system in the production method of the present invention can be appropriately changed according to the properties of the primary amide to be used, and may be, for example, a liquid phase reaction or a gas phase reaction. In particular, in the production method of the present invention, a liquid phase reaction is desirable because a heterogeneous reaction system can be formed in relation to the catalyst of the present invention. In this case, the dehydration reaction can be performed in the presence of an organic solvent or in an organic solvent. A known or commercially available organic solvent can be used as the organic solvent. Any organic solvent may be used as long as it can dissolve the primary amide to be used, but a nonpolar solvent is particularly preferable. As such an organic solvent, for example, mesitylene, p-xylene and the like can be used.

  In the dehydration reaction, the catalyst of the present invention may be coexisted with the primary amide in the reaction system. In particular, in the case of a liquid phase reaction, the dehydration reaction can be promoted more effectively by allowing the primary amide and the catalyst of the present invention to coexist in an organic solvent. The amount of the catalyst of the present invention is not limited, but is usually about 0.1 g per 1 mmol of primary amide. In addition, the content (concentration) of the primary amide in the organic solvent is generally within the range of 0.5 to 30% by weight (preferably 0.5 to 5% by weight), and the primary amide used. What is necessary is just to set suitably according to a kind etc.

  In the production method of the present invention, the primary amide is heated in the presence of the catalyst of the present invention. The heating temperature is not particularly limited, but is usually about 160 to 200 ° C, more preferably 170 to 190 ° C, and most preferably 175 to 185 ° C.

  The reaction format is not particularly limited, and may be any of continuous type, batch type and the like. For example, in the case of a batch system, both the primary amide and the catalyst of the present invention may be charged into the reaction system. In the case of the continuous type, the catalyst of the present invention is charged in advance in the reaction apparatus, or the catalyst of the present invention is continuously charged into the reaction system together with the primary amide. As the catalyst, any of a fixed bed, a fluidized bed, a suspension bed and the like can be applied.

  In the production method of the present invention, it is desirable to carry out the process while removing water that is successively generated by the dehydration reaction. For example, it is desirable to carry out the dehydration reaction while refluxing or distilling.

The nitrile produced by the dehydration reaction can be purified and recovered according to a known method such as column chromatography.
In addition, after the dehydration reaction is completed, the catalyst of the present invention can be recovered as necessary. In particular, in the production method of the present invention, since the catalyst of the present invention uses a solid catalyst, the reaction system becomes a so-called heterogeneous system, and the catalyst of the present invention can be easily recovered by an ordinary solid-liquid separation method. In this respect, in the production method of the present invention, the post-process can be greatly simplified as compared with a homogeneous system in which the catalyst is in a liquid phase.

  The features of the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to the examples.

Production Example 1
The catalyst for amide dehydration reaction of the present invention was produced as follows.
(1) Synthesis of hydrotalcite-like compound In the general formula (1), a hydrotalcite-like compound having Mg ^{2+ as} a divalent metal ion, Al ³⁺ as a trivalent metal ion, and CO ₃ ²⁻ as an anion. (Hereinafter abbreviated as “HT”) was synthesized. At this time, the Mg / Al ratio was changed to 2/1, 3/1, 5/1, 8/1, HT2-1, HT3-1, HT5-1,
Each of HT8-1 was prepared as follows.

First, Mg (NO ₃ ) ₂ · 6H ₂ O and Al (NO ₃ ) ₃ · 9H ₂ O were dissolved in 100 mL of water in a predetermined ratio at a total ratio of 0.04 mol to prepare a first solution. On the other hand, Na ₂ CO ₃ (0.03 mol) and NaOH (0.07 mol) were dissolved in 60 mL of water to prepare a second solution. The first solution was slowly added while vigorously stirring the second solution at room temperature in the atmosphere. The resulting mixture was stirred vigorously while heating at 65 ° C. for 18 hours. After cooling to room temperature, suction filtration was performed. The filtrate was washed with water while being careful not to dry it until it became neutral (it became neutral at about 1.5 L). Then, the predetermined hydrotalcite-like compound was obtained by drying at 110 degreeC for 12 hours.

(2) Supporting vanadium component Vanadium trichloride VCl ₃ (0.4 mmol) was dissolved in 100 mL of water. To the obtained aqueous solution, 1 g of the hydrotalcite-like compound (1) (average particle size: about 7 μm) was added in the atmosphere with stirring at room temperature. After stirring for 3 hours, the mixture was suction filtered and washed with 500 mL of water. After washing, when the filtrate has completely flowed, if the suction is continued for about 2 hours, the surface is dried. Then, it was dried under vacuum in a desiccator for 24 hours. Thereafter, the obtained dried product was pulverized in an agate mortar. Thus, a vanadium supported catalyst was obtained.

The vanadium-supported catalysts obtained using the above-mentioned “HT2-1”, “HT3-1”, “HT5-1”, and “HT8-1” as supports are “V / HT2-1”, “V / Indicated as “HT3-1”, “V / HT5-1”, “V / HT8-1”. Further, a vanadium-supported catalyst obtained by using “Tomita AD-500NS” manufactured by Tomita Pharmaceutical Co., Ltd. as HT is denoted as “V / HT”.

Example 1
Nitrile was produced by amide dehydration using the “V / HT” catalyst. An octagon stirrer, o-toluamide (1 mmol) and V / HT catalyst (0.1 g) were added to a glass Schlenk tube, and a reflux tube was attached and sealed. Next, after evacuating the inside of the tube, argon gas was sucked in and replaced. Mesitylene (3 mL) was added and reacted by heating and stirring at 180 ° C. for 24 hours. As a result, as shown in Table 1, o-tolunitrile was obtained with a yield of 89%. The yield was calculated using an internal standard method (standard substance: biphenyl) using gas chromatography.

  In Table 1, for comparison, magnesium oxide (entry 2), γ-zirconium phosphate (entry 3), HAP hydroxyapatite (entry 4), alumina (entry 5), FAP fluoroapatite ( entry 6), α-zirconium phosphate (entry7), no vanadium component (blank) (entry 8) The result of the dehydration reaction is also shown.

  As shown in Table 1, when the hydrotalcite-like compound is used as the carrier (entry 1), it can be seen that the yield is higher than that of the others.

Example 2
In the above Production Example 1 (2), the catalyst of the present invention was produced using each vanadium compound shown in Table 2 as a vanadium supply source, and an amide dehydration reaction was carried out in the same manner as in Example 1. The results are shown in Table 2.

In Table 2, the yield when NaVO ₃ was used was 91% (entry 1), which was superior to the case where other ones were used.

Example 3
Amide dehydration reaction was carried out in the same manner as in Example 1 except that the type of hydrotalcite-like compound and the amount of catalyst were changed. The results are shown in Table 3. In Table 3, “HT3-1 (Tomita Pharmaceutical)” (entry 5, 14) is “Tomita AD-500NS” manufactured by Tomita Pharmaceutical Co., Ltd. It is written as “V / HT3-1”.

As shown in Table 3, the catalyst of the present invention showed a predetermined activity, and in particular, V / HT2-1 and V / HT3-1 showed higher activity.

Example 4
An amide dehydration reaction was performed in the same manner as in Example 1 except that the above-mentioned “V / HT” was used and the compounds shown in Table 4 were used as amides. The results are shown in Table 4.

  As is apparent from Table 4, it can be seen that the catalyst of the present invention can be applied to various primary amides. For example, as shown in entry 1-14, it was applicable to aromatic amides with various substituents. As for toluamide, the methyl group at the ortho position showed higher reactivity than those at the meta and para positions (entry2,4,5). Aminobenzamide and chlorobenzamide also showed higher activity with a substituent at the ortho position (entry 6-10). The catalyst of the present invention can also be applied to amides having a heterocycle, and nitriles corresponding to them can be obtained in high yield (entry 15-18). The polycyclic amide was efficiently dehydrated (entry 19). Furthermore, it also showed activity on aliphatic amides (entry 22-26).

Test example 1
The possibility of use on a large scale was investigated. In Example 4, the reaction was performed on a large scale using o-toluamide as a substrate. A yield of 89% could be obtained on a 10 mmol scale.

Test example 2
The possibility of reusing the catalyst was also investigated. In Example 4, when it was reused in dehydration of o-toluamide (1 mmol scale), the first yield was 92% and the second yield was 84%. From this, it was confirmed that the catalyst of the present invention is not practically deactivated during the reaction, but is practical and can be used repeatedly.

Claims (9)

A catalyst used for producing a nitrile by dehydrating a primary amide, wherein at least one vanadium component of metal vanadium and a vanadium compound is supported on a hydrotalcite-like compound. The hydrotalcite-like compound has the following general formula (1)
M ²⁺ _1-x M ³⁺ _x (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1)
^{(Wherein, M 2+} represents a divalent metal ^{ion, M 3+} represents a trivalent metal ^{ion, A n-is} .x showing a n-valent anion of 0.1 ≦ x ≦ 0.5 The catalyst for amide dehydration reaction according to claim 1, wherein y is a positive number in the range, y is a positive number in the range of 0.1 ≦ y ≦ 0.5, and n is an integer of 1 or 2. . The catalyst for amide dehydration reaction according to claim 1 or 2, wherein M ²⁺ is Mg ²⁺ and M ³⁺ is Al ³⁺ . The amide dehydration according to any one of claims 1 to 3, wherein the molar ratio of divalent metal ions to trivalent metal ions (M2 ⁺ : M3 ⁺ ) is M2 ⁺ : M3 ⁺ = 2-7: 1. Catalyst for reaction. The catalyst for amide dehydration reaction according to any one of claims 1 to 4, comprising at least pentavalent vanadium as a vanadium component. The catalyst for amide dehydration reaction according to any one of claims 1 to 5, obtained by impregnating a hydrotalcite-like compound with a solution containing vanadium ions and then drying. A method for producing a nitrile, comprising producing a nitrile by heating and dehydrating a primary amide in the presence of the catalyst according to any one of claims 1 to 6. The manufacturing method of Claim 7 which performs dehydration reaction in presence of an organic solvent or in an organic solvent. The manufacturing method of Claim 7 or 8 whose heating temperature is 160-200 degreeC.