JPH0432056B2 - - Google Patents

Description

Detailed Description of the Invention This invention uses a compound that can be converted to methyl iodide in a reaction system, such as methyl acetate, as a raw material, and reacts it with carbon monoxide under liquid phase conditions through a catalytic reaction using rhodium as the main catalyst. The present invention relates to a method for obtaining carbonylated products such as acetic anhydride.

Acetic anhydride is widely used as an acetylating agent, such as as a raw material for the production of cellulose acetate, and is an extremely important compound industrially.

Acetic anhydride has conventionally been produced industrially by reacting ketene obtained by thermal decomposition of acetic acid with acetic acid. On the other hand, as part of so-called C ₁ chemistry, research is actively being conducted to produce acetic anhydride from carbon monoxide and ethyl acetate as raw materials. In particular, the method using rhodium as the main catalyst allows the reaction to proceed under relatively quiet conditions compared to other transition metal catalysts, but it is still not fully satisfactory as an industrial method for producing acetic anhydride.

In other words, the reaction rate of the reaction between methyl acetate and carbon monoxide using rhodium and a halogen compound reaction promoter such as methyl iodide is proportional to the rhodium concentration in the reaction solution and the concentration of the halogen compound reaction promoter such as methyl iodide. This is well known among experts in this field, but because rhodium is a very expensive metal and methyl iodide has a low vapor pressure and is difficult to handle, it is difficult to use large amounts of these materials. This is not preferable, especially when carrying out this reaction industrially. Therefore, improvements have been made using cocatalysts that increase the reaction rate without increasing the amount of rhodium or methyl iodide. For example, JP-A-51-
Patent Publication No. 115403 discloses a method using a certain metal or metal compound in addition to a rhodium catalyst and a halide.

This technique uses metals from groups B, B, and B of the periodic table and non-noble metals from group 8 as metal cocatalysts. Furthermore, such metal promoters include metals from groups A, A, A, and B of the periodic table (Japanese Patent Application Laid-Open No. 55-51036), zirconium (Japanese Patent Application Laid-open No. 56-51036),
-99437), hafnium (JP-A-56-99438),
Compounds such as titanium, aluminum, vanadium, and thorium (Japanese Patent Application Laid-Open No. 142234/1982) are known.

Based on the prior art as exemplified above, the present invention provides a cocatalyst to be used with a rhodium catalyst that has the ability to promote the carbonylation reaction of methyl cowboxate, which can become methyl iodide in the reaction system, such as methyl acetate. This was created as a result of considering the following.

That is, an object of the present invention is to provide a reaction method for increasing the carbonylation reaction rate of methyl iodide with carbon monoxide. It is useful for the production of acetic anhydride from methyl acetate and for the production of acetic anhydride and acetic acid from a mixture of methyl acetate and methanol.

The characteristics of the present invention and the cocatalyst are (1) B of the periodic table;
It consists of a combination of a zero-valent carbonyl complex compound of a group metal, ie, chromium, molybdenum, or tungsten, and (2) a Lewis acid containing a metal atom.

It has been found that by adding these two types of compounds in combination, the reaction rate of the reaction between methyl carboxylate and carbon monoxide using ozium as a main catalyst is greatly increased.

Although some prior art state that two or more of the various metals listed above can be used in combination as metal cocatalysts, it is possible to actively use them in combination as shown in the present invention. There is no disclosure of such an effect, that is, an effect of increasing the reaction rate and improving the conversion rate of methyl carboxylates such as methyl acetate, and there are no examples showing such effects. Not shown.

That is, in the present invention, methyl iodide is produced in a reaction system under liquid phase conditions in the presence of a rhodium catalyst and an iodine compound. In a method for producing a carboxylic acid anhydride by carbonylating methyl carboxylate or dimethyl ether with carbon monoxide, (1) a zero-valent carbonyl complex compound of a Group B metal of the periodic table; (2) Be, Mg,
This is a carbonylation method characterized by using a promoter in combination with a Lewis acid containing a metal atom selected from the group consisting of Al, Ti, V, Cr, Mn and Zr, and the combined addition of these metal promoters. It was unexpected from the prior art that the activity could be significantly improved by

The effect of improving the reaction rate of the reaction between methyl carboxylate and carbon monoxide using rhodium as the main catalyst by using the group B metal zero-valent carbonyl complex compound and a Lewis acid containing a metal atom in combination in the present invention will be explained below. The specific contents will be described later in Examples, but for example, chromium hexacarbonyl (Cr(CO) ₆ ) is used as a zero-valent carbonyl complex compound of Group B metal, and titanium bisacetylacetonate oxytitanium (TiO ( The reaction rate when acac) ₂ ) is used in combination is about 1.6 compared to when only Cr(CO) ₆ is added.
The improvement was approximately 2.7 times that of when only TiO(acac) ₂ was added. Surprisingly, such an effect of improving the reaction rate is not observed at all when Cr(CO) ₆ is replaced with an ionic quom compound such as chromium chloride CrCl ₃ . i.e. _CrCl3
Even when TiO(acac) 2 and TiO(acac) ₂ are added together, no improvement in the reaction rate is observed. Even more surprisingly, Cr
When (CO) ₆ and CrCl ₃ are combined, the reaction rate is approximately 1.5 times that when only Cr(CO) ₆ is added,
The improvement is approximately 2.4 times that when only CrCl ₃ is added.
This clearly shows that even with chromium compounds, the reaction rate is greatly improved by the combination of Cr(CO) ₆ as a zero-valent metal carbonyl and CrCl ₃ as a Lewis acid containing a metal atom. From the above examples, it is clear that the reaction rate is improved by the combined use of a Group B metal zero-valent carbonyl complex compound and a Lewis acid containing a metal atom.

The details of the present invention will be explained below.

Rhodium catalysts used in the present invention include inorganic rhodium salts such as rhodium chloride, rhodium bromide, rhodium iodide, and rhodium nitrate, carboxylates such as acetic acid iodide, rhodium acetylacetonate, rhodium amine complex salts, and trichlorotris. Organic rhodium complexes such as pyridine rhodium, hydridocarbonyltris(triphenylphosphine)rhodium, chlorotris(triphenylphosphine)rhodium, chlorocarbonylbis(triphenylphosphine)rhodium are used. The amount of rhodium catalyst used is not necessarily strictly limited, but the concentration in the reaction solution is 0.1 to 50 mmol/, preferably 10 to 30 mmol/.

In the present invention, methyl iodide is typically used as the halide reaction promoter. There is not necessarily a strict limit on the amount used, but the concentration in the reaction solution
It is suitable to use it in a range of 0.5 to 10 mol/, preferably 1 to 5 mol/. Furthermore, in the present invention, an organic or inorganic iodide that can generate iodonium ion I ^- is used in the reaction solution, but in some cases rhodium iodide is used as a rhodium catalyst, or if it reacts with methyl iodide in the reaction solution. Rhodium complexes containing organophosphorus compounds or organic nitrogen compounds as ligands that may generate iodonium ion I ^- , such as bidridocarbonyltris(triphenylphosphine)rhodium or trichlorotrispyridinerhodium, are used. In some cases, it is not necessary to add organic or inorganic iodonium salts. Such iodides include metal iodides that are soluble in the reaction solution, methyl trin-
Butylphosphonium iodide (n-
Bu ₃ MePI), N-methylpyridinium iodide,
Organic or inorganic iodonium salts such as ammonium iodide can be used. The amount of these iodides used is such that the atomic ratio of iodine to rhodium atoms used is about 1 to 100, preferably about 1 to 20.

Furthermore, in the present invention, a zero-valent carbonyl complex compound of a Group B metal, ie, chromium, molybdenum or tungsten, and a Lewis acid containing a metal atom are used in combination as a metal promoter to these known catalyst systems.
In other words, a zero-valent caribonyl complex compound of Group B metal has the formula M(CO) _{6-o Lo} (n=0, 1, 2 or 3) [wherein M represents either chromium, tungsten or molybdenum]. In the expression, L is a trivalent organic phosphorus compound such as triphenylphosphine or tributylphosphine, or a trivalent organic phosphorus compound such as pyridine or triethylamine.
It represents a valent organic nitrogen compound or a coordinating organic compound such as tetrahydrofuran, acetonitrile, isonitrile, etc. ]; η ⁶ -arene complexes such as tricarbonyl (p-xylene) chromium and tricarbonyl (p-chlorotoluene) chromium; or [(c ₂ H ₅ ) ₄ N] ⁺ [Cr
It can be used in the form of complex compounds such as (CO) ₅ I] ^- . Lewis acids containing metal atoms include halides, oxyhalides, acetylacetonates, oxyacetylacetonates, and alkoxides of metals selected from the group consisting of beryllium, magnesium, aluminum, titanium, vanadium, chromium, manganese, and zirconium. , carboxylate, nitrate, and sulfate. Even Lewis acids without metal atoms, such as BF ₃ , are unsuitable. Even if the Lewis acid contains a metal, it is natural that compounds such as zinc chloride that change into compounds with low solubility in the reaction system are not preferred.

The amount of the zero-valent carbonyl complex compound of chromium, molybdenum or tungsten and the Lewis acid containing a metal atom is in the range of 0.1 to 100, preferably 1 to 10, in terms of the ratio of metal atoms to rhodium, which is the main catalyst.

Furthermore, the reaction of producing acetic anhydride from methyl acetate and carbon monoxide with rhodium as the main catalyst using a zero-valent metal carbonyl complex compound and a Lewis acid containing a metal atom in combination in the catalyst system according to the present invention has a high reaction rate. The structural effect can be maximized by adding a carboxylic acid such as acetic acid as a solvent. As such a carboxylic acid, a carboxylic acid having a melting point of 50°C or less can be used, and the amount used is not strictly limited, but it is 5 to 10% by weight in the charged raw material.
It is preferable to adjust the amount to approximately 100% by weight. However, when acetic acid is produced in the reaction system by reacting a mixture of methanol and methyl acetate with carbon monoxide, it is not necessary to add carboxylic acid as a solvent.

In addition, the reaction temperature when carrying out the present invention is 130°C.
-250°C, preferably 150-200°C, and the carbon monoxide pressure used during the reaction is 5-100 Kg/cm ² G, preferably 10-80 Kg/cm ² G.

The starting material to be carbonylated in the present invention is a methyl carboxylate that yields methyl iodide in the reaction system described above. A typical example is the production of acetic anhydride by carbonylation of methyl acetate.
Dimethyl ether can also be converted into acetic anhydride by the carbonylation method of the present invention. The method of the present invention can also be applied to the production of acetic acid by carbonylating methanol, but if only acetic acid is desired, the reaction rate can be sufficiently high even without using the present invention as long as it is carried out in the presence of water in the reaction system. Proceed with However, when the carbonylation reaction is carried out in a virtually anhydrous state, such as when carbonylating a mixture of methyl acetate and methanol as a raw material to co-produce dianhydride and acetic acid, it is difficult to carbonylate methanol. In any case, the method of the present invention is useful.

The method of the present invention can also be applied to carbonylation reactions of methyl carboxylate, such as the production of propionic acid and acetic acid mixed anhydrides by carbonylation of methyl propionate.

EXAMPLES Hereinafter, the present invention will be specifically explained using Examples while comparing with Comparative Examples.

In addition, the following symbols are used as follows.

AcOMe...methyl acetate Ac ₂ O...acetic anhydride The conversion rate of methyl acetate was calculated using the following formula.

AcOMe conversion rate (%) = Amount of AcOMe charged (mmol) - AcOMe (mmol) in the solution after reaction / Amount of AcOMe charged (mmol) x 100 The remaining amount of methyl acetate in the solution after reaction (mmol)
The amount of acetic anhydride produced (mmol) was determined by gas chromatography analysis of the post-reaction solution. The reaction rate is calculated from the pressure drop for 30 minutes immediately after gas absorption is observed, and is expressed as the number of moles of carbon monoxide reacted per mole of rhodium per hour.

Example 1 0.163 g of rhodium chloride trihydrate and methyl iodide were placed in a Hastelloy B autoclave with a capacity of 300 c.c.
7.2g, methyltri-n-butylphosphoium iodide (MePn- _Bu3.I ) 1.7g, chromiumhexacarbonyl (Cr(CO) ₆ ) 0.15g, bisacetylacetonatooxytitanium (TiO(acac) ₂ ) 0.17g,
After charging 10 ml of acetic acid and 29.3 g of methyl acetate and replacing the air inside with carbon monoxide, carbon monoxide was further pressurized to 40 kg/cm ² ·G. Then heat the autoclave until it reaches 175℃.
The reaction was carried out for 80 minutes. After the completion of the reaction, the reaction mixture was cooled and the residual pressure was released, and the reaction solution was taken out and subjected to gas chromatography analysis to examine the reaction results. AcOMe conversion rate is 76%,
The amount of Ac ₂ O produced was 272 mmol and the reaction rate was 517 mol/
It was molRh.H.

Comparative Example 1 The same reaction as in Example 1 was carried out except that titanium bisacetylacetonate was omitted. The results were as follows.

AcOMe conversion rate 56%, Ac ₂ O production amount 220 mmol, reaction rate 332 mol/molRh·H Comparative Example 2 The same reaction as in Example 1 was carried out except that chromium hexacarbonyl was removed. The results were as follows.

AcOMe conversion rate 30%, Ac ₂ O production amount 98 mmol, reaction rate 190 mol/molRh・H Example 2 Chromium chloride CrCl ₃ was used in place of the bisacetylacetonatooxytitanium used in Example 1.
The same reaction as in Example 1 was carried out except that 1.36 g was added. The results were as follows.

AcOMe conversion rate 71%, Ac ₂ O production amount 252 mmol, reaction rate 483 mol/molRh・H Comparative example 3 Example 2 except that chromium hexacarbonyl was removed
A similar reaction was carried out. The results were as follows.

AcOMe conversion rate 48%, Ac ₂ O production amount 164 mmol, reaction rate 204 mol/molRh·H Comparative Example 4 0.7 g of bisacetylacetonatooxytitanium was added to Comparative Example 3 and the same reaction was carried out. The results were as follows.

AcOMe conversion rate 32%, Ac ₂ O production amount 86 mmol, reaction rate 118 mol/molRh・H Example 3 Instead of rhodium chloride trihydrate as a rhodium catalyst, 0.6 g of hydridocarbonyl tris(triphenylphosphine) rhodium was used. The reaction was carried out in the same manner as in Example 1, except that the following compounds were used. The results were as follows.

AcOMe conversion rate 76%, Ac ₂ O production amount 288 mmol, reaction rate 461 mol/molRh·H Comparative Example 5 The same reaction as in Example 3 was carried out except that titanium bisacetylacetonate was omitted. The results were as follows.

AcOMe conversion rate 69%, Ac ₂ O production amount 252 mmol, reaction rate 353 mol/molRh.H Example 4 The same reaction as in Example 3 was carried out except that methyltri-n-butylphosphonium iodite was removed.
The results were as follows.

AcOMe conversion rate 72%, Ac ₂ O production amount 293 mmol, reaction rate 427 mol/molRh・H Example 5 Same as Example 1 except that 0.23 g of tungsten hexacarbonyl (W(CO) ₆ ) was used in place of chromium hexacarbonyl. A similar reaction was performed. The results were as follows.

AcOMe conversion rate 86%, Ac ₂ O production amount 260 mmol, reaction rate 450 mol/molRh・H Comparative Example 6 The same reaction as in Example 5 was carried out except for the use of bisacetylacetonate oxytitanium. The results are as follows. It was hot.

AcOMe conversion rate 39%, Ac ₂ O production amount 152 mmol, reaction rate 171 mol/molRh・H Example 6 Triphenylphosphine chromium pentacarbonyl (Cr(CO)) ₅ in place of chromium hexacarbonyl
(PPh ₃ )) was carried out in the same manner as in Example 1, and the results were as follows.

AcOMe conversion rate 72%, Ac ₂ O production amount 266 mmol, reaction rate 431 mol/molRh・H Example 7 Bis(triphenylphosphine)tetracarbonylchromium (Cr(CO) ₄ (PPh ₃ ) _{2 )} instead of chromium hexacarbonyl ) was used, but the same reaction as in Example 1 was carried out. The results were as follows.

AcOMe conversion rate 73%, Ac ₂ O production amount 277 mmol, reaction rate 421 mol/molRh・H Example 8 Tricarbonyl (η-mesitylene) chromium [Cr(CO) ₃ 1,3,
The same reaction as in Example 1 was carried out except that 5-(CH ₃ ) ₃ C ₆ H ₃ )] was used. The results were as follows.

AcOMe conversion rate 72%, Ac ₂ O production amount 279 mmol, reaction rate 398 mol/molRh・H Example 9 The same reaction as Example 1 was carried out except that 0.1 g of beryllium chloride was used in place of bisacetylacetonatooxytitanium. Summer. The results were as follows.

AcOMe conversion rate 73%, Ac ₂ O production amount 282 mmol, reaction rate 408 mol/molRh・H Example 10 Example except that 0.12 g of methyl titanate (Ti(OCH ₃ ) ₄ ) was used in place of bisacetylacetonate oxytitanium. The same reaction as in 1 was carried out. The results were as follows.

AcOMe conversion rate 80%, Ac ₂ O production amount 310 mmol, reaction rate 493 mol/molRh・H Example 11 Aluminum isopropoxide (Al(Oi−
The same reaction as in Example 1 was carried out except that 0.27 g of Pr) ₃ ) was used. The results were as follows.

AcOMe conversion rate 74%, Ac ₂ O production amount 282 mmol, reaction rate 384 mol/molRh・H Example 12 Same as Example 1 except that 0.35 g of aluminum bromide (AlBr ₃ ) was used in place of bisacetylacetonatooxytitanium. A similar reaction was carried out. The results were as follows.

AcOMe conversion rate 69%, Ac ₂ O production amount 252 mmol, reaction rate 348 mol/molRh・H Example 13 0.35 g of bisacetylacetonatooxyvanadium (VO(acact) ₂ ) was used in place of bisacetylacetonatooxytitanium. The other reactions were the same as in Example 1. The results were as follows.

AcOMe conversion rate 64%, Ac ₂ O production amount 230 mmol, reaction rate 351 mol/molRh・H Example 14 Example 1 except that 0.3 g of zirconium oxyacetate ZrO (OAc) ₂ was used in place of bisacetylacetonate oxytitanium. A similar reaction was carried out. The results were as follows.

AcOMe conversion rate 72%, Ac ₂ O production amount 258 mmol, reaction rate 427 mol/molRh・H Example 15 Same as Example 3 except for methyl-tri-n-butylphosphonium iodide (n・Bu ₃ PMeI). The reaction was carried out. The results were as follows.

AcOMe conversion rate 72%, Ac ₂ O production amount 293 mmol, reaction rate 427 mol/molRh・H Example 16 Instead of acetic acid, 5.84 g of methanol was charged, and the methyl acetate-methanol mixture was reacted with carbon monoxide. Zirconium oxychloride octahydrate 0.43 instead of bisacetylacetonate oxytitanium
The reaction was carried out under the same conditions as in Example 1 except that g was used. The results were as follows.

Methanol conversion rate 100%, AcOMe conversion rate 55.2
%, acetic acid production amount 203 mmol, Ac ₂ O production amount 173 mmol.

Comparative Example 7 The same reaction as in Example 16 was carried out except that zirconium oxyacetate octahydrate was used.
AcOMe conversion rate was 41%.

Example 17 The same reaction as in Example 10 was carried out except that 10 ml of propionic acid was used instead of acetic acid. the result
AcOMe conversion rate 79%, reaction rate 400mol/molRh・
It was H. An exchange of acyl groups took place between the product and the solvent, and the propionic acid became virtually all propionic anhydride. Other than this, Ac ₂ O211mmol,
185 mmol of AcOH was obtained.

Example 18 The same reaction as in Example 10 was carried out except that 0.17 g of molybdenum hexacarbonyl (Mo(CO) ₆ ) was used instead of chromium hexacarbonyl. The results are as follows.

AcOMe conversion rate 59%, Ac ₂ O production amount 225 mmol, reaction rate 337 mol/molRh・H Comparative example 8 Example 18 except that methyl titanate was not added
A similar reaction was carried out. The results are as follows.

AcOMe conversion rate 45%, Ac ₂ O production amount 148 mmol, reaction rate 189 mol/mol Rh.H.

Claims (1)

[Claims] 1. A method for producing a carboxylic acid anhydride by carbonylating methyl carboxylate or dimethyl ether, which produces methyl iodide in a reaction system with carbon monoxide, under liquid phase conditions in the presence of a rhodium catalyst and an iodine compound. In, (1) a zero-valent carbonyl complex compound of Group B metal of the periodic table, and (2) Be, Mg, Al, Ti, V,
1. A carbonylation method characterized by using a cocatalyst consisting of a combination with a Lewis acid containing a metal atom selected from the group consisting of Cr, Mn and Zr. 2. The method according to claim 1, wherein the methyl carboxylate is methyl acetate. 3. The method according to claim 2, using a mixture of methyl acetate and methanol.