NL8103339A - METHOD FOR CONVERTING ACID ANHYDRIDES - Google Patents

Description

* - <'- 1 ->

Method for converting acid anhydrides.

The invention relates to the preparation of alkylidene diesters, more particularly to the preparation of ethylidene diacetate by the action of hydrogen on acetic anhydride.

Ethylidene diacetate is a chemical intermediate of primary commercial interest in view of its easy convertibility into a number of different chemicals that are commercially available in large quantity. According to a known conversion technique, ethylidene diacetate is easily converted into vinyl acetate plus acetic acid; see Kirk Othmer "Encyclopedia of Chemical Technology", (2 Ed., Vol. 21, p. 321, Interscience, New York (1970). According to another well known conversion process, ethylidene diacetate can be converted to acetic anhydride plus acetaldehyde, see 15 Kirk-Othmer "Encyclopedia of Chemical Technology, (2 Ed.), Vol. 8, 410-413, Interscience, New York (1965). Reference is also made herein to U.S. Pat. No. 2,425,389 as an indication of the pliability of ethylidene diacetate as a chemical intermediate.

Several methods have been proposed for preparing ethylidene diacetate. One such process involves the reaction of acetaldehyde and acetic anhydride, producing the ethylidene diacetate as an intermediate for the preparation of vinyl acetate, a process that has been used to a limited extent on a technical scale; see "Hydrocarbon Process" 44 (11), 287 (1965).

British Patent 1,538,782 discloses another method of preparing ethylidene diacetate, wherein methyl acetate or dimethyl ether is carbonylated in the presence of hydrogen. U.S. Patent 3,579,566 treats organic acid anhydrides, such as acetic anhydride, with hydrogen in the presence of a catalyst consisting of 8103339

* 'V

O

- 2 - from a Group VIII noble metal complex with a biphilic ligand from a group consisting of trihydrocarbylphosphines, arsines and stibins. The examples show the preparation of ethylidene diacetate from acetic anhydride by this method.

However, these examples show that the amount of ethylidene diacetate produced is relatively small with respect to the theoretical amount that can be produced from the acetic anhydride used.

Although this general process is illustrated by the "shortened" equation A on the formula sheet, the complete equation is according to scheme B. When R in this equation is methyl, the treatment of acetic anhydride with hydrogen is illustrated. In other words, in such a reaction, 1 molecule of acetic acid is formed per molecule of ethylidene diacetate produced. Side reactions tend to form other products such as acetaldehyde and ethyl acetate at the expense of the yield of ethylidene diacetate.

Belgian Patent 879,178 converts carbon-20 anhydrides into 1,1-diesters with hydrogen in the presence of certain supported metals, including Group VIII metals of the periodic table, and in the presence of a strong protonic acid, such as hydrochloric acid and fluorine - hydrochloric acid. The examples show significant carboxylic acid formation.

It is therefore an object of the invention to provide an improved process for the preparation of alkylidene diesters, for example ethylidene diacetate, from carboxylic anhydrides, for example acetic anhydride, in which the increased amount of alkylidene diesters with respect to carboxylic acid can be realized and the formation of other by-products can be minimized, ie the ratio of alkylidene diester, for example ethylidene diacetate to carboxylic acid, for example acetic acid, and the yields of the diester product are high.

8103339 * y * - 3 -

It is a further object of the invention to provide an improved process for preparing alkylidene diesters from carboxylic anhydrides, which does not require the use of Group VIII noble metals.

According to the invention, these and other objects are achieved by the reaction of a carboxylic anhydride, for example acetic anhydride, with hydrogen in the presence of a cobalt carbonyl. Surprisingly, it has been found that a cobalt carbonyl very effectively catalyzes the reaction and does not require the presence of a promoter or ligand as in the case of the process of U.S. Pat. No. 3,579,566 while additionally present. , .. precious metal. . A group of VlIIymet is required. Also, the presence of an acid of any kind is not required.

Although the presence of an acid can promote the formation of by-products and complicates the product separation, an acid can be tolerated if desired, but the absence of an acid, as used in Belgian patent 879.

178 is preferred.

Thus, according to the invention, hydrogen is reacted with an acid anhydride in the presence of a cobalt carbonyl, such as dicobalt octacarbonyl / Co (Co) 2 Z, or tetraco-bald dodecacarbonyl / Co (Co) although any other cobalt carbonyl can also be used. Thus, ethylidene diacetate 25 can be effectively prepared in a representative case by subjecting acetic anhydride to reaction with hydrogen in the presence of dicobalt octacarbonyl. In all cases, the reaction is carried out under anhydrous conditions.

When carrying out the method according to the invention, a wide range of temperatures, for example 10-250 ° C, is suitable, but temperatures of 50-150 ° C are preferably used and most preferably temperatures in the range of 70 are used. -120 ° C in general. Temperatures lower than those mentioned can be used, but they tend to lead to decreased reaction rates, and higher temperatures can also be used, but there is no particular advantage. The reaction is preferably carried out at a substantially constant temperature.

The reaction temperature is also not a parameter of the process and depends largely on the temperature used, but typical reaction or residence times will, for example, generally fall in a range of 0.1-6 hours. The reaction is preferably carried out under superatmospheric pressures, but excessively high pressures, which require special high-pressure equipment, are not necessary. Generally, the reaction is carried out effectively using a hydrogen partial pressure, which is preferably 0.35-14 MPa, most preferably 2.1-7 MPa, although hydrogen partial pressures of 0.007-70 MPa can also be used. Usually, pressures below about 14 MPa are generally used. By keeping the partial pressure of hydrogen at the indicated values, appropriate amounts of this reagent are always present.

The total pressure is preferably that required to maintain the liquid phase and in this case the reaction can advantageously be carried out in an autoclave or the like.

At the end of the desired residence time, the reaction mixture is separated into its various components, such as by distillation. Preferably, the reaction product is placed in a distillation zone, which may be a fractional distillation column or a series of columns, effective for separating the unreacted acetic anhydride, acetic acid, and other byproducts of the ethylidene diacetate product. The cobalt carbonyl is recycled.

The hydrogen is preferably used in substantially pure form, such as commercially available, but inert diluents such as carbon monoxide, carbon dioxide, nitrogen, methane and noble gases may be present if desired. The presence of inert diluents does not affect the reaction, but the presence thereof makes it necessary to increase the total pressure to maintain the desired hydrogen partial pressure. However, the hydrogen, like other reagents, must be substantially dry, that is, the hydrogen and the other reagents must be reasonably free of water. However, the presence of small amounts of water, as can be found in the commercial forms of the reagents, is entirely acceptable.

As mentioned previously, the presence of gaseous diluents, such as carbon monoxide, can increase the total pressure required to provide the desired hydrogen partial pressure, but the presence of carbon monoxide can be effective to maintain the catalyst for extended periods of time . Cobalt carbonyl tends to decompose with increasing temperature, but it has been found that such decomposition is minimized and even completely depressed if the temperature is kept below 100 ° C under the above-mentioned pressure conditions. The presence of carbon monoxide further provides assurance that the catalyst will not decompose.

The amount of cobalt carbonyl is not critical in any way and is not a parameter of the method of the invention and can vary over a wide range. As is known to those skilled in the art, the amount of conventional catalyst will be that which will provide the desired suitable and reasonable reaction rate, since the reaction is affected by the amount of catalyst. In essence, however, any amount of catalyst will facilitate the reaction. Typically, however, the cobalt catalyst is used in an amount of 1 mole per 1-100,000 moles of carboxylic anhydride, preferably 1 mole per 10-10,000 moles of carboxylic anhydride, and most preferably 30 moles per 50-5,000 moles of carboxylic anhydride.

The anhydrides which can be used in carrying out the process according to the invention are anhydrides of carboxylic acids with a maximum of 10 carbon atoms, preferably lower alkanoic acids with a maximum of 6 carbon atoms.

These anhydrides can be represented by the formula 8103339 * - 6 ->

O O

t »n

R-C-O-C-R

wherein R is a hydrocarbyl radical, which may be an alkyl group or a monocyclic aryl group. Representative anhydrides include acetic anhydride, propionic anhydride, valeric anhydride, caprylic anhydride, benzoic anhydride and the like. Acetic anhydride is preferred.

The method of the invention can be performed in the presence of a solvent or diluent, if desired. Usually, a solvent is not required. The solvent or diluent can be any organic solvent that is inert to the process environment, such as hydrocarbons, for example, octane, benzene, toluene, xylene, and tetraline, or halogenated hydrocarbons, such as chlorobenzenes, for example, trichlorobenzene, or carboxylic acids having up to 16 carbon atoms such as acetic acid or esters such as methyl acetate and cellosolve acetate and the like. Preferred solvents are halogenated hydrocarbons, chlorobenzenes and high boiling esters. It is also possible to use mixtures of solvents, such as a mixture of the above-mentioned solvents. Generally, chlorobenzenes have been found to be most suitable for use when using a solvent in the process. A solvent or diluent having a boiling point sufficiently different from the other components in the reaction mixture is suitably selected so that it can be easily separated by distillation, as will be apparent to those skilled in the art.

It will be appreciated that the above-described reaction lends itself readily to continuous processing, with the reactants and catalyst continuously added to the appropriate reaction zone and the reaction mixture continuously distilled to separate the volatile organic components and provide a net product consisting essentially of 8103339-7-alkylidene diester, with the other organic components being recycled and, in the case of liquid phase reaction, a residual catalyst-containing fraction also being recycled.

It will be appreciated that the catalytic reaction involved in the process of the invention may optionally be carried out in the vapor phase by appropriate control of the total pressure with respect to temperature so that the reactants are in vapor form when they are in contact with the catalyst. In the case of vapor phase machining and optionally in the case of liquid phase machining, the catalyst components may be on a bearing, i.e. they may be dispersed on a conventional type support such as aluminum oxide, silicon oxide, silicon carbide, zirconium oxide, coal, bauxite, attapulgus clay, solid organic polymers, for example, polyvinylpyridine and polystyrene, and the like. The catalyst components can be applied to the diggers in a conventional manner, for example, by impregnating the support with a solution of the catalyst, or the catalyst mixture, followed by drying. The catalyst component concentrations on the support can vary widely, for example 0.01-10 wt% or higher. The supported catalyst is in the active form if it has a hydride or carbonyl substituent on the cobalt carrier. Typical operating conditions for vapor phase processing are a temperature of 50-300 ° C, preferably 70-250 ° C and most preferably 100-200 ° C, a pressure of 0.007-35 MPa, preferably 0.35-10.5 MPa and most preferably -1 1.05-3.5 MPa, at space velocities of 50-10,000 hours, preferably 200-6000 ^ and most preferably 500-4000 hours ^ (STP).

The invention will now be illustrated in a non-limiting manner with the following example, in which parts refer to weight and percentages are on a molar basis unless otherwise indicated.

Example I

In this example, a magnetic 8103339-8 stirred Hastelloy Parr bombe with a glass coating is used as the reaction vessel. Place 2 parts of dicobaltoctacarbonyl as a catalyst in the bombe, then 40 parts of acetic anhydride, and flush with argon and pressurize 4.9 MPa with hydrogen. The bombe is then placed in an oil bath at room temperature and brought to 100 ° C in about 15 minutes.

The pressure is maintained at 10.15 MPa by replenishing hydrogen if necessary. The reaction is then carried out at this constant temperature for 3 hours, after which the bomb is cooled to about room temperature, sprayed and opened. From G.C. (gas chromatography) analysis of the reaction mixture shows that it contains 13 parts of ethylidene diacetate and 12.1 parts of acetic anhydride together with 7.4 parts of acetic acid and traces of ethyl acetate and acetaldehyde by-products. The yield of ethylidene diacetate is 65% and the ratio of ethylidene diacetate to acetic acid is 72%.

Example II

A Parr bombe as described in Example 1 is filled with 2 parts of dicobalt octacarbonyl as a catalyst, then with 40 parts of acetic anhydride, flushed with argon and pressurized to 2.8 MPa with hydrogen. The bombe is then placed in an oil bath at room temperature and brought to a temperature of 100 ° C in about 15 minutes. The pressure is kept at 8.4 MPa by replenishing hydrogen if necessary. The reaction is then carried out at this constant temperature for 3 hours, after which the bomb is cooled to about room temperature, sprayed and cooled. Gas chromatographic analysis of the reaction mixture shows that it contains 10.3 parts of ethylene diacetate and 22.7 parts of acetic anhydride together with 5.9 parts of acetic acid and trace amounts of ethyl acetate and acetaldehyde by-products. The yield of ethylene diacetate is 84% and the ratio of ethylene diacetate to acetic acid is 72%.

Example III

A reaction vessel, as described in 8103339 + * - 9 - example I, is charged with 1 part tetracobalt dodecacarbonyl as catalyst, then with 20 parts acetic anhydride, purged with nitrogen and pressured 1.05 MPa with carbon monoxide. and then up to 7 MPa with hydrogen. The bombe is then placed in an oil bath at room temperature and brought to 100 ° C over 15 minutes. The pressure is kept at 7 MPa with hydrogen. The reaction is then carried out at this constant temperature for 3 hours, after which the bomb is cooled to about room temperature, sprayed and opened. Gas chromatographic analysis of the reaction mixture shows that it contains 8.2 parts of ethylene diacetate and 7.4 parts of acetic anhydride, along with 3.6 parts of acetic acid and trace amounts of ethyl acetate and acetaldehyde by-products. The yield of ethylidene diacetate is 91% and the ratio of ethylidene diacetate to acetic acid is 93.3% of the theoretical value.

Example IV

In this example and in the following examples, a stirred autoclave is used as the reaction vessel. The autoclave is charged with 4.1 parts of dicobaltoctacarbonyl as a catalyst and 400.4 parts of acetic anhydride and pressurized with 2.45 MPa carbon monoxide and up to 8.05 MPa with hydrogen. The vessel is then heated to 90 ° C in about 15 minutes. During the heating period, there is absorption of gas and the pressure drops despite the increased temperature. The pressure is brought back to 8.05 MPa with hydrogen and held at this temperature for 6 hours. Gas chromatographic analysis of the reaction mixture shows that it contains 178.6 parts of ethylene diacetate and 134.9 parts of acetic anhydride along with 84.8 parts of acetic acid, 4 parts of acetaldehyde and trace amounts of by-product of ethyl acetate. The yield of ethylene diacetate is 94% and the ratio of ethylidene diacetate to acetic acid is 86.6% of theory. The ratio of ethylidene diacetate plus acetaldehyde to acetic acid is 93% of theory.

35 8103339 w V- - 10 -

Example V

The reaction vessel is charged with 2.1 parts of dicobalt octacarbonyl, 5 parts of p-toluenesulfonic acid and 400 parts of acetic anhydride and pressurized with 3.5 MPa of carbon monoxide and 8.05 MPa with hydrogen. The vessel is then heated to 100 ° C in about 15 minutes. The pressure is allowed to return to 8.05 MPa with hydrogen and kept at this pressure and temperature for 4 hours. Gas chromatographic analysis of the reaction mixture shows that it contains 83 parts of ethylidene diacetate and 10 282 parts of acetic anhydride along with 36 parts of acetic acid and trace amounts of ethyl acetate and acetaldehyde by-products. The yield of ethylidene diacetate is 98% and the ratio of ethylidene diacetate to acetic acid is 95% of theory.

Example VI

The autoclave is charged with 2 parts of dicobaltocta-carbonyl as a catalyst and 400 parts of acetic anhydrides, and it is pressured to 1.4 MPa with carbon monoxide and 9.1 MPa of hydrogen. The vessel is then heated to 90 ° C in about 20 minutes. The pressure is allowed to return to 10.5 MPa with hydrogen and kept at this temperature and pressure for 6 hours.

Gas chromatographic analysis of the reaction mixture shows that it contains 103.6 parts of ethylidene diacetate and 253 parts of acetic anhydride together with 44.3 parts of acetic acid and trace amounts of ethyl acetate and acetaldehyde by-products. The

yield of ethylidene diacetate is 98.5% and the ratio of ethylidene diacetate to acetic acid is 96.1% of theory. Example VII

4 parts of dicobaltoc-tacarbonyl as a catalyst and 400 parts of acetic anhydride are added to the reaction vessel and the vessel is pressurized with 9.1 MPa carbon monoxide and 6.09 MPa hydrogen. The vessel is then heated to 90 ° C in about 15 minutes. The pressure is allowed to return to 7 MPa with hydrogen and kept at this pressure and temperature for 1 hour.

Gas chromatographic analysis of the reaction mixture shows 8103339

V

- 11 - that it contains 94 parts of ethylidene diacetate and 296.6 acetic anhydride together with 30 parts of acetic acid and trace amounts of ethyl acetate and acetaldehyde by-products. The yield of ethylidene diacetate is 100%, and the ratio of ethylidene-5 diacetate to acetic acid is 100% of theory.

Example VIII

4.0 parts of dicobalt-octacarbonyl as a catalyst and 400 parts of acetic anhydride are introduced into the autoclave and the vessel is pressurized with 5.25 MPa carbon monoxide and 5.25 MPa hydrogen. The vessel is then heated to 90 ° C in approx

feather 15 minutes. The pressure is allowed to return to 10.5 MPa with hydrogen and kept at this pressure and temperature for 7 hours. Gas chromatographic analysis of the reaction mixture shows that it contains 141.8 parts of ethylidene diacetate and 205.2 parts of acetic anhydride together with 58.5 parts of acetic acid and trace amounts of ethyl acetate and acetaldehyde by-products. The yield of ethylidene diacetate is 100% and the ratio of ethylidene diacetate to acetic acid is 99.6% of theory. Example IX

The stirred pressure vessel is charged with 4.0 parts of dicobalt octacarbonyl as a catalyst and 400 parts of acetic anhydride and pressurized with 2.45 MPa carbon monoxide and 8.05 MPa hydrogen. The vessel is then heated to 100 ° C in about 15 minutes. The pressure is allowed to return to 10.5 MPa with hydrogen and kept at this pressure and temperature for 2 hours. Gas chromatographic analysis of the reaction mixture shows that it contains 97.6 parts of ethylidene diacetate and 263.3 parts of acetic anhydride together with 40.1 parts of acetic acid and trace amounts of ethyl acetate and acetaldehyde by-products.

The yield of ethylidene diacetate is 99.8% and the ratio of ethylidene diacetate to acetic acid is 100% of theory. Example X.

The stirred pressure vessel is charged with 20 parts of dicobalt octacarbonyl as a catalyst and 400 parts of acetic anhydride and pressurized with 2.8 MPa of carbon monoxide.

81 03 33 9 wr'w - 12 -

The vessel is then heated to 100 ° C in about 15 minutes.

The pressure is allowed to increase to 8.4 MPa with hydrogen and kept at this pressure and temperature for 7 hours. Gas chromatographic analysis of the reaction mixture shows that it contains 5 5 parts ethylidene diacetate and 22.4 parts acetic anhydride together with 119.8 parts acetic acid and 17.1 parts acetaldehyde and trace amounts of ethyl acetate by-product.

The yield of ethylidene diacetate is 73% and the ratio of ethylidene diacetate to acetic acid is 68% of theory.

The ratio of ethylidene diacetate and acetaldehyde to acetic acid is 87% of theory.

Example XI

The reaction vessel is charged with 20 parts of dicobalt octacarbonyl as a catalyst, 12 parts of acetic acid and 388 parts of acetic anhydride and pressurized with 1.4 MPa carbon monoxide and 4.9 MPa hydrogen. The vessel is then heated to 100 ° C in about 30 minutes. The pressure is allowed to increase to 7 MPa with hydrogen and kept at this pressure and temperature for 2 hours. Gas chromatographic analysis of the reaction mixture shows that it contains 153.5 parts of ethylidene diacetate and 198.9 parts of acetic anhydride along with 88.3 parts of acetic acid, 2.4 parts of acetaldehyde and trace amounts of ethyl acetate.

The yield of ethylidene diacetate is 95.7% and the ratio of ethylidene diacetate to acetic acid is 83% of theory.

The ratio of ethylidene diacetate plus acetaldehyde to acetic acid is 87% of theory.

Example XII

A reaction vessel as described in Example 1 is charged with 1 part of tetracobalt dodecacarbonyl as catalyst 30 and then with 20 parts of propionic anhydride and the reaction is carried out as described in Example III and results are obtained which are comparable to those obtained in Example III, but now propionic acid and the corresponding alkylidene diester.

35 8103339 - 13 -

Example XIII

Example XII is repeated, but now 20 parts of valeric anhydride are used and such results are obtained, but now valeric acid and the corresponding alkylidene diester are produced.

Example XIV

Example XII is repeated again, but the propionic anhydride is replaced by 20 parts of benzoic anhydride. Again, the results are similar to those obtained in Example III, but now benzoic acid and the corresponding alkylidene diester are produced.

15 81 03 339

Claims (5)

A process for converting an acid anhydride, characterized in that said acid anhydride is reacted with hydrogen in the presence of a cobalt carbonyl. 2. Process according to claim 1, characterized in that dicobalt octacarbonyl is used as cobalt carbonyl. Process according to claim 1, characterized in that the cobalt carbonyl used is tetracobalt dodecacarbonyl. 4. Process according to claim 1, characterized in that the reaction is carried out in the presence of carbon monoxide. 5. Process according to claim 1, characterized in that acetic anhydride is used as the acid anhydride. 15 8103339