JP2001064232A - Production of pentenoic acid ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the conversion and selectivity to a desired pentenoic acid ester by heating a formylpentanoic acid ester in the presence of a specific supported noble metal catalyst. SOLUTION: A pentenoic acid ester is produced by heating a 3- or 4- formylpentanoic acid ester or their mixture in the presence of a noble metal catalyst (preferably a group VIII metal such as Pd or Pt) supported on mixed oxides of the formula (M1 is an alkali metal, preferably Li, Na or Mg; M2 is an alkaline earth metal, preferably Be Mg or Ca; M3 is a group IVB metal, preferably Ti, Zr or Hf; (a) is 0.5-1.5; (b) and (c) are each 0.2-0.8; (d) is 2-8; (e) is 3-10; (x) is stoichiometrical value) at 50-400 deg.C. The amount of the noble metal catalyst is 0.01-10 wt.% based on the sum of the catalyst and the mixed oxides.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for preparing pentenoic acid esters, and more particularly to a process for preparing pentenoic acid esters.
The present invention relates to a production method for preparing a pentenoic acid ester using-and 4-formylpentanoic acid ester as a starting material and in the presence of a specific noble metal catalyst supported on a mixed oxide.

[0002]

In a conventional production method for synthesizing caprolactam, first, butadiene, carbon monoxide, and an alcohol are reacted to form a pentenoic acid ester.
Further, formylpentanoate is formed by hydroformylation of the pentenoate.
Then, after the obtained formylpentanoate forms a 6-aminocaproate by amination, the 6-aminocaproate is further cyclized to form caprolactam.

[0003] In the above-mentioned production method, when the pentenoic acid ester is hydroformylated, 3-, 4-,
And three isomers such as 5-formylpentanoate. However, since only 5-formylpentanoate can react to form 6-aminocaproate, 15-15
0% is an undesirable by-product such as 3- and 4-formylpentanoate. There have been many attempts to reduce the cost of raw materials by converting 3- and 4-formylpentanoic acid esters back to pentenoic acid esters by dehydrocarbonylation for reuse in the production of caprolactam.

[0004] 3- and 4-Formylpentanoic acid esters can form isomers such as 2-, 3-, and 4-pentenoic acid esters by a dehydrocarbonylation reaction. Among them, 3- and 4-pentenoic acid esters can be efficiently formed by hydroformylation reaction to form 5-formylpentanoic acid ester from which caprolactam can be prepared if further reacted.
However, one 2-pentenoate is very difficult to hydroformylate. As a result of the reaction of 2-pentenoate with oxygen to form hydrogen peroxide, the catalyst for the hydroformylation reaction loses its activity. For this reason, it is very important to lower the selectivity for 2-pentenoic acid esters and to improve the selectivity for 3- and 4-pentenoic acid esters.

[0005] Theoretically, when an aldehyde is reacted to form an olefin, Pd (palladium), Pt
Noble metals of group VIII such as (platinum) and Rh (rhodium) can be used as catalysts.

In J. Amer. Chem. Soc. 90 (1968), 94-98,
It is disclosed that n-decanal (an aldehyde) can be converted to an olefin by inducing a dehydrocarbonylation reaction in the presence of palladium or platinum supported on activated carbon. Also, J.Ame
R. Chem. Soc. 90 (1968), 99-107 discloses that n-heptanal can be converted to hexane by inducing a dehydrocarbonylation reaction in the presence of a rhodium complex.

In US Pat. No. 4,517,400, linear aldehydes can be split to form olefins in the presence of palladium, platinum, or rhodium, while one of the branched aldehydes is substantially It is explained that it does not react at all.

In German Patent No. 1,917,244,
Using rhodium-containing alumina as a catalyst,
A process for the dehydrocarbonylation of isobutyraldehyde at a temperature of 330 ° C. has been described.

European Patent Application No. 81,090 describes that formylpentanoate, when heated to 150-600 ° C., cyclizes to form 3,4-dihydro-2-pyrone.

In US Pat. Nos. 4,879,405 and 4,879,406, a dehydrocarbonylation reaction is carried out at a temperature of 50 to 400 ° C. in the presence of a Group VIII noble metal as a catalyst. To give 3- and 4-
It is described that formylpentanoate can be converted to pentenoate. However, according to thermodynamic equilibrium, the selectivity for 2-pentenoate and pentenoate exceeds 20% in total, so that 3
The total yield of-and 4-pentenoic acid esters is below 80%.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a novel method for producing pentenoic acid esters by converting 3- and 4-formylpentanoic acid esters. I do. In the production method according to the present invention, the yield of pentenoic acid ester is more than 85%,
The selectivity for 3- and 4-pentenoates is 8
Since it is larger than 5%, the selectivity to 2-pentenoic acid ester can be greatly reduced. Therefore, this technology leads to industrialization.

[0012]

That is, the present invention provides the following:
Heating the formylpentanoate, 4-formylpentanoate or a mixture thereof to 50 to 400 ° C. in the presence of a supported noble metal catalyst, wherein the noble metal catalyst is a mixed oxide: (M ¹ ) _a (M ² )
_b (M ³⁾ is supported on _{c P d Al e SiO x,} M 1 is an alkali metal, M ² is an alkaline earth metal, M ³ is a metal of Group IVB, a = 0.5 to 1.5 , B = 0.2-0.8, c =
0.2 to 0.8, d = 2 to 8, e = 3 to 10, and x relates to a method for producing a pentenoic acid ester having a stoichiometric value.

In the mixed oxide, M ¹ is Li, N
a or K, M ² is Be, Mg or Ca, M ³ is Ti,
It can also be Zr or Hf. Also, a = 0.7
1.3, b = 0.4-0.7, c = 0.4-0.7,
It is preferred that d = 4-7 and e = 4-8.

The noble metal catalyst used in the production method according to the present invention preferably contains a Group VIIIB metal such as Pd (palladium), Pt (platinum), Rh (rhodium), or Ru (ruthenium).

[0015]

According to the present invention, the specific supported noble metal catalyst is a noble metal catalyst itself and a mixed oxide as a support: (M ¹ ) _a (M ² ) _b (M ³ ) _c P _d Al _e SiO
_x . Here, a mixed oxide as a carrier:
_{^{(M 1) a (M 2}} ) b (M 3) c P d Al e SiO x has two functions dehydrogenation carbonylation and isomerization. In the presence of such a supported noble metal catalyst, 3- and 4
Dehydrocarbonylation of -formylpentanoic acid ester on a noble metal can give 2-, 3-, and 4-pentenoic acid esters. Of these, 2-pentenoate can be converted to 3- and 4-pentenoate by isomerization on a mixed oxide carrier. Using this method, the selectivity for 2-pentenoate can be reduced. Also, the cyclization of formylpentanoate to 3,4-dihydro-2-pyrone can be prevented by using this mixed oxide. For this reason, the mixed oxide can function as a catalyst, and also has acid and base properties as belonging to a solid acidic / base catalyst.

The noble metal catalyst can be prepared by ion exchange, impregnation, or mechanical mixing to obtain a mixed oxide: (M ¹ ) _a (M ² ) _b (M ³ ) _c P _d
It can be supported on Al _e SiO _x . The supported noble metal catalyst accounts for 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total weight of the noble metal catalyst and the mixed oxide serving as the support. If the content of the noble metal catalyst is too high, the cost tends to be high, and if it is too low, the activity tends to be too low.

The starting material for the production method according to the present invention is 3-
It may be formylpentanoate, 4-formylpentanoate, or a mixture thereof. Starting materials are
In the presence of the supported noble metal catalyst, 50 to 4
Heated to 00C, preferably 100-250C. Thus, the starting materials can be converted to pentenoates by dehydrocarbonylation. If the reaction temperature is too high, the amount of oxides such as CO and CO ₂ is too large, and if it is too low, the activity of dehydrocarbonylation tends to decrease. The 3- and 4-formylpentanoic acid esters are each independently an alkyl ester, preferably having 1 to 3 carbon atoms.
May be an alkyl ester of Examples of alkyl include:
Methyl, ethyl, propyl, and isopropyl. Representative examples of 3- and 4-formylpentanoate include methyl 3-formylpentanoate and methyl 4-formylpentanoate.

The dehydrocarbonylation is preferably carried out in the presence of an oxygen-containing gas such as air or oxygen. For example, 10-40% by volume of oxygen diluted with a rare gas can be introduced into the reactor. Here, the rare gas is nitrogen, carbon dioxide, helium,
Alternatively, it may be argon.

Furthermore, in order to minimize over-oxidation and by-product formation, it is preferred to add from 0.01 to 10% by weight of water, based on the total weight of formylpentanoate, to the starting materials. Further, in order to avoid hydrolysis of formylpentanoate and pentenoate, it is preferable to add an alcohol such as methanol, ethanol, butanol or cyclohexanol to the starting material. The amount of the alcohol is preferably 30 to 90% by weight based on the total weight of formylpentanoate.

Liquid space velocity of formylpentanoate
(LHSV) is 0.1 to 10 hours ^-1Preferably
0.5 to 5 hours^-1Is more preferable. liquid
If the space velocity is too high, the residence time will be too short and the yield will be low.
If it is too slow, the reaction will go to thermodynamic equilibrium,
Tend to increase the concentration of 2-pentenoic acid ester
is there.

The conversion and selectivity discussed in the present invention can be calculated based on the following equations. here,
FV represents formylpentanoate and PTE represents pentenoate.

[0022]

(Equation 1)

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS In order to further clarify the above and other objects, features and advantages of the present invention, preferred embodiments are described below with reference to the drawings.

Example 1 130 g of aluminum hydroxide (Al (OH) ₃ )
7.5 g of calcium carbonate (CaCO ₃ ) and 5 g
After mixing with 00 ml of deionized water, 14 g of titania (TiO ₂ : titanium dioxide) was slowly added under reflux at 100 ° C. to obtain a solution A.

120 ml of 20 g of silica (SiO ₂ )
20 g of potassium hydroxide (K
OH) was added. The obtained mixture was stirred and heated to obtain a solution B.

Solution B was added to solution A while refluxing at 100 ° C. Then, 230 g was added to the obtained mixed solution.
After adding 85% H ₃ PO ₄ solution at a rate of 18.3 g / min was continued for 8 hours at 100 ° C.. The resulting solution is
Concentration at 00 ° C. gave a sticky white product. The product was then dried in an oven at 120 ° C. to give a solid white product. Further, when this product was cracked, particles having a particle size of 30 to 40 mesh were formed. Thus, a solid acidic / base catalyst: Al ₅ Si ₁ Ca _0.5 Ti _0.5 P ₆ K ₁ O _x was obtained.

20 g of the resulting solid acidic / base catalyst
And 30 ml of 0.05MPd (NH_Three)_FourCl_TwoDissolution
Liquid (pH = 10) and stirring was continued for 1 hour. Profit
The solution was dried under reduced pressure and dried in the presence of air.
As a result of baking at 500 ° C for 6 hours, a pale yellow solid
1% by weight of Pd / Al_FiveSi₁Ca_0.5Ti_0.5P₆K₁O
_xwas gotten. This is a dehydrogenation carbohydrate with selectivity.
It can function as a catalyst for nitration.

7 ml of the resulting dehydrocarbonylation catalyst was placed in a 3/8 "stainless steel tube to form a fixed bed reactor. Methyl formylpentanoate, methanol and water (33:57 by weight). : 10) was mixed with air and fed from the top of the reactor at a liquid hourly space velocity (LHSV) of ¹ hr ^-1 .
The reactor was maintained at atmospheric pressure. When the reaction was completed, the reaction product was discharged from the reactor, cooled and recovered. The obtained liquid product was analyzed by gas chromatography, and the results are shown in Table 1.

[0029]

[Table 1]

Example 2 78 g of aluminum hydroxide and 19.8 g of magnesium nitrate
Nesium (Mg (NO _Three)_Two) And 500 ml
After mixing with deionized water, refluxed at 100 ° C
Then, slowly add 16 g of titania to obtain a solution A.
Was.

After adding 20 g of silica to 120 ml of deionized water, 20 g of potassium hydroxide were added. The obtained mixture was stirred and heated to obtain a solution B.

Solution B was added to Solution A while refluxing at 100 ° C. Then, 192 g was added to the obtained mixed solution.
After adding 85% H ₃ PO ₄ solution at a rate of 18.3 g / min was continued for 8 hours at 100 ° C.. The resulting solution is
Concentration at 00 ° C. gave a sticky white product. The product was then dried in an oven at 120 ° C. to give a solid white product. Further, when this product was cracked, particles having a particle size of 30 to 40 mesh were formed. Thus, a solid acidic / base catalyst: Al ₃ Si ₁ Mg _0.4 Ti _0.6 P ₅ K ₁ O _x was obtained.

20 g of the resulting solid acidic / base catalyst and 30 ml of a 0.05 M Pd (NH ₃ ) ₄ Cl ₂ solution (pH = 10) were mixed and stirring was continued for 1 hour. The resulting solution was dried under reduced pressure and calcined at 500 ° C. for 6 hours in the presence of air, resulting in a pale yellow solid, ie 1% by weight of Pd / Al ₃ Si ₁ Mg _0.4 Ti _0.6 P ₅ K. ₁ O
_x was obtained. It can function as a catalyst for dehydrocarbonylation with selectivity.

[0034] 7 ml of the resulting dehydrocarbonylation catalyst was placed in a 3/8 "stainless steel tube to form a fixed bed reactor. Methyl formylpentanoate, methanol and water (by weight) 33:57:10) was mixed with air and pumped from the top of the reactor at a liquid hourly space velocity (LHSV) of ¹ hr ^-1 The fixed bed was controlled at 180 ° C. and the reactor was maintained at atmospheric pressure. When the reaction was completed, the reaction product was discharged from the reactor, cooled and collected, and the obtained liquid product was analyzed by gas chromatography, and the results are shown in Table 2.

[0035]

[Table 2]

Examples 3-7 For each example, catalysts were prepared using the procedure described in Example 1. 7 ml of the resulting dehydrocarbonylation catalyst was placed in a 3/8 "stainless steel tube to form a fixed bed reactor. Methyl formylpentanoate, methanol and water were mixed in various weight ratios of air. At the top of the reactor at various liquid hourly space velocities (LHSV), the fixed bed was controlled at various temperatures and the reactor was maintained at atmospheric pressure. The liquid product was discharged from the reactor, cooled and collected, and the obtained liquid product was analyzed by gas chromatography, and the results are shown in Table 3.

[0037]

[Table 3]

Example 8 A catalyst was prepared using the procedure described in Example 1. 50
ml of the resulting dehydrocarbonylation catalyst was placed in a 1 "stainless steel tube to form a fixed bed reactor. Methyl formylpentanoate, methanol, and water (33: 59: 8 by weight) were added to air. And fed from the top of the reactor at a liquid hourly space velocity (LHSV) of 2 hr ^-1 The fixed bed was controlled at 180 ° C. and the reactor was maintained at atmospheric pressure. Was discharged from the reactor, cooled and recovered, and the obtained liquid product was analyzed by gas chromatography, and the results are shown in Table 4.

[0039]

[Table 4]

Although the preferred embodiments have been disclosed above, they are not intended to limit the scope of the invention in any way, and anyone skilled in the art will be able to provide the same without departing from the spirit and scope of the invention. Various variations and additions should be made, and therefore the protection scope of the present invention is based on the contents specified in the claims.

[0041]

As can be seen from the results of the above-mentioned examples, when a specific noble metal supported on a mixed oxide is used as a catalyst based on the production method of the present invention, a high conversion of formylpentanoate is obtained. Rate can be obtained and also the selectivity for 3- and 4-pentenoates can be improved and the selectivity for 2-pentenoates can be reduced to less than 20%.

Claims (17)

[Claims] (1) 3-formylpentanoic acid ester, 4-
Heating a formylpentanoic acid ester or a mixture thereof to 50 to 400 ° C. in the presence of a supported noble metal catalyst, wherein the noble metal catalyst is a mixed oxide: (M ¹ ) _a (M ² ) _{b ^{(M 3) c P d Al}} e supported on SiO _x, M ¹ alkali metal, M ² is an alkaline earth metal, M ³
Is a group IVB metal, a = 0.5 to 1.5, b = 0.
2 to 0.8, c = 0.2 to 0.8, d = 2 to 8, e = 3
A method for producing a pentenoic acid ester in which -10 and x are stoichiometric values. 2. The method according to claim 1, wherein M ¹ is Li, Na or K. 3. The method according to claim 1, wherein M ² is Be, Mg or Ca. 4. The method according to claim 1, wherein M ³ is Ti, Zr or Hf. 5. a = 0.7-1.3, b = 0.4-0.
7. The method according to claim 1, wherein c = 0.4-0.7, d = 4-7, and e = 4-8. 6. The method according to claim 1, wherein the noble metal catalyst contains a Group VIIIB metal. 7. The group VIIIB metal is Pd, Pt, R
7. The method according to claim 6, wherein h or Ru is used. 8. The precious metal catalyst is 0.01 to 10% by weight based on the total weight of the precious metal catalyst and the mixed oxide.
The method according to claim 1, wherein 9. The method according to claim 8, wherein the amount of the noble metal catalyst is 0.1 to 5% by weight based on the total weight of the noble metal catalyst and the mixed oxide. 10. The method according to claim 1, which is performed at a temperature of 100 to 250 ° C. 11. The method according to claim 1, which is performed in the presence of a gas containing oxygen. 12. The method according to claim 11, which is performed in the presence of air. 13. The method according to claim 11, which is carried out in the presence of oxygen. 14. The method according to claim 1, wherein said 3-formylpentanoic acid ester and 4-formylpentanoic acid ester are each independently an alkyl ester having 1 to 3 carbon atoms. 15. The 3-formylpentanoic acid ester and 4-formylpentanoic acid ester each having 3
The process according to claim 14, wherein methyl-formylpentanoate and methyl 4-formylpentanoate are used as starting materials. 16. The method according to claim 1, wherein the liquid hourly space velocity LHSV of the formylpentanoic acid ester is 0.1 to 10 hr ^-1 . 17. The liquid space velocity LHSV is 0.5 to
17. The method according to claim 16, wherein the pressure is 5 hr ^-1 .