JP3206379B2 - Method for producing pivaloyl acetate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing pivaloyl acetate, and more particularly to a method for producing pivaloyl acetate at a high yield by decarbonylating pivaloyl pyruvate. Pivaloyl acetate is a very useful compound as a synthetic intermediate for photographic materials and the like.

[0002]

2. Description of the Related Art A method for producing a pivaloyl acetate by subjecting a pivaloyl pyruvate to a decarbonylation reaction includes a process in which a metal selected from the group consisting of iron, copper, nickel, manganese, chromium, molybdenum and cobalt is used as a catalyst. (See JP-B-62-47170) and a method for carrying out a decarbonylation reaction in the presence of a powdery glass (US 252).
7306) are known.

[0003]

However, none of these methods can be said to have high activity of the catalyst, and each of them has a problem that is not industrially satisfactory. That is,
In the former method, since the heavy metal as described above is used as a catalyst, not only the recovery and post-treatment thereof become more complicated, but also the by-produced carbon monoxide and these heavy metals react to form toxic metal carbonyl. There is also the danger of creating.
Further, when the most active iron powder is used, there is a big problem that the recovery rate of the iron powder is low. On the other hand, in the latter method, in order to obtain pivaloyl acetate with a good yield, the reaction is carried out in a liquid phase using a large amount of a catalyst of 10 to 11% by weight of the raw material. Is complicated.

The present invention provides a method for producing pivaloyl acetate by subjecting a pivaloyl pyruvate to a decarbonylation reaction, which comprises producing pivaloyl acetate at a high yield using a highly active and stable catalyst. It is another object of the present invention to provide a method for producing pivaloyl acetic acid ester, which can be easily recovered and post-treated.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to convert aluminum to aluminum oxide (Al ₂ O ₃ ).
This is achieved by a method for producing pivaloyl acetate, which comprises subjecting pivaloyl pyruvate to a decarbonylation reaction in the presence of an inorganic oxide containing 0% by weight or more and containing no heavy metal.

Hereinafter, the present invention will be described in detail. Pivaloylpyruvate is a compound represented by the general formula (I).

Embedded image (Wherein, R represents an alkyl group having 1 to 4 carbon atoms)

Specific examples include methyl pivaloylpyruvate, ethyl pivaloylpyruvate and n-propyl pivaloylpyruvate.

The pivaloyl acetate formed by decarbonylation of the pivaloyl pyruvate is a compound represented by the general formula (II), specifically, methyl pivaloyl acetate, ethyl pivaloyl acetate, n-propyl pivaloyl acetate And the like.

Embedded image (Wherein, R represents an alkyl group having 1 to 4 carbon atoms)

In the present invention, aluminum is contained in an amount of 10% by weight or more, preferably 30% by weight or more, more preferably 90% by weight or more in terms of aluminum oxide (Al ₂ O ₃ ), and contains iron, copper, nickel, The decarbonylation of pivaloylpyruvate is carried out in the presence of an inorganic oxide not containing heavy metals such as manganese, chromium, molybdenum and cobalt as a catalyst. When the aluminum content in the inorganic oxide is small, the reaction time is longer when the reaction is performed in the liquid phase, and when the reaction is performed in the gas phase, the amount of the catalyst must be increased to increase the conversion rate. Thermal decomposition of the pivaloylpyruvate is also likely to occur, and the yield of the target pivaloyl acetate decreases.

Examples of the inorganic oxide include α-alumina, γ-alumina, η-alumina, β-alumina, δ
-Alumina such as alumina, zeolite A, zeolite B
And synthetic zeolites such as molecular sieve 3A, molecular sieve 4A, molecular sieve 5A, molecular sieve 13X, and silica alumina. Among these, in zeolites and synthetic zeolites having ion exchange capacity, iron,
Ions other than heavy metals such as copper, nickel, manganese, chromium, molybdenum, and cobalt, for example, alkali metal ions, alkaline earth metal ions, hydrogen ions, and ammonium ions may be supported by ion exchange.
The inorganic oxide is preferably one having a small particle size from the viewpoint of catalytic activity, and one having a large particle size from the viewpoint of handling.
Those having a particle diameter of mφ, preferably 0.5 to 3 mmφ are suitably used.

In the present invention, the decarbonylation of pivaloylpyruvate can be carried out in a liquid phase or a gas phase. In the case of the liquid phase method, the reaction is usually carried out by putting pivaloylpyruvate and the above-mentioned inorganic oxide in a reactor.
It is carried out by heating the liquid phase at 0 to 280C, preferably 150 to 200C. At this time, the reaction pressure is not particularly limited, but is usually normal pressure. The inorganic oxide is used in an amount of usually 0.1 to 10% by weight, preferably 0.1 to 10% by weight, based on the raw material pivaloylpyruvate.
5 to 5% by weight is added. The reaction is usually completed in 0.5 to 5 hours. After the reaction, the reaction product is separated and purified by directly distilling the reaction solution, and the catalyst is easily recovered by filtration or the like.

In the case of the gas phase method, the reaction is usually carried out in a reaction tube filled with the above-mentioned inorganic oxide, in a vaporizer or in a vaporized layer, with pivaloylpyruvate and an inert gas such as nitrogen gas. Is continuously supplied as a source gas. At this time, the reaction pressure is not particularly limited, but is usually normal pressure. Also,
The reaction temperature is usually 150 to 300 ° C, preferably 180 to 300 ° C.
250 ° C., and the space velocity of the source gas containing pivaloylpyruvate is usually 50 to 3000 hr ⁻¹ ,
Preferably at 100～1500Hr ^-1, the concentration of pivaloyl pyruvic acid ester in the feed gas is typically 1~300g against inert gas 1 liter, preferably from 2 to 100
g. In the gas phase method, a reaction product is easily separated and purified by distilling a condensate obtained by cooling a gas passed through a reaction tube.

The catalyst whose activity has been reduced by the gas phase method can be taken out of the reaction tube and easily recovered. However, in the present invention, the catalyst filled in the reaction tube is directly treated with acetone or acetone.
It can also be easily regenerated by washing with an organic solvent such as a lower alkyl ketone such as methyl ethyl ketone and methyl isobutyl ketone and a lower alcohol such as methanol, ethanol and propanol. Washing is usually performed by passing the organic solvent together with an inert gas such as nitrogen gas at 20 to 40 ° C. through the catalyst layer of the reaction tube. Therefore, in the present invention, it is possible to carry out the reaction continuously for a long period of time without replacing the catalyst.

[0014]

Next, the present invention will be described specifically with reference to examples. All the reactions were carried out under normal pressure, and the conversion of pivaloylpyruvate and the yield of pivaloyl acetate were determined in terms of mol. The aluminum content of the catalyst indicates the aluminum content in terms of aluminum oxide (Al ₂ O ₃ ).

EXAMPLE 1 In a 50 ml glass reactor, 20 g of methyl pivaloylpyruvate having a purity of 98.9% by weight and a catalyst having a particle size of 1 m were used.
m-γ-alumina (neobead RP-4A (aluminum content in terms of aluminum oxide: 94.5% by weight), manufactured by Mizusawa Chemical Co.)
The liquid phase was stirred at 4 ° C. for 4 hours. Carbon monoxide was gradually generated with the progress of the reaction. After the completion of the reaction, the reaction mixture was analyzed by gas chromatography to find that 15.4 g of methyl pivaloyl acetate was produced (conversion: 91.8%, yield: 91.8%). Also, the catalyst, after filtering the reaction solution,
0.8 g by washing with methanol and drying under reduced pressure
Was recovered (recovery rate 100%).

Example 2 In a 50 ml glass reactor, 20 g of methyl pivaloylpyruvate having a purity of 98.0% by weight and a catalyst having a particle size of 1 m were used.
0.8 g of γ-alumina (KHA-24 (aluminum content in terms of aluminum oxide: 99.7% by weight), manufactured by Sumitomo Chemical Co., Ltd.) was added at 170 to 175 ° C.
Stirred for hours. Carbon monoxide was gradually generated with the progress of the reaction. After the reaction was completed, the reaction mixture was analyzed by gas chromatography to find that methyl pivaloyl acetate was 14.
3 g (conversion 97.2%, yield 86.0)
%).

Example 3 In Example 1, the catalyst was changed to α-70 to 230 mesh.
180 g of alumina (aluminum content in terms of aluminum oxide: 99% by weight, manufactured by Kanto Chemical Co.)
The reaction was carried out in the same manner as in Example 1, except that the liquid phase was stirred at １８185 ° C. for 5 hours. As a result of the analysis, 14.3 g of methyl pivaloyl acetate was produced (95.6% conversion, 85.4% yield).

Example 4 In Example 1, the catalyst was changed to the molecular sieve 3A 1
/ 8 (aluminum content in terms of aluminum oxide:
30% by weight, made by Wako Pure Chemical Industries) 0.8g, 150-1
The reaction was carried out in the same manner as in Example 1 except that the liquid phase was stirred at 60 ° C. for 2 hours. As a result of the analysis, 14.7 g of methyl pivaloyl acetate was produced (97.6% conversion, yield 8).
7.7%).

Comparative Example 1 A reaction was carried out in the same manner as in Example 1 except that the liquid phase was stirred at 175 to 180 ° C. for 7 hours without using a catalyst. As a result of the analysis, 6.8 g of methyl pivaloyl acetate was obtained.
It was formed (conversion 54.3%, yield 40.2%).

Comparative Example 2 In Example 1, the catalyst was changed to 0.8 g of silica gel (manufactured by Ishizu Pharmaceutical Co., Ltd.) of 60 to 100 mesh, and the liquid phase was changed to 190 to 100.
The reaction was carried out in the same manner as in Example 1, except that the mixture was stirred at 200 ° C. for 7 hours. As a result of analysis, methyl pivaloyl acetate was found to be 1
0.3 g (conversion 77.4%, yield 61.
3%).

Comparative Example 3 In Example 1, the catalyst was 1 mmφ × 10 mm zeolite [HSD-640NAD (aluminum content in terms of aluminum oxide: 7.7% by weight), manufactured by Tosoh Corporation]
The reaction was carried out in the same manner as in Example 1, except that the liquid phase was changed to 0.8 g and the liquid phase was stirred at 160 to 170 ° C for 7 hours. As a result of the analysis, 11.5 g of methyl pivaloyl acetate was produced (conversion rate: 97.5%, yield: 68.1%).

Comparative Example 4 A 50 ml glass reactor was charged with 30 g of methyl pivaloylpyruvate having a purity of 96.7% by weight and 1.2 g of 100-mesh electrolytic iron powder (manufactured by Wako Pure Chemical Industries) as a catalyst. The liquid phase was stirred at 200 ° C. for 3 hours. Carbon monoxide was gradually generated with the progress of the reaction. After the reaction was completed, the reaction mixture was analyzed by gas chromatography to find that 21.0 g of methyl pivaloyl acetate was produced (100% conversion,
85.4%). When the catalyst was recovered in the same manner as in Example 1, only 0.85 g was recovered (recovery rate 71%). Table 1 summarizes the results of Examples 1 to 4 and Comparative Examples 1 to 4.

[0023]

[Table 1]

Example 5 γ-alumina having a particle diameter of 1 mm [Neobead RP] was used as a catalyst in a stainless steel reaction tube having an inner diameter of 29 mm and a length of 500 mm.
-4A (aluminum content in terms of aluminum oxide: 94.5% by weight), manufactured by Mizusawa Chemical Co., Ltd.] and heated to 230 ° C. while flowing nitrogen gas at a flow rate of 350 ml / min. Next, methyl pivaloylpyruvate having a purity of 99.5% by weight was vaporized and accompanied by nitrogen gas, and was added to the reaction tube at a flow rate of 2 g / min to perform a reaction. One hour after the start of the reaction, 30
When the condensate obtained by cooling the gas that passed through the catalyst layer for one minute was analyzed, methyl pivaloyl acetate was found to be 42.6 g.
It was produced (conversion 99.0%, yield 83.5%, space-time yield 1420 g / l · hr). The space-time yield of methyl pivaloyl acetate (STY) (g / l · hr) is defined as reaction time θ (hr), methyl pivaloyl acetate generated during the reaction is a (g), As b (l) by the following equation.

[0025]

(Equation 1)

Example 6 In Example 5, the catalyst was γ-alumina having a particle diameter of 1 mm (neobead RP-4A (aluminum content in terms of aluminum oxide: 94.5% by weight), manufactured by Mizusawa Chemical).
The reaction was carried out in the same manner as in Example 5 except that the flow rate was changed to 0 ml and the flow rate of the nitrogen gas was changed to 100 ml / min. The product obtained by cooling the gas that passed through the catalyst layer for 30 minutes from 1 hour after the start of the reaction was analyzed, and it was found that 41.3 g of methyl pivaloyl acetate was produced (conversion rate: 93.30 g).
2%, yield 81.4%, space-time yield 2753 g / l · h
r).

Example 7 In Example 5, the catalyst was γ-alumina having a particle diameter of 3 mm [Neobead DB-48 (aluminum content in terms of aluminum oxide: 95.3% by weight), manufactured by Mizusawa Chemical] 6
The reaction was carried out in the same manner as in Example 5, except that the flow rate was changed to 0 ml and the flow rate of the nitrogen gas was changed to 25 ml / min. The product obtained by cooling the gas that passed through the catalyst layer for 30 minutes from 1 hour after the start of the reaction was analyzed, and it was found that 45.2 g of methyl pivaloyl acetate was produced (conversion rate: 95.5).
%, Yield 88.8%, space-time yield 1507 g / lh
r).

Example 8 In Example 5, the catalyst was γ-alumina having a particle size of 3 mm (neobead GB-45 (aluminum content in terms of aluminum oxide: 100% by weight), manufactured by Mizusawa Chemical) 30
ml, and the flow rate of nitrogen gas to 100 ml / min.
Then, the flow rate of methyl pivaloylpyruvate is 1 g / mi.
The reaction was carried out in the same manner as in Example 5, except that n was changed to n. The product obtained by cooling the gas that passed through the catalyst layer for 30 minutes from 1 hour after the start of the reaction was analyzed, and it was found that 22.0 g of methyl pivaloyl acetate was produced (conversion rate: 9).
0.8%, yield 86.2%, space-time yield 1467g / l
hr).

Example 9 In Example 5, the catalyst was γ-alumina having a particle size of 1 mm [Neobead RP-4B (aluminum content in terms of aluminum oxide: 94.5% by weight): manufactured by Mizusawa Chemical] 6
0 ml and the flow rate of nitrogen gas is 100 ml / min
And the flow rate of methyl pivaloylpyruvate to 4 g /
The reaction was carried out in the same manner as in Example 5, except that the reaction time was changed to min. After 1 hour from the start of the reaction, the product obtained by cooling the gas that passed through the catalyst layer for 15 minutes was analyzed. As a result, 47.9 g of methyl pivaloyl acetate was produced (conversion rate: 96.5%). , Yield 94.0%, space-time yield 319
3 g / l · hr).

Comparative Example 5 A reaction was carried out in the same manner as in Example 5, except that the catalyst was not charged. The product obtained by cooling the gas that passed through the catalyst layer for 30 minutes from 1 hour after the start of the reaction was analyzed, and methyl pivaloyl acetate was found to be 0.0%.
36 g (conversion rate 0.14%, yield 0.14%)
%).

Comparative Example 6 A reaction was carried out in the same manner as in Example 5 except that the catalyst was changed to 30 ml of glass beads having a particle diameter of 2 mm (aluminum content in terms of aluminum oxide: 2% by weight). The product obtained by cooling the gas that passed through the catalyst layer for 30 minutes from 1 hour after the start of the reaction was analyzed, and it was found that 0.18 g of methyl pivaloyl acetate was produced (conversion rate: 0.36% , Yield 0.36%, space-time yield 12g
/ L · hr).

Comparative Example 7 In Example 5, the catalyst was changed to 30 ml of silica gel having a particle size of 1 mm (Silbead N (aluminum content in terms of aluminum oxide: 2% by weight), manufactured by Mizusawa Chemical), and the flow rate of nitrogen gas was 100 ml / min. The reaction was carried out in the same manner as in Example 5 except that the reaction was changed to. The product obtained by cooling the gas that passed through the catalyst layer between one hour and one hour after the start of the reaction was analyzed, and methyl pivaloyl acetate was found to be 1 hour.
1.0 g (conversion rate 15.5%, yield 10.
8%, space-time yield 367 g / l · hr).

Comparative Example 8 The catalyst used in Example 5 was a zeolite 1 mmφ × 10 mm [HSD-640NAD (aluminum content in terms of aluminum oxide: 7.7% by weight), manufactured by Tosoh Corporation] 30
ml, and the reaction was carried out in the same manner as in Example 5, except that the flow rate of the nitrogen gas was changed to 100 ml / min. When the product obtained by cooling the gas that passed through the catalyst layer between 1 hour and 1 hour after the start of the reaction was analyzed, 10.6 g of methyl pivaloyl acetate was produced (conversion rate 17.
2%, yield 10.4%, space-time yield 353 g / lh
r).

Comparative Example 9 In Example 5, the catalyst was 1.25 × 2.5 × 2.5 m
The reaction was carried out in the same manner as in Example 5 except that the amount of the mixture was changed to 30 ml of a stainless steel filler (Helipack: manufactured by Mutual Physics and Chemical Glass Works) and the flow rate of methyl pivaloylpyruvate was changed to 1 g / min. The product obtained by cooling the gas that passed through the catalyst layer for 30 minutes from 1 hour after the start of the reaction was analyzed, and it was found that 0.33 g of methyl pivaloyl acetate was produced (conversion rate: 1.9%). , Yield 1.3%, space-time yield 22 g / l · hr). Table 2 summarizes the results of Examples 5 to 9 and Comparative Examples 5 to 9.

[0035]

[Table 2]

Example 10 In Example 9, the catalyst was changed to γ-alumina having a particle size of 1 mm (neobead RP-4B (aluminum content in terms of aluminum oxide: 94.5% by weight), manufactured by Mizusawa Chemical).
0 ml and the flow rate of methyl pivaloylpyruvate is 2
The reaction was carried out in the same manner as in Example 9 except that the amount was changed to g / min. The product obtained by cooling the gas that passed through the catalyst layer for 30 minutes from 2 hours after the start of the reaction was analyzed, and it was found that 44.1 g of methyl pivaloyl acetate was produced (conversion rate: 99.2%). , Yield 86.8%, space-time yield 980
g / l · hr). Also, 10 minutes after the start of the reaction, 48.8 g of methyl pivaloyl acetate was produced (conversion 98.7%, yield 95.8%, space-time yield 1084 g / lhr). In 20 minutes after 30 hours, 45.5 g of methyl pivaloyl acetate was produced (conversion 93.1%, yield 89.3%, space-time yield 101).
1 g / l · hr). Further, within 30 minutes from 28 hours after the start of the reaction, 44.9 g of methyl pivaloyl acetate was produced (conversion 91.4%, yield 88.1%, space-time yield 998 g / l · hr). .

Example 11 In Example 9, the catalyst was γ-alumina having a particle diameter of 1 mm [Neobead RP-4B (aluminum content in terms of aluminum oxide: 94.5% by weight), manufactured by Mizusawa Chemical] 5
0 ml and the flow rate of methyl pivaloylpyruvate is 2
The reaction was carried out in the same manner as in Example 9 except that the amount was changed to g / min. The product obtained by cooling the gas that passed through the catalyst layer for 30 minutes from 2 hours after the start of the reaction was analyzed, and it was found that 48.1 g of methyl pivaloyl acetate was produced (conversion rate: 97.1%). , Yield 94.4%, space-time yield 192
4 g / l · hr). Further, 10 minutes after the start of the reaction, 48.1 g of methyl pivaloyl acetate was produced (conversion 95.2%, yield 94.4%, space-time yield 1924 g / l · hr) after 30 minutes from the start of the reaction. After 20 hours from the start of the reaction, 30 minutes after the start of the reaction, methyl pivaloyl acetate was 38.6.
g (conversion 79.4%, yield 75.8%,
Space-time yield 1545 g / l · hr).

Since the activity of the catalyst was reduced, acetone was fed at 3 g / min for 4 hours together with 100 ml / min of nitrogen gas at 30 ° C. after 24 hours. Thereafter, when the reaction was restarted by heating to 230 ° C. (the first reaction was restarted), 49.4 g of methyl pivaloyl acetate was produced in 30 minutes from 4 hours after the restart of the reaction (conversion rate: 97.0). %, Yield 96.9%, space-time yield 1976 g / l · hr). Further, 49.5 g of methyl pivaloyl acetate was produced in 30 minutes from 12 hours after the restart of the reaction (conversion rate: 9).
7.3%, yield 97.1%, space-time yield 1980 g / l
hr), 47.5 g of methyl pivaloyl acetate was produced within 30 minutes from 16 hours after the restart of the reaction (conversion 93.5%, yield 93.2%, space-time yield 1900 g / l).
-Hr).

Since the activity of the catalyst was slightly lowered, the reaction was restarted for the first time, and after 18 hours, acetone was flown in the same manner as above for 2 hours. Thereafter, when the reaction was restarted in the same manner (second reaction restart), 49.2 g of methyl pivaloyl acetate was obtained in 30 minutes from 4 hours after the second reaction was restarted.
(96.6% conversion, 96.4% yield, 1968 g / l · hr space-time yield), and the reaction was restarted for the second time.
8.7 g were produced (conversion 95.8%, yield 95.
6%, space-time yield 1948 g / l · hr).

[0040]

Industrial Applicability According to the present invention, in a process for producing pivaloyl acetate by subjecting pivaloyl pyruvate to a decarbonylation reaction, a pivaloyl acetate is easily prepared at a high yield using a highly active and stable catalyst. Can be manufactured. In addition, since a heavy metal catalyst is not used, the problem of complicated catalyst recovery and post-treatment or generation of dangerous metal carbonyl does not occur, and the reaction can be performed in a gas phase without replacing the catalyst. Therefore, a continuous process is facilitated, and an industrially suitable method for producing pivaloyl acetate can be provided.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C07C 69/716 CA (STN)

Claims (3)

(57) [Claims] 1. A pivaloyl pivaloyl ester, wherein pivaloylpyruvate is subjected to a decarbonylation reaction in the presence of an inorganic oxide containing not less than 10% by weight of aluminum oxide and not containing heavy metals. Method for producing acetic ester. 2. The method according to claim 1, wherein the inorganic oxide is alumina containing not less than 90% by weight of aluminum as aluminum oxide and no heavy metal.
The process for producing pivaloyl acetate according to the above. 3. The process for producing pivaloyl acetate according to claim 2, wherein the decarbonylation reaction is carried out in the gas phase.