KR810000380B1 - Process for the preparation of an anhydride of mono carboxylic acid - Google Patents

Abstract

Monocarboxylic acid anhydride, especially lower alkanoic acid such as acetic anhydride, was prepd. by reacting alkyl-alkanoate, CO, alkyliodide or alkylbromide over a Group VIII metal halide catalyst in real anhydrous condition. Thus, methyliodide, rodium trichloride hydrate and methylacetate was heated to 175-200≰C with CO in autoclave for 3 hr to give 8.7% acetic acid anhydride.

Description

Process for producing mono carboxylic anhydride

The present invention relates to a process for the preparation of carboxylic acids, more particularly mono carboxylic anhydrides, especially lower anhydrides such as acetic anhydride, by carbonylation.

Acetic anhydride has been known for many years as an industrial chemical and is used in large amounts in the production of cellulose acetate. It is typically prepared on an industrial scale by reacting ketones with acetic acid. It is also known that acetic anhydride can also be prepared, for example, by decomposing ethylidene diacetate or by oxidizing acetaldehyde. Since each of these classical methods already has well-known drawbacks and disadvantages, the discovery of an improved method of preparing acetic anhydride has been sought. A method for producing anhydrides by reacting carbon monoxide (carbonylation) with various reactants has been proposed in the United States. However, such methods involving carbonylation must use very high pressures. As a method of preparing acetic anhydride, carbonylation at low pressure has also been proposed. The French patent describes a process for carbonylating a mixture of methanol and methanol to methyl acetate in the presence of iridium, platinum, palladium, osmium and ruthenium compounds and also in the presence of bromine or iodine at lower pressures than in the US patent. Similarly, the South African patent describes a process for preparing acetic acid from the same reactant using a rhodium component in combination with bromine or iodine. Recently, a vapor phase process for preparing acetic acid using various catalysts composed of rhodium components dispersed on a carrier has been described in the US patent. However, none of these relatively recent carbonylation methods mention or predict the preparation of acetic anhydride or other carboxylic anhydrides of the present invention.

It is therefore an object of the present invention to provide an improved process for preparing lower alkanoic anhydrides such as carboxylic anhydrides, in particular acetic anhydride.

It is a further object of the present invention to provide a process for producing an improved carboxylic anhydride which does not require high pressure as before.

According to the present invention, an acyl halide such as an iodide such as acetyl iodide or bromide such as acetyl iodide which can be appropriately produced by carbonylating a lower alkyl halide such as hydrocarbyl, halide, in particular an iodide such as methyl iodide or bromide Is reacted with carboxylate esters, in particular lower alkyl alkanoates, to produce carboxylic anhydrides such as lower alkyl acid anhydrides and to regenerate halides. Thus, for example, acetic anhydride can be effectively prepared by reacting acetyl iodide. Acetyl iodide can be prepared by reacting methyl iodide with carbon monoxide at moderate carbon monoxide partial pressures, and this carbonylation reaction is carried out in the presence of a Group VIII noble metal catalyst. In the previous reaction, the iodide can be replaced with the corresponding bromide. In this way, other lower alkanoic anhydrides, such as propionic anhydride, butyric anhydride, and lower alkanoic anhydrides such as valeric anhydride, are also acyl halides such as propionyl iodide, propionyl bromide, butyryl iodide, butyryl bromide, etc. Can be prepared by reacting with lower alkyl alkanoate.

Similarly, other carboxylic acid anhydrides, such as caprylic anhydride, capric anhydride, and lauric anhydride, such as C12 or less alkanoic anhydride, or monocyclic aromatic mono carboxylic acids such as benzoic acid can also be prepared. . As in the case of lower alkanoic anhydrides, these higher anhydrides are caprylyl iodide, capryyl boromide, decanoyl iodide, decanoyl bromide, dodecanoyl iodide, dodecanoyl bromide, benzoyl Corresponding acyl halides, such as bromide, benzoyl iodide and the like, are suitable esters, e.g., alkalkanoates containing 1-11 carbon atoms in the alkyl group and 1-12 carbon atoms in the carboxylate or acyl group, or heptyl carboxes. It is prepared by reacting with aryl esters such as prylate, nonyl caproate, undecyl laurate, phenyl benzoate, and the like. As described above in lower alkanoic anhydrides, in each case acyl halides can be readily prepared by reacting the corresponding alkyl or aryl halides with carbon monoxide in the presence of a Group VIII noble metal catalyst to effect the carbonylation reaction.

The reactants are preferably selected such that the resulting anhydride has symmetric anhydrides, ie two identical acyl groups, that is to say that R in formulas (1) and (2) are the same in each case, but the preparation of asymmetric or mixed anhydrides is also It is within the scope of the present invention, which can be readily prepared by incorporating different reactants from one another, for example by using compounds having different R groups in the reaction.

The above reaction can be expressed as follows.

From the stomach

R is a saturated hydrocarbyl group (eg alkyl of C ₁ -C ₁₁ ), or a monocyclic aryl group (eg phenyl), or an alkali group (eg benzyl), preferably methyl, ethyl, n- C ₁ -C ₄ lower alkyl groups such as propyl, i-propyl, n-butyl, sec-butyl, i-butyl and t-butyl, X is I or Br. Hydrocarbyl groups may be substituted with substituents that are inert to the reaction of the present invention.

The volatile alkyl halides and unreacted acyl halides and esters in the final product mixture can be easily removed by distillation and recycled, with the total yield of the product being substantially only the required carboxylic anhydride. In the case of the preferred liquid phase reaction, the organic compound is easily separated from the noble metal catalyst by distillation. The process can be carried out in two reaction steps, namely the first step of carbonylating the hydrocarbyl halide in the presence of Group VIII noble metal catalyst and the second step of reacting the carbonylation product (acyl halide) with ether. It has been found that the process can be carried out in a single step by combining in a single reaction zone fed with carbon monoxide, ester, hydrocarbyl halide and noble metal catalyst. In the reaction, water is produced and reactants which are anhydrous or substantially anhydrous are used because it is important to operate under substantially anhydrous conditions.

Therefore, when acyl halide is prepared by carbonylation and the process is performed in two steps, the acyl halide (e.g., acetyl) is reacted with a hydrocarbyl halide (e.g., methyl iodide) in the first reaction zone in the presence of a carbon monoxide noble metal catalyst. Iodide), which is then transferred to a second reaction zone where the acyl halide is reacted with hydrocarbyl esters (eg lower alkanoic acid esters) to produce the product carboxylic anhydride and regenerate the hydrocarbyl halide. The hydrocarbyl halide is then separated from the product anhydride by distillation and recycled to the reaction zone of the first stage for carbonylation. Unreacted acyl halides and ethers are also recycled and only carboxylic anhydride is recovered as product.

The temperature at which the reaction between the hydrocarbyl halide and carbon monoxide is carried out is suitably wide, for example 20-500 ° C., preferably 100-350 ° C., more preferably 125-250 ° C.

Although a lower temperature than the above may be used, in this case, the reaction rate tends to be slow, and a high temperature may be used, but there is no special advantage in this case. The reaction time is not a variable of the process, which varies to some extent with the temperature used, but typical residence times are typically 0.1-20 hours. The reaction is, of course, carried out under superatmospheric pressure, but one of the features of the present invention is that it does not require too high a pressure and may be used if desired. In general, the reaction can be effectively carried out by using a carbon monoxide partial pressure of preferably 5-2000 p.s.i.g, most preferably 25-1000 p.s.i.g (sometimes used 0.1-15000 p.s.i.g). When using a liquid phase reaction, the total pressure is what is required to maintain the required liquid phase. Thus the liquid phase reaction is conveniently carried out in an autoclave or similar device. At the end of the required residence time, the reaction mixture is transferred to the second reaction zone and heated. Preferably, the reaction product is introduced into a fractional distillation column, a distillation zone to separate unreacted hydrocarbyl halides that may be present, and the acyl halides are separated from the catalyst. The catalyst and hydrocarbyl halide can then be recycled to the first reaction zone. Alternatively, this separation may be omitted and the whole reaction mixture may be transferred to the reaction zone of the second stage, or only hydrocarbyl halides or catalysts may be separated there.

In the second reaction zone, the acyl halide reacts with the carboxylic acid ester. This reaction is carried out by heat when the acyl halide is separated from the Group VIII noble metal catalyst, and when this separation is not carried out, the reaction with ether may occur in the presence of a catalyst.

In each case, the temperature used is preferably 0-300 ° C, preferably 20-250 ° C, and most preferably 50-200 ° C. Carboxylic anhydride is formed during the reaction and hydrocarbyl halides are regenerated. The product mixture includes product anhydrides and hydrocarbyl halides, and also unreacted esters and acyl halides and noble metal catalysts if the catalyst is not separated before the second stage reaction. The organic components are easily separated from each other by conventional fractional distillation. Hydrocarbyl halides are generally the most volatile and the anhydrous rates are generally the least volatile and anhydrides are easily distilled from the inorganic catalysts present. The recovered hydrocarbyl halide is recycled with the recovered catalyst to the reaction zone of the first stage for carbonylation. Unreacted ether and / or acyl halide can be recycled to the second stage reaction zone and carboxylic anhydride is recovered as product.

In a preferred embodiment of the present invention the two reaction stages described above are combined so that the process is carried out in a single reaction zone. Both of the carboxylate esters supplied in the zone are fed in a single reaction zone and are preferably reacted together in the presence of carbon monoxide and Group VIII noble metal catalyst in the liquid phase. Hydrocarbyl halides are formed in place and therefore the halides are not only supplied to the system as hydrocarbyl halides, but the halogen moiety is also used as other organic halides or other inorganic halides such as hydrohalides or alkali metals or other metal salts, or as iodine or bromine atoms. Supplied. After the reaction, several components of the reaction mixture are easily separated from each other by fractional distillation.

The temperature when carrying out the one-step embodiment of the present invention is suitably a wide range of temperature, for example 20-500 ° C., preferably 100-300 ° C., more preferably 125-250 ° C. Lower temperatures than those described above may be used as in the case of the two-stage embodiment, but this tends to reduce the reaction rate, and higher temperatures may be used, but there are no particular advantages. The reaction time is also not a variable of the one-step process and mainly depends on the temperature used, but typical residence times are generally 0.1-20 hours. Although the reaction is carried out under superatmospheric pressure, it is a feature of the present invention that, as mentioned above, no high pressure is required, which requires a special high pressure device. In general, the reaction can be effectively carried out by using a carbon monoxide partial pressure of preferably 5-2000 p.s.i.g, most preferably 25-1000 p.s.i.g, but a carbon monoxide partial pressure of 0.1-15.000 p.s.i.g may also be used. The total pressure is preferably at the level required to maintain the liquid phase, in which case the reaction can advantageously be carried out in an autoclave or similar device. After the required residence time, the reaction mixture is separated into several of its components by distillation. Preferably, the reaction mixture is introduced into a fractional distillation column or a series of distillation zones separating the hydrocarbyl halides, acyl halides and esters from the product anhydride. Since the boiling points of these several compounds are sufficiently different, their separation by conventional distillation does not cause any particular problem. Likewise, anhydrides are easily distilled from noble metal catalysts. Hydrocarbyl halides and precious metal catalysts and acyl halides can then be mixed with fresh esters and carbon monoxide to react to produce more anhydrides.

The final reaction mixture usually contains acyl halides with the product anhydride, and after separation from the anhydride, the acyl halides are recycled to the reaction zone to react with the esters or the second step of the two step embodiments described above (Equations 2 and 3). It is also a feature of the present invention that the ester and acyl halide can be separated and reacted to produce an additional amount of anhydride, as in.

The ratio of esters to halides in the reaction system can vary widely. Typically 1-500 equivalents of ester, preferably 1-200 equivalents, are used per equivalent of halide. Therefore, in the case of ester, 1-500 mol, preferably 1-200 mol, per mol of the halide reactant is used. By maintaining the partial pressure of carbon monoxide at a special value, a sufficient amount of reactant will always react with the hydrocarbyl halide.

The hydrocarbyl halide carbonylation (formula 1) described above in a second stage embodiment is advantageously carried out in the presence of a solvent or diluent. This solvent or diluent may be an organic solvent that is inert in the environment of the process, which may also be a carboxylate ester, so that carboxylic anhydride is produced with the acyl halide, the product required in that case. In other words, the halide-forming reaction of the two-step embodiment is based on the features of the one-step embodiment. Similarly, the one-step embodiment is advantageously carried out in the presence of a solvent or diluent, in particular when the reactants have a relatively low boiling point. The presence of the product anhydride itself or of the corresponding esterin high boiling point solvent or diluent allows the use of lower total pressures. Alternatively, the solvent or diluent is an organic solvent that is inert in the environment of the process, such as hydrocarbons (eg octane, benzene, toluene) or carboxylic acids (eg acetic acid). This is easily separated since the solvent or diluent is suitably selected to have a boiling point sufficiently different from the components of the reaction mixture.

Group VIII noble metal catalysts, i. For example, the catalyst added may be a fine metal of its own, or the metal carbonate, oxide, hydroxide, bromide, iodide, chloride, lower alkoxide (methoxide), phenoxide or carboxylate ions may be C _1- Metal carboxylates derived from an alkali acid of C ₂₀ . Similarly metal complexes such as, for example, metal carbonyls such as iridium carbonyl and rhodium carbonyl, or carbonyl halides (eg iridium tri-carbonyl chloride [Ir (CO) ₃ Cl] ₂ ) or acetylacetonate Other complexes such as rhodiumacetyl acetonate Rh (C ₅ H ₇ O ₂ ) ₃ can also be used.

Although carbon monoxide is preferably used in a substantially pure form, inert diluents such as carbon dioxide, nitrogen, methane and cyclone may be present if desired. The presence of an inert diluent does not affect the carbonylation reaction, but if they are present it is necessary to increase the total pressure to maintain the required carbon monoxide partial pressure. However, carbon monoxide must be anhydrous, as in the following reactants: carbon monoxide and other reactants must be free of water. However, the presence of a minimum amount of water, such as that found in commercial forms of reactants, can be tolerated.

It has been surprisingly found that the activity of Group VIII noble metal catalysts can be greatly improved, especially with regard to reaction rates and product concentrations, by the use of accelerators in parallel. Effective promoters include elements of atomic weight 5 or more of groups IA, IIA, IIIA, IVB, and VIB, non-noble metals of Group VIII, and lanthanides and actanides of the Periodic Table. Particularly preferred are these crowded low molecular weight metals, for example metals having a molecular weight of 100 or less, and particularly preferred are Groups IA, IIA and IIIA metals. In general, the most suitable elements are lithium, magnesium, potassium, titanium, chromium, iron, nickel and aluminum. Most preferred are lithium, aluminum and potassium, especially lithium. Accelerators are used in their elemental form, such as finely ground or powdered metals, or they are used as compounds of various forms of organic and inorganic which are effective for introducing the elements into the reaction system. Thus, typical compounds of accelerator elements include oxides, hydroxides, halides (eg bromide and iodide), oxyhalides, hydrides, alkoxides and the like. Particularly preferred organic compounds are, for example, salts of organic mono-carboxylic acids such as alkanoates and benzoates such as acetates, butyrates, decanoates and laurates and the like. Other compounds include metalalkylcarbonyl compounds and chelates, compounds and enol salts. Especially preferred are compounds such as elemental form, bromide or iodide and organic salts (eg salts of mono-carboxylic acids corresponding to the resulting anhydrides). If desired, compounds of promoters, in particular mixtures of elements from different groups of the periodic table, can be used. The exact reaction mechanism of the promoter, or the exact form in which the promoter reacts, is not known, but some induction period was observed when the promoter was added in elemental form, for example, a fine metal.

The amount of promoter may vary widely but is preferably used in an amount of 0.001-10 moles per mole of Group VIII noble metal catalyst.

When treating the reaction mixture by distillation or the like as described above, the promoter generally remains as one of the least volatile components together with the Group VIII noble metal catalyst and is suitably recycled or treated with the catalyst.

The reaction is carried out in one step or in two steps or the above reaction is easily carried out in a continuous process so that the reactants and the catalyst are continuously supplied to a suitable reaction zone, preferably with an accelerator, and the reaction mixture is continuously distilled to obtain volatile organic components. The whole product, which is separated and composed of other organic constituents, which are recycled with carboxylic anhydride, is provided, and in the case of a liquid phase reaction, the part containing the Group VIII noble metal (and promoter) is also recycled. In the case of such a continuous process, it is clear that the halogen moiety always remains in the system. Sometimes the small amount of halogen forming moiety required is preferably carried out by supplying halogen in the form of a hydrocarbyl halide, but as described above the halogen moiety is also a salt of another organohalide or a hydrogen halide or salt such as, for example, an alkali metal or other metal salt. It may be supplied as an inorganic halide or an iodine atom or a bromine element.

As described above, the carbonylation reaction in the process of the present invention may be carried out in the gas phase by appropriately adjusting the total pressure with respect to temperature so that the reactant is in gaseous form when it comes into contact with the catalyst, if desired. In the case of gas phase reactions and liquid phase reactions, catalysts and accelerators, i.e., catalyst components, are sometimes supported, that is, they are conventional materials such as alumina, silica, silicon, carbide, zirconia, carbon, bauxite, attafulgas clay, and the like. It may also be dispersed on a carrier. The catalyst component may be applied to the carrier by conventional methods, for example by immersing the carrier in a catalyst or a solution of the catalyst and promoter and then drying. The concentration of the catalyst component on the carrier varies widely, for example from 0.01-10% by weight or more.

The following examples are intended to illustrate the invention in more detail, and do not limit the invention. All parts and percentages in the examples are by weight unless otherwise indicated.

Example 1

Methyl acetate (3.7 parts) and acetyl iodide (8.5 parts) were heated together at reflux for 4 hours. The reflux condenser was maintained at a temperature of 45-50 ° and the non-condensing gas from this condenser was condensed in a second condenser held at 10 ° C. Methyl iodide (2.8 parts) and a small amount (about 15%) of methyl acetate were collected from the second condenser and the residual mixture contained 20% by weight (2.2 parts) of acetic anhydride as determined by GC analysis. The remainder of the residue mixture consisted of unreacted methyl acetate and acetyl iodide and a small amount of methyl iodide.

Example 2

Methyl iodide (71 parts) and rhodium trichloride hydrate (0.83 parts) were mixed together with 300 parts of methyl acetate to form carbon monoxide (Co partial pressure 730-590, total pressure 1000 p) in a stirred stainless oatclad with Hastelloy B liner. sig) and heated at 175-200 ° C. under an atmosphere. After reacting for 2 hours, 0.7 mol of carbon monoxide was absorbed per mol of methyl iodide, and the reaction mixture contained 7.7% of acetyl iodide, 8.7% of acetic anhydride. The remainder of the reaction mixture consisted of unreacted reagent and catalyst. After cooling the autoclave, the reaction mixture was removed. To facilitate separation of the reaction mixture, 100 parts of nonane was diluted and distilled at atmospheric pressure through a 15-plate oldershaw column.

Methyl iodide and methyl acetate were distilled at an upper temperature of 45-57 ° C., followed by acetyl iodide moiety (18.7 parts) (boiling point: 108-111 ° C.) and two layers of acetic anhydride-nonane (boiling point: 113-127.5 ° C.). ) Parts were obtained one after the other. The lower layer was separated (21.6 parts) and identified as very pure acetic anhydride by GC analysis and infrared spectrum. Acetyl iodide thus formed is suitably used in the reaction of Example 1.

Example 3

Methyl acetate (300 parts), methyl iodide (35 parts) and rhodium chloride hydrate (1.6 parts) were added to carbon monoxide (total pressure 1000 p.sig, partial pressure of carbon monoxide 590 p) in a high pressure stainless steel autoclave with Hastelloy B liner. sig) at 200 ° C. under an atmosphere. After 2 hours of reaction, 0.46 mole of carbon monoxide was absorbed per 0.246 mole of methyl iodide, and GC analysis of the reaction mixture revealed that it contained 15.3% (40 parts) of acetic anhydride and 4.5% (11.9 parts) of acetyl iodide. . The remainder of the reaction mixture consists of unreacted reagent and catalyst.

Example 4

Methyl acetate (6 parts), methyl iodide (0.7 parts) and rhodium chloride (0.1 parts) are heated at 175 ° C. for 16 hours under a carbon monoxide (initial partial pressure 300 p.s.i.g) atmosphere in a rotating glass built-in pressure vessel. GC analysis of the reaction mixtures included 16% (0.6 parts) of acetic anhydride and 2.8% (0.17 parts) of acetyl iodide. The rest of the reaction mixture is as described in Examples 2 and 3.

Example 5

Methyl acetate (6 parts), methyl iodide (0.7 parts) and iridium iodide (0.1 parts) were heated in a rotating glass vessel under carbon monoxide (initial partial pressure 300 p.sig) for 16 hours at 175 ° C. do. GC analysis of the reaction mixture contained 2.8% of acetic anhydride (0.9 parts) and acetyl iodide (0.17 parts) together with unreacted reactants and catalysts.

Example 6

Example 1-5 was repeated using acetyl bromide and methyl bromide instead of acetyl iodide and methyl iodide. Corresponding results were obtained for the reaction product, but the conversion was very low.

Example 7

Examples 1-5 were repeated using ethyl propionate, propionyl iodide and ethyl iodide instead of methyl acetate, acetyl iodide. Propionic anhydride was prepared according to the corresponding method, and propionyl iodide was also prepared according to the method of 2-5.

Example 8

Methyl acetate, rhodium trichloride hydrate (0.75 parts), iodine (1.5 parts), and chromium metal powder (3 parts) were added to carbon monoxide (gross pressure 350 p.sig, initial partial pressure of carbon monoxide 66 p.sig) in a stirred glass-containing pressure vessel. It heated at 175 degreeC under the atmosphere of.

GC analysis of the reaction mixture after 4 hours of reaction time included 59% (121 parts) of acetic anhydride. The remainder of the reaction mixture in this and the following examples, given product hydrolysis analysis, consisted of unreacted reagent reaction intermediates and catalyst components, unless otherwise noted.

Example 9

Methyl acetate (600 parts), methyl iodide (65 parts), lithium iodide (9 parts), chromium metal powder (3 parts) and rhodium chloride (3 parts) were added to the carbon oxide (total) in the stainless steel autoclave. Heating at 175 ° C. under a pressure of 350 p.sig and an initial partial pressure of carbon monoxide (66 p.sig). GC analysis of the reaction mixture after 8 hours of reaction time included 71.1% (601) parts of acetic anhydride.

Example 10

Methyl acetate (150 parts), rhodium trichloride hydrate (0.75 parts), aluminum iodide (17.5 parts) and chromium metal powder (1 part) were mixed with carbon monoxide (total pressure 350 p.sig, carbon monoxide) in a stirred glass vessel. Heating at 175 ° C. under an atmosphere of 66 p · sig. GC analysis of the reaction mixture after 4 hours of reaction time included 67.7% (141 parts) of acetic anhydride.

Example 11

Methyl acetate (150 parts), rhodium trichloride hydrate (0.75 parts), magnesium iodide (175 parts) and chromium metal powder (1 part) were mixed with carbon monoxide (total pressure 350 p.sig, carbon monoxide) in a stirred glass vessel. Was heated at 175 ° C. under an atmosphere of an initial partial pressure of 66 p · sig). GC analysis of the reaction mixture after 4 hours of reaction time included 67.7% (141 parts) of acetic anhydride.

Example 12

Methyl acetate (150 parts), rhodium trichloride hydrate (0.75 parts) and anhydrous chromium iodide (20 parts) were added to carbon monoxide (gross pressure 350p.sig, initial partial pressure of carbon monoxide 66p.sig) in a stirred glass-containing pressure vessel. It heated at 175 degreeC under the atmosphere of. The reaction mixture GC analysis after 4 hours of reaction time included 52.2% (104 parts) of acetic anhydride.

Example 13

Methyl acetate (150 parts), rhodium trichloride hydrate (0.75 parts), methyl iodide (18.5 parts), chromium metal powder (1 part) and titanium dioxide (3 parts) were mixed with carbon monoxide in a stirred glass-containing pressure vessel. Heating at 175 ° C. under a total pressure of 350 p.sig and an initial partial pressure of carbon monoxide at 66 p.sig). The reaction mixture GC analysis after 4 hours of reaction time included 39% acetic anhydride.

Example 14

Methyl acetate (150 parts), rhodium trichloride hydrate (0.75 parts), methyl iodide (18.5 parts) and chromium carbonyl (5.7 parts) were mixed with carbon monoxide (total pressure 350 p.sig, carbon monoxide) in a stirred glass vessel. Was heated at 175 ° C. under an atmosphere of an initial partial pressure of 66 p · sig). After 4 hours of reaction time, the reaction mixture was analyzed by GC and contained 51% of acetic anhydride (103 parts).

Example 15

Methyl acetate (150 parts), rhodium trichloride hydrate (0.75 parts), methyl iodide (18.5 parts) and chromium metal powder (3 parts) were mixed with carbon monoxide (total pressure 350 p.sig, carbon monoxide) in a stirred glass vessel. Was heated at 175 ° C. under an atmosphere of an initial partial pressure of 66 p · sig). The reaction mixture GC analysis after 4 hours of reaction time included 56.5% (115 parts) of acetic anhydride.

Example 16

Methyl acetate (150 parts), rhodium trichloride hydrate (0.75 parts), chromium metal powder (1 part), aluminum oxide (2.5 parts) and methyl iodide (18.5 parts) were mixed with carbon monoxide in a stirred glass Heating at 175 ° C. under a total pressure of 350 p.sig and an initial partial pressure of carbon monoxide at 66 p.sig). The reaction mixture GC analysis after 4 hours of reaction time included 59% (122 parts) of acetic anhydride.

Example 17

Methyl acetate (150 parts), rhodium trichloride hydrate (0.75 parts), methyl iodide (37 parts), chromium carbonyl (2.2 parts) and aluminum oxide (3 parts) were mixed with carbon monoxide in a stirred glass 66 p.sig) at 175 ° C. GC analysis of the reaction mixture after 3 hours of reaction time included 56% (127 parts) of acetic anhydride.

Example 18

Methyl acetate (600 parts), lithium iodide (140 parts) and rhodium chloride hydrate (6 parts) were added to the atmosphere of carbon monoxide (total pressure 350p.sig, initial partial pressure of carbon monoxide 65p.sig) in a stirred stainless steel autoclave. Under heating at 175 ° C. GC analysis of the reaction mixture after 8 hours of reaction time included 75.2% (707 parts) of acetic anhydride.

Example 19

Methyl acetate (150 parts), methyl iodide (35 parts), lithium iodide (70 parts) and rhodium chloride hydrate (3 parts) were added to the carbon monoxide (total pressure 350 p.sig, Heating at 175 ° C. under an atmosphere of 66 p · sig of the initial partial pressure of carbon monoxide. The reaction mixture GC analysis after 8 hours reaction time contained 78.4% (707 parts) of acetic anhydride.

Example 20

Methyl acetate (600 parts), lithium acetate (17 parts), lithium iodide (35 parts) and rhodium chloride hydrate (3 parts) were mixed with carbon monoxide (total pressure 350 p.sig, carbon monoxide) in a stirred stainless steel autoclave. Heating at 175 ° C. under an atmosphere of an initial partial pressure of 66 p · sig). The reaction mixture GC analysis after 8 hours of reaction time included 68% (528 parts) of acetic anhydride.

Example 21

Methyl acetate (300 parts), methyl iodide (35 parts) and iridium trichloride (2.2 parts) were prepared in a stirred stainless steel autoclave of carbon monoxide (total pressure of 1000 p.sig, partial pressure of carbon monoxide 320p.sig). It heated at 225 degreeC under atmosphere. GC analysis of the reaction mixture after 14 hours of reaction time included 22% (707 parts) of acetic anhydride. The remainder of the reaction mixture consisted of unreacted reagents, intermediates and catalysts.

Example 22

Of carbon monoxide (total pressure 630 p.sig, initial partial pressure of carbon monoxide at 350 p.sig) in a glass-mounted pressure vessel rotating methyl acetate (6 parts), lithium iodide (0.7 parts) and platinum dibromide (0.1 parts) It heated at 175 degreeC for 16 hours in atmosphere. GC analysis of the reaction mixture contained 1.4% (0.1 parts) of acetic anhydride.

Example 23

Carbon monoxide (initial pressure of carbon monoxide 350p.sig, total pressure 630p.sig) in a glass-mounted pressure vessel rotating methyl acetate (6 parts), lithium iodide (0.2 parts) and osmium chloride (1 part) Heat at 16 ° C. GC analysis of the reaction mixture contained 4.5% (0.28 parts) of acetic anhydride.

Example 24

Methyl acetate (150 parts), methyl iodide (18.5 parts) and rhodium trichloride hydrate (0.75 parts), chromium metal powder (1.0 parts) and sodium methoxide (7.0 parts) (Total pressure 630 p.sig, Co partial pressure 70 p.sig) It heated at 175 degreeC under atmosphere. GC analysis of the reaction mixture after 4 hours of reaction time included 22.5% (41.5 parts) of acetic anhydride.

Example 25

Methyl acetate (150 parts), rhodium trichloride hydrate (0.75 parts), molybdenum hexacarbonyl (1.5 parts), methyl iodide (16.0 parts) and lithium iodide (2.5 parts) in a glass vessel under agitation Was heated at 175 ° C. under a carbon monoxide (total pressure of 630 p.sig and Co partial pressure of 70 p.sig) atmosphere. GC analysis of the reaction mixture after 4 hours of reaction time included 40.0% (82.7 parts) of acetic anhydride.

Example 26

Phenylbenzoate (150 parts), iodine benzene (5 parts), rhodium trichloride hydrate (0.75 parts), lithium iodide (8 parts), chromium metal powder (1 part) and benzene (100 parts) were stirred It heated at 175 degreeC in the atmosphere of carbon monoxide (total pressure 500p.sig, Co partial pressure 350p.sig) in pressure vessel. The reaction mixture was analyzed after 10 hours of reaction, which contained 36% benzene anhydride.

Example 27

Heptyl caprylate (600 parts), rhodium trichloride hydrate (3 parts), lithium iodide (170 parts), and chromium metal powder (3 parts) were added to carbon monoxide (total pressure 500 p.sig) in a stirred stainless steel autoclave. ) Was heated at 175 ° C in the atmosphere. The reaction mixture was analyzed after 12 hours of reaction, which contained 24% caprylic anhydride (190 parts).

Example 28

Methyl acetate (150 parts), rhodium trichloride hydrate (075 parts), iodide (24.7 parts) and chromium metal powder (1 part) were mixed with carbon monoxide (total pressure 350 p.sig, Co partial pressure) in a stirred glass-containing input container. 70 p.sig) was heated at 175 캜 under an atmosphere. GC analysis of the reaction mixture after 8 hours of reaction time included 22.1% of acetic anhydride (41.5 parts).

Claims (1)

A process for preparing anhydrides of monocarboxylic acids by reacting alkyl alkanoates, carbon monoxide and alkyl iodides or bromides in the presence of Group VIII noble metal catalysts under substantially anhydrous conditions.